Wistron NeWeb DNUAE134A 802.11 a/b/g/n USB Module User Manual DNUA E134A User Manual okx
Wistron NeWeb Corporation 802.11 a/b/g/n USB Module DNUA E134A User Manual okx
Users Manual
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
1
User Manual
Model Name: DNUA-E134A
(QCA AR9374X-AL3D
2x2 802.11 abgn USB Module)
Revision: 1
Issue Date: 2013/5/2
This document and the information contained herein is the property of Wistron NeWeb
Corporation and reproduction by any means (including, but not limited to, xerographic,
chemical, electronic) and distribution is expressly prohibited without prior written consent from
Wistron NeWeb Corporation. The document and information contained herein are confidential
and may not be divulged without express written consent from Wistron NeWeb Corporation,
located at 20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Copyright 2010 by Wistron NeWeb Corporation / All rights reserved.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
2
Revision History
Edition # Reason for revision Issue date Author
1.0 Initial Draft Document 2013/5/2 Louis Wu
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
3
FCC Statement:
Federal Communication Commission Interference Statement
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one of the following measures:
● Reorient or relocate the receiving antenna.
● Increase the separation between the equipment and receiver.
● Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
● Consult the dealer or an experienced radio/TV technician for help.
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1)
This device may not cause harmful interference, and (2) this device must accept any interference received,
including interference that may cause undesired operation.
For product available in the USA/Canada market, only channel 1~11
can be operated. Selection of other channels is not possible.
This device and it's antennas(s) must not be co-located or operating in conjunction with any other
antenna or transmitter except in accordance with FCC multi-transmitter product procedures.
This device is going to be operated in 5.15~5.25GHz frequency range, it is restricted in indoor environment only.
Devices will not permit operations on channels 120-132 for 11a and 11n/a which overlap the 5600 - 5650 MHz
band.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
4
IMPORTANT NOTE:
This module is intended for OEM integrator. The OEM integrator is responsible for the
compliance to all the rules that apply to the product into which this certified RF module is
integrated.
Additional testing and certification may be necessary when multiple modules are used.
20cm minimum distance has to be able to be maintained between the antenna and the users for the
host this module is integrated into. Under such configuration, the FCC radiation exposure limits set
forth for an population/uncontrolled environment can be satisfied.
Any changes or modifications not expressly approved by the manufacturer could void the user's
authority to operate this equipment.
USERS MANUAL OF THE END PRODUCT:
In the users manual of the end product, the end user has to be informed to keep at least 20cm
separation with the antenna while this end product is installed and operated. The end user has to be
informed that the FCC radio-frequency exposure guidelines for an uncontrolled environment can be
satisfied. The end user has to also be informed that any changes or modifications not expressly
approved by the manufacturer could void the user's authority to operate this equipment. If the size of
the end product is smaller than 8x10cm, then additional FCC part 15.19 statement is required to be
available in the users manual: This device complies with Part 15 of FCC rules. Operation is subject to
the following two conditions: (1) this device may not cause harmful interference and (2) this device
must accept any interference received, including interference that may cause undesired operation.
LABEL OF THE END PRODUCT:
The final end product must be labeled in a visible area with the following " Contains TX FCC ID: NKR-
DNUAE134A ". If the size of the end product is larger than 8x10cm, then the following FCC part 15.19
statement has to also be available on the label: This device complies with Part 15 of FCC rules.
Operation is subject to the following two conditions: (1) this device may not cause harmful interference
and (2) this device must accept any interference received, including interference that may cause
undesired operation.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
5
1. General Description
The DNUA-E134A module is 802.11 a/b/g/n sign-chip solutions for USB dongle. It’s very
small and cost-effective modules which can bundle with PCs, TVs, set-top boxes, personal
video recorders and other devices to a WiFi network.
2. Usage
Thank you for purchasing the WLAN a/b/g/n USB2.0 Adapter that provides the easiest way to
wireless networking. This User Manual contains detailed instructions in the operation of this
product. Please keep this manual for future reference.
System Requirements
A laptop PC contains:
- 32 MB memory or greater
- 300 MHz processor or higher
Microsoft® Win™2000/ME/98 Second Edition/XP
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
6
3. Driver/Utility Installation / Uninstallation
3. Connecting to an Existing Network
1. Double click the shortcut icon of WLAN a+b+g+n USB2.0 Adapter on the desktop, and the
Configuration window appears.
2. Click on the Refresh button to list all available networks.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
7
Note! To automatically connect to the network with the strongest signal, select Enable Smart
Selection. Any displays in Profile List.
3. From the list of “Available Networks”, choose one network by double clicking the Network
Name. One of the following dialog boxes appears. Click “Yes” to continue.
