Alvarion Technologies EAP-10AMP Low Power Transceiver and Amplifier Unit User Manual ProbridgeAMP72399 1

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BreezeNET PRO.11 Series
Outdoor Bridge
User’s Guide
(for models using AMP2440-250/500)
July, 1999
Cat. No. 213034
Revision
Disclaimer: The diagrams in this manual are for illustrative purposes only. They
should not be confused with the transceiver operating in a standalone mode.
When these diagrams are in use, the transceiver will be installed in conjunction
with amp model AMP-2440-250/500 and the antennas listed in Table 1.
© 1999 by BreezeCOM Ltd. All rights reserved.
No part of this publication may be reproduced in any material form without the
written permission of the copyright owner.
Trade Names
BreezeNET and BreezeLINK are trade names of
BreezeCOM Ltd. Other brand and product names are registered trademarks or
trademarks of their respective companies.
Statement of Conditions
The information contained in this manual is subject to change without notice. BreezeCOM Ltd. shall not be
liable for errors contained herein or for incidental or consequential damages in connection with the
furnishing, performance, or use of this manual or equipment supplied with it.
Warranty
In the following warranty text, “the Company” shall mean:
- BreezeCOM Inc., for products located in the USA.
- BreezeCOM Ltd., for products located outside the USA.
This BreezeNET product is warranted against defects in material and workmanship for a period of one year.
During this warranty period the Company will, at its option, either repair or replace products that prove to be
defective.
For warranty service or repair, the product must be returned to a service facility designated by the Company.
Authorization to return products must be obtained prior to shipment. The buyer shall pay all shipping charges
to the Company and the Company shall pay shipping charges to return the product to the buyer.
The Company warrants that the firmware designed by it for use with the unit will execute its programming
instructions when properly installed on the unit. The Company does not warrant that the operation of the unit
or firmware will be uninterrupted or error-free.
Limitation of Warranty
The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the
buyer, buyer supplied interfacing, unauthorized modification or misuse, operation outside of the
environmental specifications for the product, or improper site preparation or maintenance. No other warranty
is expressed or implied. The Company specifically disclaims the implied warranties of merchantability and
fitness for any particular purpose.
Electronic Emission Notices
This device complies with Part 15 of the FCC rules, ETSI 300-328, UL, UL/C, TUV/GS,
and CE.
Operation is subject to the following two conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference received, including interference that may
cause undesired operation.
FCC Radiation Exposure Statement
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled
environment when installed as directed. This equipment should be installed and operated
with the minimum distance between any persons body and the antenna as shown below:
Antenna
Type
Uni 24
Uni 21
Uni 18
Uni 16
Uni 16
Uni 13
Omni 12
Omni 8
Omni 6
Gain
(dBi)
Gain
Numeric
24
21
18
16
16
13
12
251.2
125.9
63.1
39.8
39.8
20.0
15.8
6.3
4.0
Amp Peak
output Power
(mW)
250
250
250
250
500
500
250
500
500
Peak Power
Exposure Distance
(cm)
70.7
50.1
35.4
28.1
39.8
28.2
20.0
20.0
20.0
WARNING: It is the responsibility of the professional installer to ensure that when
using the outdoor antenna kits in the United States (or where FCC rules apply),
only these antenna configurations shown in the table in section 1.4 are used. The
use of any antenna other than those listed is expressly forbidden in accordance to
FCC rules CFR47 part 15.204.
Information to User
Any changes or modifications of equipment not expressly approved by the manufacturer could void the user’s
authority to operate the equipment and the company’s warranty.
CONTACTING BREEZECOM TECHNICAL
SUPPORT
Should you need assistance beyond the scope of this guide, please contact
your local BreezeCOM reseller or distributor. If they cannot solve your
problem, feel free to contact the BreezeCOM Technical Support
Depatrment. The support representatives can assist you in solving any
problems that cannot be solved by your reseller.
When requesting support, please have the following items available:
•
Configuration of the system, including models of the BreezeCOM
equipment used.
•
Antenna type and cable lengths.
•
Site information such as, possible radio path problems (trees, machines,
and buildings).
•
Distance between devices.
•
Configuration, statistic counters, and error messages, as seen on the
monitor.
•
Description of problems encountered.
To contact BreezeCOM Technical Support, refer to the Technical Support
page of the BreezeCOM website: www.breezecom.com
Introduction To The BreezeNET PRO.11 Series
TABLE OF CONTENTS
1. Introduction To The BreezeNET PRO.11 Series ......................................1-4
1.1. How to Use This Guide .........................................................................1-4
1.2. BreezeNET PRO.11 Series Features ......................................................1-5
1.3.1. Access Point ..............................................................................1-6
1.3.4. Workgroup Bridge ................................................................... 1-10
1.4. BreezeNET PRO.11 Functional Description ........................................ 1-11
2. Basic Installation ........................................................................................2-1
2.1. Basic Installation Checklist....................................................................2-1
2.2. Check the Package List..........................................................................2-1
2.3. Position the Unit....................................................................................2-2
2.3.1. Additional Considerations When Positioning the Access Point...2-3
2.4. Connect the Unit to the Power Supply ...................................................2-3
2.5. Connect the Unit to the Ethernet Port ....................................................2-4
2.6. Check Unit Functionality using LED indicators.....................................2-5
2.6.1. Station (SA-10, SA-40) and Bridge (WB-10) LEDs ...................2-5
2.6.2. Access Point LEDs.....................................................................2-6
2.6.3. Verifying the Ethernet Connection .............................................2-6
3. Device Setup and Management..................................................................3-1
3.1. Accessing and Using Local Terminal Management ...............................3-1
3.2. Configuration Screens ..........................................................................3-2
3.3. Main Menu............................................................................................3-4
3.4. System Configuration Menu ..................................................................3-5
3.4.1. Station Status .............................................................................3-5
3.4.2. IP and SNMP Parameters ...........................................................3-6
3.4.3. Wireless LAN (WLAN) Parameters ...........................................3-7
3.4.4. Bridging.....................................................................................3-9
3.4.5. Station Control......................................................................... 3-10
3.4.6. Security................................................................................... 3-11
3.5. Advanced Settings Menu ..................................................................... 3-12
3.5.1. Translation Mode (read-only)................................................... 3-13
3.5.2. Roaming (read-only) ................................................................ 3-13
3.5.3. Performance............................................................................. 3-13
3.5.4. Radio ....................................................................................... 3-15
3.5.5. Rate ......................................................................................... 3-16
3.5.6. AP Redundancy Support (read-only) ........................................ 3-16
3.5.7. Maintenance............................................................................. 3-16
3.6. Site Survey Menu ................................................................................ 3-17
BreezeNET PRO.11 Series
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User’s Guide
Introduction To The BreezeNET PRO.11 Series
3.6.1. System Counters ..................................................................... 3-18
3.6.2. Survey Software...................................................................... 3-22
3.6.3. Event Log ............................................................................... 3-22
3.6.4. Display Neighboring AP’s....................................................... 3-22
3.6.5. Using the Site Survey Software ................................................ 3-23
3.6.6. Using the Rx Packets per Frequency Histogram ....................... 3-26
3.7. Access Control Menu .......................................................................... 3-27
4. Planning and Installing Wireless LANs..............................................5-2
4.1. System Configurations ..........................................................................5-2
4.1.1. Single Cell Configuration...........................................................5-3
4.1.2. Overlapping Cell Configuration .................................................5-7
4.1.3. Multicell Configuration..............................................................5-9
4.1.4. Multi-hop Configuration (Relay).............................................. 5-11
4.3. Outdoor Installation Considerations..................................................... 5-13
4.3.1. Site Selection Factors............................................................... 5-13
4.3.2. Rooftop Installation.................................................................. 5-14
4.3.3. Antennas for Outdoor Applications .......................................... 5-14
4.3.4. Antenna Seal ............................................................................ 5-16
4.3.5. Cell Size................................................................................... 5-16
4.3.6. Link Distance........................................................................... 5-18
4.3.7. Using Outdoor Range Tables.................................................... 5-18
4.5. Precautions.......................................................................................... 5-19
4.5.1. Professional Installers Only...................................................... 5-19
4.5.2. Transmit Antenna Gain ............................................................ 5-19
4.5.3. Spurious Radio Frequency Emissions....................................... 5-19
4.5.4. Lightning Protection................................................................. 5-20
4.5.5. Rain Proofing........................................................................... 5-20
6. Upgrade Procedure ................................................................................6-1
7. System Troubleshooting.............................................................................7-1
7.1. Troubleshooting Guide ..........................................................................7-1
7.2. Checking Counters ................................................................................7-3
7.2.1. WLAN Counters .......................................................................7-3
7.2.2. Ethernet Counters......................................................................7-3
8. Appendix
8.1. Supported MIBs and Traps ....................................................................9-1
8.1.1. Supported MIBs.........................................................................9-1
8.1.2. Supported Traps.........................................................................9-2
BreezeNET PRO.11 Series
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User’s Guide
Introduction To The BreezeNET PRO.11 Series
8.2. Technical Specifications........................................................................9-3
8.2.1. Specifications for BreezeNET PRO.11 Units..............................9-3
8.2.5. Specifications for AL 1 Lightning Arrestor ................................9-6
8.3. Wireless LAN Concepts ........................................................................9-7
8.4. Radio Signal Propagation .................................................................... 9-13
8.4.1. Introduction.............................................................................. 9-13
8.4.2. RF Terms and Definitions ........................................................ 9-13
8.5. IEEE 802.11 Technical Tutorial........................................................... 9-20
8.5.1. Architecture Components......................................................... 9-20
8.5.2. IEEE 802.11 Layers Description .............................................. 9-21
8.5.3. The MAC Layer....................................................................... 9-22
8.5.4. How Does a Station Join an Existing Cell (BSS)? .................... 9-28
8.5.5. Roaming .................................................................................. 9-28
8.5.6. Keeping Synchronization ......................................................... 9-29
8.5.7. Security.................................................................................... 9-29
8.5.8. Power Saving ........................................................................... 9-30
8.5.9. Frame Types ............................................................................ 9-31
8.5.10. Frame Formats ......................................................................... 9-31
8.5.11. Most Common Frame Formats................................................. 9-36
8.5.12. Point Coordination Function (PCF) .......................................... 9-38
9.5.13. Ad-hoc Networks ..................................................................... 9-38
BreezeNET PRO.11 Series
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User’s Guide
Professional Installation for Model BreezeNET PRO.11/AMP1440 System
Intended use
All BreezeCOM devices are used to provide high speed data connections to remote networks.
The BreezeNET PRO.11/AMP2440 System is not intended nor is it marketed for home use. It is
designed for use by commercial businesses only.
Installation
The installation of the Model BreezeNET PRO.11/AMP2440 System will be controlled.
BreezeCOM will ensure that the professional doing the installation is made aware of the
requirements so that the final installation complies with FCC rules. Specifically the installer must
ensure that the ERP of the transmitting antenna does not exceed the requirements of paragraph
15.247(b) by using an HP 436A power meter and an HP 8481H power sensor. Power meters
that measures average power must not be used when installing the transmitter, amplifier and
antenna combination.
It will be explicitly explained to the professional installer that they will install a 250mW or 500mW
version of the amplifier based on the antenna to be used in the installation. (See attached chart).
The output power of the BreezeNET PRO.11/AMP2440 System is limited to 250mW or 500mW,
regardless of the loss of cable between the DC injector and the amplifier any length or type of 50
ohm coax transmission can be used.
Since BreezeNET PRO.11/AMP2440 System are shipped labeled as "BreezeNET
PRO.11/AMP2440-250 System" for a 250mW output and a "BreezeNET PRO.11/AMP2440-500
System" for a 500mW maximum output, the installer will be aware of the output power of the
system. Further, all installations of the Model BreezeNET PRO.11/AMP2440 System will require
topographic analysis, site survey and link budget calculation. Therefore, the system will require a
BreezeCOMed trained professional to do the installation.
This ensures compliance with the maximum transmitter ERP allowed with the antenna provided
as a system.
The following statement is in the BreezeNET user's guide (section 5.5.1) and is also supplied as
a separate sheet with each device sold:
"Professional Installers Only :
Detached antennas, whether installed indoors or out, should be installed ONLY by experienced
antenna installation professionals who are familiar with local building and safety codes and,
wherever applicable, are licensed by the appropriate government regulatory authorities. Failure to
do so may void the BreezeNET product warranty and may expose the end user to legal and
financial liabilities."
"Regulations regarding maximum antenna gains vary from country to country. It is the
responsibility of the end user to operate within the limits of these regulations and to ensure that
the professional installer is aware of these regulations, as well. "
Marketing and sales channels
BreezeCOM DOES NOT sell direct to end users. BreezeNET PRO.11/AMP2440 System will be
sold only to BreezeCOM's Authorized Resellers. Those authorized resellers are technically
trained by BreezeCOM's Engineers periodically and must follow the rules set by BreezeCOM.
The BreezeNET/AMP2440 system is designed for Long Range (10-25 miles) applications and it
involves a complicated mandatory site survey, roof top mast installation, high gain antennas,
accurate antenna alignment, etc. Those activities can be done ONLY by professional installers
that are familiar with the FCC regulations. BreezeCOM do not play in the consumer business at
all. We have no resellers in this market and we do not advertise in consumers based publications
or attend consumer oriented trade shows. The system will be advertised in technical trade shows
and magazines.
Conclusion
BreezeCOM requires professional installation for the Model BreezeNET PRO.11/AMP2440
System in-order to provide the highest reliable system possible. We therefore fully support the
mandate for professional installation of our complete system.
Introduction To The BreezeNET PRO.11 Series
1. INTRODUCTION TO THE BREEZENET
PRO.11 SERIES
This chapter explains how to use this guide, presents the members of the
BreezeNET PRO.11 Series, describes the benefits of BreezeNET PRO.11
Wireless LANs, and lists the product specifications.
1.1. How to Use This Guide
This User’s Guide contains instructions for overall planning and setting up
your wireless LAN, and provides details of how to install each unit, and
how to install antennas and accessories.
This guide contains the following chapters:
•
Chapter 1 Introduction – Explains how to use this guide and presents
the members of the BreezeNET PRO.11 Series.
•
Chapter 2 Basic Installation – Details how to install most BreezeNET
PRO.11 Series units.
•
Chapter 3 Device Setup and Management – Describes how to use the
local terminal to setup, configure, and manage BreezeNET PRO.11 Series
units.
•
Chapter 4 Planning and Installing Wireless LANs – Provides
guidelines and restrictions regarding antenna selection and installation,
and includes outdoor antenna range tables.
•
Chapter 6 Upgrade Procedure – Explains how to perform future
upgrades for BreezeNET PRO.11 Series units using a TFTP application.
•
Chapter 7 System Troubleshooting – Contains a troubleshooting guide
that provides answers to some of the more common problems which may
occur when installing and using BreezeNET PRO.11 Series products.
•
Chapter 8 Appendix – This appendix lists MIBs, and traps supported
by BreezeNET PRO.11 Series products, lists product and attachment
specifications, provides an overview of the concepts related to wireless
LANs, discusses the concepts and applications of radio signal
propagation relevant to wireless LANs, and introduces the new 802.11
standard.
BreezeNET PRO.11 Series
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User’s Guide
Introduction To The BreezeNET PRO.11 Series
1.2. BreezeNET PRO.11 Series Features
Following is a partial list of the features in the BreezeNET PRO.11 Series:
•
IEEE 802.11 Compliant – All BreezeNET PRO.11 Series units are fully
compliant with the final IEEE 802.11 specification for wireless LANs,
and thus support interoperability with other 802.11 compliant vendors.
•
Fully integrated product family – One high-performance Access Point
for all products in the series.
•
Increased Throughput – Up to 2 Mbps data throughput; the best figure
in the market!
•
Translation Bridging – Support for both translation and transparent
bridging as defined in the IEEE 802.1.h and RFC 1042 standards.
•
Seamless Roaming – Network connection is maintained while roaming
between overlapping coverage areas. Transmission and reception can be
continued while moving at high speeds with no data packet loss or
duplication.
•
Load Sharing – Traffic is equally distributed among all Access Points
in the area.
•
Redundancy – In co-located cell environments, upon failure of an
Access Point, stations will switch to other available Access Points.
•
LED Display – Power, Network Activity, and WLAN Load or Signal
Quality LEDs indicate the current status of the unit.
•
Upgrading – Simple, quick, and free software upgrades via TFTP.
•
Future-proof Investment – All “infrastructure” items in the PRO.11
Series line offer Flash updates.
BreezeNET PRO.11 Series
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User’s Guide
Introduction To The BreezeNET PRO.11 Series
1.2.1.
Access Point
The Access Point is fully compliant with the IEEE 802.11 wireless LAN
standard.
The BreezeNET Access Point is a wireless hub that provides access for
wireless workstations into wired Ethernet LANs. It also contains a wireless
coordinating function which enables workstations equipped with a Station
Adapter (Station Adapter, Bridge) to communicate with one another inside
the cell coverage area (even if they are not in direct line of sight) via the
Access Point. Any two wireless stations in two different cells can
communicate through their Access Points.
Disclaimer: This diagram is for
illustrative purposes only. It should
not be confused with the transceiver
operating in a standalone mode.
When this diagram is in use, the
transceiver will be used in
conjunction with amp model
AMP-2440-250/500 and the
antennas listed in this manual.
Mobile workstations, such as laptops and hand-held devices, can roam
between Access Points that belong to the same Extended Service Set (ESS).
In an Extended Service Set, all Access Points have the same ESSID. When
the access points are set up so that their coverage areas overlap, users can
roam seamlessly from cell to cell. This means that there is no interruption of
network connection when moving from one coverage area to the other
through the overlap and is completely transparent to the user and the
applications. The Station Adapters decide when a mobile user becomes
disassociated from one access point and associated with another. This
process is fully transparent, requires no user intervention and involves no
loss of data packets.
Position multiple access points in locations where heavy network traffic is
expected to create a multicell and increase the aggregate throughput
capacity in areas where it is needed most. The system implements a Load
BreezeNET PRO.11 Series
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User’s Guide
Introduction To The BreezeNET PRO.11 Series
Balancing algorithm to divide the stations equally between the available colocated Access Points.
The BreezeNET Access Point contains an embedded SNMP agent enabling
effective management by BreezeVIEW or any standard SNMP management
station. Software upgrades can be downloaded by TFTP protocol via the
wired LAN or wireless LAN.
1.2.2.
Workgroup Bridge
The BreezeNET Workgroup Bridge is a high-speed, wide-range wireless
LAN bridge that provides connectivity to remote Ethernet networks.
