Globalstar USA FAU200RA Globalstar Fixed Access Unit with Remote Antenna User Manual Front

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Description of the Globalstar System
GS-TR-94-0001
Revision E
Description
of the
Globalstar System
December 07, 2000
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Description of the Globalstar System
GS-TR-94-0001
Revision E
DOCUMENT REVISION HISTORY
Revision
Date of Issue
6/3/94
12/20/94
8/10/95
2/24/97
12/07/00
Scope
Incorporated QUALCOMM Comments
Updated after SRR/PDR Reviews
Updated after the HLDR Reviews
Update to incorporate design changes
Added Photographs & Revised Services
Abstract
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This document is written to introduce new people to Globalstar. It
attempts to provide a general overview of the system and to provide some
information on the design of the system. It also attempts to define how
Globalstar is envisioned to operate. As such, this is primarily tutorial in
nature. In the interests of brevity, simplifications are made in the material
herein. There is no attempt to be totally complete or comprehensive for all
cases.
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This document should not be interpreted as a binding specification. It does
not contain requirements that should be interpreted as either complete or
binding. Globalstar is an evolving system. This document will be updated
as the design of the system progresses. When each revision is issued there
is an attempt to represent the current thinking on the system.
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For binding specifications and requirements please consult the released
requirements documents and the released design information.
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Globalstar, L.P.
3200 Zanker Road
San Jose, Ca. 95164-0670
Copyright © 1997 Globalstar, L.P. All rights reserved. Printed in the United States of America.
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Description of the Globalstar System
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Contents
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1. SERVICES OFFERED
1-1
1.1 Service Types ..........................................................................................................1-1
1.2 IS-41 Services .........................................................................................................1-1
1.3 GSM Services ..........................................................................................................1-8
1.4 Globalstar Specific Services and Quality ........................................................1-15
1.5 External Network Supported Services ............................................................1-17
2. SYSTEM SEGMENT DESCRIPTIONS
2-1
2.1 Globalstar System..................................................................................................2-1
2.2 User Terminal.........................................................................................................2-3
2.2.1 Hand Held and Mobile Units.........................................................................2-3
2.2.2 Fixed Terminals ...............................................................................................2-7
2.3 Gateway....................................................................................................................2-8
2.4 User Terminal and Gateway Interaction........................................................2-12
2.5 Globalstar Control Centers................................................................................2-13
2.5.1 Ground Operations Control Center............................................................2-14
2.5.2 Satellite Operations Control Center ..........................................................2-17
2.5.3 Globalstar Business Office ...........................................................................2-19
2.6 Globalstar Satellite..............................................................................................2-20
3. FREQUENCIES AND COVERAGE ANALYSIS
3-1
3.1 Frequency Plans ....................................................................................................3-1
3.2 Satellite Antenna Beam Configuration ............................................................3-2
3.3 Earth Surface Coverage .......................................................................................3-7
3.4 Position Determination.......................................................................................3-10
3.5 Channel Characteristics.....................................................................................3-12
3.6 Link Analysis........................................................................................................3-14
4. CODE DIVISION MULTIPLE ACCESS (CDMA)
4-1
4.1 Introduction ............................................................................................................4-1
4.2 Diversity Combining .............................................................................................4-2
4.3 Fade Mitigation......................................................................................................4-2
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4.4
4.5
4.6
4.7
Acquisition...............................................................................................................4-3
Forward CDMA Channel .....................................................................................4-5
Return Link CDMA Channel............................................................................4-10
CDMA End to End Performance ......................................................................4-12
5. TERRESTRIAL INTERFACE
5-1
5.1 Telecommunication Network Interface .............................................................5-1
5.2 Registration Process..............................................................................................5-4
5.3 Authentication Process.........................................................................................5-7
5.4 GSM - A Interface in Globalstar .......................................................................5-10
6. CALL PROCESSING
6-1
6.1 Call Processing between Globalstar and PLMN .............................................6-1
6.2 TIA and ETSI Call Flow Examples ...................................................................6-5
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Figures
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Figure 2-1 Globalstar System Integrates with Terrestrial Network ........................ 2-1
Figure 2-2 Globalstar Constellation Serves Temperate Areas .................................. 2-2
Figure 2-3 Typical Hand Held User Terminal ............................................................. 2-3
Figure 2-4 Globalstar User Terminal Block Diagram ................................................. 2-5
Figure 2-5 User Terminal Startup Scenario within Globalstar ................................. 2-6
Figure 2-6 Typical Fixed Terminal Application........................................................... 2-7
Figure 2-7 Typical Gateway Installation....................................................................... 2-8
Figure 2-8 Gateway Simplified Block Diagram............................................................ 2-9
Figure 2-9 Globalstar Control Center ......................................................................... 2-13
Figure 2-10 Ground Segment Support for Communications .................................... 2-14
Figure 2-11 GOCC Simplified Block Diagram............................................................ 2-15
Figure 2-12 Ground Equipment Support for T&C Functions................................... 2-17
Figure 2-13 Spacecraft Bus Characteristics - Highly Autonomous ......................... 2-20
Figure 2-14 Communications Payload Pictorial ......................................................... 2-21
Figure 2-15 Communications Payload Simplified Block........................................... 2-21
Figure 2-16 Satellite T&C - Compatible with Communications .............................. 2-22
Figure 3-1 Frequency Plan - Emphasizes Conservation of Spectrum ....................... 3-1
Figure 3-2 S - Band Beams .............................................................................................. 3-2
Figure 3-3 L- Band Beams............................................................................................... 3-3
Figure 3-4 L - Band Channel Frequencies .................................................................... 3-4
Figure 3-5 S - Band Channel Frequencies..................................................................... 3-4
Figure 3-6 Full Earth Coverage-Except Polar Regions............................................... 3-7
Figure 3-7 Enhanced Coverage for Temperate Regions ............................................. 3-8
Figure 3-8 Orbital Parameters for Globalstar Satellites ............................................ 3-9
Figure 3-9 Channel Characteristics Considerations ................................................. 3-12
Figure 4-1 Acquisition Search Space ............................................................................. 4-3
Figure 4-2 Acquisition Time as a function of Latitude................................................ 4-4
Figure 4-3 Forward CDMA Channel Transmitted by a Gateway .............................. 4-5
Figure 4-4 Forward Link Pilot, Sync and Paging Channel ......................................... 4-6
Figure 4-5 Forward Link Traffic Channel - Rate Set 1 ............................................... 4-7
Figure 4-6 Forward Link Traffic Channel - Rate Set 2 ............................................... 4-8
Figure 4-7 Forward Link Modulation and Spreading ................................................. 4-9
Figure 4-8. Reverse CDMA Channels Received at a Gateway................................. 4-10
Figure 4-9 Return Link Access Channel ..................................................................... 4-11
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Figure 4-10 Return Link Traffic Channel ................................................................... 4-12
Figure 4-11 Forward Link Delay Budget .................................................................... 4-13
Figure 4-12 Reverse Link Delay Budget ..................................................................... 4-13
Figure 4-13 Power Control Simplified Diagram ........................................................ 4-14
Figure 4-14 Acquisition Time as a function of Eb/No ................................................ 4-15
Figure 5-1 Gateway Architecture................................................................................... 5-1
Figure 5-2 Gateway Connections to the PSTN - Flexible Interface .......................... 5-3
Figure 5-3 Registration of a U.S. based User with an IS-41 HLR.............................. 5-4
Figure 5-4 Registration of a European User in a GSM HLR...................................... 5-5
Figure 5-5 Registration of a U.S. User in a GSM Environment ................................. 5-6
Figure 5-6 Registration of a European User in an IS-41 Environment..................... 5-7
Figure 5-7 Authentication for a GSM User in IS-41 System....................................... 5-9
Figure 5-8 GSM DTAP on Mobile Terminated Call................................................... 5-10
Figure 5-9 GSM DTAP on Mobile Originated Call .................................................... 5-11
Figure 6-1 Mobile Originated Call ................................................................................. 6-1
Figure 6-2 Roaming Call Delivery - Successful ............................................................ 6-2
Figure 6-3 Roaming Call Delivery - Subscriber Busy.................................................. 6-3
Figure 6-4 Simple Call Flow, User Terminal Origination Example Using Service
Option 1 (TIA Call Control Procedures) .................................................. 6-6
Figure 6-5 Simple Call Flow, User Terminal Origination Example Using Service
Option 1 (ETSI Call Control Procedures) (Part 2 of 2)........................... 6-7
Figure 6-6. Simple Call Flow, User Terminal Termination Example Using Service
Option 1 (TIA Call Control Procedures) .................................................. 6-8
Figure 6-7 Simple Call Flow, User Terminal Termination Example Using Service
Option 1 (ETSI Call Control Procedures) (Part 2 of 2)........................... 6-9
Figure 6-8. Simple Call Flow, User Terminal Initiated Call Disconnect Example
(TIA Call Control Procedures)................................................................. 6-10
Figure 6-9 Simple Call Flow, User Terminal Initiated Call Disconnect Example
(ETSI Call Control Procedure) (Part 2 of 2)........................................... 6-10
Figure 6-10. Simple Call Flow, Gateway Initiated Call Disconnect Example (TIA
Call Control Procedures).......................................................................... 6-11
Figure 6-11 Simple Call Flow, Gateway Initiated Call Disconnect Example (ETSI
Call Control Procedure) (Part 2 of 2)...................................................... 6-12
Figure 6-12. Simple Call Flow, Three-Party Calling Example (TIA Call Control
Procedures) ................................................................................................ 6-13
Figure 6-13. Simple Call Flow, Call-Waiting Example (TIA Call Control
Procedures) ................................................................................................ 6-14
Figure 6-14. Call Processing During Soft Handoff.................................................... 6-15
Figure 6-15. Call Processing During Sequential Soft Handoff................................ 6-16
Figure 6-16 Call Processing During Sequential Soft Handoff (Part 2 of 2) ............ 6-17
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Tables
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Table 1-1 Teleservices....................................................................................................1-1
Table 1-2 Basic Bearer Services ..................................................................................1-2
Table 1-3 IS-53 Call Number Presentation...............................................................1-2
Table 1-4 IS-53 Call Forwarding .................................................................................1-3
Table 1-5 IS-53 Call Delivery .......................................................................................1-4
Table 1-6 Short Message Services ...............................................................................1-4
Table 1-7 Miscellaneous Services ................................................................................1-5
Table 1-8 Future IS-41 C Services ..............................................................................1-6
Table 1-9 Bearer Service - Full Duplex Asynchronous Data.................................1-8
Table 1-10 Bearer Service - Full Duplex Synchronous Data.................................1-9
Table 1-11 Bearer Service - PAD Asynchronous Data............................................1-9
Table 1-12 Bearer Service - Packet Synchronous.................................................1-10
Table 1-13 Teleservices Speech..................................................................................1-10
Table 1-14 Teleservices - Short Message Service...................................................1-10
Table 1-15 Teleservices - Facsimile Transmission................................................1-12
Table 1-16 Supplementary Services - Line Identification....................................1-12
Table 1-17 Supplementary Services - Call Forwarding.......................................1-13
Table 1-18 Supplementary Services - Call Waiting & Call Hold........................1-13
Table 1-19 Supplementary Services - Closed User Group....................................1-13
Table 1-20 Supplementary Services - Advice of Charge.......................................1-13
Table 1-21 Supplementary Services - Call Barring...............................................1-14
Table 1-22 Supplementary Services - Multiparty Services..................................1-14
Table 1-23 External Network - Value Added Services..........................................1-17
Table 2-1 Production User Terminals ........................................................................2-3
Table 3-1 Satellite C-Band to S-Band ........................................................................3-5
Table 3-2 Satellite L-Band to C-Band ........................................................................3-5
Table 3-3 Satellite Telemetry & Command Frequencies .......................................3-6
Table 3-4 Worst Case Doppler......................................................................................3-6
Table 3-5 Forward Link C-Band - Case 1 - Detailed Budget ...............................3-14
Table 3-6 Forward Link S-Band - Case 1 - Detailed Budget................................3-15
Table 3-7 Forward Link - Case 2 - Link Blockage..................................................3-16
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Table 3-8 Forward Link - Case 3 - Rare Two Link Fade.......................................3-16
Table 3-9 Return Link L-Band - Case 1 - Detailed Budget..................................3-17
Table 3-10 Return Link C-Band - Case 1 - Detailed Budget ...............................3-18
Table 3-11 Return Link - Case 2 - Link Blockage..................................................3-18
Table 3-12 Return Link - Case 3 - Rare Two Link Fade.......................................3-19
Table 4-1 Vocoder and Channel Rates ....................................................................4-14
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1. SERVICES OFFERED
1.1 Service Types
Four types of communications services are supported by Globalstar depending on the environment in
which they operate (1) IS-41 Services, (2) GSM Services, (3) Globalstar Specific Services and (4)
Network Value Added Services.
1.2 IS-41 Services
The following IS-41-based services are supported directly by the gateway. The IS 41 switch is in the
Gateway. The IS-41 C teleservices are listed in Table 1-1.
Table 1-1 Teleservices
Service Option
Description
Telephony (circuit speech)
Variable rate vocoded speech. – Comparable or better than IS96A.
Emergency Services (911)
Globalstar emergency calls are routed to a single LAC directory
number for further processing. Although the Gateway
retrieves position location data of the calling subscriber,
position data is not provided to the Emergency Service Center.
Automatic Facsimile Group III
Normal Group III FAX – Digital PC Only - (Future)
Lawful Intercept
GS complies with the laws in the areas where they operate. In
the U.S.A, this is call content and call associated data per DOJ
J-STD-25 with minor exceptions.
DTMF Support
Dual Tone Multi Frequency. Used for voice Message Retrieval
etc. Signal via GAI. Generated in GW or UT.
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The IS-41 switch within the Gateway does not perform routing to sub-tier emergency numbers. The
Gateway can be configured to support multiple Location Area Codes (LAC). A different emergency
number can be assigned to each LAC.
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Basic bearer services are listed in Table 1-2.
Table 1-2 Basic Bearer Services
Service Option
Description
2.4 Kb/s: DCA, (ADS)
(Future)
4.8 Kb/s: DCA, (ADS)
(Future)
9.6 Kb/s: DCA, (ADS)
(Future)
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Data Requires Flow Control: The Globalstar Air Interface (GAI) and the Gateway support packet
data. Because there is overhead in the GAI, external flow control is required to offer a 9.6 Kb/s service.
End to end peak throughput of the Globalstar link will be on the order of 7.2 Kb/s.
The initial offering (near future – 1.5 D2) of Async Data will be Mobile Originated (MO) only. Mobile
Terminated (MT) will require modifications to the HLR (future). Connecting the call will require about 5
seconds. This is then followed with a variable time to train the modem.
IS-53 Supplementary Services supported by the Gateway are listed in Table 1-3.
Table 1-3 IS-53 Call Number Presentation
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IS-53 Supplementary Services - Call Number Presentation
Service Option
Description
Calling number identification presentation
(CNIP)
CNIP provides the number identification of the calling party to
the called subscriber. One or two numbers may be presented to
identify the calling party.
Calling number identification restriction (CNIR)
CNIR restricts presentation of that subscriber’s calling number
identification (CNI) to the called party.
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Table 1-4 lists some of the IS-53 call forwarding features.
Table 1-4 IS-53 Call Forwarding
IS-53 Supplementary Services - Call Forwarding
Service Option
Description
Call forwarding unconditional (CFU)
CFU permits a called subscriber to send incoming calls
addressed to the called subscriber’s directory number to
another directory number or to the called subscriber’s
designated voice mail box. If this feature is activated, calls are
forwarded regardless of the condition of the termination.
Call forwarding default (CFD)
CFD permits a called subscriber to send incoming calls
addressed to the called subscriber’s directory number to the
subscriber’s voice mail box or to another directory number
when the subscriber is engaged in a call, does not respond to
paging, does not answer the call within a specified period after
being alerted or is otherwise inaccessible.