4. If the chosen network has security enabled, the Security tab displays. Select the security
option used by the network. Contact the network administrator for the correct settings.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
8
5. If selecting WPA or 802.1X, select the EAP type, then click on the Configure button to
select the certificate.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
9
6. If selecting WPA-PSK, click on the Configure button to enter the PassPhrase.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
10
7. If selecting Pre-Shared Key, click on the Configure button to enter the correct Encryption
Keys.
Key entry method:
a.10hex digits: User must enter 10 hexadecimal digits.
The hexadecimal define is "0-9" and "A-F".
ex: 123456abc
b.5 chars: User must enter 5 characters. ex: ab3#@
c.13 chars: User must enter 13 characters.
ex: ab3#@kf08&kdk
d.16 chars: User must enter 16 characters.
ex: ab3#@kf08&kdk456
For WEP key, please contact with MIS administrator.
8. Click on OK (or Apply if using the other tabs) when done to save the settings.
9. Once connected (the icon or in front of the name of the Connected Network), you
can check the signal strength from the icon in the Windows System Tray.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
11
Additional Note for Windows XP
In Windows XP, it is recommended that you use the WLAN a+b+g+n USB2.0 Adapter
Configuration Utility. Before using the Utility, please follow the steps below to disable the
Windows XP Zero Configuration:
Option 1:
1. Double click the shortcut icon to open the Utility.
2. From the Windows System Tray, you should see the signal icon. Right-click it and select
“Disable Zero-Configuration”.
Option 2:
Go to “Control Panel” and double click “Network Connections”.
Right-click “Wireless Network Connection” of “WLAN a+b+g USB2.0 Adapter”, and select
“Properties”.
Select “Wireless Networks” tab, and uncheck the check box of “Use Windows to configure my
wireless network settings”, and then click “OK”.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
12
4. Creating an Ad Hoc New Network
NOTE! Ad-hoc mode is available only for 802.11b/g. It is not available for 802.11a. This is a
client product and do not have radar detection function specified by FCC. The software will
not let you to use ad-hoc under 802.11a.
1. In the Configuration window, click New .
2. Select the “Profile Editor” tab.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
13
3. Choose the check box of Enable Advanced Setting to edit all settings.
4. If joining or creating an Ad-Hoc network, choose Ad Hoc.
5. Click OK (or Apply if using the other tabs) to save the settings.
For details of each setting, refer to Modifying a Wireless Network on page 20.
6. Click the Security tab. If not using security, select None.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
14
7. If security is used, select Pre-Shared Key and click on the Configure button.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
15
8. Enter an encryption key in the Shared: First field.
9. Click OK (or Apply if using the other tabs) to save the settings. The new Network Name
is listed in the Profile List.
The driver does not allow channel selection in Ad-Hoc mode. Instead, the driver starts with
an initial channel then checks channel status. If the channel is busy, the driver
automatically uses a different channel.
For details of each setting, please see chapter 5.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
16
5. Modifying a Wireless Network
5.1 Infrastructure Mode and Ad Hoc Mode
You can set the Wireless Network Adapter to work in either Infrastructure mode or Ad Hoc
mode.
NOTE! Ad-hoc mode is available only for 802.11b/g. It is not available for 802.11a. This is a
client product and do not have radar detection function specified by FCC. The software will
not let you to use ad-hoc under 802.11a.
Infrastructure Mode
In infrastructure mode, devices communicate with each other by first going through an Access
Point (AP). Wireless devices can communicate with each other or can communicate with a
wired network. When one AP is connected to wired network and a set of wireless stations, it
is referred to as a BSS (Basic Service Set).
Ad Hoc Mode
Ad-hoc mode is also called “peer-to-peer mode” or “Independent Basic Service Set (IBSS)”.
In ad hoc mode, devices communicate directly with each other without using an Access Point
(AP).
NOTE! Ad-hoc mode is available only for 802.11b/g. It is not available for 802.11a. This is a
client product and do not have radar detection function specified by FCC. The software will
not let you to use ad-hoc under 802.11a.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
17
5.2 Modifying a Wireless Network
1. Open “WLAN a+b+g USB2.0 Adapter Configuration” by double clicking the shortcut icon
on the desktop.
Note! If there’s no network name listed in the “Profile List”, click Refresh button and
double click a Network Name from Available Networks. The chosen Network
Name is listed in the Profile List.
2. From the Profile List, select one Profile and click Modify button .
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
18
3. Select Profile Editor tab and edit the settings. Click OK to save the modifications.
Configuration Name: This name identifies the configuration. This name should be
unique.