Figure 1.1: WB-10D PRO.11 with Two
External Antenna Connector Ports
Disclaimer: This diagram is for illustrative purposes only. It should not be
confused with the transceiver operating in a standalone mode. When this
diagram is in use, the transceiver will be used in conjunction with amp
model AMP-2440-250/500 and the antennas listed in this manual.
The Workgroup Bridge communicates with the BreezeNET Access Points of
the remote LANs effectively creating an extended wireless network
spanning sites situated up to 6 miles apart (in Europe this range is limited by
ETSI regulations to 2.5 Km.). In this way a central Ethernet LAN may be
connected with one or more branch office LANs.
In addition, an island consisting of a Workgroup Bridge together with an
Access Point can work as a relay. Transmissions from the central LAN and
from the remote LAN are relayed via the island located between them. This
configuration effectively doubles bridge range.
BreezeNET PRO.11 Series
1-7
User’s Guide
Introduction To The BreezeNET PRO.11 Series
Workstations that can be connected to the wireless LAN include PCs, XTerminals, Digital, SUN, HP, IBM, and Apple computers, and any other
device that supports Ethernet. The unit is transparent to the workgroup
devices’ hardware, software, and network operating system.
The BreezeNET Workgroup Bridge contains an embedded SNMP agent and
software downloading capabilities enabling effective management. Software
upgrades are downloaded using TFTP protocol via the Ethernet ports or via
the wireless LAN and Access Point.
1.3. Extending Range with the AMP2440
To extend the range of the AP10-D or WB-10D, the AMP2440-250 or
AMP2440-500 is used. These devices amplify the RF output and receive
power to allow long range connections or connections with longer cable
runs. The diagram below shows a typical installation of the BreezeNet and
AMP2440. (See the addendum at the end of this manual for instructions on
how to install the AMP2440).
BREEZECOM AMPLIFIER INSTALLATION DETAILS
ANTENNA
Omni-directional (shown), or
Grid or Panel Antennas (not shown)
1.4. Antenna Selection
AMP2440
Drip
Loop
(mounted to mast with U-Bolt)
N-Male connector
Transmission Line
LMR-400, or other
low loss cable to radio room
Mast
Coax Cable to
Pole Mounted
Amplifier
110/220 VAC
AC Main Power
110/220 VAC
AC Main Power
Barrel Plug
RF + DC
N-Male to
N-Male adapter
to attach to the
N-Female on
cable
5ft. LMR-400
DC POWER
INJECTOR
N-Male to
N-Male adapter
to attach to the
N-Female on
cable
BreezeNet
Radio
UTP Cable
To Ethernet
Hub
Special SMA Right angle
Male connector
is required in the United States when the 24dB grid dish
* Filter
antenna is used in order to comply with FCC emission requirements.
BreezeNET PRO.11 Series
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User’s Guide
Introduction To The BreezeNET PRO.11 Series
The AMP2440 and the BreezeNET radio modem must be professionally installed.
Table (1) shows the FCC approved configuration of the AMP2440, BreezeNET Radio
and antenna configurations.
WARNING: It is the responsibility of the installer to ensure that when used in the
United States (or where FCC rules apply), only these configurations are used. The use
of any antenna other than those listed below is expressly forbidden in accordance to
FCC rules CFR47 part 15.204.
Table (1) FCC Type Acceptance Configurations
U N I -24
U N I -18
U N I -16
U N I -13
U N I -11
24 dBi
Grid
18 dBi
Grid
16 dBi
Panel
13 dBi
Panel
11 dBi
Panel
OMNI-8
8 dBi
Omni
OMNI-6
6 dBi
Omni
BreezeNET
PRO.11
X*
BreezeNET
PRO.11 with
Amp2440-250
X*
Radio
Equipment
BreezeNET
PRO.11 with
AMP2440-500
*: External filter (P/N: SPF-1) is required in the United States with the 24dBi grid
antenna to comply with FCC spurious emission requirements. Install this between
the amplifier and the antenna.
1.5. BreezeNET PRO.11 Functional Description
BreezeNET PRO.11 units add wireless functionality to existing Ethernet
LANs.
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Introduction To The BreezeNET PRO.11 Series
1.5.1.
Quick Review of Ethernet
Standard Ethernet LAN stations are wired to a common bus. When one of
the stations sends a message, it assigns a destination address to the message
and sends the message on the bus. All stations on the bus “hear” the
message, but only the station with the proper address processes the message.
1.5.2.
Startup Procedure
When wireless units (other than AP-10) start up, they scan the frequencies
for an AP-10. If an active AP-10 is in range, the units synchronize with it.
The addresses associated with the units are registered in the AP-10 (the
registration process is different for each unit type). From then on, the units
can send and receive messages to and from the wired LAN.
1.5.3.
AP-10 Access Point
The AP-10 Access Point is connected to a wired Ethernet LAN, and it keeps
a list of known stations on its wireless side. When an AP-10 “hears” a
message that is destined for a wireless station, the AP-10 forwards the
message wirelessly to the station. If the message has a destination address
that the AP-10 does not recognize, the AP-10 ignores the message.
The AP-10 is constantly “listening” for wireless messages as well. When the
AP-10 “hears” a wireless message destined for another wireless unit, it
relays the message directly to the wireless unit without forwarding the
message to the wired LAN. When the AP-10 “hears” a wireless message
whose destination it does not recognize (since it does not keep a list of
known stations on its wired side), it forwards the message to the wired
LAN. Messages cannot be sent directly between wireless stations without an
AP-10 to relay the message.
1.5.4.
SA-10 Station Adapter
The SA-10 station adapter is connected to a station’s network card. When
the station sends a message, the SA-10 wirelessly forwards it to the AP-10.
And when the AP-10 receives a message destined for the station, it
wirelessly forwards the message to the SA-10.
The first time the station sends a message, the station’s address is registered
in the AP-10. The AP-10 keeps only the first address for each SA-10, so the
SA-10 will not work properly if connected to more than one station.
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Introduction To The BreezeNET PRO.11 Series
1.5.5.
SA-40 Station Adapter
The SA-40 station adapter has four connectors for up to four stations and
works just like the SA-10. As each station connected to the SA-40 sends its
first message, each address is registered in the AP-10. The AP-10 keeps
only up to four addresses for each SA-40, so the SA-40 will not work
properly if connected to more than four stations.
1.5.6.
WB-10 Wireless Bridge
As opposed to the SA-10 and SA-40 that connect directly to stations, the
WB-10 wireless bridge connects to a wired Ethernet LAN (Hub). When a
station on the WB-10’s LAN sends a message that is not destined for a local
station, the WB-10 wirelessly forwards the message to the AP-10. And
when the AP-10 receives a message destined for a station on the WB-10s
LAN, the AP-10 wirelessly forwards it to the WB-10. In this way, the
WB-10 and AP-10 work together like a standard network bridge.
The first time each station on the WB-10’s LAN sends a message, the
station’s address is registered in the WB-10 and the AP-10. The WB-10 and
AP-10 can hold all the addresses necessary to support an entire LAN
connected to a WB-10.
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Basic Installation
2. BASIC INSTALLATION
The BreezeNET PRO.11 Series is a plug-and-play solution, and the units
begin to function when the following basic installation is complete.
However, you can adapt the system to your particular needs using the local
terminal (see Chapter 3).
For a description of various overall system configurations, refer to
Chapter 4.
2.1. Basic Installation Checklist
Standard installation involves the following steps:
•
Check the Package List.
•
Position the unit and the antenna in the best location.
•
Connect the power supply to the unit.
•
Connect the Ethernet port to the unit.
•
Check unit functionality using the LED indicators.
2.2. Check the Package List
When you first open the package, verify that the unit is complete with the
following components:
•
The unit, complete with two RF connectors for use with external
antennas (“D” models).
•
Quick Installation Guide/Card.
•
5V DC power supply transformer.
•
Mounting bracket for wall or ceiling installations and torque key for
antenna connectors (supplied with "D" models).
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The AP-10 PRO.11 Access Point comes with the following additional
components:
•
The BreezeNET PRO.11 Series User’s Guide.
•
A monitor connector cable for connecting the units to a monitor in order
to perform Local Terminal Management functions (see section 3.1).
•
Proprietary MIB disk for performing remote unit configuration and
monitoring via SNMP (see section 8.1.1).
Open the packaging carefully and make sure that none of the items listed
above are missing. Do not discard packaging materials. If, for any reason,
the unit is returned, it must be shipped in its original package.
2.3. Position the Unit
BreezeNET PRO.11 wireless LAN products are robust, trouble-free units,
designed to operate efficiently under a wide range of conditions. The
following guidelines are provided to help you position the units to ensure
optimum coverage and operation of the wireless LAN.
Metal Furniture
Position the units clear of metal furniture and away from moving objects
such as metal fans or doors.
Microwave Ovens
For best performance, position the units clear of radiation sources that emit
in the 2.4 GHz frequency band, such as microwave ovens.
Antennas
For models with integrated antennas, make sure the antennas are extended
upward vertically in relation to the floor. For models with external antennas,
connect the external antennas and RF cable. For information about external
antenna installation, refer to section 4.2
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Outdoor Installation Considerations.
Heat Sources
Keep the units well away from sources of heat, such as radiators, airconditioners, etc.
2.3.1.
Additional Considerations When Positioning the
Access Point
When positioning the AP-10 PRO.11 and AP-10DE Access Points, take into
account the following additional considerations.
Height
Install the Access Point at least 1.5m above the floor, clear of any high
office partitions or tall pieces of furniture in the coverage area. The Access
Point can be placed on a high shelf, or can be attached to the ceiling or a
wall using a mounting bracket.
Central Location
Install the Access Point in a central location in the intended coverage area.
Good positions are:
•
In the center of a large room.
•
In the center of a corridor.
•
At the intersection of two corridors.
Many modern buildings have partitions constructed of metal or containing
metal components. We recommend that you install the Access Points on the
corridor ceilings. The radio waves propagated by the BreezeNET PRO.11
LAN are reflected along the metal partitions and enter the offices through
the doors or glass sections.
2.4. Connect the Unit to the Power Supply
The unit operates on a power input of 5V DC, (1200mA , 1500mA peak)
supplied by the power transformer included with the unit.
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•
Plug the output jack of the power transformer into the DC input socket
on the unit. This socket may be located on the rear or side panel of the
unit.
•
Connect the supplied power transformer to a power outlet 110/ 220VAC.
2.5. Connect the Unit to the Ethernet Port
•
Connect one end of a an Ethernet 10BaseT cable (not supplied) to the
RJ-45 port on the rear panel of the unit (marked UTP).
•
Connect the other end of the connector cable to the Ethernet outlet:
• When connecting an SA-10 or SA-40 to a PC, use a straight cable.
• When connecting an AP-10 or WB-10 to a LAN, use a straight
cable.
• When connecting an AP-10 or WB-10 to a PC, use a crossed cable.
• When connecting an AP-10 to a WB-10, use a crossed cable.
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2.6. Check Unit Functionality using LED indicators
Check the unit functionality by using the LEDs on the front panel. The
following tables describe the front panel LEDs for Stations (SA-10, SA-40)
and Bridges (WB-10), and for Access Points.
2.6.1.
Station (SA-10, SA-40) and Bridge (WB-10) LEDs
Name
Description
Functionality
PWR
power supply
On – After successful power up
WLNK
WLAN Link
ETHR
Ethernet activity
QLT
Quality of reception
Off – Power off
On – Unit is synchronized or associated with an AP
Off – Unit is not synchronized or associated with an AP
On – Reception on Ethernet port
Off – No reception on Ethernet port
very low quality reception or
not synchronized with Access Point
less than -81 dBm
low quality reception
(usually enabling 1 Mbps traffic)
from -81 to -77 dBm
medium quality reception
(usually enabling 2 Mbps traffic)
from -77 to -65 dBm
high quality reception
(usually enabling 3 Mbps traffic)
greater than -65 dBm
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2.6.2.
Access Point LEDs
Name
Description
Functionality
PWR
power supply
On – After successful power up
INFR
radio interference
ETHR
Ethernet activity
Off – Power off
Off – No interference
Blinking – Interference Present
On – Reception of data from Ethernet LAN that is forwarded to
WLAN (in reject unknown mode)
Off – No reception of data from Ethernet LAN that is forwarded
to WLAN
LOAD
WLAN load
Number of associated stations
no stations
1-8 stations
9-16 stations
17 or more stations
2.6.3.
Verifying the Ethernet Connection
Once you have connected the unit to an Ethernet outlet, verify that the
ETHR LED on the front panel is blinking. The ETHR LED should blink
whenever the unit receives LAN traffic.
At the other end of the Ethernet link, verify that the LINK indicator is ON.
For APs the LINK indicator is located on the attached hub port, and for
Station Adapters the LINK indicator is located on the NIC.
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Device Setup and Management
3. DEVICE SETUP AND MANAGEMENT
This chapter explains how to access the local terminal program, and how to
use the terminal program to setup, configure, and manage most BreezeNET
PRO.11 Series units.
The BreezeNET PRO.11 Series is a plug-and-play solution and operates
immediately after physical installation without any user intervention.
However, you can adapt the system to your particular needs using the local
terminal. In addition, all products in the series contain an SNMP agent and
are configurable remotely via the network.
Note: Reset the unit after making configuration changes so that the changes will
take effect.
3.1. Accessing and Using Local Terminal
Management
⇒
To access Local Terminal Management:
1. Use the Monitor cable (supplied with the Access Point) to connect
the MON jack on the rear panel of the unit to the COM port of your
ASCII ANSI terminal or PC.
2. Run a terminal emulation program (such as HyperTerminal™).
3. Set up communication parameters to the following:
• Baud Rate: 9600
• Data Bits: 8
• Stop Bits: 1
• Parity: None
• Flow Control: NONE
• Connector: Connected COM port.
4. Press Enter. The main menu appears.
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⇒
To use Local Terminal Management:
1. Press an option number to open/activate the option. You may need
to press Enter in some cases.
2. Press Esc to exit a menu or option.
3. Reset the unit after making configuration changes.
3.2.
Configuration Screens
Listed below are the menus, sub-menus, and parameters/options in the
terminal program. Default values are listed where applicable. Numbers in
the table below indicate how to reach each option. For example, to reach the
1.2.1 IP Address option, start at the main menu, press 1, then 2, and then 1.
Menu
1. System
Configuration
Sub-Menu
1.1 Station
Status
Parameter/Option
•
•
•
•
•
•
•
•
•
Default Values
Unit’s Mode
Unit’s H/W Address
Unit’s WLAN Addr (SA-10/40,WB-10)
Station Status (SA-10-40, WB-10 Only)
Total Number of Associations since
last reset (SA-10-40, WB-10 Only)
Current Number of Associations (AP)
Maximum Number of Associations
since last reset (AP)
Current Number of Authentications
(AP)
Maximum Number of Authentications
since last reset (AP)
1.2 IP and
SNMP
Parameters
1.2.1 IP Address
1.2.2 Subnet Mask
1.2.3 Default Gateway Address
1.2.4 SNMP Traps
1.2.5 Display Current Values
Not set
Not set
Not set
Enabled
1.3 Wireless
LAN (WLAN)
Parameters
1.3.1 Hopping Sequence (AP Only)
1.3.2 Hopping Set (AP Only)
1.3.3 ESSID
1.3.4 Maximum Data Rate
1.3.5 Transmit Antenna
1.3.6 Mobility
1.3.7 Load Sharing
1.3.8 Preferred AP (SA-10/40, WB-10 Only)
1.3.A Display Current Values
1 (FCC standard)
1 (FCC standard)
ESSID1
3Mbps
Use 2 Antennas*
Low
Disabled**
Not set
1.4 Bridging
1.4.1 LAN-WLAN Bridge Mode (AP Only)
1.4.2 Intelligent Bridging Period (AP Only)
1.4.3 IP Filtering
1.4.4 Tunneling
1.4.5 Broadcast Relaying
1.4.6 Unicast Relaying
Reject Unknown
15 sec
Disabled
Both
Enabled
Enabled
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2. Advanced
Settings
3. Site Survey
1.5 Station
Control
1.5.1 Reset Unit
1.5.2 Load Factory Defaults
1.6.Security
(Not activated)
1.6.1 Authentication Algorithm
1.6.2 Default Key ID
1.6.3 Preauthentication
A. WEP Default Key #1
B WEP Default Key #2
C. WEP Default Key #3
D. WEP Default Key #4
2.1 Translation
Mode
Open System Key
#1
Disabled
User defined User
defined User
defined User
defined
Enabled
2.2 Roaming
2.2.1 Max Number of Scanning
2.2.2 Roaming Decision Window
2.2.3 Roaming Decision Numerator
2.2.4 Roaming Decision RSSI Threshold
2.2.5 Jogging Decision RSSI Threshold
2.2.6 Number of Beacons for Disconnect
Decision
2.2.7 Number of Probe Responses
Neighboring Beacon Rate
70
10
60
65
Sent every 40
dwell times
2.3 Performance
2.3.1 Dwell Time (AP Only)
2.3.2 RTS Threshold
2.3.3 Max Number of Re-Transmissions
2.3.4 Number of Dwells to Re-Transmit
2.3.5 Max Multicast Rate
2.3.6 Power Saving (Not activated)
2.3.7 DTIM Period (Not activated)
2.3.8 IP Stack
2.3.9 Acknowledge Delay
128 millisecs
120 bytes
1 Mbps
Disabled
Enabled
Regular
2.4 Radio
2.4.1 Hopping Standard
2.4.2 Display Site Proprietary Sequences
2.4.3 Power Level
2.4.4 Carrier Semse Level
2.4.5 Carrier Sense Difference Level
US FCC
User defined
High
50
14
2.5 Rate
2.5.1 Multi – Rate Support
2.5.2 Multi – Rate Decision window Size
Enabled
2.6 AP
Redundancy
Support
Enter New AP Redundancy Support
Decision Period (in seconds)
Disabled
2.7 Maintenance
2.7.1 Auto Calibration
2.7.2 Wait for association Address
2.7.3 Japan Call sign
Enabled
Wait for update
3.1 System
Counters
3.1.1 Display Ethernet and WLAN
Counters
3.1.2 Display Rate Counters
3.1.3 Display Rx Packets per Frequency
3.1.4 Reset All Counters
3.1.5 Power Saving Counters
3.2 Survey
Software
3.2.1 Operation Mode (Rx/Tx)
3.2.2 Start Statistics
3.2.3 Stop Statistics
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Menu
Sub-Menu
Parameter/Option
3.3 Event Log
3.3.1 Display Event Log
3.3.2 Erase Event Log
3.3.3 Event Storage Policy
Default Values
From level
warning up
3.4 Display
Neighboring
AP’s
4. Access
Control
4.1 Change Access Rights
4.2 Change Installer Password
4.3 Show Current Access Right
* Option 1.3.5 Transmit Antenna has the default value Use #2 for the SA-40
unit only.