Call Forwarding - Busy (CFB)
CFB permits a called subscriber to have the system send
incoming calls addressed to the called subscriber’s directory
number to another directory number or to the called
subscriber’s designated voice mail box when the subscriber is
engaged in a call or service.
Call Forwarding - No Answer (CFNA)
CFNA permits a called subscriber to have the system send
incoming calls addressed to the called subscriber’s directory
number to another directory number or to the called
subscriber’s designated voice mail box when the subscriber
fails to answer or is otherwise inaccessible. CFNA does not
apply when the subscriber is considered to be busy.
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Table 1-5 lists some of the IS-53 Call Delivery features.
Table 1-5 IS-53 Call Delivery
IS-53 Supplementary Services - Call Delivery Features
Service Option
Description
3-way calling (3WC)
3WC provide the subscriber the capability of adding a third
party to an established two-party call, so that all three parties
may communicate in a three-way call. Calling party initiated.
Do not disturb (DND)
DND prevents a called subscriber from receiving calls. When
this feature is active, no incoming calls will be offered to the
subscriber. DND also blocks other alerting, such as CFU
reminder alerting and message waiting notification alerting.
DND also makes the subscriber inaccessible for call delivery.
DND does not impact a subscriber’s ability to originate calls.
Call transfer (CT)
CT enables the subscriber to transfer a call that is already in
process to a third party. The call to be transferred may be an
incoming or outgoing call. While CT is invoked, CT impacts
the subscriber’s ability to receive calls. After CT is finished or
when CT is not invoked, CT does not impact a subscriber’s
ability to originate calls or to receive calls.
Call delivery (CD)
CD permits a subscriber to receive calls to his or her directory
number while roaming.
Call waiting (CW)
CW provides notification to a controlling subscriber of an
incoming call while the subscriber is in the 2-way state.
Subsequently, the controlling subscriber can either answer or
ignore the incoming call. If the controlling subscriber answers
the second call, he or she may alternate between the two calls.
Lawful Intercept Implications: The IS-53 Call Delivery services are coded and operational in the
present software release. When Release 1.5 D-3, with Lawful Intercept is released (Future), many of
the IS-53 Call Delivery features will have to be disabled.
Short Message Services are supported as listed in Table 1-6.
Table 1-6 Short Message Services
Service Option
Description
Short message delivery–point-to-point (SMDPP)
SMD-PP provides delivery of a short message. The SMD-PP
service attempts to deliver a message to a Globalstar UT
whenever the UT is registered even when the UT is engaged in
a voice or data call.
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The IS-41 SMS will be compliant with IS-637. A few examples will clarify how MT SMS is
envisioned (future) to operate:
1. If a short message comes into the gateway from the SMSC that is less than about 65
characters (45 characters of payload) it will be routed to the UT over the paging channel.
2. If an SMS message arrives while the traffic channel is set up, it will be routed over the already
established traffic channel. This can be a message of up to about 246 characters (200
characters of payload).
3. If a long message arrives and a traffic channel is not set up, it will be set up and the SMS
message will be sent.
The Gateway will support about 5,000 Busy Hour Short Message Access (BHSMA).
Lawful Intercept: The SMS LI will be supported as Call Associated Data (CAD) in future software
release 1.5 D3.
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There are several other items that may be considered services listed in Table 1-7. These are primarily
associated with validating the caller and with providing privacy.
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Table 1-7 Miscellaneous Services
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Service Option
Description
Authentication
Authentication provides a secure way to identify authorized
subscribers in order to prevent fraudulent use of the network
resources.
Voice Privacy (VP)
VP provides a degree of privacy for the subscriber over the
Globalstar Air Interface. When VP is invoked, the speech or
traffic channel used is encrypted.
(Function provided in different manner)
Data Privacy
(Function provided in different manner)
Signaling Privacy
(Function provided in different manner)
Over the Air Encryption is supported. Private keys between
SM and Authentication Center.
Over the Air Encryption is supported. Private keys between
SM and Authentication Center.
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Security Module (SM) in the context above should not be confused with the GSM Subscriber
Identification Module (SIM). It is a security module function. The over the air encryption of traffic is an
algorithm similar to the GSM A5 algorithm.
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Table 1-8 lists services that may be offered in the future. They are not presently within the scope of
work. The initial offering will include 3-way calling. If Conference Calling (CC) is adopted later, the
older service could be dropped or continued.
Table 1-8 Future IS-41 C Services
Future IS-41 C Services
Acronym
Service
Description
CPT
Cellular Paging Teleservice
CMT
Cellular Messaging Teleservice
SPINA
Subscriber PIN Access
A PIN is required. Network based lockout feature.
CC
Conference Calling
Provides ability to connect more than 3 parties.
FA
Flexible Alerting
A call to a pilot number to alert several numbers
simultaneously.
MWN
Message Waiting Notification
Informs subscribers a voice message is waiting.
MAH
Mobile Access Hunting
Causes a call to a pilot directory to search a list of enrolled
subscribers. Terminates with the first available subscriber in
the list.
PCA
Password Call Acceptance
This is a call-screening feature that limits incoming calls to
subscribers able to provide a password.
PL
Preferred Language
Allows the subscriber to specify language for network
services. This includes help lines, announcements, message
waiting notifications and SMS.
VMR
Voice Message Retrieval
Allows subscriber to retrieve voice messages.
VP
Voice Privacy
Provides a degree of voice privacy.
SP
Signaling Privacy
Provides a degree of signaling privacy.
PACA
Priority Access and Channel
Assignment
Allows subscriber to move to top of queued list. Available
in levels, permanent or on demand. Called numbers such as
911 may be given priority at the Service Provider option.
RFC
Remote Feature Control
Calls to a special RFC directory number validated by a PIN
can be used to activate features. DTMF digits are required.
SCA
Selective Call Acceptance
Allows only calls whose Calling Party Numbers are in a
screening list.
SPINI
Subscriber PIN Intercept
A PIN is required. User Terminal based lockout.
These are mentioned here so that we recognize that these may be offered eventuality and Globalstar will
do nothing in the design to preclude their incorporation at a later date.
Globalstar has some of the functions with some interpretation specifically:
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1. MWN: Message Waiting Notification is mechanized via the SMS.
2. VMR: Facilities are available to access voice messages although not precisely as specified in
IS-41.
3. VP: The Traffic Channel is encrypted.
4. SP: Any signaling within the traffic channel is encrypted.
5. PACA: The User Terminal, the GAI, and the Gateway support 10 priority levels. These may
be used to control which call gets resources. Calls that are setup are not broken down to
support PACA functions within Globalstar.
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1.3 GSM Services
The Globalstar Gateway can incorporate a GSM switch or the Gateway can be utilized with an external
GSM switch. In either case the Gateway proper is connected to the GSM switch by the GSM A1
interface. This section lists the bearer services and teleservices supported by the Alcatel GSM MSC
Table 1-9 Bearer Service - Full Duplex Asynchronous Data
Bearer Service - Full Duplex Asynchronous Data
Acronym
Service
Description
BS 21
300 bps Asynchronous
Full Duplex Data Circuit - Asynchronous
BS 22
1200 bps Asynchronous
Full Duplex Data Circuit - Asynchronous
BS 23
1200/75 bps Asynchronous
Not Supported
BS 24
2400 bps Asynchronous
Full Duplex Data Circuit - Asynchronous
BS 25
4800 bps Asynchronous
Full Duplex Data Circuit - Asynchronous
BS 26
9600 bps Asynchronous
Full Duplex Data Circuit - Asynchronous
The Information Transfer may be 3.1 kHz (External to Public Land Mobil Network (PLMN)). The Gateway will not
support an Unrestriced Digital Interface (UDI). The connection is digital within the PLMN. The service can be
transparent (T) or Non Transparent (NT). Transparent service is characterized by constant throughput, constant transit
delay and variable error rate. Non-Transparent service is characterized by improved error rate with variable transit delay
and throughput.
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The Globalstar Air Interface is a packet system. The top rate for a single channel is 9.6 kb/s. This
includes some overhead. This means Globalstar will not support a true 9.6 kb/s throughput service.
The best estimate is the actual throughput will be on the order of 7.2 kb/s. The difference is required for
overhead. The data connections on each end can operate asynchronously at 9.6 kb/s so that can be the
“apparent peak” service rate. Expansion buffers will be required to allow the peak rate of 9.6 kb/s with
an average around 7.2 kb/s.
Services Requiring Constant Transit Delay: The Globalstar Air Interface is a packet data system
that exhibits a high error rate. While some of the errors can be corrected by Forward Error Correcting
Codes, repeat transmissions will be required. This means:
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1. Through put time delay is variable.
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2. Cannot support true synchronous operation
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There are ways, with flow control, to provide these as “apparent” services by providing smart
equipment at the ends of each link.
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DTAP Based Services: Any services that use the DTAP messages can be supported as long as the
switch and the User Terminal support the service. DTAP messages are passed transparently thorough
the gateway, the air interface, and the Globalstar User Terminal.
GSM Data Services: GSM Asynchronous Services are targeted for Release 1.5 D4 (future). This is
required for before Synchronous Services could be considered even with elastic buffer equipment in the
link termination equipment.
Table 1-10 Bearer Service - Full Duplex Synchronous Data
Bearer Service - Full Duplex Synchronous Data Service Typo
Acronym
Service
Description
BS 31
1200 bps Synchronous
Data Circuit, Duplex Synchronous
BS 32
2400 bps Synchronous
Data Circuit, Duplex Synchronous
BS 33
4800 bps Synchronous
Data Circuit, Duplex Synchronous
BS 34
9600 bps Synchronous
Data Circuit, Duplex Synchronous (not supported)
The Information Transfer may be Unrestricted Digital (UDI) or 3.1 kHz (External to PLMN). The connection is digital
within the PLMN. Operating mode can be transparent (T) or Non Transparent (NT). Transparent service is
characterized by constant throughput, constant transit delay and variable error rate. Non-Transparent service is
characterized by improved error rate with variable transit delay and throughput. Synchronous operation can be
simulated in Globalstar by external equipment. Throughput is at a lower rate.
11
Technically this service could be offered. The Service Provider must provide some end to end
adaptation equipment on each end to make the link look synchronous. Throughput is limited by the flow
control. Specifically, end to end encryption devices can be used that normally operate with
synchronous links.
12
Table 1-11 Bearer Service - PAD Asynchronous Data
10
Bearer Service - PAD Asynchronous Data Service Type
Acronym
Service
Description
BS 41
300 bps Asynchronous
Data Circuit, Duplex Asynchronous
BS 42
1200 bps Asynchronous
Data Circuit, Duplex Asynchronous
BS 43
1200/75 bps Asynchronous
Data Circuit, Duplex Asynchronous
BS 44
2400 bps Asynchronous
Data Circuit, Duplex Asynchronous
BS 45
4800 bps Asynchronous
Data Circuit, Duplex Asynchronous
BS 46
9600 bps Asynchronous
Data Circuit, Duplex Asynchronous
PAD: provides an asynchronous connection to a Packet Assembler/Disassembler. This service is available only for
mobile originated calls.
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Table 1-12 Bearer Service - Packet Synchronous
Bearer Service - Packet Synchronous
Acronym
Service
Description
BS 51
2400 bps Synchronous
Data Circuit, Duplex Synchronous
BS 52
4800 bps Synchronous
Data Circuit, Duplex Synchronous
BS 52
9600 bps Synchronous
Data Circuit, Duplex Synchronous
Provides a synchronous connection to a packet network. Can be simulated in Globalstar by external equipment.
Throughput is at a lower rate.
Globalstar is a packet system. It does not directly support synchronous services. Devices on each end
can operate so that the connection is “apparent” synchronous. True synchronous operation is not
feasible. Technically this service could be offered. The Service Provider must provide some end to end
adaptation equipment on each end to make the link look synchronous. Throughput is limited by the flow
control. Specifically, end to end encryption devices can be used that normally operate with
synchronous links.
Table 1-13 Teleservices Speech
Teleservices - Speech
Acronym
Service
Description
TS 11
Telephone Service
This is the basic voice telephone service.
TS 12
Emergency Calls
Emergency Calls do not require registration. They can be on
IMSI or IMEI.
11
The Gateway requires an IMSI for all calls. This means emergency calls too. The User Terminal could
be designed to provide a pseudo-IMSI so that at UT could be used without the SIM.
12
Table 1-14 Teleservices - Short Message Service
10
Teleservices - Short Message Service
Acronym
Service
Description
MT/PP
Short Message Mobile Terminated
Point-to-Point
Permits the SMS service center to send a message to any
subscriber that is less than 160 ASCII characters (future)
Short Message Mobile Originated
Point-to-Point
Permits any subscriber to send a message to any other
subscriber that is less than 160 ASCII characters. The SMS
service center acts as a store and forward node (future).
TS 21
MO/PP
TS 22
13
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An IS-41 Mobile Originated only variant will be offered in the near future. The Alcatel switch will
require modification to support Mobile Originated SMS. Although the switch supports SMS Mobile
Terminated broadcast, Globalstar does not support this service.
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Table 1-15 Teleservices - Facsimile Transmission
Teleservices - Facsimile Transmission (Not Supported by Globalstar)
Acronym
Service
Description
TS 61
Alternate Speech and Facsimile Group
3 (T or NT)
Speech and data can be alternated during the call.
TS 62
Automatic Facsimile Group 3 (T or NT)
Dedicated service.
Operating mode can be transparent (T) or Non Transparent (NT). Transparent service is characterized by constant
throughput, constant transit delay and variable error rate. Non-Transparent service is characterized by improved error
rate with variable transit delay and throughput.
Although the Alcatel switch supports these modes, they are not available over Globalstar. The air
interface operates NT. Timing could be adjusted so digital FAX machines will not timeout.
Table 1-16 Supplementary Services - Line Identification
Supplementary Services - Line Identification - GSM 02.81 (Not Supported by Globalstar)
Acronym
Service
Description
CLIP
Calling Line Identification
Presentation
Permits the called party to receive the line identity of the
calling party.
CLIR
Calling Line Identification
Restriction
Permits the calling party to block his line identity to the called
party.
COLP
Connected Line Identification
Presentation
The calling party can receive the line identity of the
connected party.
COLR
Connected Line Identification
Restriction
Permits the connected party to block his line identity to the
calling party.
COLP and COLR are mandatory.
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Table 1-17 Supplementary Services - Call Forwarding
Supplementary Services - Call Forwarding (CF) GSM 02.82
Acronym
Service
Description
CFU
Call Forwarding Unconditional
Incoming calls are forwarded to another number.
CFB
Call Forwarding - Busy
Line is busy, calls are sent to another number.
CFNRy
Call Forwarding on No Reply
When there is no reply within a specified period of time,
calls are sent to another number.
CFNRc
Call Forwarding on Mobile Subscriber
Not Reachable
When the called party is not reachable, calls are forwarded
to another number.
Table 1-18 Supplementary Services - Call Waiting & Call Hold
Supplementary Services - Call Waiting (CW) and Call Holding (HOLD) GSM 02.83 (Not Supported by G*)
Acronym
Service
Description
CW
Call Waiting
Notify the called party that a call is waiting.
HOLD
Call Hold
Place an active call on hold.
Table 1-19 Supplementary Services - Closed User Group
Supplementary Services - Closed User Group GSM 02.85 (Not Supported by Globalstar)
Acronym
Service
Description
CUG
Closed User Group
Communications permitted only with group. The switch
supports a MS belonging to up to 10 CUGs.
Table 1-20 Supplementary Services - Advice of Charge
Supplementary Services - Advice of Charge GSM 02.86 (Not Supported by Globalstar)
Acronym
Service
Description
AOC
Advice of Charge Information
Provides and estimate of the size of the bill.
AOC
Advice of Charge Charging
Provides an accurate charge to support immediate billing
(e.g. Taxi phone).
The Alcatel GSM-MSC supports “Warm” billing. Partial records can also be obtained for long calls.