Network Name (SSID1) (SSID2) (SSID3): The name of the wireless network. This
name cannot be longer than 32 characters. If the field is set to be “ANY” or is left
blank, your computer will connect to an AP with the best signal strength.
Network Connection: Specifies the mode of the network. Two options are
“Infrastructure” and “Ad Hoc”.
Power Saving: Minimizes power consumption while maintaining network
connectivity and high data transfer performance. In Ad Hoc mode, Power Savings
function cannot be enabled. The power management options are:
• Off: PC Card is powered up at all times.
• Normal: PC Card sleeps less often and stays asleep for a shorter period.
• Maximum: PC Card sleeps more frequently and stays asleep as much as
possible.
Wireless Mode: Three options are “802.11b”, “802.11a”, “802.11g”, “Super A”,
“Super G” or “Auto”. “Auto” allows the use of either 802.11a, 802.11g or 802.11b
mode.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
19
NOTE! Ad-hoc mode is available only for 802.11b/g. It is not available for 802.11a.
This is a client product and do not have rador detection function specified by FCC.
The software will not let you to use ad-hoc under 802.11a.
Ad Hoc Net Start: Specifies a band to establish an Ad Hoc network if no matching
SSID is found. Options available are the following: 802.11b and 802.11g.
NOTE! Ad-hoc mode is available only for 802.11b/g. It is not available for 802.11a.
This is a client product and do not have radar detection function specified by FCC.
The software will not let you to use ad-hoc under 802.11a.
802.11b Range: Options are Normal Range and Extended Range. This function
can let user to determine the transfer range in 802.11b mode. Extended Range can
prolong the transfer range with a lower data transmitting rate.
Scan Mode: Options are Active Scan, Passive Scan and Auto. In Active Scan, the
driver sends out the probe request frames from each channel and collects the
response frames from the responding. In Passive Scan, the driver scan each
requested channel, listening the beacons on each channel.
Transmit Power: This setting allows you to change the output power of the PC Card
to increase or decrease the coverage area.
QoS: Disables or enables the PC Card to cooperate in a network using QoS
(Quality of Service).
2.4 GHz Preamble: Allows Ad-Hoc compatibility with other 2.4 GHz devices. Two
options are Short and Long and Long only. Use Long Only when configuring the
client for an 802.11b RoamAbout AP wireless network.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
20
4. Select Security tab and choose the security mode.
Note! Check with your Network Administrator for the security features supported by your
AP.
WPA: Enables the use of WiFi protected Access (WPA). This option requires IT
administration.
a) Select WPA to open the WPA EAP drop-down menu. The options includes TLS
and PEAP.
b) Click on the Configure button and complete the configuration information in the
Define Certificate dialog.
WPA-PSK: Enables the WPA-Pre Shared Key (PSK). Click on the Configure button
and complete the configuration information in the WPA Passphrase dialog.
802.1x: Enables 802.1x security. This option requires IT administration.
a) Select 802.1x to open the 802.1x EAP drop-down menu. The options include TLS
and PEAP.
b) Click on the Configure button and complete the configuration information in the
Define Certificate dialog.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
21
Pre-Shared Key: Enables the use of pre-shared keys that are defined on the AP and
the station.
a) Select the Pre-Shared Key radio button.
b) Click on the Configure button and complete the configuration information in the
Define Certificate dialog.
None: No security.
5. Define the Certificate.
Select a Certificate: Select the Certificate to Authenticate to the RADIUS server
from the drop-down menu.
Use any Certificate Authority: The Default Setting. Select this radio button to use
any Certificate Authority (CA) for authentication.
Choose a Certificate Authority: Select this radio button to choose the desired
Certificate Authority for authentication from the drop-down menu.
Server/Domain Name: The the RADIUS server name or the domain name used for
the network access.
Login Name: The username used to log into the server or domain.
Define User Information (PEAP): Click on the Define User Information button and
complete the configuration information in the Define User Information dialog.
6. If selecting WPA-PSK, click on the Configure button to enter the PassPhrase. The
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
22
PassPhrase must be a minimum of 8 printable ASCII characters. The PassPhrase should
be at least 20 characters to make it more difficult for an attacker to decipher the key.
7. If selecting Pre-Shared Key, click on the Configure button to enter the Encryption
Keys.When finished, click OK. For WEP key, please contact with MIS administrator.
Key Entry Method: Determines the entry method for the key. Hexadecimal (0-9, A-F)
or ASCII text (all keyboard characters).
Default Encryption Key: Allows you to choose one encryption key (First, Second,
Third, or Fourth) as the transmit key, which encrypts transmissions from the PC Card.