** Option 1.3.7 Load Sharing has the default value Enabled for the AP-10
unit only.
3.3. Main Menu
PRO.11 Series
Unit Model (SA-10, SA-40, WB-10, AP-10)
BreezeNET PRO.11 Series (SA-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
Software
Version
BreezeNET Monitor
==================
1 – System Configuration
2 – Advanced Settings
3 – Site Survey
4 – Access Control
Select option >
Figure 3.1: Main Menu
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3.4. System Configuration Menu
BreezeNET PRO.11 Series (SA-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
System Configuration menu
=========================
1 - Station Status
2 - IP and SNMP Parameters
3 - Wireless LAN Parameters
4 – Bridging
5 - Station Control
6 – Security
Select option >
Figure 3.2: System Configuration Menu
3.4.1.
Station Status
Station Status is a read-only sub-menu that displays the current values of the
following parameters:
•
Unit Mode – Identifies the unit’s function. For example, if the unit is an
Access Point, “AP” appears in this field. If the unit is a Station Adapter
(SA-10, SA-40) or a WB-10, "SA" appears in this field.
•
Unit H/W Address – Displays the unit’s unique IEEE MAC address.
•
Unit WLAN Address (SA or WB) – The address by which the unit
associates. For the SA-10, this is the address of the PC. For the SA-40
and WB-10, this is the address of the hardware. This field does not
appear when the unit is an AP.
•
Station Status (SA or WB) – Current status of the station. There are
three options:
• Scanning - The station is searching for an AP with which to
associate.
• Sync Waiting for Address - (this option is relevant only to the SA10). The station is synchronized with an AP but has not yet learned
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its WLAN MAC address. The AP does not forward packets to the
station when it is in this mode.
• Associated - The station is associated with an AP and has adopted
the attached PC MAC address (for SA-10) or uses the unit’s H/W
address (SA-40 and WB-10), and is receiving packets from the LAN.
•
AP Address (Station Only) – MAC Address of the AP with which the
unit is currently associated.
•
Total Number of Associations since last reset – Total number of
stations currently associated with an AP.
•
Current Number of Associations (AP Only) – Total number of
stations currently associated with an AP.
•
Maximum Number of Associations since last reset (AP Only – For
stations, this indicates the total number of associations and
disassociations with various AP’s. This is usually an indication of
roaming. When the unit is an AP, this field indicates how many stations
are currently associated with this particular AP.
•
Current Number of Authentications (AP Only) – The current number
of stations that are authenticated to this AP, including stations that are
“pre-authenticated” and not associated to this AP.
•
Maximum Number of Authentications since last reset (AP Only) –
The number of authentications (and “preauthentications”) to this AP;
since it was last reset. This number includes stations that were
disauthenticated for different reasons.
3.4.2.
IP and SNMP Parameters
All BreezeNET PRO.11 units contain IP Host software. This software is
used for testing the unit for SNMP management functions and for
downloading software upgrades using the TFTP protocol.
•
IP Address – IP address of the unit.
•
Subnet Mask – Subnet mask of the unit.
•
Default Gateway Address – Gateway address of the unit.
•
SNMP Traps – Whether this unit sends SNMP traps. If enabled, when
an event occurs, a trap is sent to the defined host address (see section
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8.1.2 for a list of traps). You can configure the host address to which the
traps are sent through SNMP management.
•
3.4.3.
Display Current Values – Displays information concerning the current
status of all IP-related items.
Wireless LAN (WLAN) Parameters
The WLAN Parameters Menu contains the following options:
•
Hopping Sequence (AP Only) – Hopping sequence of the unit.
A hopping sequence is a pre-defined series of channels (frequencies) that
are used in a specific, pseudo-random order as defined in the sequence.
The unit “hops” from frequency to frequency according to the selected
sequence. When more than one AP is co-located in the same area (even
if they are not part of the same network) it is recommended to assign a
different hopping sequence to each AP.
Hopping sequences are grouped in three hopping sets. The hopping set
selected in the Hopping Set screen (see next parameter) determines
which hopping sequences are available in this screen. When setting up
multiple APs in the same site, always choose hopping sequences from
the same hopping set. This reduces the possibility of collisions on the
WLAN.
This parameter is set only in AP-10 PRO.11 Access Point. It is not
accessible from any other BreezeNET PRO.11 unit. All other stations
learn it from the Access Point during the association process. Different
co-located WLAN segments should use different hopping sequences.
•
Hopping Set (AP Only) – Hopping set (between 1 and 3) of the unit.
Hopping sequences are grouped in several hopping sets. The hopping set
selected in this screen determines which hopping sequences are available
in the Hopping Sequence screen (see previous parameter). Always use
the same hopping set per site.
Following is the list of hopping sequences and sets for each country.
The default value for all countries is:
Hopping Sequence=1, Hopping Set=1.
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•
ESSID – ESSID of the unit (up to 32 printable ASCII characters). The
ESSID is a string used to identify a WLAN. This ID prevents the
unintentional merging of two co-located WLANs. A station can only
associate with an AP that has the same ESSID. Use different ESSIDs to
segment the WLAN network and add security.
Note: The ESSID is case-sensitive.
•
Maximum Data Rate – Maximum data rate of the unit. BreezeNET
PRO.11 units operate at 1 Mbps, 2 Mbps or 3 Mbps. The unit adaptively
selects the highest possible rate for transmission. Under certain
conditions (compatibility reasons or for range/speed trade-off) you may
decide to limit the use of higher rates.
•
Transmit Antenna – Which antennas are used for transmission. During
reception, a BreezeNET PRO.11 unit dynamically selects the antenna
where reception is optimal. In contrast, before transmission the unit
selects the antenna from which it will transmit. It usually uses the
antenna last used for successful transmission. In models with external
antennas, sometimes only a single antenna is used. In this case, Transmit
Antenna should be configured to transmit only from that single antenna.
Similarly, models using a booster or an LNA use only a single antenna
for transmission. There are three possibilities for configuration:
•
Use Two Antennas
Use Antenna No. 1 only
Use Antenna No. 2 only
Mobility – BreezeNET PRO.11 stations optimize their roaming
algorithms according to the mobility mode parameter. For example, a
stationary station is more tolerant of bad propagation conditions. It
assumes that this is a temporary situation and is not caused by the station
changing position. Initiating a roaming procedure in such a case would
be counter-productive. In general, Wireless stations can be used in one
of three mobility modes:
• High – For stations that may move at speeds of over 30 km per hour.
• Medium – For stations that may move at speeds of over 10 km per
hour, but not over 30 km per hour.
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• Low – For stations that will not move at speeds of over 10 km per
hour. Low is the default value. In most cases this is the best choice.
•
Load Sharing – When installing a Wireless LAN network in a hightraffic environment; you can increase the aggregate throughput by
installing multiple APs to create co-located cells. When load sharing is
enabled, the wireless stations distribute themselves evenly among the
APs to best divide the traffic between the APs.
•
Preferred AP – AP MAC (Ethernet) address of the preferred AP. You
can configure a station to prefer a specific AP unit. When the station
powers up, it will associate with the preferred AP even if the signal from
that AP is lower than the signal from other APs. The station will roam to
another AP only if it stops receiving beacons from the preferred AP.
•
Display Current Values – This read-only status screen displays current
WLAN parameters. Press any key to return to the WLAN Parameters
Menu.
3.4.4.
Bridging
The Bridging Menu contains the following options:
•
LAN to WLAN Bridging Mode (AP Only) – The options are:
• Reject Unknown – Type 0 to allow transmission of packets only to
stations that the AP knows to exist in the Wireless LAN (behind the
Wireless Bridge).
• Forward Unknown – Type 1 to allow transmission of all packets
except those sent to stations that the AP recognizes as being on its
wired Ethernet side. When connecting very large networks; it is
recommended to set this parameter to forward unknown.
•
Intelligent Bridging Period (AP Only) – Intelligent bridging enables
smooth roaming of WB-10 units. When intelligent bridging is enabled,
the AP goes into a special bridging mode for a fixed amount of time
whenever a wireless bridge (WB) roams into its area. This mode causes
the AP to forward packets destined for the stations behind the WB-10.
Even though, they are known or were learned from the wired side
(except that no learning of the wired LAN will take place). Afterwards,
the AP will switch back to Reject Unknown bridging mode.
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This procedure prevents packets destined for stations behind the bridge
from getting lost. The value of this parameter is the length of time in
seconds that the AP will remain in special mode.
•
IP Filtering – Whether IP filtering is enabled for the unit. Enable IP
Filtering to filter out any other protocol (such as IPX) if you want that
only IP traffic will pass through the WLAN.
•
Tunneling – Whether the unit performs Apletalk or IPX tunneling.
•
Disable Appletalk Tunneling. This parameter allows to disable or
enable (default) Appletalk tunneling; if the network contains a mix of
Ethertalk1 (ET1) and Ethertalk2 (ET2) stations to ensure smooth
communications. Be sure to set all units to the same tunneling
setting.
•
Disable IPX Tunneling. This parameter allows to disable or enable
(default) IPX tunneling; if the IPX protocol is running over your
network. Be sure to set all units to the same tunneling setting.
•
Broadcast Relaying (AP Only) – When Broadcast Relaying is enabled,
Broadcast packets originated in WLAN devices are transmitted by the
AP back to the WLAN devices, as well as to the LAN. If it is disabled,
these packets are sent only to the local wired LAN and are not sent back
to the WLAN. Disable Broadcast Relaying only if you know that all
Broadcast messages from the WLAN will be destined to the wired LAN.
•
Unicast Relaying – When Unicast Relaying is enabled, Unicast packets
originated in WLAN devices can be transmitted back to the WLAN
devices. If this parameter is disabled, these packets are not sent to the
WLAN even if they are intended for devices on the WLAN. Disable
Unicast Relaying only if you know that all Unicast messages from the
WLAN will be destined to the local wired LAN.
Note:
Notice that some of the most common internet applications use peer-to-peer traffic, such
as “chat”, ICQ and even internet browsing between a client and a server which are connected
wirelessly on the same subnet. Disabling Broadcast or Unicast relaying will cause such
applications to become unavailable.
3.4.5.
Station Control
The Station Control Menu contains the following options:
•
Reset Unit – Resets the BreezeNET PRO.11 unit and applies any
changes made to the system parameters.
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•
Set Factory Defaults –When this option is implemented, system
parameters revert back to the original factory default settings. There are
two options:
• Full – All parameters revert to defaults except for the Hopping
Standard and Japan Call Sign (if applicable).
• Partial – All parameters revert except for the Hopping Standard and
Japan Call Sign (if applicable), IP Address, SubNet Mask, Default
Gateway, Hopping Sequence, Hopping Set, ESSID, Transmit
Antenna, Acknowledge Delay, Preferred AP, IP Filtering, Hopping
Standard, Power Level, Auto Calibration.
3.4.6.
Security
Security options are not activated yet.
The security mechanism involves configuring four different modules:
• Authentication Algorithm – This module operates in two modes:
• Open System (Default). There is no privacy implemented by
authentication. After synchronization, a station will send a
request for authentication and immediately receive a
“successful authentication” message from the AP.(2 frames)
• Shared Key authentication (for users with access keys). This
option will activate the WEP cryptographic authentication.
After synchronization, a station will send a request for
authentication, the AP will answer with a “challenge text”
(ASCII characters), the station will encrypt this text using RC4
(not yet implemented) with the encryption key in use and send
this text back to the AP, the AP will decrypt the received
message and if it matches the original text it will send a
“successful authentication” message. (4 frames).
The association process will begin only after a successful
authentication (in either system).
•
Default Key ID – In order to authenticate, the value of the key used
by the station and the AP must be identical. During the
authentication process a station must notify the AP which key it
used to encrypt the challenge text. The station will do this by
passing the number of the current default key it uses. The AP and
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station must have the same keys (values).
•
•
Preauthentication – During the authentication process the AP is
notifying the other AP’s connected to the Ethernet backbone to
preauthenticate the station that has been authenticated to this AP. It
is recommended to use this feature when there is plenty of roaming
between the AP’s. Preauthentication must be activated on both the
AP’s and the Station.
WEP Key#1-4 – These 4 Access Keys must be configured before they
can be used. In this screen you may enter the encryption key. The key
is made of 10 Hex (0-9,A-F) characters. In order to change the unit to
work in shared key authentication all four keys must be entered.
Entering zeros (0000000000) which is the default for this parameter
will cause the unit to work in open system authentication.
3.5. Advanced Settings Menu
BreezeNET PRO.11 Series (SA-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
Advanced menu
================
1 – Translation Mode
2 – Roaming
3 – Performance
4 – Radio
5 – Rate
6 - AP Redundancy Support
7 – Maintenance
Select option >
Figure 3.3: Advanced Settings Menu
The following sections describe the important parameters and relevant
information in the Advanced Settings Menu. All menu options can be
viewed by the Installer; However, the modification of certain parameters
from this menu, require the Technician access rights level.
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3.5.1.
Translation Mode (read-only)
The translation of Ethernet packets can be enabled (default) or disable.
3.5.2.
Roaming (read-only)
The Roaming menu contains parameters related to when and how the unit
roams from one AP to another. The following windows can be accessed
from the Roaming menu:
•
•
•
•
•
Max. Number of Scanning
Roaming Decision Window
Roaming Decision Numerator
Roaming Decision RSSI Threshold – At what signal strength the unit
roams to another AP
Joining Decision RSSI Threshold – At what signal strength the unit
associates with an AP
Number of Beacons for Disconnect Decision
Number of Probe Responses
Neighboring Beacon Rate
Neighboring AP‘s – Currently known number of AP‘s
•
•
•
•
3.5.3.
Performance
The Performance menu contains parameters regarding unit performance:
•
Dwell Time (AP Only) – The time spent on a radio channel before
hopping to the next channel in the sequence. The default value is 128ms.
•
RTS Threshold (read-only) – Minimum packet size to require an RTS.
For packets smaller than this threshold, an RTS packet is not sent and
the packet is transmitted directly to the WLAN. The threshold is 120
bytes. A station wanting to transmit a packet, first transmits a short
control packet called RTS (Request To Send), which includes the
source, destination, and the duration of the following transaction (i.e. the
packet and the respective ACK). The destination station responds (if the
medium is free) with a response control Packet called CTS (Clear to
Send), which includes the same duration information.
•
Max. Number of Re-Transmissions (read-only) – If a packet was
received with errors or not received at all, the station will not transmit an
ACK (acknowledgement) packet. The station that initiated the first
transmission will try to re-transmit the packet. The number of times the
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unit will try to re-transmit this packet is determined by two parameters in
this menu, Max. Number of Re-Transmissions and Number of Dwells to
Re-Transmit. This parameter can be presented as a counter. This counter
is decreased each time a re-transmission occurs. It will be the minimum
number of times a packet will be re-transmitted.
•
Number of Dwells to Re-Transmit (read-only) – A re-transmission will
be performed after a set number of Dwells. This parameter works in
conjunction with the Max Number of Re-Transmissions parameter.
•
Max Multicast Rate (read-only) – Multicast and Broadcast transmissions
are not yet acknowledged, the chance of error increases. Therefore by
default, the unit will always transmit broadcasts, multicasts and control
frames in the minimum possible rate, 1Mbps.
•
Power Saving – This option is not activated yet.
There are three modes:
• Disable (Active Mode): The station is Active all the time, uses full
power.
• Enable (Power Save Mode): In this mode the station has two states:
Awake state, uses full power. Doze (sleep) state, uses
approximately 5% power.
• Enable and test PM bit. In this mode the station will test every frame
and check if the power management bit is enabled.
Power Management Mechanism:
Stations inform AP about their Power Management Mode (Active or
Power Save). Stations in Power Save Mode are usually in sleep state. A
station will enter awake state in order to transmit data and also from
time to time in known intervals (DTIM period). AP’s maintain a table
indicating the Power Save mode of each associated station. Data
destined for Active Mode stations is sent immediately by AP. Data
destined for Power Save Mode stations is buffered by AP. Every
Beacon includes TIM (Traffic Identification Map). TIM identifies the
stations (by SID) of data buffered in the AP, waiting to be retrieved. If
a station recognizes its address in the TIM, the station will send a PSPOLL (Power Save Poll) to the AP. In response to this, the AP will
forward a data frame buffered for that station.
Aging: If a data frame is buffered in the AP more than 50 seconds, it
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Device Setup and Management
will be deleted along with all other frames buffered for that station.
This process is done every 2 seconds.
Notice that although power save mode is set in the AP it will not effect
the APs’ power consumption, but only the handling and management.
•
DTIM Period (read-only) – This is the number of dwells between
broadcast transmissions of messages for stations in power saving mode.
Note: This option is not activated yet.
•
IP Stack – By default this parameter is enabled. If it is disabled, it will
improve performance, but IP support will not be available.
•
Acknowledge Delay – Acknowledge delay is designed to increase the
performance in links LONGER THAN 20 KM. This parameter increases
the ACK timeout in the units, and therefore allows a more efficient
operation. When a BreezeNET unit transmits a certain packet, it waits
for a pre defined time interval (ACK Timeout) for an ACK packet to be
received. If the ACK is not received during that interval, the unit will
assume the transmission has failed, and will retransmit the packet. In
links longer than 20 km, that ACK timeout is not long enough for the
ACK to arrive to the other side on time, and therefore unnecessary
retransmissions are made, causing the performance to drop. This
parameter increases the ACK timeout and allows the ACK to arrive to
the other side on time, in links longer than 20 km.
Note: Acknowledge delay must be enabled on both sides of the link, when the distance is
greater than 20 km. If used in links shorter than 20 km, a significant performance drop may
occur.
3.5.4.
Radio
The Radio menu contains the following major parameters:
•
Hopping Standard (read-only) – The Hopping Standard is a set of rules
regarding the radio transmission standard allowed in each country. Units
will work together only if set to the same hopping standard.
•
Power level – Output power level at which the unit is transmitting.
There are two possibilities, Low (4dBm) or High (17 dBm) at the
antenna connector.
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Device Setup and Management
•
Carrier Sense Level (read-only) – Before transmission a station will
check if the media is free of other transmissions. This parameter is a
threshold in RSSI units that determines the sensitivity of the Carrier
Sense mechanism. Signals with a lower RSSI are considered “noise” and
are disregarded by the unit.