The SP should consider carefully before offering any service that requires “Hot Billing”.
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Table 1-21 Supplementary Services - Call Barring
Supplementary Services - Call Barring (CB) GSM 02.88
Acronym
Service
Description
BAOC
Barring of All Outgoing Calls
There are no outgoing calls except emergency calls.
BOIC
Barring of Outgoing International
Calls
Bars international calls from the PLMN in which the
subscriber is presently located.
BOIC-exHC
Barring of Outgoing International
Calls except those directed to the
Home PLMN Country
Outgoing calls are barred except local calls and to the home
PLMN country.
BAIC
Barring of All Incoming Calls
No incoming calls are permitted. GSM 02.88
BIC ROAM
Bar Incoming Calls - Roaming
No incoming calls are permitted when roaming outside the
home PLMN.
Table 1-22 Supplementary Services - Multiparty Services
Supplementary Services - Multiparty Services (Not Supported by Globalstar)
Acronym
Service
Description
MPTY
Multi Party Service
Establish and delete multiple parties in any order.
Conference Calling or Multi-Party Service is mandatory.
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1.4 Globalstar Specific Services and Quality
The following services and statements result from the Globalstar implementation and apply to both GSM
and IS-41.
Globalstar Specific Services
Position Location (high resolution), 300 m (Future)
Position Location (low resolution), 10 km
Global Roaming
Terminal Services
CDG Sleep Mode
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17
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19
20
21
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23
24
25
26
27
Internet Services: Internet services have been tested and operate reliably. In order to offer the
service, the gateway must supply some modem equipment and must interface at the Selector Bank
Subsystem (SBS). Offering the packet service implies Internet, e-mail, stock quotes and a host of
attractive services. . The billing is quantized to 0.1 second intervals. Byte based billing is not
supported. The Gateway support will be in Release 1.5 D2, which should be in the near future
Slotted Mode: An IS-41 slotted mode operation will be available is software release 1.5 D2
scheduled for the near future. This will increase battery receive battery life on the order of 2:1. Longer
slot delays cause unacceptable latency and result in very slight improvements. This IS-41 service is
mechanized by storing the slots in the VLR located in the gateway. It would be necessary to access the
GSM VLR to offer slotted mode as a GSM feature. Slotted mode is turned off when the handset is
placed in a car kit.
Throughput Rates: The data rate of the air interface plus overhead for the radio link protocol, etc.
limits the effective data rate to approximately 7.2 Kb/s (if enough power has been allocated and there is
no blockage of view). It is possible to interface to a higher rate service at the network interface (e.g.,
V.32), but the actual data rate is limited.
Short Message Service: The gateway will support interfaces to GSM and IS-41 short message
service centers for SMS.
Voice Quality - Voice service is based on a Code Excited Linear Prediction (CELP) variable rate
vocoder. The voice processing will incorporate a procedure to aid in cancellation of background noise.
The voice quality will meet or exceed the voice quality provided by IS-96A, the terrestrial CDMA
standard. This superior voice quality can be offered at the lower data rates in large part due to the
adaptable rate vocoders used in Globalstar. The voice quality cited is based on a Ricean channel model
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that requires a forward link Eb/No and return link Eb/No as defined in the link budget. A soft
degradation is incorporated into the design. In marginal areas where the User Terminal cannot generate
sufficient power to close the link, the peak data rate is reduced to 4.8 Kb/s or 2.4 Kb/s. This will
provide intelligible voice communications in areas that otherwise could not be served. The Vocoders
will incorporate echo cancellation, which can be disabled if this function is provided by the network.
Data Quality - Data services are provided up to 7.2 Kb/s. The a Bit Error Rate contributed by
Globalstar is less than 1 X 10 -6. Higher terminal rates (e.g. 9.6 Kb/s) can be processed if the
equipment incorporates elastic buffers to accommodate the required flow control.
Encryption: Over the air signaling (in band), voice and data encryption is offered.
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13
14
15
Registration - The Gateway is capable of providing a position location function on the User Terminal
with which it is communicating. The accuracy is within 10 km for registration. This is used to determine
assignment of User Terminals to Gateways.
Location Service: Globalstar can locate the position of a User Terminal and provide the location as a
service in the future. Accuracy of the position location service is a function of several variables
including:
16
a. Number of Satellites in View.
17
b. Position Accuracy of the Satellites
18
c. Geometry of the User Terminals, Satellites and Gateways.
19
d. The length of time that the User Terminal is connected to the Gateway.
20
21
22
23
24
25
26
27
The architecture will support better precision once the gateway locations are known with sufficient
accuracy and the topographical maps are correctly registered. With this a likely service, this document
includes some description of the position location methods.
Location Privacy - The location of a user is protected. Only duly constituted authorities will have
access to these data unless approved by the owner of the User Terminal.
Tracking Service - The Gateway is able to use sequential position locations to determine and maintain
tracking services for mobile users. Offering these services is dependent upon the legality within the
regions supported by the Service Providers.
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1.5 External Network Supported Services
The Gateway design will incorporate nothing to block network operator value added service such as
those listed in Table 1-23. Whether the service can be offered depends upon the details of how the
service offering is to be interfaced with the Gateway. This assumes of course that the Globalstar Air
Interface (GAI) and the User Terminal (UT) will support the value-added service.
Table 1-23 External Network - Value Added Services
External Network - Value Added Services
Acronym
Service
Description
Automatic IMSI replacement
Old SIM remains valid until first use of new SIM.
Operator Determined Barring
CAMEL Phase I
GSM Mobile Intelligent network
Core-INAP
Warm/Hot Billing
Billing can be to the OMC in less than 5 minutes.
Single Numbering
One number follows the subscriber.
Operator Services
Assistance or Help Desk.
Operator Defined Barring (ODB)
Network operator can bar even if UT selects.
Mail Boxes
Store and forward Voice, FAX or Digital Messages.
Dial in information.
Can be Voice, FAX and/or data.
Alarm and Wake up calls.
Alert under defined conditions.
Paging Services
Page a Subscriber
Credit Control
Network Operator Managed.
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2. SYSTEM SEGMENT DESCRIPTIONS
2.1 Globalstar System
The Globalstar system consists of a Space Segment, a User Segment, a Ground Segment, and a
Terrestrial Network as shown in Figure 2-1.
S a t e lli t e
S a t e lli t e
S a t e lli t e
Sp a c e
Se g m e nt
S - B a n d D o w n L in k
Use r
L - B a nd Up L in k
Se g m e nt
M o b il e
P o r t a b le
C -B an d D o w n L i n k
C -B a n d U p L i n k
LAN
G r o u nd
F ix e d
Se g m e nt
GBO
GO C C
SO C C
TCU
GDN Interface
G at e w a y
CDA
G lo b a ls t a r D a t a N e t w o r k
T e r r e st r ia l
G S M -M SC
Ne t w o r k
C e llu la r
C a r r ie r
Long
In t e r n a t io n a l
PT T
C a r r ie r
W i r el in e
D ist a n c e
P S T N / P LM N
T e l co
C a r r ie r
Figure 2-1 Globalstar System Integrates with Terrestrial Network
2-1
SP CC
P r iv a te
N et wo r k
Description of the Globalstar System
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The Globalstar system provides communications from any point on the earth surface to any other point
on the earth surface, exclusive of the Polar Regions as shown in Figure 2-2.
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19
20
21
22
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24
25
26
27
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29
Figure 2-2 Globalstar Constellation Serves Temperate Areas
The satellite orbits are optimized to provide highest link availability in the area between 70 degrees south
latitude and 70 degrees north latitude. Service is feasible in higher latitudes with decreased link
availability. The Globalstar space segment consists of 48 satellites in 1410 km Low Earth Orbits. The
low orbits permit low power hand sets similar to cellular phones. These satellites are distributed in 8
orbital planes with 6 equally spaced satellites per orbital plane. Satellites complete an orbit every 114
minutes. User Terminals in a particular location on the surface of the earth are illuminated by a 16-beam
satellite antenna as it passes over the earth.
User Terminals can be served by a satellite 10 to 15 minutes out of each orbit. A smooth transfer
process between beams within a satellite and between satellites provides unbroken communications for
the users. The orbital planes are inclined at 52 degrees. Coverage is maximized in the temperate areas
with at least two satellites in view, providing path diversity over most of the area. There is some small
sacrifice in multiple satellite coverage at the equator and at latitudes above 60 degrees.
The Gateways to the terrestrial network are illuminated by an earth coverage beam. The Gateway
connects the User Terminal to the terrestrial network via the Gateway. The terrestrial network is not a
part of Globalstar.
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2.2 User Terminal
The User Terminals come in several varieties. There are hand held units, mobile units and fixed station
units. The available types of User Terminals are listed in Table 2-1
Table 2-1 Production User Terminals
Fixed Terminal
Globalstar Only
Hand Held and Mobile
Dual Mode Globalstar & GSM
Tri Mode Globalstar & Terrestrial CDMA & AMPS
2.2.1 Hand Held and Mobile Units
Typical hand held units are shown in Figure 2-3.
Qualcomm
Tri-mode
Ericsson
Dual-Mode
Telit
Dual-Mode
AMPS
CDMA
Globalstar
GSM
Globalstar
GSM
Globalstar
Figure 2-3 Typical Hand Held User Terminal
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Globalstar Mode: Hand held User Terminals look like a standard cellular telephone. These are
multiple mode handsets that operate with the local cellular system or Globalstar. The radiating element
of the antenna is positioned above the head of the user. The antenna is positioned vertically to
effectively utilize the symmetrical radiation pattern of the hand held antenna. The area next to the head is
not used for radiation. This meets the safety requirements.
Cellular Mode: When operating as a cellular mode handset, normal cellular operation can be
expected. Cellular uses a separate and smaller antenna as is the custom with cell phones.
Mobile - The mobile units consist of a hand held unit inserted in an adapter in the vehicle. The Mobile
units typically have a higher gain antenna, a lower noise receiver and a higher RF power output. This is
part of the adapter kit. The improved transmitter and receiver are mounted in the base of the antenna.
The car kit that goes with a mobile typically includes:
12
1. Hands Free Speaker and Microphone
13
2. Outdoor Unit with a superior antenna
14
3. Operation with the Vehicle battery
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Block Diagram - Figure 2-4 is a simplified block diagram of the Globalstar portion of a User Terminal,
which includes Globalstar/CDMA/AMPS.
Ringer
Diagnostic
Monitor
115.2K Serial I/O
Intel
386EX:
LCD Display
Address
49.152 MHz
Clock
Rx Antenna
LNA
S Band
Downconverter
2 ch DMA
2 ch Serial
3 Timer/ctrs
Watchdog
Refresh ctl
Chip Sel unit
TC554161
256K X 16
SRAM
28F016
1Meg X 16
Flash
16L Data
Rx IF
Irq
10L Add
TCXO &
Synths
BBII ASIC
Ref Clk
8 bit I&Q
ChipX8
Tx Antenna
Tx IF
GUM ASIC:
rake receiver/
deinterlvr/dec
xmit
enc/interleave
dig FM , fart
Data
Port
RS-232
translator
38.4K Serial I/O
L Band
PA
Upconverter
SM
Socket
Sync & Clk
RF Assembly
Fr_Ref
ADSP-2185L
Vocoder
TLV320AV
Codec
5.0V PA
Power
Converter
16.6 MHz Resonator
8L Data
7.2V
1.4AHr
3.6Vaa
3.3Vdd
Figure 2-4 Globalstar User Terminal Block Diagram
Since there is no hand off between the local cellular system and Globalstar, if the user crosses a service
boundary between the local cellular system and Globalstar, the call could be dropped and must be
placed again. The indicators tell the operator that the mode has changed.
The system will not thrash in a boundary area. The user can select the preferred mode. If cellular is
preferred and coverage is not available the UT will drop the call. The call can be placed in Globalstar
mode. This call will continue until the phone is in an idle state. The reverse is also true.
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Function Performed : The start up functions of a User Terminal are programmable. As an example,
when a dual-mode User Terminal first powers up it may attempt to log into the local cellular system.
This addresses a scenario where the cellular system gets first priority to provide the service. If this fails
the User Terminal then attempts to log onto the Globalstar system. Figure 2-5 illustrates a typical
startup scenario within Globalstar.
Power-up
User Terminal
Initialization
State
User Terminal has
fully acquired
system timing
User
Terminal
Idle State
Receives an
acknowledgment
to an Access
Channel
transmission
other than an
Origination
Message or a
Page Response
Message
Receives a Paging
Channel message
requiring an
acknowledgment or
response; originates
a call or performs
registration.
System
Access State
Note: Not all state
transitions are shown.
Ends use of
the Traffic
Channel
Directed to a Traffic Channel
User Terminal
Control on the
Traffic Channel
State
Figure 2-5 User Terminal Startup Scenario within Globalstar
The User Terminal looks for the best satellite pilot signal. When this is found it then switches to the sync
channel and obtains the satellite database and other information. This database facilitates rapid
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acquisition of the pilot for any future calls. To place a call the user dials the number and presses
"SEND". The User Terminal contacts the Gateway via the access channel. The Gateway and the User
Terminal then work together to connect the call and support communications. Since the satellites are
moving, the user is continuously being illuminated by different satellite beams or even different satellites.
Diversity combining within the receivers supports a process of transferring traffic that is completely
transparent to the user. The diversity combining process also provides better call reliability. The hand
off process is accomplished without interruption to the call in process. If the user moves into an area
that shadows or blocks access to one satellite, the space diversity link through a satellite that is not
blocked maintains uninterrupted user communication
2.2.2 Fixed Terminals
Fixed station terminals are normally Globalstar only. The fixed User Terminals have a performance
equivalent to the mobile terminal except that the antenna gain and transmitter power may be even higher.
Fixed terminals do not require path diversity to combat fading and blockage. Fixed Terminals must
support seamless beam to beam and satellite to satellite hand of
15
16
17
Gateway
Gateway
18
19
20
21
22
PSTN
23
24
25
26
27
Figure 2-6 Typical Fixed Terminal Application
The fixed terminals can operate with a fixed phone, a payphone or other equipment.
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2.3 Gateway
The Gateways are geographically distributed by the service providers to serve their customer base.
Figure 2-7 is a typical Gateway
Figure 2-7 Typical Gateway Installation
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11
Gateways are designed for unmanned operation. A gateway consists of up to four 5.5-meter antennas
as shown on the left and electronics equipment installed in a building or shelter as show on the lower
right. In addition to the equipment racks, the facility supplied by the Service Provider includes prime
power, an Uninterrupted Power System (UPS), as well as any maintenance or office facilities. The
antenna layout is flexible. The major constraint is to place the antennas so that they do not block
visibility of the satellite constellation. Safety considerations for the operating area must also be
observed.
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Figure 2-8 is a simplified block diagram of a typical Gateway.
DG lo
12
7453
*8 6
DIG
0#9
ITA
GDN
SOCC
ba
ls ta
E1 or T1
BCN MSSL
Ethernet
IFL
BY
ROPI
GOCC
GW Links
SPCC
ABC
GDN Router
TCU
GMS
OPI
(Telemetry & Command Unit)
GSS
(Gateway Management System)
(Gateway Switching System)
TCU
TCU
GM
TCU Panel
TCU
CDA
GWRDB
SPCC Router
TCU
SS7
VME Cage
FL Cabinet
Server
GPS Rcvr
FL Shelf
(40)
5/polarize/ant
FL
ls ta
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11
12
13
14
15
16
17
NIS
CSU
Patch Panel
T1
Patch Panel
OMC
E1
Trunks
SSA
Patch Panel
GWC
VME Cage
Interface
Card
SS7
SBSShelf
Selector
Cards (12)
(Gateway RF System)
LHCP
Cabinets
(up to 13)
Demod
Cards
GRS
Digital
Cabinets
(up to 13)
Common
Card
Receive
Controller
Card
BY
Cabinet
Cabinet
(2)
(2)
BSCI
SBS
SS7
GSM
MSC
1/96 calls
Router
Receiver
Cards
AL
TFU
TFU
RHCP
Splitters
Splitters
IT
(DISCO)
RL
RL
Down
Converter
DIG
VLR
CIS
LNA
(up to 4)
LHCP
GTS
Antennas
OFF
ΣΣ
TFU
GCU
GSM
HLR
VME Cage
VME
Backplane
11 12 1
10
7 6 5
Modulator
Cards
ba
Upconverter
Cards
Up Converter
RHCP
SSPA
G lo
IS-41
HLR
SS7
VLR
CCP
T1/E1
Trunks
PSTN
T1
GCS
VIP
(Gateway CDMA System)
Trunk Set Combinations
( m o s t l i k e l y: )
1 2
· IS-41 territory:
· GSM territory:
2 3
Figure 2-8 Gateway Simplified Block Diagram
Appearance : The Gateway consists of up to four identical parabolic antennas that are at least 5.5
meters in diameter. The antenna structure contains drive mechanisms for positioning the antenna, low
noise receivers and high power transmitters. The antenna structure may be enclosed in a Radome to
provide protection from the environment.