Unique Key: Defines the per-session encryption key for the current network
configuration. Not used in Ad-Hoc mode.
Shared Keys: Use these fields to enter the wireless network’s encryption keys. The
keys must be in the correct position (First, Second, Third, or Fourth).
Key Length: Defines the length of each encryption key.
o For 40/64 bit (enter 10 digits for hexadecimal or 5 characters for ASCII)
o For 104/128 bit (Enter 26 digits for hexadecimal or 13 characters for ASCII)
When the length is changed, the number of available characters in the field
automatically changes. If a previously entered key is too long, the key is automatically
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
23
truncated to fit. If the key length is increased again, the key does not update to the
previous value.
8. Click OK to save the settings.
9. Select “TCP/IP Property” tab. Enter the settings and click “OK” to save the settings.
If the network uses DHCP server, choose Obtain an IP address automatically.
If the network does not use DHCP server, choose Use the following IP address to set
the relative settings. For the IP configuration information, please contact the network
administrator.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
24
Appendix A: FAQ about WLAN
1. Can I run an application from a remote computer over the wireless network?
This will depend on whether or not the application is designed to be used over a network.
Consult the application’s user guide to determine whether it supports operation over a
network.
2. Can I play computer games with other members of the wireless network?
Yes, as long as the game supports multiple players over a LAN (local area network).
Refer to the game’s user guide for more information.
3. What is Spread Spectrum?
Spread Spectrum technology is a wideband radio frequency technique developed by the
military for use in reliable, secure, mission-critical communications systems. It is designed to
trade off bandwidth efficiency for reliability, integrity, and security. In other words, more
bandwidth is consumed than in the case of narrowband transmission, but the trade-off
produces a signal that is, in effect, louder and thus easier to detect, provided that the receiver
knows the parameters of the spread-spectrum signal being broadcast. If a receiver is not
tuned to the right frequency, a spread-spectrum signal looks like background noise. There are
two main alternatives, Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping
Spread Spectrum (FHSS).
4. What is DSSS? What is FHSS? And what are their differences?
Frequency-Hopping Spread-Spectrum (FHSS) uses a narrowband carrier that changes
frequency in a pattern that is known to both transmitter and receiver. Properly synchronized,
the net effect is to maintain a single logical channel. To an unintended receiver, FHSS
appears to be short-duration impulse noise. Direct-Sequence Spread-Spectrum (DSSS)
generates a redundant bit pattern for each bit to be transmitted. This bit pattern is called a
chip (or chipping code). The longer the chip, the greater the probability that the original data
can be recovered. Even if one or more bits in the chip are damaged during transmission,
statistical techniques embedded in the radio can recover the original data without the need for
retransmission. To an unintended receiver, DSSS appears as low power wideband noise and
is rejected (ignored) by most narrowband receivers.
Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: 886-3-666-7799 Fax: 886-3-666-7711
Website: www.wneweb.com
Wistron NeWeb Confidential Document
25
5. Would the information be intercepted while transmitting on air?
WLAN features two-fold protection in security. On the hardware side, as with Direct Sequence
Spread Spectrum technology, it has the inherent security feature of scrambling. On the
software side, WLAN offers the encryption function (WEP) to enhance security and access
control.
6. What is WEP?
WEP is Wired Equivalent Privacy, a data privacy mechanism based on a 64-bit or 128-bit
shared key algorithm, as described in the IEEE 802.11 standard.
7. What is infrastructure mode?
When a wireless network is set to infrastructure mode, the wireless network is configured to
communicate with a wired network through a wireless access point.
8. What is roaming?
Roaming is the ability of a portable computer user to communicate continuously while moving
freely throughout an area greater than that covered by a single access point. Before using the
roaming function, the workstation must make sure that it is the same channel number with the
access point of dedicated coverage area.
To achieve true seamless connectivity, the wireless LAN must incorporate a number of
different functions. Each node and access point, for example, must always acknowledge
receipt of each message. Each node must maintain contact with the wireless network even
when not actually transmitting data. Achieving these functions simultaneously requires a
dynamic RF networking technology that links access points and nodes. In such a system, the
user’s end node undertakes a search for the best possible access to the system. First, it
evaluates such factors as signal strength and quality, as well as the message load currently
being carried by each access point and the distance of each access point to the wired
backbone. Based on that information, the node next selects the right access point and
registers its address. Communications between end node and host computer can then be
transmitted up and down the backbone. As the user moves on, the end node’s RF transmitter
regularly checks the system to determine whether it is in touch with the original access point
or whether it should seek a new one. When a node no longer receives acknowledgment from
its original access point, it undertakes a new search. Upon finding a new access point, it then
re-registers, and the communication process continues.