•
Carrier Sense Difference Level (read-only) - Carrier Sense Difference
Level refers to a sudden rise of the signal level. This parameter is the
minimum rise in RSSI units to be considered a Carrier Sense postitive
result, in which case the unit will not attempt to transmit. It is
recommended not to change this parameter
3.5.5.
Rate
The Rate menu contains the following relevant parameters:
•
Multi-Rate Support (read-only) – When this parameter is enabled, the
unit will automatically switch to the best transmission rate at any given
time.
•
Multi-Rate Decision Window Size (read-only) – This parameter indicates
the number of packets to be used for multi-rate decisions. It is
recommended not to change the value of this parameter.
3.5.6.
AP Redundancy Support (read-only)
When the AP identifies the Ethernet wire connection has been disconnected
over a defined time period; it stops transmitting. The default mode is
disabled (the AP continues transmitting even when the link is discontinued).
3.5.7.
Maintenance
The Maintenance menu contains the following major parameters and
information:
•
Auto Calibration – When the unit is started, it performs an internal
self-test. Part of this test is automatic calibration of the DC Offset and
deviation pattern. Auto Calibration is not supported in the “DE” models,
and it therefore must be disabled for “DE” units.
•
Wait for Association Address (SA only) – For the SA-10, the
Association address is the MAC address of the NIC (Network interface
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Device Setup and Management
Card) card that the station is connected to through the Ethernet UTP port
(usually the Ethernet card of the PC). The station uses the Association
Address as its identification in the Wireless Cell (WLAN address).
When a station is first connected to an ethernet port, it waits for the
Association Address update over the Ethernet. You can also have the
device use its own MAC address (Use Mine) for testing purposes, in
which case there will not be a proper network connection.
3.6. Site Survey Menu
BreezeNET PRO.11 Series (SA-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
Site Survey menu
================
1 - System Counters
2 - Survey Software
3 – Event Log
4 – Display Neighboring AP’s
Select option >
Figure 3.4: Site Survey Menu
The Site Survey Menu gives access to the sub-menus necessary to perform a
Site Survey that helps you position your units and align their antennas, as
well as perform troubleshooting.
The following sections first describe the sub-menus in the Site Survey
menu, and then explain step-by-step how to perform a Site Survey. The Site
Survey menu contains four sub-menus:
•
System Counters
•
Survey Software
•
Event Log
•
Display Neighboring AP’s
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3.6.1.
System Counters
BreezeNET PRO.11 Series (AP-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
System Counters menu
====================
1 - Display Ethernet and WLAN Counters
2 - Display Rate Counters
3 - Display Rx packets per frequency
4 - Reset All Counters
5 - Power Saving Counters
Select option >
Figure 3.4b: Systems Counters Menu
The System counters are a simple yet very efficient tool to monitor, interpret
and analyze the Wireless LAN performance. The counters contain statistics
concerning Wireless and Ethernet frames.
The submenu contains the following options:
•
Display Ethernet and WLAN Counters – Choose this option to
display the current value of the Ethernet and Wireless counters.
Ethernet Counters
Ethernet counters display statistics about the unit’s Ethernet port activity.
The unit receives Ethernet frames from its UTP port and forwards them to
its internal bridge, which decides whether or not to transmit them to the
Wireless LAN. The units have a smart hardware filter mechanism which
filters most of the frames on the LAN, and hardware filtered frames are not
counted.
On the other side, frames which where received from the wireless LAN and
some frames generated by the unit (answers to SNMP queries and pings
which reached to the unit via the UTP port), will be transmitted to the UTP
port.
Available Counters:
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Device Setup and Management
•
Total Received frames – The total number of frames received from the
UTP port. This counter includes both bad and good frames.
•
Received Bad Frames – The number of frames with errors received
from the UTP port. High values (more than just a few) indicate a
problem in the UTP connection such as a bad UTP cable or hub port.
•
Received good frames – The number of good frames (i.e. frames with
no errors) received from the UTP port.
•
Forwarded to the bridge – The number of received frames that were
forwarded to the unit’s internal bridge. This counter should be equal to
the number of good frames unless the internal bridge is overloaded.
•
Missed Frames – Frames that the unit recognized but failed to read due
to internal bridge overload. This counter should equal zero unless the
internal bridge is overloaded.
•
Transmitted to Ethernet – The number of frames transmitted by the
unit to the UTP port. These mainly include frames that have been
received from the Wireless side, but also includes frames generated by
the unit itself.
Wireless LAN Counters
Wireless counters display statistics about the unit’s Wireless LAN activity.
Transmission to the wireless media includes data frames received from the
UTP ports, as well as self generated control and management frames. When
a data frame is transmitted, the unit will wait for an acknowledge from the
receiving side. If an acknowledge is not received, the unit will retransmit the
frame until it gets an acknowledge (there are no retransmissions for control
frames). If the unit has retransmitted a frame for the maximum number of
retransmissions (refer to section 3.5.3) it will stop re-transmitting the frame
and drop this frame.
Available Counters:
•
Total Transmitted Frames – The number of frames transmitted to the
wireless media. The count includes the first transmission of data
frames (without retransmissions), and the number of control and
management frames.
Notice that an AP continuously transmits a control frame called
beacon in every frequency to which it hops, in order to publish its
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existence and keep its associated stations synchronized. Thus, the total
transmitted frames counter will get high values even if the AP-10 is
not connected to an active LAN.
•
Total Transmitted Frames (Bridge) - The total number of data
frames transmitted to the wireless media (i.e. frames that were received
form the UTP port and forwarded to the internal bridge which decided
to transmit them to the wireless media).
•
Total Transmitted Data Frames – This counter is similar to the
above but counts only data frames. In most BreezeNET PRO.11 units,
the number of total transmitted frames and total transmitted frames
(bridge) are identical. In the case of the AP, due to the inclusion of
beacon frames, this number will be higher than that for Total
transmitted frames.
•
Frames Dropped (too many retries) – The number of frames which
were dropped since they were retransmitted for the maximum number
of allowed retransmissions and weren’t acknowledged.
•
Total Transmitted Fragments – The total number of transmitted
frames. The count includes data, control and management frames, and
the number of retransmissions of data frames (for example, if the same
data frame is retransmitted ten times, the count will increase ten times).
•
Total Retransmitted Fragments – The total number of
retransmissions of data frames (for example, if the same data frame is
retransmitted ten times then the count will increase ten times). In a
point-to-point application, this counter should relatively correspond to
the number of bad fragments received on the other side.
•
Total Tx Errors – The number of transmit errors that have occurred.
Currently this counter also includes normal situations where a
fragment has not been transmitted because the dwell time has elapsed.
•
Internally Discarded – The number of frames that the AP discarded
due to a buffer overflow. Frame discard will occur mainly when the
wireless conditions are bad and the unit is busy re-transmitting frames
and doesn’t have time for handling new frames.
•
Power Saving Aged – The AP buffers frames for stations in a power
saving sleep mode. This counter counts the number of frames dropped
by the AP because a station did not wake up for a long time.
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Device Setup and Management
•
Power Saving Free Entries – Number of free buffers (one frame
each) available for power save management. These buffers hold
messages for stations that only periodically make contact with the AP
due to power considerations.
•
Total Received Frames - The number of frames received from the
wireless media. The count includes data and control frames (including
beacons received from AP’s).
•
Total Received Data Frames – The number of data frames received
from the wireless media.
•
Total Received Fragments – The total number of frames received,
including data, control and duplicate data frames (see duplicates and
dwell timeouts parameter below).
•
Bad Fragments Received – The number of frames received from the
WLAN with errors. In a point-to-point application, this counter should
relatively correspond to the number of retransmitted fragments on the
other side.
•
Duplicates and Dwell timeouts – When a unit receives a frame; it
sends an acknowledgement for it. If the acknowledge is lost, than it
receives a second copy of the same frame, since the other side thinks
this frame was not received. Although duplicate frames are count, only
the first copy of the frame is forward to the UTP port.
•
Display Rate Counters – Displays contents of packets at each rate. The
AP displays counters per station.
•
Display Rx Packets per Frequency - Histogram of the number of
frames received on each channel. This graph is explained fully in section
3.6.6 , Using the Rx Packets per Frequency Histogram.
•
Reset Counters - Choose this option to reset all the counters. After
choosing this option, you will be requested to type 1 for confirmation or
0 to cancel the reset.
•
Power Saving Counters – Displays the power saving per station, the
number of transmitted frames and the number of discarded frames. This
applies only to AP’s.
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3.6.2.
Survey Software
The Survey Software sub-menu enables you to align antennas and to assess
the radio signal quality of a point-to-point link. The sub-menu includes the
following options:
•
Operation Mode – When running a Site Survey, set the units on either
side of the link to either receive (option 1) or transmit (option 2) packets
(one unit should be set to transmit and the other to receive). Option 0
(Idle mode) is not active at present.
•
Start Statistics – Press 2 and then press any digit to start Site Survey.
•
Stop Statistics – Press 3 and then press any key to stop update of Site
Survey statistics.
3.6.3.
Event Log
•
Display Event Log - The last four error messages that the unit displayed
since the last Factory Defaults reset. The Event log stores events in four
levels of error notifications: Message, Warning, Error, and Fatal.
•
Erase Event Log – Erase a specific event log.
•
Event Storage Policy – Defines storage level for the event log.
The following are the levels which events are stored in log:
0 - Store all events (beginning at message level)
1 - Store all events from warning level up
2 - Store all events from error level up
3 - Store fatal events only
3.6.4.
Display Neighboring AP’s
Displays neighboring AP’s on the same ESS. The information displayed in
this option refers to the CURRENT or NEIGHBOR AP that the station can
hear. The following information is displayed.
•
The MAC Address of the AP described.
•
Good or bad frames: The number of frames, out of the total number of
frames received from the current AP, that are considered “good or bad”.
A frame is considered good or bad; if it was received in an RSSI level
higher or lower than the value set at the “Roaming Decision RSSI
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Device Setup and Management
Threshold” parameter (see “Roaming” on section 3.5.2).
•
Total: The number of frames set as the “Roaming Decision Window” 10 in the example shown above (see “Roaming” on section 3.5.2).
•
avr RSSI: The average RSSI level of the total number of frames (only
includes the frames received without errors).
•
bcn cnt: (Beacon Count) - How many dwells have passed since the last
beacon has been received.
•
Load: The number of stations currently associated with the descried AP.
This parameter will be displayed only when “Load Sharing’” (page 24)
is Enabled.
3.6.5.
⇒
Using the Site Survey Software
To use the Site Survey Software:
1. Roughly, align the antennas on either side of the link before
starting the Site Survey procedure.
2. Verify that the Ethernet cables are disconnected from both units.
3. Press 1 to go to the Operation mode screen. Set the units on either
side of the link to either receive (option 1) or transmit (option 2)
packets (one unit should be set to transmit and the other to receive).
4. Start the survey by selecting option (2) in the Survey Software
menu in both units. When performing a site survey from a station
to an AP (transmitting from the station to the AP), always begin
with the station (select option (2) on the station).
5. On the transmit side, a screen appears displaying a table with the
number of packets and the frequency at which each packet was
transmitted (refer to Figure 3.5). This list is updated continuously.
Select option (3) to stop sending packets.
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Version :
4.3.10
Date: 15 Feb 1999 23:49:56
# Tx Packets Channel
37
10
30
28
44
35
12
48
76
10
42
Figure 3.5: Transmit Statistics
6. On the receive side of the link, the screen displays a table showing
the packet number received, the antenna port that was selected for
the reception, the Received Signal Strength Indicator (RSSI) for
each antenna, the bit error rate, the frequency at which each packet
was transmitted, the data rate at which the packet was transmitted,
and the quality of the signal (refer to Figure 3.6). Use only the
RSSI reading from the selected antenna.
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BreezeNET PRO.11 Series (AP-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
#Pack Ant RSSI1 RSSI2 Bit_Err Freq Rate
58
108
91
19
59
110
112
42
60
86
88
14
61
109
112
46
62
109
107
24
63
108
106
22
64
112
108
33
65
111
107
25
66
111
111
41
67
111
110
79
68
115
111
64
69
115
111
65
70
111
111
56
71
110
111
55
Quality
###########
###########
########...
###########
###########
###########
###########
###########
###########
###########
###########
###########
###########
###########
Figure 3.6: Receive Statistics
7. The RSSI is given in arbitrary units. Use the following graph
(Figure 3.7) to correlate RSSI to dBm.
RSSI Vs. dBm
130
120
110
RSSI Value
100
90
80
70
60
50
-30
-40
-45
-50
-55
-60
-65
-70
-75
-78
-81
-83
-85
RF Level [dbm]
Figure 3.7: RSSI to dBm Graph
8. Re-align the antennas until the maximum received signal strength
is obtained. As you align the antennas, you will see that the RSSI
(received signal strength indicator) continually increases until it
reaches a certain level after which the RSSI begins to decrease.
This is the maximum attainable RSSI level indicating optimum
receive antenna alignment.
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9. Switch the functions of either side of the link (set the transmit unit
to receive and the receive unit to transmit) and repeat the procedure
to check the link from the opposite direction.
3.6.6.
Using the Rx Packets per Frequency Histogram
Use the Display Rx Packets per Frequency option to see a histogram of the
number of frames received on each channel.
BreezeNET PRO.11 Series (AP-10)
Version :
4.3.10
Date:
15 Feb 1999
23:49:56
Max = 187
Min = 112
## ##
####
###
## ######## ######
# # #
# ##
## # #
##
# ######## # ### ##
## # #
## # ##
####### ## ######################################################### ########
#############################################################################
+10
+20
+30
+40
+50
+60
+70
Hit any key to return >
Figure 3.8: Display Rx Packets per Frequency
Each point of the histogram line corresponds to a frequency. The base
frequency appears at the far left, and gradations are marked in steps of ten
along the line. A hash represents each packet received on a given frequency
(#). The Max and Min values indicate the highest and lowest number of
frames received across all frequencies. This graph is very useful for tracking
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interference. Frequencies with low numbers of packets received probably
have more interference than other frequencies.
3.7. Access Control Menu
Access Control functions enable the System Administrator or Installer to
limit the access to the Local Terminal Maintenance setup and configuration
menus.
BreezeNET PRO.11 Series (AP-10)
Version :
4.3.10
Date: 15 Feb 1999 23:49:56
Access Control menu
===================
1 - Change Access Rights
2 - Change Installer Password
S - Show Current Access Right
Select option >
Figure 3.9: Access Control Menu
The Access Control menu includes the following options:
•
Change Access Rights – This screen determines the level of access
rights to the BreezeNET PRO.11 unit’s setup and configuration menus.
When the unit is first installed, the default setting is option (1), Installer
and the default password is “user”:
• User – The Local Terminal Management menus are read-only for a
user who does not possess the correct password. The ESSID and
security parameters are hidden by asterisks (*) at this level.
• Installer – The installer has access to configure all required
parameters in the system configuration menu, as well as some of the
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advanced settings. Access is password-protected. After
configuration, the installer should change access rights to option (0),
User. The installer can also change the installer password (see next
parameter).
• Technician – Only a Certified BreezeCOM Engineer possessing the
correct password can select this option to configure all the
parameters and settings.
•
Change Installer Password – Type in the new password according to
the directions on screen. This screen changes the installer password to
prevent unauthorized persons from making any changes in system
configuration and setup. The password is limited to eight printable
ASCII characters. This option is not available at User level.
•
Show Current Access Right – This read-only screen presents the
current access right configuration.
Important: If you change the Installer password do not forget it, or you will be
unable to change the unit's access rights.
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Planning and Installing Wireless LANs
4. PLANNING AND INSTALLING
WIRELESS LANS
This chapter describes various possible system configurations, lists points to
consider when performing indoor and outdoor installations, presents
guidelines and restrictions regarding external antenna installation. It also
describes some antennas that work well with BreezeNET PRO.11 units.
4.1. System Configurations
This chapter describes various wireless LAN configurations, and how to set
them up:
•
Single Cell Configuration – The wireless LAN consists of an Access
Point and the wireless workstations associated with it.
•
Overlapping Cell Configuration – The wireless LAN consists of two
or more adjacent Access Points whose coverage slightly overlaps.
•
Multicell Configuration – The wireless LAN consists of several Access
Points installed in the same location. This creates a common coverage
area that increases aggregate throughput.
•
Multi-Hop Configuration – The wireless LAN contains AP-WB pairs
that extend the range of the wireless LAN.
Many wireless LANs contain several of these configurations at different
points in system. The Single Cell configuration is the most basic, and the
other configurations build upon it.
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4.1.1.
Single Cell Configuration
A basic BreezeNET cell consists of an Access Point and the wireless
workstations associated with it. You can convert most workstations (PCs,
X-Terminals, Apple, Digital, SUN, HP, IBM and others) that are equipped
with an Ethernet network interface card (NIC) to wireless workstations
simply by connecting a BreezeNET SA-10 PRO.11 Station Adapter.
There are three types of Single Cell Configuration:
•
Point-to-Point
•
Point-to-Multipoint
•
Mobile Applications
Each type is explained in the following sections.
4.1.1.1
Point-to-Point
Point-to-Point installations (refer to Figure 5.1) require directional antennas
at either end of the link. To select the best antenna for a specific application,
consider the following factors:
•
Distance between sites
•
Required throughput
•
Clearance between sites
•
Cable length.
Refer to the range tables (section 4.2.7) to determine the best combination of
antennas for your application.
4.1.1.2
Point-to-Multipoint
Point-to-Multipoint applications consist of one or more APs at the central
site and several remote stations and bridges (SA-10, SA-40, WB-10). In this
case, use an Omni antenna with the Access Point because of its 360°
radiated pattern. Ιn the United States, the Omni-8 antenna (which also has a
360° radiated pattern but has a wider range) can also be used. The Omni-8
antenna comes with 20ft. of low loss cable and a mast mount bracket for
rooftop installations.
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The remote units should use directional antennas aimed in the direction of
the AP’s antenna(s).
4.1.1.3
Mobile Applications
In mobile applications, station orientation changes continuously. In order to
maintain connectivity throughout the entire coverage area, most mobile
applications require omni-directional antennas for both Access Points and
wireless stations. In a motor vehicle, for example, you can install an SA-10
in the cabin, and mount the antennas on the roof.
4.1.1.4
Extending the LAN with WLAN Bridging
The figures below demonstrate how the WB-10 can be used to extend a
regular network with a wireless link.