The antennas connect to a building that houses the electronics equipment. The Code Division Multiple
Access (CDMA) equipment, PSTN interface equipment that interfaces with the terrestrial telephone
network, and computer equipment to operate the Gateway and collect status and performance data are
located in the electronics facility.
Function Performed : The Gateway supports voice communications, paging, and data transmissions.
Position location services are also supported.
The Globalstar Gateway connects the Globalstar space segment to terrestrial switching equipment. The
Gateway receives telephone calls from the terrestrial switching equipment and generates Code Division
Multiple Access (CDMA) carriers to transmit through the satellite. The satellite then re-transmits the
signal to User Terminals. These User Terminals may be either hand held, fixed or mobile and located
anywhere within the satellite antenna footprint.
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In the return direction, the User Terminal transmits to the satellite(s) and the satellite(s) re-transmit the
signal to the Gateway. The Gateway connects the call to terrestrial switching equipment, which can then
connect to any subscriber using the standard telephone system. Connections can also be made to
terrestrial cellular subscribers or to other Globalstar User Terminals.
The Gateways are designed to operate without operator intervention. Maintenance is performed by
service provider personnel as required. Status may be remotely monitored by the Service Provider's
Control Center (SPCC).
Functions of the major elements of the Gateway are listed below.
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25
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29
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31
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33
Telemetry and Control Unit (TCU): The TCU acts as a telemetry and control interface between the
satellite constellation and the SOCC. The TCU interfaces with the SOCC via the router in the GMS.
The TCU interfaces with individual satellites via the GTS and the GRS.
Gateway RF Subsystem (GRS): The GRS interfaces the gateway to Globalstar users via the
Globalstar satellite constellation.
Gateway Management Subsystem (GMS): The GMS interfaces the gateway with external
management entities (SPCC). The GMS performs non-real-time configuration and management of the
gateway.
Call Detail Access (CDA): The Call Detail Access (CDA) is a separate, fault-tolerant workstation
within the GMS, with stricter reliability requirements than the rest of the GMS. The CDA uses a
confirmed-transfer protocol to retrieve accounting from the SBS, CCP and GC.
CDMA Subsystem (CS): The CS performs real-time operation of individual calls, maintaining the
integrity of each physical link and performing physical layer format conversion between the CDMA
wave form on the GRS side and PSTN signals on the GSS side.
Gateway Controller (GC): The GC is responsible for operation and supervision of the CS and of the
GRS.
Gateway Transceiver Subsystem (GTS): The GTS is responsible for the physical layer
implementation of the Globalstar Air Interface. Under the control of the GC, control elements in the
GTS set up and operate overhead and traffic channels as required.
CDMA Interconnect Subsystem (CIS): The CIS provides packet-level and timing reference
connectivity between all subsystems in the gateway.
Selector Bank Subsystem (SBS): The SBS provides an interface between the SSA and the CS, and
performs layer two operation and radio link management of individual traffic channel circuits. The SBS
also performs service option-specific processing of traffic channel data. Service options may include
voice, data, and short message services.
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Base Station Controller Interface (BSCI): the BSCI provides an interface between the CDMA
Subsystem (CS) and the GSM MSCs. The BSCI implements the BSC side of the A1 Interface,
providing the SS7 transport, the protocol discrimination function, BSSMAP processing, and passes the
DTAP messaging between the GSM MSC and the CS. The BSCI can be configured to terminate
multiple A1 Interface links between multiple GSM MSCs. The configuration and setup of the BSCI is
controlled through the GMS interface (by way of the CS).
Time and Frequency Unit (TFU): The TFU provides a highly reliable and stable source of timing and
frequency references to the CS and to the GRS. The TFU output is synchronized to the Global
Positioning System (GPS).
Gateway Switching Subsystem (GSS): The GSS interfaces the gateway to the PSTN and controls
the state of each call.
Separation of CDMA & Switch: Although not often done, it is technically feasible to separate the
Selector Bank Subsystem from the switch equipment. The interface between the two elements is an
unformatted T1. Communications Service Units (CSUs) could be used at this point to separate the
switching subsystem from the remainder of the gateway.
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2.4 User Terminal and Gateway Interaction
Hand Off: The moving satellite constellation requires hand off to different satellites and to different
beams. In general, hand off is transparent to the user. Hand off on the forward link does not imply
hand off on the return link.
Forward Link: In the forward link direction (from the Gateway to the User Terminal), hand off is
totally under control of the Gateway. The User Terminal finds pilots and reports quality to the Gateway.
When a second pilot is seen, the quality is reported to the Gateway. If the Gateway determines that it is
advisable, the Gateway will instruct the User Terminal to incorporate the signal into the diversity
combiner. At all times the user terminal is using a fast algorithm to search for other pilots. Once a
suspected pilot is detected, it is turned over to one of the fingers used as a clincher. So at one point in
time, the User Terminal may have 3 fingers active. One is the traffic finger, one is used for diversity
combing and the third finger is used as the clincher. In the forward direction the role of the User
Terminal can be summed up as the proposer. The Gateway can be viewed as the disposer. The User
Terminal suggests which pilots should be used. The Gateway decides.
Return Link: In the Return Link direction, the Gateway uses up to 6 fingers. Eb/No is measured. If
the Eb/No is above a usable threshold it is added into the diversity combiner multiplex. New signals are
added in until the Gateway runs out of fingers. A stronger signal will not cause the Gateway to take a
weaker signal out of the diversity combining process as long as it is above the threshold. Once a signal
drops below the acceptable threshold, it will be taken out of the diversity combining process and the
finger released for assignment to other incoming User Terminal signals.
Soft Hand Off: In soft hand-off, two or more received signals through different links are simultaneously
demodulated, combined, and decoded by the same entity. It is characterized by commencing
communications using a new pilot on the same CDMA frequency before terminating communications
with the old pilot. This is a hand off occurring while the user terminal is operating on the Traffic
Channel.
Hard Hand Off: In hard hand off, the receiving entity stops demodulating and decoding information
transmitted on one link and starts demodulating and decoding information transmitted on another link
with possible loss of information. A hard hand off is characterized by a temporary disconnection of the
Traffic Channel. Hard hand off occur when the user terminal changes frequency or frame offsets. The
“temporary disconnect” does not mean the call is dropped. There is sufficient hysteresis in the system
to avoid dropping the call.
Access Channel: The access channel is slotted aloha (TDMA). It does not use diversity. This channel
is activated by the User Terminal to contract the gateway in the event the User Terminal is attempting to
initiate a call.
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2.5 Globalstar Control Centers
There are two operations control centers. Each is completely capable of operating the network and
managing the satellite constellation. There are two to circumvent the possibility of earthquake, power
grid failure or other disaster. One is located in San Jose, California and one is located near
Sacramento. Each includes:
1. Ground Operations Control Center.
2. Satellite Operations Control Center
3. Globalstar Business Office
The integrated control center is shown below in Figure 2-9
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Figure 2-9 Globalstar Control Center
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2.5.1 Ground Operations Control Center
Ground Operations Control Centers (GOCC) are responsible for planning and management of the
communications resources of the Globalstar satellite constellation. This is coordinated with the Satellite
Operations Control Center (SOCC). Figure 2-10 illustrates how the Ground Segment Equipment
operates together to support Globalstar Communications Functions.
• Relays signalling from gw to users
– paging
– pilot
– power control
– synch
• Relays signalling from user to gw
– Access request
– Power change request
– Registration
• Relays communications
C-BAND
L-BAND
(return)
– voice & data comm
• manage within resources
• data for billing
( GW )
• Provides orbits
• Satellite health
– satellite
• Battery state
– gateway
• monitor performance
• Selects filters
• Sets gains
Ground Operations
Co ntrol Center
Gat e w ay
• signalling
• voice & data communications
• multi-mode - including cellular
Planning
• generate traffic plans
• allocate resources
Re al Time
• connect user to switch
– signalling
S-BAND
(forward)
– ephemeris update
- Downloads
(GOCC)
Satellite Operations
Control Center
(SOCC)
Globalstar Data Network (GDN)
File: CommFunc
Figure 2-10 Ground Segment Support for Communications
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The GOCC and the SOCC may be collocated or they may be physically separated with linkage via the
Globalstar Data Network as shown in Figure 2-10. If the two are collocated, the connection will be by
a Local Area Network (LAN). In either case, the GDN connections are required to accommodate
failure scenarios. These collocations will reduce long term personnel costs since both the GOCC and
the SOCC are manned facilities.
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Figure 2-11 is a simplified block diagram of the Ground Operations Control Center (GOCC)
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Resource
Allocation
Management
Applications
High
Performance
Computer
Operations
Remote
Display
Work
Work
Stations
Stations
Remote
Display
GPS
Rcvr
Systems
Admin.
Console
Local Area Network
(redundant)
4 mm
Tape
Subsystem
Backups and
Archives
File
Server
GDN
Processor
Printers &
Scanners
Large Screen
Display
Visitor
Display
Disks
Local
SOCC
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Figure 2-11 GOCC Simplified Block Diagram
In addition to the planning functions, the GOCC is responsible for monitoring performance and ensuring
that the Gateways remain within the allocated satellite resources.
Appearance: The Ground Operations Control Center consists of a number of workstations in a
control center environment. Besides the workstations used by the operators, there are other displays in
the control center.
1. There are large screen remote displays located in the area. The computer operators can
project any of the screen displays onto the large screen displays and continue operations. The
large screen displays will update as the status changes.
2. There is also a large display that shows the position, coverage and status of the space
segment.
3. A separate animated communications network display indicates the number of circuits flowing
through Globalstar and indicates any congestion or circuit outages.
Function Performed: The Ground Operations Control Center (GOCC) is the planning element for the
Globalstar communications system. The redundant GOCCs plan the communications schedules for the
Gateways and control the allocation of satellite resources to each Gateway. The Gateways process real
time traffic within these assigned resources. The GOCC incorporates facilities to:
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1. Generate long-range plans based on projected traffic requirements and constraints such as
available frequencies, Gateway capacities, service areas, etc.
2. Monitor usage and refine plans based on measured performance of the system and
constraints imposed by the SOCC.
3. Report satellite usage to the Satellite Operations Control Center.
The GOCC facilities are operated 24 hours per day.
Emergency Power: Critical elements of the ground equipment require a no-break power source or
some form of backup power.
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2.5.2 Satellite Operations Control Center
The Satellite Operations Control Center (SOCC) manages the satellites. Redundant SOCCs control
the orbits and provide Telemetry and Command (T&C) services for the satellite constellation. In order
to accomplish this function on a worldwide basis, the SOCC communicates with T&C units collocated
at selected Gateways. The T&C units share the RF links with the Gateway communications equipment
to relay commands and to receive telemetry. Figure 2-12 illustrates how the various elements of the
Globalstar Ground Segment operate together to support the command and telemetry functions.
• T ransmit satellite telemetry
• R eceives & acts on commands
– D ecrypts
– S tores if time tagged
• E ncrypts commands
• M onitors telemetry
• O rbit determination
• T racks satellites
C-BAND
– P rogram track
• S ends commands
• R eceives telemetry
• I nforms
• A llocates satellite
resources to
GWs
• P rovides gateway
T racking schedules
G ateway
(GW)
TCU
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File: ContFunc
Ground Operations
Control Center
(GOCC)
GOCCs
– S atellite available
– S atellite capacity
– S atellite ephemeris
Satellite Operations
Control Center
(SOCC)
GlobalstarData Network (GDN)
Figure 2-12 Ground Equipment Support for T&C Functions
Telemetry Down link and Command Up link: Globalstar satellites continuously transmit telemetry
data, which contains orbit position data and measurements of current on-board health and status of the
spacecraft. Because both the telemetry stream and the communications payload feeder links will utilize
C-band communications, T&C operations utilize antennas and RF-equipment at selected
communications Gateways. Since only selected Gateways have T&C units, telemetry is available only
when an antenna with a T&C Unit is tracking the satellite. All Gateways equipped with T&C Units
have the ability to command the satellite. The T&C unit consists of special purpose RF cards and a
DSP controlled by a Pentium based Personal Computer. A single self-contained rack will
accommodate up to 5 T&C Units (1 spare). The T&C units are designed to run automatically, with
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control from the SOCC. Routine staffing is not required. Any maintenance will be provided by service
provider personnel dispatched on call from the Globalstar Control Center (GCC).
Telemetry Reception: Telemetry from each satellite will be received at the T&C Gateway that have
an antenna trained on that satellite. The T&C unit will be able to either directly send the demodulated
data (bent-pipe mode) or store it for later transmission (store and forward mode). Stored data will be
sent to the SOCC upon SOCC request, typically during a period of lower system utilization or lower
communications network costs. The SOCC will coordinate the T&C data transmission to avoid
receiving identical data sets from multiple T&C sites. The telemetry data sent from the T&C site is
routed to the SOCC as packet messages on the Globalstar Data Network (GDN). Should more than
one SOCC be providing support, the T&C equipment will route the data to multiple destinations.
Command Transmission: Commands received from the SOCC are immediately transmitted to the
satellite (bent pipe mode only). Depending upon the command, the satellite can execute the command
immediately or store the command for execution at a later time. The TCU does not incorporate a
command storage facility. The SOCC is responsible for directing the command message to the proper
T&C at the correct time for transmission.
SOCC Operations: The SOCC will receive minor frames over the Globalstar Data Network. Data
received in the telemetry bent-pipe mode is immediately routed to the user workstations assigned to
monitor or control the specific satellite. At any one time, all satellites in contact are automatically
monitored by the software, with only selected satellites directly monitored by a member of the flight
operations team. A single workstation can monitor up to 6 satellites. An operations controller may
have asked for up to 6 specific satellites to monitor or may have defined the criteria by which the system
can automatically determine which satellites are to be monitored. For example, the controller could
request to see all satellites for which real-time data is being received for which the power subsystem
monitoring software detects a possible area of concern.
Because of the very low telemetry rates, it is possible to have remotely located workstations, connected
to the SOCC via simple modem or ISDN communications. A workstation at the satellite
manufacturer's facility, for example, could routinely be used to monitor a single satellite to support
problem investigation, routine monitoring, or analysis.
The SOCC is also responsible for coordinating activities with the GOCC. The three primary interface
functions are:
a. Orbit position information: The SOCC will provide information to the GOCC so that each
Gateway can accurately track each satellite. The data will consist of data tables sufficient to allow the
Gateway software to generate its own contact lists.
b. Utilization statistics: The GOCC will provide statistics to the SOCC pertaining to the actual
communications quality and utilization (Gateway assessment) of each satellite. This information will be
correlated with satellite telemetry to distinguish between expected and anomalous behavior.
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c. Spacecraft status: The SOCC will report to the GOCC spacecraft/transponder availability. This
data will include limitations associated with any satellite, which may constrain or preclude its use for
communications.
Use of Multiple SOCCs : Two SOCCs are planned. The San Jose, California location will support
primary operations and a second one in El Dorado Hills, California serves as a backup to the prime.
Both SOCCs will be able to receive telemetry data from the same satellites so that dual-site monitoring
and "hot backup" functions could be supported; however, the baseline is a single string SOCC
operation.
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The main reason for the second SOCC is to create a backup operational facility in case of a
catastrophic failure (fire, etc.) at the primary site. The two SOCCs, however, could be used routinely
to share the load between two sites, to conduct training and to support development and test of
software upgrades.
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2.5.3 Globalstar Business Office
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To support the Globalstar Business Office (GBO), the Globalstar Accounting & Billing System (GABS)
is collocated with the GOCC and the SOCC. The GABS is responsible for all financial activities
associated with Globalstar.
Appearance: The GABS is a client/server system with many workstations and the requisite office
facilities required to support the assigned accounting and billing activities. The server for the primary
GABS is located in the GCC. A back-up GABS server is located in the alternate GCC. Multiplatform client support is provided.
Functions: The GABS provides basic accounting and billing functions for GLP. The accounting
functions are provided by a Commercial - Off - The - Shelf (COTS) package, ORACLE Financial, and
include accounts payable, accounts receivable, general ledger, purchasing , and financial planning
software. The wholesale billing function, provided by custom developed software, receives data from
both the Gateways and the Service Providers. These data, call usage summaries, subscriber counts,
etc. are used to calculate charges for usage of the Globalstar system and to generate bills which are sent
to the service providers monthly.
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2.6 Globalstar Satellite
The Globalstar satellite is a simple low cost satellite designed to minimize both satellite costs and launch
costs. A pictorial of the satellite and some of the major characteristics are shown in Figure 2-13.
STRUCTURE
• Rigid Al Frame
• Al Honeycomb Panels
RELIABILITY
• Ps = 0.85 for 7.5 years, providing
15 of 16 beam pairs
MASS
• <450 kg (Wet)
AUTONOMY
• FDIR
• Safe Mode (Earth & Sun)
ELECTRICAL POWER
• 1.1 kW EOL Solar Array
• Single-Axis Track(Rotate)
• Peak Power Tracker
• 14-23 V Unregulated Bus
• Ni- H2 Battery, 14 Cells, 64 Ah
TELEMETRY & COMMANDING
• C-Band CMD/TLM - 1.0 KBPS
• Real Time, Stored and Macro
• CMD Encryption - KI - 23
• <500 Hardware Commands
THERMAL
• Generally Passive
• Heat Pipes
• Thermostatic Control Heaters
• <500 Hardware Telemetry Items
ORBIT DETERMINATION
• GPS Tensor (<90 M. Semi-Major Axis)
PROPULSION
• Mono-Hydrazine (76.6 kg)
• Blow Down Regulation (4:1)
• Passive Management Device
• 5-1 Newton Thrusters
ATTITUDE DETERMINATION ( 0.7 half cone)
• Earth Sensor
• Magnetometer
• 3 Sun Sensors
ON-BOARD PROCESSING
• 1750 A
• 16 BIT, 1.8 MIPS, 64K SRAM
& 128K PROM
• 16K SUROM
• RS422 & RS485 I/O
• ADA
• 8K Safeguard Memory (SGM)
ATTITUDE CONTROL (NORMAL)
• Yaw steering & Momentum Bias
• 4 Reaction Wheels
• Mag. Torquer along X&Y
Figure 2-13 Spacecraft Bus Characteristics - Highly Autonomous
Communications Payload : A pictorial of the communications payload is shown in Figure 2-14.
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Beam Configuration (L - Band)
S-BAND TRANSMIT ANTENNA
• Satellite to User
• Generally Isoflux
• Active Phased Array
• 16 Beams
• 91 Elements
• 1 - Central Beam 22.5 deg
• Frequency = 2483.5 to 2500 MHz
• 15 - Outer Beams to 54 deg
• Max. SSPA RF 4.2 Watts
COMMUNICATIONS CHANNEL
L-BAND RECEIVE ANTENNA
• 16 total channels
• User to Satellite
• 1 channel per beam
• Active Phased Array
• Each channel is 16.5 MHz with
• 61 Elements
19.38 MHz centers
• Frequency = 1610 to 1626.5 MHz
C-BAND XMT/RECEIVE ANT.
S-BAND ELECTRICAL POWER
• Scalar Horn
• Continuously
• Bi-Polarized, 8 channels per
Payload senses SSPA input power
Transmit Freq. = 6875 to 7053 MHz
Rec. Freq. = 5091 to 5250 MHz
level and adjusts transmit power
• Dedicated high efficiency
COVERAGE (ALL BANDS & ANTENNA)
TELEMETRY & COMMANDING
• Fill subtended angle = 108 deg
• C-Band for command & telemetry
(with respect to satellite nadir)
• Telemetry 1 of 12 selectable
Beam Configuration (S-Band)
carriers uniformally spaced
• Generally Isoflux
• 16 Beams
• Single command frequency with
• 1 - Central Beam Radius 16 deg
unique satellite ID
• 6 - Middle Beams to 37 deg
MASS
• 9 - Outer Beams to 54 deg
• <154 kg
Figure 2-14 Communications Payload Pictorial
The communications payload is a simple bent pipe communications package as shown in Figure 2-15.
RET U RN T RA N S P O N DER
R ETU RN
LINK F ROM
U SER
L -B AN D RX
ACT IVE
A NT ENNA
S AW
S AW
S AW
S AW
C BAN D
SSPA
L- C BAND
FREQU E NC Y CONVERSION SEC TION
TLM
RE TUR N
LIN K TO
GAT EWAY
MA ST ER F RE QUE NC Y
GENERATOR
FO RWAR D
LIN K FROM
GAT EWAY
C-S B A ND
FOR WA RD
LINK T O
U SER
FR EQUE NC Y C ONVERSION SEC TION
S-B A ND TX
ACT IVE
A NT ENNA
FO R WA R D TR AN S PO N D E R
C MD
C BAN D
LN A
File: Sat C omm
Figure 2-15 Communications Payload Simplified Block
Function Performed : A User Terminal transmits to the satellite by L-Band. The signal enters the
satellite through the L-Band low noise amplifier. It is amplified and then converted into a C-Band signal
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after which it is further amplified. This is radiated to the Gateway. The Gateway receives the signal and
block down converts to an intermediate frequency. A sample of the intermediate frequency is provided
to the TCU for processing. The communications traffic is presented to the CDMA equipment for
demodulation.
In the forward link direction, the Gateway combines the up link CDMA signals with the signal from the
command transmitter and radiates it at C-Band up to the satellite. The satellite then down converts the
signal and radiates an S-Band down link signal to the User Terminals.
Telemetry & Command : The Telemetry and Command carriers share the C-Band with the
communications feeder links. Figure 2-16 is a simplified block diagram of the T&C package on the
satellite.
CMD Channel
Extractor
OBPE
Data (NRZ-L )
Command
Inp ut Fil ter
Recei ve r
(LHCP)
AE CMD Fil ter
To
C-Band LNAs
RS-422
Clock
DC/DC
Command
Decoder
Sque lch
Data (NRZ-L )
Command
Receiver
DC/ DC
Command
Decoder
Clock
Sque lch
RS-422
L NAs
AE CMD Ante nna
TLM channel
Insertor
Telemetry
Encoder
Telemetry
Encoder
11
12
13
14
Data (Mancheste r)
RS-422
Data (Mancheste r)
RS-422
Teleme try
Transmitter DC/DC
From
C-Band
SSPAs
Output Fi lter
(LHCP)
Teleme try
Transmitter DC/DC
AE TLM Filter
OBPE
AE TL M Antenna
Figure 2-16 Satellite T&C - Compatible with Communications
The T&C connects to the normal C-Band communications antenna for on-orbit operations. There is
also a T&C antenna on the anti-earth face of the satellite. This antenna functions when the satellite is not
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oriented correctly or when there are problems. The anti-earth antenna is to ensure that telemetry can be
obtained and commands entered under all recoverable contingencies. Note that the anti-earth antenna
bypasses the Low Noise Amplifier. This means that the transmitted power from the commanding earth
terminal will have to be higher than the normal power required for commanding. This can be
accommodated because there is no communications traffic when the satellite is not oriented correctly.
Yaw Steering: The satellite is steered in yaw to keep the solar panels oriented toward the sun to
extract the maximum energy. This increases the communications capacity of the Globalstar System.
There are some minor penalties that cause a slightly slower acquisition time and may cause more hand
offs than would be otherwise required.
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3. FREQUENCIES AND COVERAGE ANALYSIS
3.1 Frequency Plans
Globalstar uses C-Band between the Gateway and the Satellites as shown in Figure 3-1.
TO GATEWAY
TO USER TERMINAL
16 BEAMS
6875 MHz
7055 MHz
180 MHz
LHCP
S-B and
LHCP
Channel
Beam
2483.5 MHz
2500 MHz
X1
X2
X3
X4
X5
X6
X7
X8
10
14
12
16.5 MHz
Satellite Transponder
RHCP
Y1
Y2
Y3
Y4
Y5
Y6
Y7
Y8
Channel
11
13
15
Beam
Y1
Y2
Y3
Y4
Y5
Y6
Y7
Y8
15
13
11
16
RHCP
16.5 MHz
19.38 MHz
X1
X2
X3
X4
X5
X6
X7
X8
12
14
16
10
Satellite Transponder
Beam
LHCP
L-B and
159 MHz
5091 MHz
10
11
Fil e: Fr eq Pl an
16.5 MHz
Channel
LHCP
1626.5 MHz
1610 MHz
5250 MHz
FROM UT
FROM GATE WAY
Figure 3-1 Frequency Plan - Emphasizes Conservation of Spectrum
The C-Band antennas on the satellite use an earth coverage beam. The Gateways use a parabolic
antenna and program track the satellites. Program tracking uses the orbital data provided by the
Satellite Operation Control Center to position the Gateway antenna.
Efficient Spectrum Utilization - The spectrum is used efficiently by incorporating frequency
reuse and spread spectrum into the design. Both Right Hand Circular Polarization (RHCP) and
Left Hand Circular Polarization (LHCP) are used for C-Band. This allows 8 frequencies to
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connect to 16 beams on the satellite. The beam numbers shown in Figure 3-1 map to the S-Band
beams shown in Figure 3-2 and the L-Band beams in Figure 3-3 which follows. The alpha
characters used within the spectrum blocks and on the following diagram indicate polarization.
X= Left Hand Circular Polarization
Y= Right Hand Circular Polarization
3.2 Satellite Antenna Beam Configuration
The S-Band antennas on the satellite are configured to produce 16 beams as shown in Figure 32.
View from Satellite
Looking at Earth Nadir
+ Ysc
Y3
X1
Y2
X2
Y8
X7
13
12
14
11
+ Xsc
Y6
X5
X6
Y4
X4
15
10
X8
Y7
X3
Y1
Fil e: S -B eams
16
Y5
X= LHCP
Y=RHCP
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11
12
13
14
Channel Assignments
Beam Assignments
Figure 3-2 S - Band Beams
The antennas are multiple beam antennas designed to provide an isoflux pattern on the earth in
the service region. The isoflux pattern is obtained by shaping the beam so that the gain at the
edge of coverage is higher than at the beam center. This compensates for the difference in losses
due to the longer slant range at the beam edges.
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L-Band Pattern: The L-Band pattern consists of 16 beams. Beam 1 is in the center. The
remaining 15 beams are arranged in an annular ring around the center beam as shown in Figure
3-3.
View from Satellite
Looking at Earth Nadir
+ Ysc
X2
Y6
X1
Y7
+ Xsc
X8
X4
Y5
13
14
Y2
X7
12
X6
Y1
11
Y3
X5
X3
10
Y4
15
Y8
16
X= LHCP
Fil e: L-B eam s
Y=RHCP
Ch annel Assign men ts
B eam Assignments
Figure 3-3 L- Band Beams
This configuration provides better coverage on the earth to reduce the power requirements on the
L-Band transmitters in the User Terminals.
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Efficient Spectrum Utilization - As shown in Figure 3-4 and Figure 3-5, only 16.5 MHz of LBand and S-Band spectrum are used. The same set of frequencies are reused in each of the 16
beams. Note that C-Band frequencies are assigned to beams to minimize interference. The
Globalstar approach is very efficient in its use of the valuable L-Band and S-Band spectrum. LBand is used to communicate from the User Terminal to the satellite and S-Band is used to
communicate from the Satellite to the User Terminal. Within each of the beams, there are 13
FDM channels.
161 0.0 MHz
162 6.5 MHz
161 1.960 MHz
16 10 .7 30 MHz
16 14.42 0 MHz
161 3.190 MH z
16 16.88 0 MHz
1615 .6 50 MHz
16 19.34 0 MHz
1 618.110 MHz
16 21.80 0 MHz
1620 .5 70 MHz
16 24.26 0 MHz
1623.030 MH z
162 5.490 MHz
1010 kHz
730 kHz
1.23 MH z
1.23 MHz
1 .2 3 MHz
1 .2 3 MHz
10
1.23 MH z
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12
1.23 MH z
13
1.23 MH z
16.5 MHz
Fil e: L- Band
Figure 3-4 L - Band Channel
10
Frequencies
2 483 .5 MHz
250 0.0 MHz
2 485.6 20 MHz
24 84.390 MHz
2488 .0 80 MHz
2486.85 0 MHz
2 490.5 40 MHz
2489.310 MH z
2 493 .0 00 MHz
249 1.770 MH z
249 5.460 MH z
249 4.230 MH z
2497.920 MH z
2496 .6 90 MHz
24 99.150 MHz
850 kH z
89 0 kHz
1.23 MH z
1.23 MHz
1 .2 3 MHz
1 .2 3 MHz
1.23 MH z
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11
1.23 MH z
12
13
1.23 MH z
16.5 MHz
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12
13
14
15
16
Fi le:S -B and
Figure 3-5 S - Band Channel Frequencies
Spectrum Sharing - Within a channel, spread spectrum is used to convey the voice or data
intelligence. Multiple voice or data circuits may be carried within a single 1.23 MHz FDM
channel. The circuit data is separated by unique PN spreading sequences. This allows the same
spectrum to be shared by other CDMA users.
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Satellite Frequency Plan: Table 3-1 illustrates how the C-Band up link signals are converted
to S-Band down link signals and indicates how the signals are connected to down link beams.
The table shows the assigned C-Band Frequencies.
Table 3-1 Satellite C-Band to S-Band
C-Band Frequencies
S-Band LHCP
S-Band RHCP
RF Freq.(MHz)
L.O. Freq (MHz)
Chan
Beam
Chan
Beam
5105.21
7596.96
X1
12
Y1
5124.59
7616.34
X2
14
Y2
11
5143.97
7635.72
X3
16
Y3
13
5163.35
7655.10
X4
10
Y4
15
5182.73
7674.48
X5
Y5
5202.11
7693.86
X6
Y6
5221.49
7713.24
X7
Y7
5240.87
7732.62
X8
Y8
5091.50
CMD
Table 3-2 illustrates the how the Return link is processed in the Satellite. The table shows the
assigned C-Band Frequencies.
Table 3-2 Satellite L-Band to C-Band
L-Band to C-Band
L-Band LHCP
L-Band RHCP
RF Freq(MHz)
L.O. Freq (MHz)
Chan
Beam
Chan
Beam
6908.99
5290.74
X1
Y1
6928.37
5310.12
X2
10
Y2
15
6947.75
5329.50
X3
Y3
13
6967.13
5348.88
X4
Y4
11
6986.51
5368.26
X5
Y5
7005.89
5387.64
X6
14
Y6
7025.27
5407.02
X7
Y7
7044.65
5426.40
X8
12
Y8
16
6876.0-6877.1 (12 ea.)