Disclaimer: This diagram is for illustrative purposes only. It should not be
confused with the transceiver operating in a standalone mode. When this
diagram is in use, the transceiver will be used in conjunction with amp
model
AMP-2440-250/500 and the antennas listed in this manual.
Figure 5.1: Connecting Remote Offices to Main Office Network
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The WB-10 PRO.11 also enables connectivity between a wireless LAN and
individual workstations or workgroups located outside the LAN. The
WB-10 PRO.11 enables these wireless stations in its coverage area to
communicate with the wireless LAN and gain access to all of the network
resources such as file servers, printers and shared databases.
Figure 5.2: Wireless Bridging Between Two or More Wireless LAN Segments
4.1.1.5
⇒
Setting Up a Single BreezeNET Cell
To set up a single BreezeNET cell:
1. Install the Access Point (refer to section 2, Basic Installation). Be
sure to position the Access Point as high as possible.
Note: It is not necessary at this point to connect the Access Point to an Ethernet
backbone, since Access Points continuously transmit signals (beacon
frames) whether they are connected to an Ethernet backbone or not.
2. Install a Station Adapter (refer to section 2, Basic Installation).
3. Check the LED indicators of the front panel of the Station Adapter,
to check signal strength.
4. Make any necessary adjustments, for example:
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•
Adjust the antennas
•
Adjust the location of the Station Adapter
•
Adjust the location of the Access Point
5. Proceed to setup the other workstations.
Figure 5.3: Single Cell Configuration
Disclaimer: This diagram is for illustrative purposes only. It should not be
confused with the transceiver operating in a standalone mode. When this diagram
is in use, the transceiver will be used in conjunction with amp model
AMP-2440-250/500 and the antennas listed in this manual.
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4.1.2.
Overlapping Cell Configuration
When two adjacent Access Points are positioned close enough to each other,
a part of the coverage area of Access Point #1 overlaps that of Access Point
#2. This overlapping area has two very important attributes:
•
Any workstation situated in the overlapping area can associate and
communicate with either Access Point #1 or Access Point #2.
•
Any workstation can move seamlessly through the overlapping coverage
areas without losing its network connection. This attribute is called,
Seamless Roaming.
Figure 5.4: Three Overlapping Cells
⇒
To set up overlapping BreezeNET cells:
1. Install an Access Point (refer to section 2, Basic Installation). Be
sure to position the Access Point as high as possible.
2. Install the second Access Point so that the two are positioned closer
together than the prescribed distance (refer to section Error!
Reference source not found.).
3. To allow roaming, configure all Access Points and stations adapters
to the same ESSID.
4. To improve collocation and performance, configure all Access
Points to different hopping sequences of the same hopping set.
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5. Install a Station Adapter or SA-PCR Card on a workstation.
6. Position the wireless workstation approximately the same distance
from the two Access Points.
7. Temporarily disconnect the first Access Point from the power
supply. Verify radio signal reception from the first Access Point.
View the LED indicators of the front panel of the Station Adapter,
or the Site Survey application of the SA-PCR Card, to check signal
strength of the first Access Point.
8. Disconnect the second Access Point from the power supply and reconnect the first Access Point. View the LED indicators of the front
panel of the Station Adapter, or the Site Survey application of the
SA-PCR Card, to check signal strength of the second Access Point.
7. If necessary, adjust the distance between the Access Points so the
coverage areas overlap.
8. Continue setting up overlapping cells until the required area is
covered.
Note: It is not necessary at this point to connect the Access Points to an Ethernet
backbone, since Access Points continuously transmit signals (beacon
frames) whether they are connected to an Ethernet backbone or not.
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4.1.3.
Multicell Configuration
Areas congested by many users and a heavy traffic load may require a
multicell structure. In a multicell structure, several Access Points are
installed in the same location. Each Access Point has the same coverage
area, thereby creating a common coverage area that increases aggregate
throughput. Any workstation in the overlapping area can associate and
communicate with any Access Point covering that area.
⇒
To set up a BreezeNET multicell:
1. Calculate the number of Access Points needed as follows: Multiply
the number of active users by the required throughput per user, and
divide the result by 1.5Mbps (net throughput supported by
collocated Access Points). Consider the example of 5 active
stations, each requiring 0.5 Mbps throughput. The calculation is
(5*.5)/1.5=1.6. Two Access Points should be used. This method is
accurate only for the first few Access Points.
The aggregate throughput of the common coverage area is equal to
the number of co-located Access Points, multiplied by the
throughput of each individual Access Point, minus a certain amount
of degradation caused by the interference among the different
Access Points.
2. Install several Access Points in the same location a few meters
from each other so they cover the same area. Be sure to position the
Access Points as high as possible.
3. To allow roaming and redundancy, configure all Access Points and
stations adapters to the same ESSID.
4. To improve collocation and performance, configure all Access
Points to different hopping sequences of the same hopping set.
5. Install Station Adapters or SA-PCR Cards on workstations.
6. Make sure that the Load Sharing option is activated. Stations will
automatically associate with an Access Point that is less loaded and
provides better signal quality.
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Note: It is not necessary at this point to connect the Access Points to an Ethernet
backbone, since Access Points continuously transmit signals (beacon
frames) whether they are connected to an Ethernet backbone or not.
Figure 5.5: Multicell Configuration
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4.1.4.
Multi-hop Configuration (Relay)
When you want to connect two sites between which a line-of-sight does not
exist, an AP-WB pair can be positioned at a third location where line-ofsight exists with each of the original locations. This third location then acts
as a relay point.
In areas where a wired LAN backbone is not available, another AP can be
added to the AP-WB relay to distribute a wireless backbone. In this way, the
range of a wireless system can be extended.
System configuration is as follows:
⇒
To set up a BreezeNET multi-hop cell:
1. Install an AP at the main office (refer to section 2, Basic
Installation).
2. Install a WB at the remote site (refer to section 2, Basic
Installation).
3. Install an AP-WB pair in a high location that has a clear line of
sight to both the main office and the remote site. Many AP-WB
pairs can form a chain.
4. When an AP and WB communicate over the wireless LAN, set
them both to the same ESSID. For example, set the AP of the main
office and the WB of the first AP-WB relay pair to the same
ESSID. Also, set the AP of the last AP-WB relay and the WB of
the remote site to the same ESSID; this ESSID should be different
from the first ESSID.
Another option is to use one ESSID, and to set the Preferred AP
parameter of each WB to its paired AP (refer to section 3.4.3). This
option allows stations to roam between the sites.
5. As usual, make sure that the hopping sequence of the Access Points
are different.
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Figure 5.6: Multihop Configuration
6. If desired, an additional AP may be added at the main office and
remote site, and between each AP-WB pair to provide wireless
LANs at those points (see illustration).
Figure 5.7: Advanced Multihop Configuration
7. Install Station Adapters or SA-PCR Cards on workstations (refer to
section 2, Basic Installation).
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4.2. Outdoor Installation Considerations
This chapter describes various considerations to take into account when
planning an outdoor installation including site selection, antenna alignment,
antenna diversity, antenna polarization, antenna seal, and cell size.
4.2.1.
Site Selection Factors
When selecting a location for external antennas, remember to take into
consideration the following guidelines:
•
Minimum distance between sites
•
Maximum height above the ground
•
Maximum line of sight clearance
•
Maximum separation between antennas (diversity option)
Path of Clearest Propagation
A propagation path is the path that signals traverse between the antennas of
any two bridges. The “line” between two antenna sites is an imaginary
straight line which may be drawn between the two antennas. Any obstacles
in the path of the “line” degrade the propagation path. The best propagation
path is, therefore, a clear line of sight with good clearance between the
“line” and any physical obstacle.
Physical Obstacles
Any physical object in the path between two bridges can cause signal
attenuation. Common obstructions are buildings and trees. If a bridge’s
antenna is installed indoors, the walls and/or windows between the two sites
are physical obstructions. If the antenna is positioned outdoors, any
buildings or other physical structure such as trees, mountains or other
natural geographic features higher than the antenna and situated in the path
between the two sites can constitute obstructions.
Install indoor antennas as close as possible to a window (or wall if a
window is not accessible) facing the required direction. Avoid metal
obstacles such as metal window frames or metal film anti-glare windows in
the transmission path. Install outdoor antennas high enough to avoid any
obstacles which may block the signal.
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Minimal Path Loss
Path loss is determined mainly by several factors:
•
Distance between sites
Path loss is lower and system performance better when distances
between sites are shorter.
•
Clearance
Path loss is minimized when there exists a clear line of sight. The
number, location, size, and makeup of obstacles determine their
contribution to path loss.
•
Antenna height
Path loss is lower when antennas are positioned higher. Antenna height
is the distance from the imaginary line connecting the antennas at the
two sites to “ground” level. “Ground” level in an open area is the actual
ground. In dense urban areas, “ground” level is the average height of the
buildings between the antenna sites.
4.2.2.
Rooftop Installation
Warning: Rooftop antenna installations are extremely dangerous! Incorrect
installation may result in death, serious injury and/or damage. Such
installations should be performed by professional antenna installers
only!
Rooftop installations offer several advantages:
•
Increased antenna range.
•
Less obstacles in path.
•
Improved performance due to greater height.
•
Reduced multipath problems.
4.2.3.
Antennas for Outdoor Applications
The BreezeNET PRO.11 Series can be used in point-to-point or point-tomultipoint configurations.
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4.2.3.1
Point-to-Point
A point-to-point link is based on the use of one Access Point with external
antennas and one adapter (SA-10/40D, WB-10D). The AP and the WB must
be equipped with one or two directional antennas. The necessary antenna
gain depends on the required range and performance.
4.2.3.2
Point-to-Multipoint
Setting up a point-to-multipoint link requires the use of an AP-10D
equipped with omni-directional antennas and a remote WB-10D (or SA10/40D) equipped with high-gain directional antennas.
4.2.3.3
Antenna Alignment
Low gain antennas do not require alignment due to their very wide radiation
pattern. High gain antennas have a narrow beamwidth necessitating an
alignment procedure in order to optimize the link.
Check antenna alignment by using the LED indicators on the front panel of
whichever adapter is used in the link (WB-10D or SA-10/40D). These LED
indicators provide indication of reception quality.
⇒
To perform antenna alignment:
1. Assemble antennas according to the assembly instructions included
with the antenna set.
2. Mount the antennas as high as possible.
3. Connect the coaxial cable to the AP at the main site.
4. Connect the coaxial cable to the WB (or SA) at the remote site.
5. Power on the AP and the WB (or SA).
6. Synchronize the units by aligning the antennas manually until the
WLNK indicator LED on the front panel of the wireless Bridge
and/or Station Adapter illuminates.
7. Align antennas at the main and remote sites until maximum signal
quality is obtained. (Check QLT LEDs on the front panel of the
Station Adapter and the wireless Bridge.)
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If the received signal quality is lower than expected for this antenna/range
combination, change antenna height and verify RF cables connections.
4.2.3.4
Antenna Diversity
In applications where no multipath propagation is expected, a single antenna
is sufficient to ensure good performance levels. However, in cases where
multipath propagation exists, BreezeCOM recommends that two antennas
be used. This takes advantage of space diversity capabilities. By using two
antennas per unit, the system can select the best antenna on a per-packet
basis (every several milliseconds).
Multipath propagation is to be expected when there are potential reflectors
between the main and remote sites. These reflectors may be buildings or
moving objects such as airplanes and motor vehicles. If this is the case, the
radio signal does not travel in a straight line, but is reflected or deflected off
of the object, creating multiple propagation paths.
When installing a single antenna, modify the transmit antenna option to
either antenna 1 or antenna 2, according to the antenna being used (refer to
section 3.4.3). Note: Only antennas from Table 1 FCC Type Acceptance
Configurations can be used.
4.2.3.5
Antenna Polarization
Antenna polarization must be the same at either end of the link. In most
applications, the preferred orientation is vertical polarization. Above-ground
propagation of the signal is better when it is polarized vertically. To verify
antenna polarization, refer to the assembly instructions supplied with the
antenna set.
4.2.4.
Antenna Seal
When using outdoor antennas, you must seal the antenna connectors against
rain. Otherwise the antennas are not suitable for use in outdoor installations.
4.2.5.
Cell Size
Cell size is determined by the maximum possible distance between the
Access Point and the Station Adapter, usually related to point-to-multipoint
installations using external antennas. For open outdoor areas with an
unobstructed line of sight between the Access Point and the BreezeNET
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PRO.11 workstation, the suggested maximum distance between Access
Point and workstation is:
Standard AP-10 PRO.11 .........................700m (2000 ft.)
4.2.6.
Link Distance
Link distance is the maximum distance between the AP and the station
adapter, usually related to point-to-point installations using external
antennas. For open outdoor areas with an unobstructed line of sight between
the Access Point and the wireless bridge, the suggested maximum distance
is:
AP-10D PRO.11 with external antennas .......up to 10Km (7 miles) in the USA
Note: The maximum distance of 10Km/7 miles is achieved using 24 dBi antennas.
4.2.7.
Using Outdoor Range Tables
Outdoor installations must have a clear line-of-sight. Solid obstacles such as
buildings or hills prevent the establishment of a link. Partial obstacles such
as trees or traffic can reduce range. Extending coaxial cables can cause an
increase in assembly signal loss and a reduction in range.
The ranges in the following tables are attained under good propagating
conditions when using the standard cables supplied in the antenna set.
Actual ranges may vary due to specific multipath and interference
conditions.
For specific range guidelines and information about extending cables,
consult your local dealer or BreezeCOM central offices.
Ranges are subject to change without notice.
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4.3. Precautions
4.3.1.
Professional Installers Only
Caution: Detached antennas, whether installed indoors or out, should be
installed ONLY by experienced antenna installation professionals who
are familiar with local building and safety codes and, wherever
applicable, are licensed by the appropriate government regulatory
authorities.
Failure to do so may void the BreezeNET Product Warranty and may
expose the end user to legal and financial liabilities. BreezeCOM and
its resellers or distributors are not liable for injury, damage or
violation of government regulations associated with the installation of
detached antennas.
4.3.2.
Transmit Antenna Gain
Regulations regarding maximum antenna gains vary from country to
country. It is the responsibility of the end user to operate within the limits of
these regulations and to ensure that the professional installer is aware of
these regulations, as well. The FCC in the United States and ETSI in Europe
limit effective transit power to 36dBm (USA) and 20dBm (Europe). The
maximum total assembly gain of antennas and cables in this case equals
19dBi (USA) and 3dBi (Europe).
Violation of government regulations exposes the end user to legal and
financial liabilities. BreezeCOM and its resellers and distributors shall not
be liable for expense or damage incurred as a result of installations which
exceed local transmit gain limitations.
4.3.3.
Spurious Radio Frequency Emissions
The regulations referred to in the previous section also specify maximum
“out-of-band” radio frequency emissions. Install a filter as close as possible
to the BreezeNET PRO.11 “D” model unit connector.
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4.3.4.
Lightning Protection
Lightning protection is designed to protect people, property and equipment
by providing a path to ground for the lightning’s energy. The lightning
arrestor diverts the strike energy to ground through a deliberate and
controlled path instead of allowing it to choose a random path. Lightning
protection for a building is more forgiving than protection of electronic
devices. A building can withstand up to 100,000 volts, but electronic
equipment may be damaged by just a few volts.
Lightning protection entails connecting an antenna discharge unit (also
called an arrestor) to each cable as close as possible to the point where it
enters the building. It also entails proper grounding of the arrestors and of
the antenna mast (if the antenna is connected to one).
The lightning arrestor should be installed and grounded at the point where
the cable enters the building. The arrestor is connected to the unit at one end
and to the antenna at the other end.
The professional installer you choose must be knowledgeable about
lightning protection. The installer must install the lightning protector in a
way that maximizes lightning protection. BreezeCOM offers the following
high-quality lightning arrestor assembly:
BreezeNET AL 1 Lightning Arrestor - Part No. 872905 5 ft (1.5m), “N”
Male to “N” Female.
4.3.5.
Rain Proofing
12, 18, and 24 dBi antennas must be sealed against rain at the point the
cable enters the pole before they are suitable for external use.
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5. ACCESSORY INSTALLATION
This chapter introduces some of the accessories available for specific
installations, and describes how to install them.
5.4. AL 1 Lightning Arrestor
The AL 1 Lightning Arrestor is used to protect transmitters and receivers
from transients originating from lightning or EMP.
The AL 1 is gas tube-based and is not radioactive. The gas discharge tube
can sustain several transients if the time period between transients is
sufficient to allow the tube to cool down.
For technical specifications, refer to section 8.2.2, Specifications for AL 1
Lightning Arrestor.
Figure 6.4:
AL-1 Connection Block Diagram
One of the female-type N connectors is mounted directly through a hole in
the shelter wall and held in place with a lockwasher and nut.
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Upgrade Procedure
6. UPGRADE PROCEDURE
Firmware upgrades to the unit's flash memory is done by a simple download
procedure using a TFTP application. Before beginning an upgrade, be sure
you have the correct files and latest instructions. Upgrade packages can be
obtained at the BreezeCOM web site: www.breezecom.com.
In general terms, upgrading includes the following steps:
1. Set up an IP connection to the device. You can verify working
connection using the Ping command.
2. Run TFTP software and connect to the device.
3. Use TFTP to download the erase file to the device Use the tables
below to determine the specific file to use, according to the unit’s
current version. This causes the flash memory to be cleared. Do not
reset the device now.
4. Use TFTP to download the software file to the device. Use the
tables below to determine the specific file to use, according to the
unit’s current version.
5. The unit resets itself and comes up with the new upgraded version.
Table 7.1: Upgrade Files
Current Version
of Unit
Software Download File Name
Flash Erase
File Name
AP-10
SA-10, SA-40, WB-10
3.2, 3.38, 3.42, 3.50
download
eanaf
eansf
3.52, 4.204
erase
eanafb
eansfb
3.62, 4.211, 4.310
erase_fw
ap_fw
sawb_fw
The current version and type of the unit determine the files used for
upgrade. For example, when upgrading an AP-10 from version 3.52 to
version 4.310, use the erase and eanafb files.
When upgrading a SA-10 from version 3.62 to version 4.310, use the
erase_fw and sawb_fw files.
When upgrading an AP-10 from version 4.211 to version 4.310, use the
erase_fw and ap_fw files.
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System Troubleshooting
7. SYSTEM TROUBLESHOOTING
The following troubleshooting guide provides answers to some of the more
common problems which may occur when installing, and using BreezeNET
PRO.11 Series products. If problems not mentioned in this guide should
arise, checking the Ethernet and WLAN counters may help (see section
3.6.1). If the problem persists, please feel free to contact your local
distributor or the BreezeCOM Technical Support Department.