TLM
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Command and Telemetry Frequencies: The telemetry frequencies are listed in Table 3-3
Table 3-3 Satellite Telemetry & Command Frequencies
Command
Channel
Bandwidth
5091 to
5092 (*)
No. of
Channels
Telemetry
Channel
Bandwidth
6875.95 to
6877.15
No. of
Channels
12
Chnl
No.
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11
12
Channel
Width(s)
240 KHz
Frequency
Center(s)
5091.5
Channel
Width(s)
100 KHz
Frequency
Center(s)
6876.0
6876.1
6876.2
6876.3
6876.4
6876.5
6876.6
6876.7
6876.8
6876.9
6877.0
6877.1
Doppler: The Frequencies that appear at the Globalstar nodes (Gateway, Satellite, UT) differ
from the assigned frequencies. Doppler is one of the primary contributors. Doppler can be
computed and the nodes can compensate for the differences in frequency. Table 3-4 indicates
the magnitude of the Doppler components.
Table 3-4 Worst Case Doppler
Frequency
Doppler
Rate
(MHz)
(KHz)
Hz/sec
Path Name
From
To
Forward Uplink
Gateway
Satellite
5250
97.2
468.8
Fwd Downlink
Satellite
UT
2500
46.5
224.3
Return Uplink
UT
Satellite
1626.5
30.2
146.0
Return Downlink
Satellite
Gateway
7052.9
131.6
634.9
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3.3 Earth Surface Coverage
The surface of the earth, with the exception of the polar regions, is covered with multiple
overlapping satellite beams as shown in Figure 3-6.
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Figure 3-6 Full Earth Coverage-Except Polar Regions
The contours shown indicate that a User Terminal within the contour can communicate with the
satellite at an elevation angle above 10 degrees.
Constraining the User Terminals to operate with satellites that have higher elevation angles
referred to the User Terminal will reduce the overlapping coverage but would provide an
advantage in that it would reduce the power demands placed on the User Terminal to close the
link. This would result in longer battery life for the User Terminal.
Conversely, lowering the angle to the satellite will increase the overlapping coverage. Small
changes dramatically increase the coverage area. This is particularly apparent in the polar
regions. If operated at low elevation angles, polar areas that otherwise could not be covered can
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receive service. In polar areas, overlapping coverage would be increased and power demands
may be increased. In this region the look angle to the satellite is limited. High gain directional
antennas become practical for fixed and even portable installations. The pay back is that
Globalstar could now serve areas that otherwise might be unserviceable.
To a degree, some of these same considerations discussed for polar areas apply to equatorial
areas where the overlapping coverage is less than 100%.
Satellites in View as a Function of Latitude: Figure 3-7 illustrates the multiple satellite
coverage more clearly.
Multiple Satellite Coverage Versus Latitude
(10 degree elevation angle, 48 satellite constellation)
100.0
1 or more
2 or more
3 or more
4 or more
90.0
80.0
70.0
% of Time
60.0
50.0
40.0
30.0
20.0
10.0
0.0
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
Latitude
USA (CONUS)
CENTRAL
EUROPE
SCANDINAVIA
AUSTRALIA
9408061
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12
13
14
Figure 3-7 Enhanced Coverage for Temperate Regions
Note that the coverage is optimized to provide multiple coverage in the temperate regions. In
areas within this temperate region, the User Terminal can communicate via multiple satellites.
This enhances the link availability and allows the User Terminal to operate with nominal link
margins.
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Orbital Parameters: The orbital parameters for the initial injection orbit and for the final on
station orbit are shown in Figure 3-8.
On Station
Phasing Orbit
Parameter
Mean
Tol (3 V )
Mean
Tol (3 V )
Radius (km)
7778
+/- 0.1
7298
+/- 20
Orbit Period-Nodal
114 min
+/- 0.13 sec
103.35
+/-0.4
Eccentricity
0.000
+ 0.008
0.000
+ 0.01
Inclination (Degrees)
52
+/- 0.01
52
+/- 0.6
RAAN Spacing for plane
J=1...8 (Degrees)
45
+/- 1.0
Relative Phasing between
satellites in a plane (Degrees)
60
+/- 1
Relative Phasing between
adjacent planes (Degrees)
7.5
+/- 1
File: Orbi tp
Rev 11 /0 6/96
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13
14
15
16
17
18
Figure 3-8 Orbital Parameters for Globalstar Satellites
Supplementary Coverage: There are two problem areas in the coverage.
1. One is over the equator where the beam is narrow. There has been some study of using some
additional satellites to cover the equatorial area. At this point in time, this is not financially
justified. If more business is identified as we penetrate Indonesia, the Philippines, India,
Central Africa, and Central America enhanced coverage may be examined again.
2. The second area that is not covered well is the polar area. Some study of supplementing
coverage with Molniya orbit satellites has been performed. This type of orbit “hangs” in the
polar areas for a long period and then orbits over the south polar area very rapidly. If
coverage of the northern areas becomes economically justified, this may be re-visited.
The other thing to be considered in northern areas, such as the islands north of mainland Russia,
is the inclination of the satellites. They do not go beyond 52 degrees north. This means a fixed
UT antenna can be pointed south only. Gain can be obtained due to the directivity. Fixed User
Terminals could operate much further north if they do not require an omni-directional Fixed
User Terminal antenna.
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3.4 Position Determination
The location of the User Terminal is determined by Globalstar and used for several purposes.
Any position location services that may be provided should be considered a by product of the
Globalstar System. The primary purpose of Globalstar is to provide communications. It should
not be considered as a competitor or replacement for GPS or GLONASS. Two basic accuracy
are supported.
Low Accuracy: The user terminal is located to within 10 km for purposes of National
Sovereignty, to assign the user to a gateway, and to support registration. This accuracy is
sufficient for the gateway to determine which satellite/beam should be used for phone
paging. This avoids having to page on multiple satellites/beams at the cost of capacity.
High Accuracy: A higher accuracy on the order of 300 meters is feasible in under some
conditions. This may be attractive as a service. This high accuracy results from the high
degree of precision with which the position and velocity of the satellite constellation is
know. Each satellite incorporates a GPS receiver to determine position and rate of
change of position. When this data is processed with other data at the SOCC the
precision of the orbit becomes quite good. The CDMA, for its own purposes, needs to
align chips within 1/8 of a chip. Potential for high positioning accuracy is inherent.
The User Terminal may determine its position with the assistance of the Gateway or it may
determine its position autonomously. In all cases, determination of position is based on
determining the intersection of three or more spheres in 3-dimensional space. The surface of the
earth can be used as one of the spheres. The Gateway has the processing power to make active
determination attractive. This must be traded for additional messaging that will be required to
support active determination of position.
Active Determination: The Gateway calculates range based on time delay between the
User Terminal and the Gateway through a satellite. The phone transmission can be an
access probe or an ongoing call, but it must be synchronized in some fashion to the
forward link signal. When this accomplished through two satellites with the proper
geometry, excellent positioning accuracy can be achieved.
Passive Determination: The User Terminal can determine its location without the
assistance of the Gateway. In this mode, since time is not known very well this means
the system has an extra degree of freedom. The phone measures a 'T between two
different satellites, and another 'T using a third satellite. Three 3 satellites are required,
to solve for the phone's clock offset. An additional form of passive position
determination incorporates measurements of the satellite velocities relative to the phone,
instead of or in addition to the satellite ranges to the phone. This is done by measuring
the received Doppler shift of the satellite signal.
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Any of the techniques must incorporate the following generic considerations.
Geometric Dilution Of Precision (GDOP): This is a phenomenon that affects all
forms of position determination. It is due to the orientation of the satellites from the
phone's perspective. When the geometry is good, precision is good. When poor, the
accuracy degrades very quickly.
Time to Position: Time to achieve an accurate position depends on the time. In simple
forms, the more time the more precise the location.
Geographical Constraints: Position determination becomes more difficult when the
User Terminals are on the equator or at high latitudes. In these cases, only one satellite
may be visible. This means that range must be determined at one point in time and the
range determined again at another point in time. Under these conditions the geometry is
less than optimal, resulting in a long time to achieve a valid position determination and
an inaccurate determination of position.
Terrain Maps: For the surface of the earth to be used as one of the intersecting spheres,
a terrain map must be used to determine altitude above the mean surface of the earth.
The degree of granularity of this map will impact the accuracy that can be achieved and
will impact the time to achieve a position indication.
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3.5 Channel Characteristics
Figure 3-9 illustrates the orientation of a User Terminal in a typical temperate climate scenario
with multiple satellite coverage.
Globalstar 1
Globalstar 2
S2
S2
S1
S1
Channel 5
Channel 5
Globalstar Gateway
Globalstar
Handset
RECEIVER 1
Decoder
COMBINER
RECEIVER 2
Vocoder
RECEIVER 3
Figure 3-9 Channel Characteristics Considerations
Line of Sight: For the Globalstar system, many of the obstructions in the direct line of sight do
not completely block the line of sight, but rather simply attenuate the signal. Given two
satellites in view at the same time, the probability of signal blockage or shadowing to both
satellites is significantly less than the probability of blockage to a single satellite.
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Specular Reflection: The specular reflection component is the signal reflected off the surface
of the earth. The magnitude of the reflected signal can be large if the surface is relatively smooth
and flat at the point of reflection. The specular component will prove to be an insidious problem
for the hand held antennas. It can either add to or subtract from the signal received from the
direct line of sight. This problem can be managed effectively for the mobile and the fixed
station antennas.
Diffuse Reflection: The diffuse component is composed of a sum of a large number of
individual terrain scatter from outside the first Fresnel zone. This diffuse component is
characterized by phase incoherent multi-path with a uniform phase distribution and a Rayleigh
amplitude distribution. The signal fading associated with the diffuse component combining with
the direct component produces the fast-fading characteristics of the propagation channel.
Building Penetration: Globalstar has limited ability to penetrate buildings. Operation is
possible in wood frame buildings or near windows with a wide angle view of the sky. The best
locations within building results in 6 to 13 dB added insertion loss. There is a high degree of
sensitivity to antenna location within the building. A change in lateral position of 20 to
30 centimeters can produce a 30-dB variation in signal power.
In Pocket: With the antenna extended, operation depends on orientation. Body blockage can
insert attenuation in excess of 15 dB. If the antenna is stowed, operation is not considered
feasible.
24
Interference: User Terminal receivers may experience interference when operating in close
proximity to microwave ovens, plywood plants or hospitals. The transmitters are frequency
coordinated for operation with Radio Astronomy sites, for operation with GPS, and with
GLONASS. The Gateway site locations are selected to avoid interference with the Microwave
Landing Systems (MLS) associated with airports.
25
Conclusions: Several Conclusions can be drawn for Globalstar operations.
20
21
22
23
26
1. Operation at higher elevation angles is preferred.
28
2. Mobile will suffer less from specular. Power control may be less effective at some
operating speeds.
29
3. Fixed terminals will suffer less degradation from all sources.
27
30
31
4. Forward and Return link behavior are not correlated. Conclusions from one direction
cannot be used to derive control information for the other direction.
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3.6 Link Analysis
The Globalstar system provides spatial diversity to overcome shadowing and blocking. The link
analysis in this section is based on the current FCC filing which assumes nominal 5.5 meter
antennas at the Gateways. There are 3 cases that are presented.
Case 1: This is a detailed link budget. This case considers the forward and return links between
the Gateway to the User Terminal. The up link from the Gateway to the satellite is C-Band. The
down link from the satellite to the User Terminal is S-Band. The Return Link is L-Band from
the User Terminal to the Satellite and C-Band from the satellite to the Gateway. There is no
shadowing or blocking and diversity is used.
12
Case 2: This is an abbreviated link budget that shows only the differences from case 1. One
path is blocked. Only the C-Band or the S-Band can be blocked; since, the Gateway will be in
one location.
13
Case 3: This is a rare case where both links are shadowed or faded by 10 dB.
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Table 3-5 Forward Link C-Band - Case 1 - Detailed Budget
14
Up Link Gateway to Satellite C-Band
Frequency
Nominal EIRP per user
Path loss(40 degree. GW elev.)
Polarization & Tracking. Loss
Satellite Antenna gain (incl. line loss)
5125.0
MHz
26.8
dBW
-172.5
dB
-1.1
dB
3.1
dB
Receive power/user at LNA
-143.7
dBW
Average User Data Rate
2400.0
b/s
System Noise Temperature
549.5
Thermal Noise Density, No
-201.2
dBW/Hz
Estimate Interference Density
-198.5
dBW/Hz
Up link Eb/(No+Io)
19.1
15
3-14
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Table 3-6 Forward Link S-Band - Case 1 - Detailed Budget
Down Link Satellite to User Terminal
Frequency
2495.0
Nominal EIRP per user
-2.9
Satellite Altitude
1414.0
Typical Elevation Angle
50.0
MHz
dBWi
km
degrees
Range
1740.5
km
Free Space Loss
-165.2
dB
-1.0
dB
0.0
dB
Polarization & Tracking. Loss
Shadowing Loss
Receive Signal Strength /user/sat.
-169.1
User Antenna Gain(incl. line loss)
2.6
User Signal at antenna output
-166.5
dBWi
dBi
dBW
System Noise Temperature
293.7
Thermal Noise Density, No
-203.9
dBW/Hz
Average Data Rate, Rb
2400.0
b/s
3.6
dB
Down link Eb/No
Interference per Channel
-148.6
dBW
1.23
MHz
-10*log(spreading BW)
-60.9
dB/Hz
Interference Density, Io
-209.5
Spreading Bandwidth
dBW/Hz
Down link Eb/(No+Io)
2.6
dB
Coherent combining gain
2.5
dB
Overall Eb/(No+Io) (up&dn)
5.0
dB
Operating Eb/No
5.0
dB
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Table 3-7 Forward Link - Case 2 - Link Blockage
C-Band Up Link and S-Band Down Link
Up link
EIRP per user
28.8
dBW
Up link Eb/(No+Io)
21.1
dB
-0.4
dBW
Down link
EIRP per user
Down link Eb/(No+Io)
5.1
dB
Coherent combining gain
0.0
dB
Overall Eb/(No+Io)
5.0
dB
Table 3-8 Forward Link - Case 3 - Rare Two Link Fade
C-Band Up Link and S-Band Down Link
Up link
EIRP per user
36.3
dBW
Up link Eb/(No+Io)
28.6
dB
Down link
EIRP per user
7.1
Shadowing loss
dBW
-10.0
dB
Down link Eb/(No+Io)
2.6
dB
Coherent combining gain
2.5
dB
Overall Eb/(No+Io)
5.0
dB
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Table 3-9 Return Link L-Band - Case 1 - Detailed Budget
Up Link User Terminal to Satellite
Frequency
1615.0
Nominal EIRP per user
-11.2
Satellite Altitude
1414.0
Typical elevation angle
70.0
MHz
dBWi
km
degrees
Range
1487.1
km
Free Space Loss
-160.1
dB
-1.0
dB
0.0
dB
Polarization & Tracking. Loss
Shadowing loss
S/C Receive Signal Strength
-172.3
S/C Antenna Gain (incl. line loss)
11.5
User Signal at antenna output
-160.8
dBWi
dBi
dBW
System Noise Temperature
500.0
Thermal Noise Density, No
-201.6
dBW/Hz
Average data rate, Rb
2400.0
b/s
7.0
dB
Up link Eb/No
Interference per channel
Spreading bandwidth
-142.2
dBW
1.23
MHz
Interference Density
-203.1
Up link Eb/(No+Io)
4.7
3-17
dBW/Hz
dB
Description of the Globalstar System
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Table 3-10 Return Link C-Band - Case 1 - Detailed Budget
Down Link Satellite to Gateway
Frequency
Nominal EIRP per user
Path loss (40 degree GW elev.)
6975.0
MHz
-27.7
dBW
-175.2
dB
Polarization & Tracking. loss
-1.1
dB
GW antenna gain
49.4
dB
Receive power/user
-154.5
System noise temp.
127.7
dBW
Thermal noise density, No
-207.5
dBW/Hz
Interference Density, Io
-212.3
dBW/Hz
Down link Eb/(No+Io)
18.0
dB
Combining gain
1.8
dB
Overall Eb/(No+Io)(up&dn)
6.3
dB
Operating Eb/No
6.3
dB
Table 3-11 Return Link - Case 2 - Link Blockage
L-Band Up Link and C- Band Down Link
Up link
EIRP per user
-9.4
Up link Eb/(No+Io)
6.5
dBW
dB
Down link
EIRP per user
-25.9
Down link Eb/(No+Io)
dBW
19.8
dB
Combining gain
0.0
dB
Overall Eb/(No+Io)(up&dn)
6.3
dB
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Table 3-12 Return Link - Case 3 - Rare Two Link Fade
L- Band Up Link and C- Band Down Link
Up link
EIRP per user
-1.2
Shadowing loss
Up link Eb/(No+Io)
dBW
-10.0
dB
4.7
dB
Down link
EIRP per user
Down link Eb/(No+Io)
-27.7
dBW
18.0
dBW
Combining gain
1.8
dB
Overall Eb/(No+Io)(up&dn)
6.3
dB
Forward Link: The link from the Gateway to the User Terminal reduces self interference
within an FDM channel by coherent transmissions and by using CDMA Walsh codes which are
orthogonal.
Return Link: The Return link uses paths through multiple satellites to combat the effects of
shadowing, blockage and multi-path.
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4. CODE DIVISION MULTIPLE ACCESS (CDMA)
4.1 Introduction
The Globalstar Air Interface uses a modified form of IS-95 to support Code Division Multiple Access.
CDMA was selected for Globalstar because it represents a proven technology that can provide a
bandwidth efficient modulation scheme for satellite communications. It is relatively interference tolerant,
both from the standpoint of generation of interference to other services and tolerating outside
interference. As a bonus, there is a level of security inherent in the modulation scheme. It is difficult to
listen into conversations or to pirate services from the system. CDMA is able to provide good voice
quality while operating at relatively low RF power levels. The Globalstar CDMA is based on the
existing QUALCOMM CDMA product line used for terrestrial cellular communications.
Path Diversity combats fades and blockage - Probably one of the most important aspects of
CDMA is associated with the way Globalstar uses CDMA. Diversity combining is used to provide
continuous communications even under conditions where a path to one satellite is totally blocked. The
Globalstar system can operate with relatively low link margins and still provide a high link availability.
CDMA supports spectrum sharing - There are other useful and interesting aspects of CDMA. In
CDMA two or more systems can occupy the same frequency-power space. Separation of the
intelligence is accomplished by demodulating the PN spreading sequence. This supports band sharing
by more than one system.
Soft Capacity Limit: There is another useful aspect of CDMA. Since CDMA is basically a system
whose capacity is limited by self generated interference, the limit is a soft limit. Unlike bandwidth limited
systems like Time Division Multiple Access (TDMA) or Frequency Division Multiple Access (FDMA),
CDMA allows the predicted capacity limit to be exceeded with soft degradation occurring.
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4.2 Diversity Combining
Diversity combining is used to mitigate the effects of link phenomena. In a simple form, diversity
combining uses the signal with the best signal to noise ratio. Rake receivers are used to receive and
combine the signals from multiple sources. As an example, the User Terminal will provide diversity
combining for the forward link signals received through up to two different links simultaneously.
Diversity increases Availability - The performance in the diversity mode will always exceed the
performance that would be achieved with communications via a single string link. Diversity combining is
continuous. There is no break in service if one or more of the diversity links is lost.
Multiple Satellite - Forward Link: In the forward direction, the use of diversity brings substantial
gain if one of the satellites is obstructed and is break even for unobstructed operation without multi-path.
With multi-path fading (typically with high values of Ricean k) the diversity also provides benefit.
Multiple Satellite - Return Link: In the reverse direction, there is a clear advantage because gain
results even with no obstruction. Because this is non coherent diversity combining, the gain is not quite
as much as with coherent operation.
Multiple Beam - Forward Link: There is no diversity advantage for using multiple beams. All beams
come from precisely the same point in the sky and are at the same sub-channel frequency. Whatever
shadowing or multi-path occurs for one beam occurs for the other.
20
Multiple Beam - Return Link: On the Return Channel the signals the gateway sees through the
different beams are, of course, the same; they fade in exactly the same way. But the noise backgrounds
in which they are received are essentially independent. There is some advantage to using diversity.
21
4.3 Fade Mitigation
18
19
22
23
24
25
26
27
28
29
30
31
The Gateway will support power control to address slow fades and interleaving to address medium to
fast fades. Power control is implemented on both the forward and return links.
Power Control: To support forward link power control, the user terminal reports pilot quality statistics
to the gateway. For return link power control, the Gateway measures frame error rate. The response
time of the power control is adjusted to accommodate the satellite round trip time delays. Average
round trip delay is on the order of 30 ms.
Forward Link: Forward link power control is closed loop under control of the Gateway. The
dynamic range of the forward link power control is at least 20 dB.
Return Link: The return link is operated open loop when a fade is first sensed, then closed
loop under control of the Gateway. The dynamic range of the return link power control is a
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maximum of 20 dB with a 0.5 dB step size. The User Terminal will limit the integrated
transmitted power to conform with regulatory requirements.
Interleaver: The Interleavers will operate over a 20 ms vocoder packet frame which will effectively
address medium and fast fades.
4.4 Acquisition
Search to Acquire: When a Globalstar phone hunts for a pilot channel it must search through a multidimensional space. Three of the more obvious dimensions are illustrated in Figure 4-1.
PN Co de
PN Timing
10
11
12
Frequency Doppler
Figure 4-1 Acquisition Search Space
The goal is to reduce the search volumes by all means practical. Given that the search volume is
decreased; then parallel processing can be used to speed the search process without compromise to the
probability of a correct acquisition.
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Latitude Dependence: The acquisition time is also a function of other variables such as latitude as
shown in Figure 4-2.
T im e ( s e c s )
PP S M e an
PP S 9 5 %
20
40
60
L a t it u d e ( d e g )
Figure 4-2 Acquisition Time as a function of Latitude
The Search is latitude dependent due to the orbital geometry. Less satellites are visible at high latitudes.
10
11
12
13
14
15
16
Several approaches are used to attain this apparent rapid response. Parallel searching speeds the
search process materially. The Ground Operations Control Center (GOCC) is also involved in speed
up of the search process. The search times shown in Figure 4-2 apply if the pilot frequency is known.
The GOCC can help by assigning the pilot frequencies near the center of the band in a given
geographical area. This basically collapses the search frequency dimension shown in Figure 4-1 to the
uncertainty due to Doppler.
Summary: This means that if the User Terminal stays in its home gateway area the acquisition process
can be very quick. If the pilot frequency is unknown due either to poor assignment by the GOCC or
due to the User Terminal roaming to another gateway area, the search time can extend. Basically the
maximum search time is the number of pilots that must be searched times the time to acquire as shown in
Figure 4-2. The mean time to acquire is roughly half of the maximum time to acquire.
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4.5 Forward CDMA Channel
An example assignment of the code channels transmitted by a gateway is shown in Figure 4-3. Out of
the 128 code channels available for use, the example depicts the Pilot Channel (always required), one
Sync Channel, seven Paging Channels (the maximum number allowed), and 119 Traffic Channels of
Rate Set 1. Another possible configuration could replace all the Paging Channels and the Sync Channel
one for one with Traffic Channels of Rate Set 1, for a maximum of one Pilot Channel, zero Paging
Channels, zero Sync Channels, and 127 Traffic Channels of Rate Set 1.
FORWARD CDMA CHA NNEL
( 1.23 MHz channel transmitted
by gateway)
Pilot
Sync
Paging
Chan
Chan
Ch 1
• • • Paging
Up Ch 7
Traffic
Ch 1
• • • Traffic
Ch N
••• ••• •• ••• ••• •
to
Traffic Data
Up
to
Traffic
Ch 119
Power Control
Sub-Channel
10
11
12
Figure 4-3 Forward CDMA Channel Transmitted by a Gateway
The forward CDMA channel consists of the Pilot Channel, one Sync Channel, up to seven Paging
Channels, and a number of Forward Traffic Channels. Multiple Forward Channels are used in a
Gateway
by
placing
each
Forward
Channel
on
different
frequency.
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Description of the Globalstar System
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The forward link Pilot, Sync and Paging Channel is generated as shown in Figure 4-4.
Walsh Funct io n
0 or 1
PN Chip,
1.2288 Mc ps
Pilot
Channel
( All 0' s)
Walsh Function
32 or 33
Sync
Channel
Bits
1.2 kbps
Convolutional
Enco der
r=1/2 K=9
Code
Symbol
2.4 ksps
Modulatio n
Symbol
Symbol
Repetition
4.8 ksps
Modulation
Symbol
Block
Interleav er
PN Chip,
1.2288 Mcps
4.8 ksps
Walsh Funct io n p
Paging
Channel
Bits
4.8 kbps
2.4 kbps
Co nvo lutional
Encoder
r=1/2 K=9
Code
Symbol
9.6 ksps
4.8 ksps
Symbo l
Repetition
10
11
12
13
14
15
16
17
18
19
9.6 ksps
Modulation
Symbol
Block
Interleav er
PN Chip,
1.2288 Mcps
9.6 ksps
9.6 ksps
Long Code
Mas k fo r
Paging
Channel k
Modulation
Symbol
Long Code
Ge nerato r
1.2288 Mcps
Decimator
Figure 4-4 Forward Link Pilot, Sync and Paging Channel
The forward link is modulated as follows.
Pilot Channel: The Pilot Channel is transmitted continuously by the Gateway and is utilized by the
User Terminals operating within the coverage area of the Gateway to acquire timing on the forward
channel, to provide a phase reference for coherent demodulation and to provide signal strength
comparisons that govern when to do hand offs. The Pilot channel will generate an all zeros Walsh
Code. This is combined with the short code used to separate signals from different Gateways and
different satellites. The pilot channel is modulo 2 added to the 1.2288 Mc/s short code and is then
QPSK spread across the 1.23 MHz CDMA bandwidth. The User Terminal monitors the pilot channel
and assesses its signal strength at all times except when it is operating in the slotted mode.
Sync channel: The Sync Channel is an encoded, interleaved, spread and modulated spread spectrum
signal that is used by the User Terminals operating within the gateway coverage area to acquire initial
time synchronization. The Sync channel will generate a 1200 b/s data stream that includes (1) time, (2)
transmitting Gateway identification, (3) assigned paging channel. This is convolutionally encoded and
Block Interleaved to combat fast fades. The resulting 4800 symbols per second data stream is modulo
two added to the sync Walsh code at 1.2288 Mc/s and the short code. It is then QPSK spread across
the 1.23 MHz CDMA bandwidth.
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Paging Channel: The Paging Channel is used for transmission of control information and pages from a
gateway to a user terminal. The paging channel is convolutionally encoded at Rate = 1/2, Constraint
length K = 9 and block interleaved. The resulting symbol rate is combined with the long code. The
paging channel and the long code are modulo two added and provided to the symbol cover where the
resulting signal is modulo two added to the 1.2288 Mc/s Walsh Code and the short code. The results
are then QPSK spread across the 1.23 MHz CDMA bandwidth.
Forward Traffic Channel: The Forward Link Traffic Channel - Rate Set 1 is generated as shown in
Figure 4-5.
Forward Traffic
Channe l
Information
Bit s for User i with 3.95 kbps
1.6 kbps
Rat e Set 1
0 kbps
( 79, 32 , or 0
bit s/f rame)
Add Re se rved
Bit (1, 1, or 0
bits /f rame)
Add Frame Quality
Indica-t ors ( 8 , 7,
or 0 bits/frame ) 4.4 kbps
4.0 kbps
2.0 kbps
1.65 kbps
0 kbps
0 kbps
Add 8-bit
Encode r Tail
4.8 kbps
2.4 kbps
0 kbps
Power
Cont rol
Bits
Modulat ion
Symbol
Symbol
Re pet ition
10
Long Code
Mask for
Us er i
9.6 ksps
0 ks ps
Long Code
Generator
1 .2288 Mc ps
9.6 ksps
0 ksps
Dec imat or
Walsh
Funct ion j
PN Chip,
1.228 8 Mc ps
MUX
9.6 ks ps
De cimat or
Figure 4-5 Forward Link Traffic Channel - Rate Set 1
4-7
9.6 ksps
4.8 ksps
0 ksps
50 bps
Modulat ion
Symbol
Block
Inte rle av er
Code
Symbol
Conv olut ional
Enc ode r
r=1 /2 K=9
50 Hz
Description of the Globalstar System
GS-TR-94-0001
Revision E
The Forward Link Traffic Channel - Rate Set 2 is generated as shown in Figure 4-6.
Code
Forward Traf f ic
Symbol
Add Reserv ed
Channe l Inf ormation
Add Frame Quality
Bit ( 1, 1, 1, o r 0
Bits for User m with
Add 8-bi t
Indic at o rs ( 12, 8 , 7,
Encoder
Rate Set 2
(171, 79, 32, or 0
3.95 kbps
4.0 kbps
4.4 kbps
4.8 kbps
9.6 ksps
1.6 kbps
1.65 kbps
2.0 kbps
2.4 kbps
4.8 ksps
0 kbps
0 kbps
0 kbps
0 kbps
0 ksps
bits/f rame)
or 0 bit s /frame)
9.2 kbps
Encode r Tail
8.55 kbps
bits/f rame )
8.6 kbps
Convolut ional
9.6 kbps
19.2 ksps
r= 1/2 K= 9
Walsh
50 bps
Po wer
Funct ion n
Control
PN Chip,
Bits
Modulation
Modulatio n
Symbol
Symbol
Symbol
19.2 ksps
Interleaver
Mask f or
User m
19.2 ksps
Long Code
Generator
19.2 ksps
0 ksps
0 ksps
Block
Repet ition
Long Code
1.2288 Mcps
MUX
1.2288 Mcps
Dec imator
50 Hz
Dec imator
Figure 4-6 Forward Link Traffic Channel - Rate Set 2
The Vocoder encodes the voice into a PCM data stream. The data stream is the processed as shown
in Figure 4-5. The resulting data stream is then power controlled and modulo two added to the 1.2288
Mc/s Walsh code and the short code. The results is then QPSK Spread across the 1.23 MHz CDMA
communication channel bandwidth. The Globalstar Air Interface will support two different rate sets
from the Gateway. Within a rate set, the Globalstar Air Interface (GAI) will support variable data rate
operation. When the high rate shown in Figure 4-5 is used, two Walsh codes are required.
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Modulation and Spreading: Modulation and spreading is applied as shown in Figure 4-7.
I-Channel Inne r PN Se quence
1 .228 8 Mc ps
Base band
Filt er
I( t )
cos
( 2š f ct)
Outer PN
Seq uence
Gene rat or
Baseband
Filter
Σ
s ( t)
Q( t)
Oute r PN Chip
Q-Channe l Inner PN Se quence
1 .22 88 Mcps
1.2 kcps
sin
( 2š f ct)
10
11
12
13
14
15
1 Outer PN Chip Delay
= 8 33.3 33 µ s
Figure 4-7 Forward Link Modulation and Spreading
The spreading sequence structure for a given Globalstar CDMA channel is comprised of an inner PN
sequence pair and a single outer PN sequence. The inner PN sequence has a chip rate of 1.2288 Mcps
and a length of 1024, while the outer PN sequence has an outer chip rate of 1200 outer chips per
second and a length of 288; the outer PN sequence modulates the inner PN sequence to produce the
actual spreading sequence, lasting exactly 240 msec. Exactly one inner PN period is contained within a
single outer PN chip. The spreading and modulation process applies to all forward link channels.
Path Identification: It is necessary to know the path that a signal has taken in order to facilitate
gateway sharing of a forward CDMA channel and to support diversity combining. Path information is
derived from the pilot signal.