8.1. Troubleshooting Guide
Problem and Indication
Possible Cause
Corrective Action
No Power to Unit. PWR LED is
1. Power cord is not properly
1. Verify power cord is properly connected to the
off.
connected.
BreezeNET unit and to the power outlet.
2. Power supply is defective.
2. If this is not the cause, replace the power supply.
Failure to establish wireless link. 1. Power supply to units may be
1. Verify power to units (AP and SA/ WB).
WLNK LED is off and unit resets faulty
2. Verify that all units in the network have the same ESSID
every few minutes.
2. The units may not have the
as the AP (ESSID must be identical in all units in the
same ESSID as the AP-10.
network):
3. Verify wireless link:
• Set AP and unit (SA or WB) side by side.
• Power on each unit and see if a wireless link is
established (even “D” models without their external
antennas should establish a link if placed side by side with
the AP).
• If the units fail to associate, reset units to factory
default values reset unit (see section 3.4.5). The units
should now establish a wireless link.
Failure to establish wireless link
1. Power supply to units may be
1. Verify power to units.
(“D” models/external antennas)
faulty.
2. Verify that all cables are connected securely.
2. Cables may be improperly
3. Refer to previous section and verify wireless link
connected
between the units.
3. There may be some problem
4. Verify that the antenna(s) are properly installed (see
with antenna installation.
relevant section in this manual):
• Check antenna alignment.
• Verify that antenna polarization is the same at both
ends.
• Verify that the range matches specifications.
• Verify line-of-sight/antenna alignment/antenna height.
Wireless link established, but
1. Ethernet hub port or UTP
1. Check that the LINK LED is on and solid at the hub port.
there is no Ethernet activity (AP
cable is faulty.
If this is not the case, the port is inactive. Try another port
and WB units).
2. Ethernet port in unit is faulty.
on the hub or another UTP cable.
2. Verify that Ethernet port in unit is working. Ping unit to
verify Ethernet connection.
3. Verify that you are using a cross-over UTP cable (pins 1
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Problem and Indication
Possible Cause
Corrective Action
& 3, 2 & 6) if connected directly to workstation, or a
straight-through cable if connected to a hub.
4. Check ETHR LED indicator in unit and Ethernet
counters in Monitor to verify Ethernet activity.
Wireless link established, but
1. Ethernet port on Network
there is no Ethernet activity (SA- Interface card is faulty.
10 and SA-40 units).
1. Verify that the LINK LED is lit and solid at the NIC port.
If this is not the case, the port is inactive. Try using
2. Ethernet port of unit is faulty.
another UTP cable or another workstation.
3. UTP cable is faulty.
2. Ping the unit to check the Ethernet port. If you cannot
ping the unit, this may indicate failure of cable, Ethernet
port of unit or Ethernet port of workstation’s NIC. Change
UTP cable and retry. If you still cannot ping the unit,
exchange units and try to ping the new unit using the
same NIC and cable.
No network detected at Station
1. Workstation networking is
Adapter (SA-10, SA-40)
improperly configured.
workstation.
2. UTP cable connection is faulty.
1. Reset both Access Point and Station Adapter.
• Re-establish network connection.
• Verify proper workstation network configuration.
3. Failure to pass Ethernet
2. Try to ping the remote network. Failure to detect the
packets.
network may indicate a failure to pass Ethernet packets.
3. Verify UTP cable connection. Solid LINK LED in
workstation NIC indicates proper Ethernet connection.
4. Check monitor messages for errors or other indications
of problems.
5. Check station counters to verify increase in Ethernet
counters which indicates Ethernet activity.
High quality signal but throughput 1. Too much interference or
1. Move the unit or the antennas out of the range of
is poor.
interference.
multipath propagation.
2. Ethernet port of the unit may
be faulty.
• Check counters to see if more than 10% of total
transmitted frames are retransmitted fragments.
• Check if more than 10% of total received data frames
are bad fragments.
2. Verify Ethernet port activity by checking Ethernet
counters.
Link signal quality low or not as
1. Possible multipath or structural Reposition the unit outside range of possible interference.
good as expected (indoor
interference.
• Check for heavy metal structures (e.g. elevators,
installation).
racks, file cabinets) near unit.
• Check counters for excessive retransmissions or
received bad fragments.
• Site may require higher gain antennas.
• site may require a multicell structure (multiple AP units)
due to multipath/structural interference.
Refer to section 4.2, Outdoor Installation Considerations:
Link signal quality low or not as
There may be a problem with
good as expected (outdoor
certain aspects of outdoor
• Verify that there is a clear line-of-site.
installation).
installation considerations (see
• Verify antenna height.
relevant section in this manual).
• Verify antenna polarization.
• Verify antenna alignment.
• Check length of cable between antenna and unit (an
overly long extension cable may adversely affect
performance).
Unit associates with the wrong
In a multicell structure with
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For a unit to associate with a specific Access Point, assign
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Problem and Indication
Access Point.
Possible Cause
Corrective Action
overlapping cells, the units may
a unique
not associate with the closest
ESSID to the Access Point and to all the units you want to
Access Point.
include in that wireless network.
Reduced performance in a multi- The APs in the same coverage
Assign a unique hopping sequence to each AP in the
AP configuration.
coverage area. Each AP must have a unique hopping
area have not been assigned
unique hopping sequences.
sequence regardless of ESSID.
Rx / Tx calibration
Auto Calibration is enabled for a
Disable Auto Calibration for the unit (refer to section 3.5).
error messages.
“DE” unit.
8.2. Checking Counters
Checking counters is also a good way to pinpoint any problems that may
occur in the BreezeNET wireless LAN. Counters can be checked from the
monitor. See section Error! Reference source not found..
8.2.1.
WLAN Counters
When checking WLAN counters, total retransmitted fragments should be
below 10% of total transmitted (bridge) frames. If total retransmitted
fragments are above 10%, this indicates errors in data transmission. Too
many retransmissions may be an indication of interference between the
transmitting and receiving units. Also, the ratio between Frames Dropped
(too many retries) and Total Transmitted Frames (Bridge) should not exceed
1:40 (2.5%)
Received bad fragments should be no more than 10% of the total received
data frames. If more than 10% of the total received data frames are bad
fragments, this may indicate that there is a problem with the wireless link.
Refer to the Troubleshooting guide (section 7) above for possible corrective
action.
8.2.2.
Ethernet Counters
When checking the Ethernet counters, received bad frames should be zero
(0). If this is not the case, this may indicate a problem with the Ethernet
connection. Verify Ethernet port link at hub, workstation, and unit. Assign a
unique IP address to the unit and ping.
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8. APPENDIX
This appendix includes the following sections:
•
Supported MIBs and Traps – Lists MIBs and traps supported by
BreezeNET PRO.11 Series products.
•
Technical Specifications – Lists product and attachment specifications.
•
Wireless LAN Concepts – Provides an overview of the concepts related
to wireless LANs.
•
Radio Signal Propagation – Discusses the concepts and applications of
radio signal propagation relevant to wireless LANs.
•
IEEE 802.11 Technical Tutorial – Introduces the new 802.11 standard.
8.1. Supported MIBs and Traps
This chapter lists MIBs and traps supported by BreezeNET PRO.11 Series
products.
8.1.1.
Supported MIBs
All products in the BreezeNET PRO.11 Series as well as the Extended Range
Access Point (AP-10 DE) and Workgroup Bridge (WB-10 DE) contain an
embedded SNMP (Simple Network Management Protocol) agent. All
functions can be accessed from the Management Information Base (MIB)
using an SNMP application.
BreezeNET PRO.11 Series agents support the following MIBs:
•
MIB-II (RFC1213)
•
BRIDGE-MIB (RFC1286)
•
BreezeCOM Private MIB
The BreezeCOM Private MIB can be viewed by opening the MIB file on the
provided diskette.
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8.1.2.
Supported Traps
The following traps are implemented by BreezeNET PRO.11 units. All
BreezeNET PRO.11 units with enabled Trap Sending will send traps to the
network’s designated managers. The traps can be viewed and filtered using
SNMPc.
To enable/disable Trap Sending for a device, use the IP and SNMP
Parameters menu (see section 3.4.2).
The following table lists the traps implemented by BreezeCOM PRO.11
units:
Trap
Variables
brzAProamingIn
brzTrapSTAMacAddr
brzAPassociated
brzTrapSTAMacAddr
brzAPdisassociated
brzTrapSTAMacAddr
brzAPaging
brzTrapSTAMacAddr
Description
A station has roamed into this AP coverage area. The trap
contains the MAC address of the associated station.
A new station is associated with this AP. The trap contains
the MAC address of the associated station.
A station has disassociated itself from this AP. The trap
contains the MAC address of the associated station.
A station association was aged out and removed from this
AP. The trap contains the MAC address of the aged-out
station.
brzAProamedout
brzTrapSTAMacAddr
A station has roamed out of this AP’s range. The trap
brzSTAassociated
brzLastAPMacAddr
A station has become associated with, or roamed to, a new
brzTrapAPMac
AP. The trap contains the MAC address and average RSSI
brzTrapLastRssiQuality
level of the new AP (TrapAPMac and TrapRssiQuality
brzTrapRssiQuality
variables). If the station has been roaming, the MAC
contains the MAC address of the station that roamed out.
address of the old AP and the RSSI level prior to roaming
are also provided (LastAPMacAddr and LastRssiQuality
variables). For an association, the second address appears
as all zeros.
brzWlanStatus
brzTrapToggle
The wireless media condition has changed. An ON value is
brzTrapMacAddress
sent when the wireless LAN quality for a station or AP drops
below the WLAN trap threshold. An OFF value is sent if the
quality improves beyond the threshold. The current value of
wireless LAN quality is also sent.
brzWlanStatusOfStation
brzTrapToggle
The quality of the wireless connection to the AP has
brzTrapMacAddress
changed. An ON value is sent when the connection goes
lower than the predetermined threshold. An OFF value is
sent when the quality improves above the threshold. The
brzTrapMacAddress variable contains the MAC address of
the applicable station.
brzGeneral
brzTrapIndex
For future use.
brzTrapText
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8.2. Technical Specifications
8.2.1.
Specifications for BreezeNET PRO.11 Units
The following table provides the technical specifications for all products in
the BreezeNET PRO.11 Series.
Technical Specifications
AP-10 PRO.11, SA-10/40 PRO.11,
WB-10 PRO.11
Wired LAN interface
Compliant with
Ethernet / IEEE 802.3 CSMA/CD standard
Physical Interface
10BaseT
Network Operating Systems supported
All
Network protocols supported
All
Wireless LAN interface
Compliant with
IEEE 802.11 CSMA / CA Wireless LAN standard
Physical interface – two antennas
Integrated or External
Radio Specifications
Type
Frequency Hopping Spread Spectrum (FHSS)
Frequency range
2.4 GHz – 2.4835 GHz (ISM band)
(different ranges available for countries using other bands)
Dwell time
32, 64, 128 ms
Transmitted power:
- integrated antennas
Transmitted power:
- external antennas
Up to 100 mW (20dBm) EIRP
D models:
- High Power (at the connector): 17dBm (50mW)
- Low Power (at the connector): 4dBm (25 mW)
DE models:
At the connector: 0.01mW (-2dBm)
Sensitivity
- @ 1 Mbps
- 81 dBm
- @ 2 Mbps
- 75 dBm
- @ 3 Mbps
- 67 dBm
Modulation
Multilevel GFSK
Demodulation Technology
DSP-based with adaptive equalization
Antenna Diversity
Two antennas, selected for use on a packet basis
Frequency Accuracy
+/- 10 PPM
Approvals of Compliance
FCC part 15, ETS 300-328, UL, UL/C, TUV/GS, CE
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Access
Points
Station
Adapters
Ethernet
Bridges
AP-10 PRO.11
SA-10/40 PRO.11
WB-10 PRO.11
Technical Specifications
Configuration and Management
Configuration and Setup
Via Local Monitor port (serial RS-232)
SNMP management
- SNMP agents
MIB II, Bridge MIB, WLAN MIB, and private MIB
- Access via
Wired LAN, Wireless LAN
Site Survey
Via Local Monitor port (serial RS-232)
Via SNMP
Front Panel Display LED indicators
- Power on
- Wired LAN activity
- Wireless LAN synchronization
- Wireless LAN signal quality/Load
S/W upgradeable
Through TFTP download
System Considerations
Range (Access Point to Station)
Depends on rate and antenna cable length/quality.
(Accurate values must be calculated for specific installations. )
Refer to section 4.2.7, Using Outdoor Range Tables.
- Range - unobstructed with integrated
2000 ft. (600m)
antennas
- Range - unobstructed with external
antennas (models D and DE)
USA FCC - up to 6 miles
Europe ETSI - up to 2.5 km
Europe ETSI (DE model only) - up to 5 km
Non-Regulated - 30 km and above
- Range - Office Environment
Up to 500 ft. (150m)
Maximum no. of APs per wired LAN
Unlimited
Maximum no. of co-located (overlapping)
15
cells (Access Points)
Data Rate
- over the air
1, 2, or 3 Mbps
- nominal net
Up to 2 Mbps
- aggregate
Over 5 Mbps with overlapped cells
High Speed roaming
up to 60 mph (90 kph)
Load sharing support
yes (with WIX)
Dynamic rate selection based on radio
Yes
medium quality
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Technical Specifications
Access
Points
Station
Adapters
Ethernet
Bridges
AP-10 PRO.11
SA-10/40 PRO.11
WB-10 PRO.11
Electrical
External Power Supply
100V - 250V, 50-60Hz, 0.5A
Input Voltage
5Vdc
Power Consumption
1.5A (peak)
1.2A (average)
Dimensions (without antennas
and power supply)
5.1” x 3.4” x 1.35”
Weight (without antennas and
power supply)
0.9 lb. (0.4 kg.)
(13cm x 8.6cm x 3cm)
Environmental
Operating Temperature
32° F - 105° F (0° C - 40° C)
Operating Humidity
5% - 95% non-condensing
Note: All specifications are subject to change without notice.
8.2.2.
Specifications for AL 1 Lightning Arrestor
Turn on voltage
75V
Insertion loss
0.3dB typical
DC path from input to output
existing
Operating Temperature
-55° C to +70° C
Dimensions
67.5mm x 25mm x 25mm (2.7” x 1” x 1”)
Connectors
• Antenna Port: N-type, Female
Operating Environment
Indoor/Outdoor
Grounding
One of the female-type N connectors is mounted directly through a hole in the
• Equipment Port: N-type, Female
shelter wall and held in place with a lockwasher and nut.
Note: All specifications are subject to change without notice.
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8.3. Wireless LAN Concepts
Wireless LAN technology is becoming increasingly popular for a wide
variety of applications. After evaluating the technology, users are convinced
of its reliability, more than satisfied with its performance, and are ready to
use it for large-scale and complex wireless networks.
Originally designed for indoor office applications, today’s wireless LANs
can be used for both indoor client-server and peer-to-peer networks as well
as for outdoor point-to-point and point-to-multipoint remote bridging
applications.
Wireless LANs are designed to be modular and very flexible. They can also
be optimized for different environments. For example, point-to-point
outdoor links are less susceptible to interference and can have higher
performance if designers increase the “dwell time” and disable the “collision
avoidance” and “fragmentation” mechanisms described later in this section.
Topology
Wired LAN Topology
Traditional LANs (Local Area Networks) link PCs and other computers to
one another and to file servers, printers and other network equipment using
cables or optic fibers as the transmission medium.
Figure 9.1: Wired LAN Topology
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Wireless LAN Topology
Wireless LANs allow workstations to communicate and to access the
network using radio propagation as the transmission medium. Wireless
LANs can be connected to existing wired LANs as an extension, or can
form the basis of a new network. While adaptable to both indoor and
outdoor environments, wireless LANs are especially suited to indoor
locations such as office buildings, manufacturing floors, hospitals and
universities.
The basic building block of the wireless LAN is the Cell. This is the area in
which wireless communication takes place. The coverage area of a cell
depends on the strength of the propagated radio signal and the type and
construction of walls, partitions and other physical characteristics of the
indoor environment. PC-based workstations, notebook and pen-based
computers can move freely in the cell.
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Disclaimer: This diagram is for illustrative purposes only. It should not be
confused with the transceiver operating in a standalone mode. When this
diagram is in use, the transceiver will be used in conjunction with amp
model AMP-2440-250/500 and the antennas listed in this manual.
Figure 9.2: The Basic Wireless LAN Cell
Each wireless LAN cell requires some communications and traffic
management. This is coordinated by an Access Point (AP) which
communicates with each wireless station in its coverage area. Stations also
communicate with each other via the AP, so communicating stations can be
hidden from one another. In this way, the AP functions as a relay, extending
the range of the system.
The AP also functions as a bridge between the wireless stations and the
wired network and the other wireless cells. Connecting the AP to the
backbone or other wireless cells can be done by wire or by a separate
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wireless link, using wireless bridges. The range of the system can be
extended by cascading several wireless links, one after the other.
Figure 9.3: Wireless LAN Connectivity
Roaming
When any area in the building is within reception range of more than one
Access Point, the cells’ coverage is said to overlap. Each wireless station
automatically establishes the best possible connection with one of the
Access Points. Overlapping coverage areas are an important attribute of the
wireless LAN setup, because this enables seamless roaming between
overlapping cells.
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Figure 9.4: Roaming Through Overlapping Cells
Roaming allows mobile users with portable stations to move freely between
overlapping cells, constantly maintaining their network connection.
Roaming is seamless: a work session can be maintained while moving from
one cell to another. Multiple Access Points can provide wireless coverage
for an entire building or campus. When the coverage area of two or more
APs overlap, the stations in the overlapping area can establish the best
possible connection with one of the APs, continuously searching for the best
AP. In order to minimize packet loss during switchover, the “old” and
“new” APs communicate to coordinate the process.
Load Balancing
Congested areas with many users and heavy traffic load per unit may require
a multi-cell structure. In a multi-cell structure, several co-located APs
“illuminate” the same area creating a common coverage area which
increases aggregate throughput. Stations inside the common coverage area
automatically associate with the AP that is less loaded and provides the best
signal quality. The stations are equally divided between the APs in order to
equally share the load between all APs. Efficiency is maximized because all
APs are working at the same low level load. Load balancing is also known
as load sharing.
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Figure 9.5: The Common Coverage Area of a Multi-cell Structure
Dynamic Rate Switching
The data rate of each station is automatically adjusted according to the
received signal quality. Performance (throughput) is maximized by
increasing the data rate and decreasing re-transmissions. This is very
important for mobile applications where the signal quality fluctuates
rapidly, but less important for fixed outdoor installations where signal
quality is stable.
Media Access
When many users are located in the same area, performance becomes an
issue. To address this issue, wireless LANs use the Carrier Sense Multiple
Access (CSMA) algorithm with a Collision Avoidance (CA) mechanism in
which each unit senses the medium before it starts to transmit.
If the medium is free for several microseconds, the unit can transmit for a
limited time. If the medium is busy, the unit will back off for a random time
before it senses again. Since transmitting units compete for air time, the
protocol should ensure equal fairness between the stations.
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Fragmentation
Fragmentation of packets into shorter fragments adds protocol overhead and
reduces protocol efficiency when no errors are expected, but reduces the
time spent on re-transmissions if errors are likely to occur. No
fragmentation or longer fragment length adds overhead and reduces
efficiency in case of errors and re-transmissions (multi-path).
Collision Avoidance
To avoid collisions with other incoming calls, each station transmits a short
RTS (Request To Send) frame before the data frame. The Access Point
sends back a CTS (Clear To Send) frame with permission to start the data
transmission. This frame includes the time that this station is going to
transmit. This frame is received by all the stations in the cell, notifying them
that another unit will transmit during the following Xmsec, so they can not
transmit even if the medium seems to be free (the transmitting unit is out of
range).
Channelization
Using Frequency Hopping Spread Spectrum (FHSS), different hopping
sequences are assigned to different co-located cells. Hopping sequences are
designed so different cells can work simultaneously using different
channels.
Since hopping sequences and hopping timing of different cells cannot be
synchronized (according to FCC regulations), different cells might try to use
the same channel occasionally. Then, one cell uses the channel while the
other cell backs off and waits for the next hop. In the case of a very noisy
environment (multiples and interference), the system must hop quickly. If
the link is quiet and clean, it is better to hop slowly, reducing overhead and
increasing efficiency.
8.4. Radio Signal Propagation
8.4.1.
Introduction
This section explains and simplifies many of the terms relating to antennas
and RF (Radio Frequency) used when dealing with an RF installation
system.
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The following diagram depicts a typical radio system:
Figure 9.6: A Typical Radio System
A radio system transmits information to the transmitter. The information is
transmitted through an antenna which converts the RF signal into an
electromagnetic wave. The transmission medium for electromagnetic wave
propagation is free space.
The electromagnetic wave is intercepted by the receiving antenna which
converts it back to an RF signal. Ideally, this RF signal is the same as that
originally generated by the transmitter. The original information is then
demodulated back to its original form.
8.4.2.
RF Terms and Definitions
dB
The dB convention is an abbreviation for decibels. It is a mathematical
expression showing the relationship between two values.
RF Power Level
RF power level at either the transmitter output or the receiver input is
expressed in Watts. It can also be expressed in dBm. The relation between
dBm and Watts can be expressed as follows:
PdBm = 10 x Log Pmw
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For example:
1 Watt = 1000 mW; PdBm = 10 x Log 1000 = 30 dBm
100 mW; PdBm = 10 x Log 100 = 20 dBm
For link budget calculations, the dBm convention is more convenient than
the Watts convention.
Attenuation
Attenuation (fading) of an RF signal is defined as follows:
Figure 9.7: Attenuation of an RF signal
Pin is the incident power level at the attenuator input
Pout is the output power level at the attenuator output
Attenuation is expressed in dB as follows:
PdB = -10 x Log (Pout/Pin)
For example:
If, due to attenuation, half the power is lost (Pout/Pin = 1/2),
attenuation in dB is -10 x Log (1/2) = 3dB
Path Loss
Loss of power of an RF signal travelling (propagating) through space. It is
expressed in dB. Path loss depends on:
•
The distance between transmitting and receiving antennas
•
Line of sight clearance between the receiving and transmitting antennas
•
Antenna height
Free Space Loss
Attenuation of the electromagnetic wave while propagating through space.
This attenuation is calculated using the following formula:
Free space loss = 36.5 + 20xLog(FMHz) + 20xLog(DMile)
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F is the RF frequency expressed in Mhz.
R is the distance between the transmitting and receiving antennas.
At 2.4 GHz, this formula is: 105+20xLog(DMile)
Antenna Characteristics
Isotropic Antenna
A hypothetical, lossless antenna having equal radiation intensity in all
directions. Used as a zero dB gain reference in directivity calculation (gain).
Antenna Gain
A measure of directivity. It is defined as the ratio of the radiation intensity
in a given direction to the radiation intensity that would be obtained if the
power accepted by the antenna was radiated equally in all directions
(isotropically). Antenna gain is expressed in dBi.
Radiation Pattern
A graphical representation in either polar or rectangular coordinates of the
spatial energy distribution of an antenna.
Side Lobes
The radiation lobes in any direction other than that of the main lobe.
Omni-directional Antenna
Radiates and receives equally in all directions in azimuth. The following
diagram shows the radiation pattern of an omnidirectional antenna with its
side lobes in polar form.
Figure 9.8: Side View
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Figure 9.9: Top View
Directional Antenna
Radiates and receives most of the signal power in one direction. The
following diagram shows the radiation pattern of a directional antenna with
its side lobes in polar form:
Figure 9.10: Radiation Pattern of Directional Antenna
Antenna Beamwidth
The directiveness of a directional antenna. Defined as the angle between two
half-power (-3 dB) points on either side of the main lobe of radiation.
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System Characteristics
Receiver Sensitivity
The minimum RF signal power level required at the input of a receiver for
certain performance (e.g. BER).
EIRP (Effective Isotropic Radiated Power)
The antenna transmitted power. Equal to the transmitted output power
minus cable loss plus the transmitting antenna gain.
Pout
Ct
Gt
Gr
Cr
Pr
Sr
Output power of transmitted in dBm
Transmitter cable attenuation in dB
Transmitting antenna gain in dBi
Receiving antenna gain in dBi
Path loss in dB
Receiver cable attenuation is dB
Received power level at receiver input in dBm
Receiver sensitivity is dBm
Pr = Pout - Ct + Gt - L + Gr - Cr
EIRP = Pout - Ct + Gt
Example:
Link Parameters:
Frequency: 2.4 Ghz
Pout = 17 dBm (50 mW)
Tx and Rx cable length (Ct and Cr) = 50ft. cable type LMR-400 (6.8 dB/100ft)
Tx and Rx antenna gain (Gt and Gr) = 18 dBi
Distance between sites = 5 miles
Receiver sensitivity (Sr) = -74 dBm
Pr >= Sr
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Link Budget Calculation
EIRP = Pout - Ct + Gt = 31.6 dBm
L = 36.5 + 20xLog(FMhz) + 20xLog(DMile) ≅ 118 dB
Pr = EIRP - L + Gr - Cr = -72 dBm
In conclusion, the received signal power is above the sensitivity threshold,
so the link should work. The problem is that there is only a 2 dB difference
between received signal power and sensitivity. Normally, a higher margin is
desirable due to fluctuation in received power as a result of signal fading.
Signal Fading
Fading of the RF signal is caused by several factors:
•
Multipath
The transmitted signal arrives at the receiver from different directions, with
different path lengths, attenuation and delays. The summed signal at the
receiver may result in an attenuated signal.
Figure 9.11: Multipath Reception
•
Bad Line of Sight
An optical line of sight exists if an imaginary straight line can connect
the antennas on either side of the link.
Radio wave clear line of sight exists if a certain area around the optical
line of sight (Fresnel zone) is clear of obstacles. A bad line of sight exists
if the first Fresnel zone is obscured.
•
Link Budget Calculations
•
Weather conditions (Rain, wind, etc.)
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At high rain intensity (150 mm/hr), the fading of an RF signal at 2.4 GHz
may reach a maximum of 0.02 dB/Km
Wind may cause fading due to antenna motion
•
Interference
Interference may be caused by another system on the same frequency
range, external noise, or some other co-located system.
The Line of Sight Concept
An optical line of sight exists if an imaginary straight line can be drawn
connecting the antennas on either side of the link.
Clear Line of Sight
A clear line of sight exists when no physical objects obstruct viewing one
antenna from the location of the other antenna.
A radio wave clear line of sight exists if a defined area around the optical
line of sight (Fresnel Zone) is clear of obstacles.
Fresnel Zone
The Fresnel zone is the area of a circle around the line of sight.
The Fresnel Zone is defined as follows:
Figure 9.12: Fresnel Zone
R = ½ √ (λxD)
R: radius of the first Fresnel zone
λ: wavelength
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D: distance between sites
Figure 9.13: Fresnel Zone Clear of Obstacles
When at least 80% of the first Fresnel Zone is clear of obstacles,
propagation loss is equivalent to that of free space.
8.5. IEEE 802.11 Technical Tutorial
The purpose of this chapter is to give technical readers a basic overview of
the new IEEE 802.11 Standard, enabling them to understand the basic
concepts, principles of operation, and the reasons behind some of the
features and/or components of the Standard.
The document does not cover the entire Standard and does not provide
enough information for the reader to implement an 802.11-compliant device
(for this purpose the reader should refer to the Standard itself).
8.5.1.
Architecture Components
An 802.11 LAN is based on a cellular architecture where the system is
subdivided into cells. Each cell (called Basic Service Set, or BSS, in the
802.11 nomenclature) is controlled by a Base Station (called Access Point
or, in short, AP).
Although a wireless LAN may be formed by a single cell, with a single
Access Point, (and as will be described later, it can also work without an
Access Point), most installations will be formed by several cells, where the
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Access Points are connected through some kind of backbone (called
Distribution System or DS). This backbone is typically Ethernet but, in
some cases, might be wireless itself.
The whole interconnected wireless LAN, including the different cells, their
respective Access Points and the Distribution System, is seen as a single 802
network to the upper layers of the OSI model and is known in the Standard
as the Extended Service Set (ESS).
The following diagram shows a typical 802.11 LAN including the
components described above:
Figure 9.14: Typical 802.11 LAN
The standard also defines the concept of a Portal. A portal is a device that
interconnects between an 802.11 and another 802 LAN. This concept is an
abstract description of part of the functionality of a “translation bridge”.
Even though the standard does not necessarily require it, typical installations
will have the AP and the Portal on a single physical entity. This is also the
case with BreezeCOM’s AP which provides both functions.
8.5.2.
IEEE 802.11 Layers Description
As in any 802.x protocol, the 802.11 protocol covers the Media Access
Control Layer (MAC) and Physical Layer (PHY). The Standard currently
defines a single MAC which interacts with three PHYs (all of them running
at 1 or 2 Mbit/s) as follows:
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•
Frequency Hopping Spread Spectrum (FHSS) in the 2.4 GHz Band
•
Direct Sequence Spread Spectrum (DSSS) in the 2.4 GHz Band, and
•
InfraRed
802.2
802.11 MAC
FH
DS
IR
Data Link
Layer
PHY Layer
Beyond the standard functionality usually performed by MAC Layers, the
802.11 MAC performs other functions that are typically related to upper
layer protocols, such as Fragmentation, Packet Retransmissions, and
Acknowledges.
8.5.3.
The MAC Layer
The MAC Layer defines two different access methods, the Distributed
Coordination Function and the Point Coordination Function:
8.5.3.1
The Basic Access Method: CSMA/CA
The basic access mechanism, called the Distributed Coordination
Function, is basically a Carrier Sense Multiple Access with Collision
Avoidance mechanism (known as CSMA/CA). CSMA protocols are wellknown in the industry, the most popular being Ethernet, which is a CSMA/
CD protocol (CD standing for Collision Detection).
A CSMA protocol works as follows: A station desiring to transmit senses
the medium. If the medium is busy (i.e. some other station is transmitting)
then the station defers its transmission to a later time. If the medium seems
free then the station is allowed to transmit.
These kinds of protocols are very effective when the medium is not heavily
loaded since it allows stations to transmit with minimum delay. But there is
always a chance of two or more stations simultaneously sensing the medium
as being free and transmitting at the same time, causing a collision.
These collision situations must be identified so the MAC layer can
retransmit the packet itself, not by the upper layers, to avoid significant
delay. In the Ethernet case, a collision is recognized by the transmitting
stations which listen while transmitting and go into a retransmission phase
based on an exponential random backoff algorithm.
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While these Collision Detection Mechanisms are a good idea on a wired
LAN, they cannot be used on a wireless LAN environment for two main
reasons:
1. Implementing a Collision Detection Mechanism would require the
implementation of a Full-Duplex radio capable of transmitting and
receiving at the same time, an approach that would increase the price
significantly.
2. In a wireless environment we cannot assume that all stations can hear
each other (a basic assumption of the Collision Detection scheme), and
the fact that a station wants to transmit and senses the medium as free
doesn’t necessarily mean that the medium is free around the receiver’s
area.
In order to overcome these problems, 802.11 uses a Collision Avoidance
(CA) mechanism together with a Positive Acknowledge scheme, as follows:
1. A station wanting to transmit senses the medium. If the medium is busy
then it delays. If the medium is free for a specified time (called Distributed Inter Frame Space (DIFS) in the standard), then the station is
allowed to transmit.
2. The receiving station checks the CRC of the received packet and sends
an acknowledgment packet (ACK). Receipt of the acknowledgment indicates to the transmitter that no collision occurred. If the sender does not
receive the acknowledgment, then it retransmits the fragment until it
either receives acknowledgment or is thrown away after a given number
of retransmissions.
8.5.3.2
Virtual Carrier Sense
In order to reduce the probability of two stations colliding because they
cannot hear each other, the standard defines a Virtual Carrier Sense
mechanism:
A station wanting to transmit a packet first transmits a short control packet
called RTS (Request To Send), which includes the source, destination, and
the duration of the following transaction (i.e. the packet and the respective
ACK), the destination station responds (if the medium is free) with a
response control Packet called CTS (Clear to Send), which includes the
same duration information.
All stations receiving either the RTS or the CTS, set their Virtual Carrier
Sense indicator (called NAV, for Network Allocation Vector), for the
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given duration, and use this information together with the Physical Carrier
Sense when sensing the medium.
This mechanism reduces the probability of a collision on the receiver area
by a station that is “hidden” from the transmitter to the short duration of the
RTS transmission because the station hears the CTS and “reserves” the
medium as busy until the end of the transmission. The duration information
on the RTS also protects the transmitter area from collisions during the
ACK (from stations that are out of range of the acknowledging station).
It should also be noted that, due to the fact that the RTS and CTS are short
frames, the mechanism also reduces the overhead of collisions, since these
are recognized faster than if the whole packet was to be transmitted. (This is
true if the packet is significantly bigger than the RTS, so the standard allows
for short packets to be transmitted without the RTS/CTS transmission. This
is controlled per station by a parameter called RTS Threshold).
The following diagrams show an exchange between stations A and B, and
the NAV setting of their neighbors:
Figure 9.15: Transaction Between Stations A and B
The NAV State is combined with the physical carrier sense to indicate the
busy state of the medium.
8.5.3.3
MAC Level Acknowledgments
As mentioned earlier in this document, the MAC layer performs Collision
Detection by expecting the reception of an acknowledge to any transmitted
fragment (Packets that have more than one destination, such as Multicasts,
are not acknowledged.)
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8.5.3.4
Fragmentation and Reassembly
Typical LAN protocols use packets several hundred bytes long (the longest
Ethernet packet could be up to 1518 bytes long).
There are several reasons why it is preferable to use smaller packets in a
wireless LAN environment:
•
Due to the higher Bit Error Rate of a radio link, the probability of a
packet getting corrupted increases with the packet size.
•
In case of packet corruption (either due to collision or noise), the smaller
the packet, the less overhead it causes to retransmit it.
•
On a Frequency Hopping system, the medium is interrupted periodically
for hopping (in our case every 20 milliseconds), so, the smaller the
packet, the smaller the chance that the transmission will be postponed
after dwell time.
However, it doesn’t make sense to introduce a new LAN protocol that
cannot deal with packets 1518 bytes long which are used on Ethernet, so the
committee decided to solve the problem by adding a simple fragmentation/
reassembly mechanism at the MAC Layer.
The mechanism is a simple Send-and-Wait algorithm, where the
transmitting station is not allowed to transmit a new fragment until one of
the following happens:
1. Receives an ACK for the said fragment, or
2. Decides that the fragment was retransmitted too many times and drops
the whole frame.
It should be noted that the standard does allow the station to transmit to a
different address between retransmissions of a given fragment. This is
particularly useful when an AP has several outstanding packets to different
destinations and one of them does not respond.
The following diagram shows a frame (MSDU) being divided to several
fragments (MPDUs):
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Figure 9.16: Frame Fragmentation
8.5.3.5
Inter Frame Spaces
The Standard defines 4 types of Inter Frame Spaces, which are use to
provide different priorities:
•
SIFS - Short Inter Frame Space, separates transmissions belonging to
a single dialog (e.g. Fragment-Ack), and is the minimum Inter Frame
Space. There is always at most one single station to transmit at any given
time, therefore giving it priority over all other stations.
This value is a fixed value per PHY and is calculated in such a way that
the transmitting station will be able to switch back to receive mode and
be capable of decoding the incoming packet. On the 802.11 FH PHY this
value is set to 28 microseconds
•
PIFS - Point Coordination IFS, is used by the Access Point (or Point
Coordinator, as called in this case), to gain access to the medium before
any other station. This value is SIFS plus a Slot Time (defined in the following paragraph), i.e. 78 microseconds.
•
DIFS - Distributed IFS, is the Inter Frame Space used for a station willing to start a new transmission, which is calculated as PIFS plus one slot
time, i.e. 128 microseconds.
•
EIFS - Extended IFS, which is a longer IFS used by a station that has
received a packet that it could not understand. This is needed to prevent
the station (which could not understand the duration information for the
Virtual Carrier Sense) from colliding with a future packet belonging to
the current dialog.
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8.5.3.6
Exponential Backoff Algorithm
Backoff is a well known method used to resolve contention between
different stations wanting to access the medium. The method requires each
station to choose a Random Number (n) between 0 and a given number, and
wait for this number of Slots before accessing the medium, always checking
if a different station has accessed the medium before.
The Slot Time is defined in such a way that a station will always be capable
of determining if another station has accessed the medium at the beginning
of the previous slot. This reduces collision probability by half.
Exponential Backoff means that each time the station chooses a slot and
happens to collide, it will increase the maximum number for the random
selection exponentially.
The 802.11 standard defines an Exponential Backoff Algorithm, that must
be executed in the following cases:
•
When the station senses the medium before the first transmission of a
packet, and the medium is busy
•
After each retransmission, and
•
After a successful transmission
The only case when this mechanism is not used is when the station decides
to transmit a new packet and the medium has been free for more than DIFS.
The following figure shows a schematic of the access mechanism:
Figure 9.17: Access Mechanism
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8.5.4.
How Does a Station Join an Existing Cell (BSS)?
When a station wants to access an existing BSS (either after power-up, sleep
mode, or just entering the BSS area), the station needs to get
synchronization information from the Access Point (or from the other
stations when in ad-hoc mode, which will be discussed later).
The station can get this information by one of two means:
1. Passive Scanning: In this case the station just waits to receive a Beacon
Frame from the AP, (the beacon frame is a frame sent out periodically
by the AP containing synchronization information), or
2. Active Scanning: In this case the station tries to locate an Access Point
by transmitting Probe Request Frames, and waits for Probe Response
from the AP.
Both methods are valid. A method is chosen according to the power
consumption/performance trade-off.
8.5.4.1
The Authentication Process
Once the station has located an Access Point, and decides to join its BSS, it
goes through the Authentication Process. This is the interchange of
information between the AP and the station, where each side proves the
knowledge of a given password.
8.5.4.2
The Association Process
Once the station is authenticated, it then starts the Association Process,
which is the exchange of information about the station and BSS capabilities,
and which allows the DSS (the set of APs) to know about the current
position of the station). A station is capable of transmitting and receiving
data frames only after the association process is completed.
8.5.5.
Roaming
Roaming is the process of moving from one cell (or BSS) to another without
losing connection. This function is similar to the cellular phones’ handover,
with two main differences:
1. On a packet-based LAN system, the transition from cell to cell may be
performed between packet transmissions, as opposed to telephony where
the transition may occur during a phone conversation, this makes the
LAN roaming a little easier, but
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2. On a voice system, a temporary disconnection may not affect the conversation, while in a packet-based environment it significantly reduces performance because retransmission is then performed by the upper layer
protocols.
The 802.11 standard does not define how roaming should be performed, but
defines the basic tools. These include active/passive scanning, and a reassociation process, where a station which is roaming from one Access
Point to another becomes associated with the new one1.
8.5.6.
Keeping Synchronization
Stations need to keep synchronization, which is necessary for keeping
hopping synchronized, and other functions like Power Saving. On an
infrastructure BSS, this is achieved by all the stations updating their clocks
according to the AP’s clock, using the following mechanism:
The AP periodically transmits frames called Beacon Frames. These frames
contain the value of the AP’s clock at the moment of transmission (note that
this is the moment when transmission actually occurs, and not when it is put
in the queue for transmission. Since the Beacon Frame is transmitted using
CSMA rules, transmission may be delayed significantly).
The receiving stations check the value of their clocks at the moment the
signal is received, and correct it to keep in synchronization with the AP’s
clock. This prevents clock drifting which could cause loss of synch after a
few hours of operation.
8.5.7.
Security
Security is one of the first concerns that people have when deploying a
wireless LAN. The 802.11 committee has addressed the issue by providing
what is called WEP (Wired Equivalent Privacy).
Users are primarily concerned that an intruder should not be able to:
•
Access the Network resources by using similar wireless LAN equipment
•
Capture wireless LAN traffic (eavesdropping)
The BreezeNET product line provides a patented enhanced roaming mechanism which allows stations to
roam at speeds of 60 Km/h without losing or duplicating packets.
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8.5.7.1
Preventing Access to Network Resources
This is done by the use of an Authentication mechanism where a station
needs to prove knowledge of the current key. This is very similar to Wired
LAN privacy, in the sense that an intruder needs to enter the premises (by
using a physical key) in order to connect his workstation to the wired LAN.
8.5.7.2
Eavesdropping
Eavesdropping is prevented by using the WEP algorithm which is a Pseudo
Random Number Generator initialized by a shared secret key. This PRNG
outputs a key sequence of pseudo-random bits equal in length to the largest
possible packet which is combined with the outgoing/incoming packet
producing the packet transmitted in the air.
The WEP is a simple algorithm based on RSA’s RC4 which has the
following properties:
•
Reasonably strong:
Brute-force attack to this algorithm is difficult because every frame is
sent with an Initialization Vector which restarts the PRNG for each
frame.
•
Self Synchronizing:
The algorithm re-synchronizes for each message. This is necessary in
order to work in a connection-less environment, where packets may get
lost (as any LAN).
8.5.8.
Power Saving
Wireless LANs are typically related to mobile applications. In this type of
application, battery power is a scare resource. This is the reason why the
802.11 standard directly addresses the issue of Power Saving and defines an
entire mechanism which enables stations to go into sleep mode for long
periods of time without losing information.
The main idea behind the Power Saving Mechanism is that the AP
maintains a continually updated record of the stations currently working in
Power Saving mode, and buffers the packets addressed to these stations
until either the stations specifically request the packets by sending a polling
request, or until they change their operation mode.
As part of its Beacon Frames, the AP also periodically transmits information
about which Power Saving Stations have frames buffered at the AP, so these
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stations wake up in order to receive the Beacon Frame. If there is an
indication that there is a frame stored at the AP waiting for delivery, then
the station stays awake and sends a Polling message to the AP to get these
frames.
Multicasts and Broadcasts are stored by the AP, and transmitted at a preknown time (each DTIM), when all Power Saving stations who wish to
receive this kind of frames are awake.
8.5.9.
Frame Types
There are three main types of frames:
•
Data Frames: which are used for data transmission
•
Control Frames: which are used to control access to the medium (e.g.
RTS, CTS, and ACK), and
•
Management Frames: which are frames that are transmitted in the same
manner as data frames to exchange management information, but are not
forwarded to upper layers (e.g. beacon frames).
Each frame type is subdivided into different Subtypes, according to its
specific function.
8.5.10.
Frame Formats
All 802.11 frames are composed of the following components:
Preamble
PLCP Header
MAC Data
CRC
8.5.10.1
Preamble
This is PHY dependent, and includes:
•
Synch: An 80-bit sequence of alternating zeros and ones, which is used
by the PHY circuitry to select the appropriate antenna (if diversity is
used), and to reach steady-state frequency offset correction and
synchronization with the received packet timing.
•
SFD: A Start Frame delimiter which consists of the 16-bit binary pattern
0000 1100 1011 1101, which is used to define frame timing.
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8.5.10.2
PLCP Header
The PLCP Header is always transmitted at 1 Mbit/s and contains Logical
information used by the PHY Layer to decode the frame. It consists of:
•
PLCP_PDU Length Word: which represents the number of bytes contained in the packet. This is useful for the PHY to correctly detect the
end of packet.
•
PLCP Signaling Field: which currently contains only the rate information, encoded in 0.5 Mbps increments from 1 Mbit/s to 4.5 Mbit/s.
•
Header Error Check Field: Which is a 16 Bit CRC error detection
field.
8.5.10.3
MAC Data
The following figure shows the general MAC Frame Format. Part of the
fields are only present in part of the frames as described later.
Figure 9.18: MAC Frame Format
Frame Control Field
The Frame Control field contains the following information:
Figure 9.19: Frame Control Field
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Protocol Version
This field consists of 2 bits which are invariant in size and placement across
following versions of the 802.11 Standard, and will be used to recognize
possible future versions. In the current version of the standard the value is
fixed as 0.
Type and Subtype
These 6 bits define the Type and SubType of the frame as indicated in the
following table:
Type Value
Type Description
Subtype Value
b3 b2
Subtype Description
b7 b6 b5 b4
00
Management
0000
Association Request
00
Management
0001
Association Response
00
Management
0010
Association Request
00
Management
0011
Reassociation Response
00
Management
0100
Probe Request
00
Management
0101
Probe Response
00
Management
0110-0111
Reserved
00
Management
1000
Beacon
00
Management
1001
ATIM
00
Management
1010
Disassociation
00
Management
1011
Authentication
00
Management
1100
Deauthentication
00
Management
1101-1111
Reserved
01
Control
0000-0001
Reserved
01
Control
1010
PS-Poll
01
Control
1011
RTS
01
Control
1100
CTS
01
Control
1101
ACK
01
Control
1110
CF End
01
Control
1111
CF End + CF-ACK
10
Data
0000
Data
10
Data
0001
Data + CF-Ack
10
Data
0010
Data + CF-Poll
10
Data
0011
Data + CF-ACK + CF-Poll
10
Data
0100
Null Function (no data)
10
Data
0101
CF-Ack (no data)
10
Data
0110
CF-Poll (no data)
10
Data
0111
CF-Ack + CF-Poll (no data)
10
Data
1000-1111
Reserved
10
Data
0000-1111
Reserved
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ToDS
This bit is set to 1 when the frame is addressed to the AP for forwarding to
the Distribution System (including the case where the destination station is
in the same BSS, and the AP is to relay the frame).
The Bit is set to 0 in all other frames.
FromDS
This bit is set to 1 when the frame is received from the Distribution System.
More Fragments
This bit is set to 1 when there are more fragments belonging to the same
frame following the current fragment.
Retry
This bit indicates that this fragment is a retransmission of a previously
transmitted fragment. This is used by the receiver station to recognize
duplicate transmissions of frames that may occur when an Acknowledgment
packet is lost.
Power Management
This bit indicates the Power Management mode that the station will be in
after the transmission of this frame. This is used by stations which are
changing state either from Power Save to Active or vice versa.
More Data
This bit is used for Power Management as well as by the AP to indicate that
there are more frames buffered for this station. The station may decide to
use this information to continue polling or even changing to Active mode.
WEP
This bit indicates that the frame body is encrypted according to the WEP
algorithm
Order
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This bit indicates that this frame is being sent using the Strictly-Ordered
service class.2
Duration/ID
This field has two meanings depending on the frame type:
•
In Power-Save Poll messages this is the Station ID
•
In all other frames this is the duration value used for the NAV
Calculation.
Address Fields
A frame may contain up to 4 Addresses depending on the ToDS and
FromDS bits defined in the Control Field, as follows:
•
Address-1 is always the Recipient Address (i.e. the BSS station that is
the immediate recipient of the packet). If ToDS is set, this is the AP
Address; if ToDS is not set, then this is the address of the end-station.
•
Address-2 is always the Transmitter Address (i.e. the station which is
physically transmitting the packet). If FromDS is set, this is the AP
address; if it is not set, then it is the Station address.
•
Address-3 is in most cases the remaining, missing address. On a frame
with FromDS set to 1, Address-3 is the original Source Address; if the
frame has the ToDS set, then Address 3 is the destination Address.
•
Address-4 is used in special cases where a Wireless Distribution System
is used, and the frame is being transmitted from one Access Point to
another. In such cases, both the ToDS and FromDS bits are set, so both
the original Destination and the original Source Addresses are missing.
The following Table summarizes the usage of the different Addresses
according to ToDS and FromDS bits setting:
To DS From
DS
Address Address Address Address
DA
SA
BSSID
N/A
The Strictly-Ordered Service Class is defined for users that cannot accept change of ordering between Uni-
cast Frames and Multicast Frames (ordering of Unicast frames to a specific address is always maintained).
The only known protocol that would need this service class is DEC’s LAT.
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DA
BSSID
SA
N/A
BSSID
SA
DA
N/A
RA
TA
DA
SA
Sequence Control
The Sequence Control Field is used to represent the order of different
fragments belonging to the same frame, and to recognize packet
duplications. It consists of two subfields, Fragment Number and Sequence
Number, which define the frame and the number of the fragment in the
frame.
CRC
The CRC is a 32-bit field containing a 32-bit Cyclic Redundancy Check
(CRC)
8.5.11.
Most Common Frame Formats
8.5.11.1
RTS Frame Format
The RTS frame looks as follows:
Figure 9.20: RTS Frame Format
The RA of the RTS frame is the address of the STA on the wireless medium
that is the intended immediate recipient of the next Data or Management
frame.
The TA is the address of the STA transmitting the RTS frame.
The Duration value is the time, in microseconds, required to transmit the
next Data or Management frame, plus one CTS frame, plus one ACK frame,
plus three SIFS intervals.
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8.5.11.2
CTS Frame Format
The CTS frame looks as follows:
Figure 9.21: CTS Frame
The Receiver Address (RA) of the CTS frame is copied from the
Transmitter Address (TA) field of the immediately previous RTS frame to
which the CTS is a response.
The Duration value is the value obtained from the Duration field of the
immediately previous RTS frame, minus the time, in microseconds, required
to transmit the CTS frame and its SIFS interval.
8.5.11.3
ACK Frame Format
The ACK frame looks as follows:
Figure 9.22: ACK Frame Format
The Receiver Address of the ACK frame is copied from the Address 2 field
of the immediately previous frame.
If the More Fragment bit was set to 0 in the Frame Control field of the
previous frame, the Duration value is set to 0, otherwise the Duration value
is obtained from the Duration field of the previous frame, minus the time, in
microseconds, required to transmit the ACK frame and its SIFS interval.
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8.5.12.
Point Coordination Function (PCF)
Beyond the basic Distributed Coordination Function, there is an optional
Point Coordination Function, which may be used to implement timebounded services, like voice or video transmission. This Point Coordination
Function makes use of the higher priority that the Access Point may gain by
the use of a smaller Inter Frame Space (PIFS).
By using this higher priority access, the Access Point issues polling requests
to the stations for data transmission, hence controlling medium access. To
still enable regular stations to access the medium, there is a provision that
the Access Point must leave enough time for Distributed Access in between
the PCF.
8.5.13.
Ad-hoc Networks
In certain circumstances, the users may wish to build up wireless LAN
networks without an infrastructure (more specifically without an Access
Point). This may include file transfer between two notebook users,
co-workers meeting outside the office, etc.
The 802.11 Standard addresses this need by the definition of an “ad-hoc”
mode of operation. In this case, there is no Access Point and part of its
functionality is performed by the end-user stations (such as Beacon
Generation, synchronization, etc.). Other AP functions are not supported
(such as frame-relaying between two stations not in range, or Power
Saving).
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AMP2440-250
AMP2440-500
Installation Instructions
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Amplifier Kit
AMPLIFIER KIT
Each Amplifier Kit Includes:
•
•
•
•
•
•
•
•
Bi-directional Amplifier, AMP2440-250 or AMP2440-500
DC Power Injector
5ft. LMR-400 cable (N-male to N-female)
2 N-male to N-male adapters
110/220 VAC to 12VDC Power Supply, and power cord
Stainless Steel U-Bolt and mounting bracket
Vapor wrap coaxial connector sealing tape
Installation Manual
Cable Length vs. Output Power
The AMP2440 is an amplifier designed for installation by
professional radio installers. Several key factors unique to the
particular installation determine the power level at the input
of the amplifier. The most important consideration is the
cable loss in the transmission cable between the radio and the
pole mounted amp. It is important that the installer
understand these and other factors when computing the input
power to the amplifier. The table below shows cable length
and output power for both the 250mW and 500mW models.
Power Output vs. Cable Length
AMP model
Cable type
Length
Power in
Power out
AMP2440-250
LMR-400
30 ft.
13.9dBm
24dBm/250mW*
AMP2440-250
LMR-400
50 ft.
12.5dBm
24dBm.250mW*
AMP2440-250
LMR-400
100 ft.
9dBm
24dBm/250mW
AMP2440-250
LMR-600
150 ft.
9dBm
24dBm/250mW
AMP2440-500
LMR-600
22 ft.
15dBm
27dBm/500mW
AMP2440-500
LMR-600
100 ft.
11.5dBm
26.5dBm/447mW
* higher output power is not possible because the output is limited.
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Amplifier Kit
Installation and Mounting
The amplifier can be mast mounted using the steel U-bolt included with the unit.
The amplifier should be installed with the connectors facing downward. After
placing the assembly on the mast, use an open-end wrench to carefully tighten the
nuts. Take care not to over-tighten the nuts or you may inadvertently strip the
threads. See the diagram below for proper assembly.
AMP
MAST
It is very important to waterproof the RF connectors on the
amplifier. However, it is recommended that you do not seal the connectors until
after all system tests have been performed. Be sure to use the high quality weather
resistant vapor wrap included with you amplifier kit to seal all the outside
connections.
The DC Power Injector is not in a waterproof enclosure and must be protected from
the weather. It can be permanently mounted to a surface using the mounting flanges.
Refer to the BreezeCom Amplifier Installation Details diagram shown later in this
manual.
NOTE: When using the 24dB gain dish antenna in the United States,
the external filter (P/N: SPF-1) must be installed to comply
with FCC emission requirements.
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Amplifier Kit
Amplifier Connections and Indicators
Transmit This LED glows RED in transmit mode.
LED:
Receive This LED glows GREEN in the “receive” mode. (When DC power is supplied, the unit defau
LED: mode).
DC Injector This “N” Female connector is connected to the DC Power Injector via the transmission cable
Connection:
Antenna This “N” Female connector connects to the antenna with a short length of coax cable.
Connection:
DC Power Injector Connections and Indicators
A DC Power Injector is an in-line device which “injects” the DC power necessary to
operate the amplifier onto a transmission line. This allows the cable to carry both
RF signals and DC power to the mast-mounted amplifier.
Transmit This LED glows RED when the pole mounted amplifier goes into the transm
LED: The Remote Transmit LED is driven by unique circuitry, which actually de
in the DC current traveling through the transmission line to the amplifier.
Receive This LED glows GREEN when DC power is applied to the amplifier and it
LED: receive mode. When toggling between transmit and receive this LED will
dimmer.
To Radio This “N” Female connector is connected to the radio modem via a short jum
Connection:
To This “N” Female connector connects to the amplifier on the mast via the tra
Amplifier line.
Connection:
12 VDC: This is the DC power input for the injector and is a standard 2.1mm barrel j
+12VDC should be applied with center positive.
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Amplifier Kit
Power Supply
The AMP2440 comes with power supplies that have standard 2.1 mm barrel plugs
(which are configured as positive (+) tip and negative (-) outer conductor).
Although normally supplied with a power supply, any regulated 12 Volt DC 1 amp
supply can be used. The power supply can be used with 110 or 240 VAC power.
Operation
The unit operates automatically and there are no user adjustments.
The amplifier is only intended for use with the BreezeNET Radios. These radios
“ping pong” back and forth between transmit and receive so quickly, during normal
operation, that both the TX and RX LEDs will appear to be lit simultaneously. In
fact, they are turning on and off so quickly that they appear to be on all the time.
You can tell how quickly one of these LEDs are turning on and off by their
brightness. Their glow will be slightly dimmer when they are off.
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