Gateway: Two gateways can share a forward CDMA channel. Pilot channel 0 is assigned to
the first gateway can be allocated more power and serve as a beacon pilot within the beam to
increase acquisition speed of the User Terminals in the beam.
17
Orbital Plane: The inner PN sequence is used to identify the orbital plane. The length of the
sequence is 2 10 chips at a chip rate of 1.2288 mcps. there are 24 repetitions every 20 ms.
18
Satellite: Each satellite is identified by a pilot PN sequence.
19
Beam: Each Satellite Beam has a unique outer PN sequence offset.
16
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11
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14
Beam Juxtaposition: Each Adjacent beam within a satellite is identified by a unique inner PN
sequence offset. Inner PN offsets are reused among non adjacent beams of a satellite.
Sharing of Forward CDMA Channel: It is also possible for two gateways to share a single
subbeam. This mode is used when a gateway’s traffic needs only a fraction of a subbeam and each
gateway must supply a separate pilot. In particular, this mode is useful when a satellite beam is moving
from gateway service area A to gateway service area B. Gateways A and B can then share a subbeam
as the traffic from A is ramping down and the traffic from B is ramping up. When sharing the first
gateway will use all even-numbered code channels, and the second gateway will use all odd-numbered
code channels.
The Pilot Channel of the first gateway is transmitted on code channel 0. The Sync Channel associated
with this Pilot Channel, if it exists, is transmitted on code channel 32. The Primary Paging Channel
(Paging Channel number 1) of the first gateway, if it exists, is transmitted on code channel 64. Paging
Channel numbers 2, 3, 4, 5, 6, and 7, if they exist, are transmitted on code channels 2, 66, 4, 68, 6, and
70, respectively.
19
The Pilot Channel of the second gateway is transmitted on code channel 1. The Sync Channel
associated with this Pilot Channel, if it exists, is transmitted on code channel 33. The Primary Paging
Channel (Paging Channel number 1) of the second gateway, if it exists, is transmitted on code channel
65. Paging Channel numbers 2, 3, 4, 5, 6, and 7, if they exist, are transmitted on code channels 3, 67,
5, 69, 7, and 71, respectively.
20
4.6 Return Link CDMA Channel
15
16
17
18
21
22
The Reverse CDMA Channel is composed of Access Channels and Reverse Traffic Channels as shown
in Figure 4-8.
REVERSE CDMA CHANNEL
( 1.23 MHz channe l re ceive d
by g at eway)
23
24
Access
Ch
Traf fic
Ch 1
••••••••••••••••••••••••••••••••
Figure 4-8. Reverse CDMA Channels Received at a Gateway
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Traffic
Ch m
Description of a Globalstar Gateway
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Revision E
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11
12
13
Figure 4-8 shows an example of all of the signals received by a gateway on the Reverse CDMA
Channel. These channels share the same CDMA frequency assignment using direct-sequence CDMA.
Each Traffic Channel is identified by a distinct user long code sequence. Each Access Channel is
identified by its quadrature spreading codes and the gateway identification in the long code mask.
Multiple Reverse CDMA Channels on different frequencies may be used by a gateway.
The Reverse CDMA Channel has the overall structure shown in Figure 4-9 and Figure 4-10. Data
transmitted on the Reverse CDMA Channel is grouped into 20 ms frames. All data transmitted on the
Reverse CDMA Channel is convolutionally encoded, block interleaved, modulated by the 64-ary
orthogonal modulation, and direct-sequence spread prior to transmission.
Access Channel: The Access Channel is used by the User Terminal for communicating to the
Gateway. It is used for short signaling message exchanges such as call origination, response to pages,
and registrations. The Access channel is a slotted random access channel. Each Access Channel, as
shown in Figure 4-9, is identified by a distinct Access Channel long code sequence.
Acce ss Channel
Inf ormation
Bits
( 88 bits/frame)
Co de
Symbol
4.4 kbps
Add 8 bit
Enco der
Tail
4.8 kbps
Co nvolutional
Enco der
r= 1/2 K=9
9.6 ksps
Code
Symbol
Blo ck
Inte rle aver
9.6 ksps
64- ary
Orthogo nal
Modulator
1. 6 ksps ( 102.4 kcps)
I-channel Se quence
1.2 288 Mcps
PN chip
1.228 8 Mcps
Lo ng
Code
Generator
14
15
cos( 2 π fc t)
1/2 PN chip
Delay = 406 .9 ns
I( t)
Baseband
Filter
Baseband
Filte r
Q( t)
sin( 2 π fc t)
Q-channel Sequence
1 .2288 Mcps
Long Co de
Mask
Figure 4-9 Return Link Access Channel
4-11
ΣΣ
s( t)
Modulation
Symbol
( Walsh chip)
Description of the Globalstar System
GS-TR-94-0001
Revision E
Return Link Traffic Channel: Each Traffic Channel is identified by a distinct user long code
sequence as shown in Figure 4-10.
Reverse Traf fic
Cha nnel Inf ormat ion
Bits
( 171, 79, 32, or 0
bits/f rame)
Add Power Control
Bit fo r 9. 6, 4.8 &
8.55 kbps
2.4 kbps
Add Frame Quality
8.6 kbps
9.6, 4.8 & 2 .4 kbps 9.2 kbps
Code
Symbol
Convolutional
A dd 8 bit
Indic at o rs fo r
Code
Symbol
Block
Enco der
Encoder Tail
9.6 kbps
r=1/2 K=9
19.2 ksps
3.95 kbps
4.0 kbps
4.4 kbps
4.8 kbps
9.6 ksps
1.6 kbps
0 kbps
1.65 kbps
0 kbps
2.0 kbps
0 kbps
2.4 kbps
0 kbps
4.8 ksps
0 ksps
Interleaver
I-channe l Sequence
1.2288 Mcps
Modulation
I( t)
Baseband
Filter
Symbol
64-ary
( Walsh chip)
Orthogonal
Modulat or
3.2 ksps
( 204.8 kcps)
Power Control Bit
1.6 ksps
for 0 kbps Frame
( 102.4 kcps)
co s( 2 π f c t)
1/2 PN chip
PN chip
1.2288 Mcps
0.8 ksps
( 51.2 kcps)
0.2 ksps
Long
Code
( 12.8 kcps)
ΣΣ
s( t)
Delay = 406.9 ns
Baseband
Q( t)
Filt er
sin( 2 π f c t)
Q-channel Seque nce
1.2288 Mcps
Generator
Long Code
Mask
Figure 4-10 Return Link Traffic Channel
The rate 1/2 code used for the Globalstar return link takes advantage of longer coherence times for the
channel and will perform better in the Additive White Gaussian Noise (AWGN) channel typical of
Globalstar. The rate 1/3 code, typically used in terrestrial CDMA, performs better in a Rayleigh
channel because it offers greater diversity. The return link does not use the randomizer used in cellular
CDMA. It uses a continuous transmission with code symbol repetition to maintain the same rate.
10
4.7 CDMA End to End Performance
11
There are a number of other CDMA topics that span both the forward and return links.
12
13
14
15
16
17
18
19
Time: All gateway digital transmissions are referenced to a common CDMA system-wide time scale
that uses the Global Positioning System (GPS) time scale, which is traceable to and synchronous with
Universal Coordinated Time (UTC). GPS and UTC differ by an integer number of seconds, specifically
the number of leap second corrections added to UTC since January 6, 1980. The start of CDMA
System Time is January 6, 1980 00:00:00 UTC, which coincides with the start of GPS time. System
Time keeps track of leap second corrections to UTC but does not use these corrections for physical
adjustments to the System Time clocks. When receiving the paging channel, the User Terminal is within
1.0 microseconds of the earliest arriving signal used for demodulation.
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Description of a Globalstar Gateway
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Link Delay: Delay through a link is an important end to end parameter. It becomes particularly
important in conversations when one party attempts to interrupt the other. The LEO orbit satellites will
provide a much more benign delay than the more common synchronous orbit satellites. Delay is held to
150 ms in each direction. There is a design margin, of course. Figure 4-11 summarizes the delay for the
forward link.
GTS
User
Terminal
18 ms
43.4 ms
SBS
Modulator
Card
Distribute
MSSL
Queue &
Transmit
3.25 ms
5 ms
1 ms
User
Terminal
10
11
12
MSSL
Queue &
Transmit
0.5 ms
Sample &
Vocoder
Encode
69 ms
Figure 4-12 illustrates the delay budget for the return link.
GTS
HDLC
Consolidate
ATM
Figure 4-11 Forward Link Delay Budget
CIS
69.5 ms
CIS
Demodulator
Card
43.4 ms
15 ms
SBS
Distribute
MSSL
Queue &
Transmit
HDLC
Consolidate
ATM
3.5 ms
1 ms
MSSL
Queue &
Transmit
0.5 ms
Select &
Vocoder
Decode
3.5 ms
Figure 4-12 Reverse Link Delay Budget
Tradeoffs are possible to improve voice quality, improve capacity or other system level parameters at
the expense of end to end delay.
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Description of the Globalstar System
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Vocoder: The Globalstar vocoder is uses a Code Excited Linear Prediction (CELP) algorithm with a
structure similar to that used by the IS-96 coder but with several improvements. The percentage of time
between rates of 0 b/s and 8,550 can be adjusted. Voice quality can be traded for capacity. Voice
quality can also be traded for signal delay. The Globalstar design will operate with high voice quality
when the capacity is not stressed and when the links can be closed. If the links cannot be closed or if
the capacity is being stressed, voice quality can be sacrificed. Vocoder rates and resulting channel rates
are shown in Table 4-1.
Table 4-1 Vocoder and Channel Rates
Configuration
Vocoder Rate
Channel Rate
Purposes
Rate 1
8,550
9,600
High Quality Option
Rate 1/2
3,950
4,800
Baseline Voiced
Rate 1/4
1,750
2,400
Baseline Unvoiced
Rate 1/8
800
1,200
Baseline Pauses/Background
10
11
12
13
14
15
16
17
18
19
Some improvements are envisioned that may increase capacity. In the forward direction, a zero rate
can be used. Since this is the coherent direction, the User Terminals can stay locked on by using the
pilot. This is the direction that constrains capacity. In the return direction, some energy must be
transmitted to keep the receiver locked since the return direction is not coherent.
Power Control: The objective of power control is to transmit the minimum power necessary in order
to achieve a given quality of service. Quality of service could be specified in terms of the Frame Error
Rate (FER) and the probability of outage. Accurate power control reduces the transmit power needed
to achieve a given quality of service objective, thereby prolonging battery life of portable phones. In
addition, it also enhances capacity. Figure 4-13 is a simplified end to end diagram to support the
description of power control.
Phone
Channel
tx
Reverse Link
Gateway
rx
Correlation
rx
Forward Link
tx
A Transmit Gain Setting: Power Control Algorithm
20
21
22
B Segment Transmit Path
Figure 4-13 Power Control Simplified Diagram
Power Control and time to acquire are intimately related as shown in Figure 4-14.
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Description of a Globalstar Gateway
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90
80
70
95% Time
Mean Time
60
50
40
30
20
10
-20
-18
-16
-14
-12
-10
Ec/Io (dB)
Figure 4-14 Acquisition Time as a function of Eb/No
Once the target for Eb/No is established, the task of power control is to maintain the desired Eb/No.
Acquisition time will extend if the Eb/No is not well established correctly or controlled to the desired
value. In order to achieve the power control there are two loops.
Inner Loop: The inner loop controls to the target Eb/No on a one bit per frame basis.
Outer Loop: The outer loop adjusts the target Eb/No based on the measured Frame Error Rate.
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Description of the Globalstar System
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5. TERRESTRIAL INTERFACE
5.1 Telecommunication Network Interface
The Gateway Architecture emphasizing the terrestrial interface is shown in Figure 5-1.
GOCC
SPCCs
GMS
IS-41 HL R
IS-41 MAP
CDMA
S ubsystem
IS-41
CCP/VLR
SSA
Q Interface
T1/E1 - ISUP/MF-R2
(GTS/TFU/CIS/
SBS/GC)
PSTN
BSCI
A1 Interface(s)
GSM
GSM
MSC/VLR
GSM
MS C/VLR
MS C/V LR
BSS
T1/E1 - ISUP/MF-R2
GSM MAP
GSMHLR
HLR
GSM
GSM
HLR
Gateway
OMC/SPCC
10
11
12
13
14
15
Figure 5-1 Gateway Architecture
The Gateway can operate in territories with terrestrial systems which are predominately GSM based or
IS-41 C based.
GSM: In a GSM environment, the GSM-MSC can either be incorporated in the Gateway or it can be
external. If external, it can be directly associated with the Gateway or shared with other terrestrial
cellular systems. A protocol conversion process may be required to support IS-41 roamers whose
home networks use ANSI SS-7 for MAP signaling rather than ITU SS-7. Protocol conversion may be
performed by the international SS-7 carrier or by a separate device. GSM roamers whose home
networks comply with ITU SS-7 do not require protocol conversion support.
IS-41: In an IS-41 network, a GSM-MSC must be available to provide GSM roaming services. The
switch can either be in the gateway or can be back hauled to a GSM-MSC in another location.
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Revision E
Protocol conversion may be required to convert between ITU SS-7 and ANSI SS-7 for mobility
signaling to support international roamers with different home signaling protocols.
Flexible Interface: In areas where there is no infrastructure or where there is an infrastructure other
than GSM or IS-41, the Gateway can interface directly to the PSTN. The Gateway has a built in
switch than can be adapted to a variety of PSTNs. This, of course, does not address type qualification
which may or may not be a large problem depending on the specific country and situation involved.
The entities associated with the terrestrial network of primary interest include:
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
GSM MSC/VLR: The GSM Mobile Switching Center (MSC) and Visitor Location Register (VLR)
provide the call control and mobility management functions for GSM based users in the GW coverage
area. The GSM MSC terminates one end of the A1 Interface, processing the BSSMAP and DTAP
messages carried on this interface. The GSM VLR maintains the subscriber records for GSM based
UTs operating on the GW. In addition, the GSM VLR interfaces to the existing GSM terrestrial cellular
mobile Home Location Register (HLR) network. The GSM MSC also provides an interface to the
local PSTN via standard signaling protocols (ISUP, MF-R1, MF-R2, etc.).
GSM HLR/AuC: The GSM HLRs that are accessible from the GW are new or existing terrestrial
cellular HLRs in the GSM MAP network. These HLRs contain the home subscriber records for GSM
based GW UT subscribers.
IS-41 CCP/VLR/SSA: For IS-41 based users in the GW, the IS-41 based call control and mobility
management functions are processed by the IS-41 CCP/VLR/SSA entity. The IS-41 VLR maintains
the subscriber records for IS-41 based UTs operating on the GW. In addition, the VLR interfaces to
the existing IS-41 terrestrial cellular mobile Home Location Register (HLR) network. The SSA
interfaces the GW to the local PSTN via standard signaling protocols (ISUP, MF-R1, MF-R2, etc.).
The GW can also be configured in such a manner where the SSA can directly interface to one or more
of the GW GSM MSCs if desired.
IS-41 HLR/AuC: The IS-41 HLRs that are accessible from the GW are existing terrestrial cellular
HLRs in the IS-41 MAP network. These HLRs contain the home subscriber records for IS-41 based
GW UT subscribers. The IS 41 C Authentication Center provides authentication for its IS-41 C based
Globlastar Subscribers.
5-2
Description of the Globalstar System
GS-TR-94-0001
Revision E
Figure 5-2 provides more details on what is inside the Globalstar Gateway.
DG lo
14 2
7 53
* 8 69
DIG
0#
ITA
GDN
SOCC
GOCC
ba
ls ta
GW Links
SPCC
E1 or T1
BCN MSSL
Ethernet
IFL
BY
ROPI
ABC
GDN Router
TCU
GMS
OPI
(Telemetry & Command Unit)
GSS
(Gateway Management System)
(Gateway Switching System)
TCU
TCU
GM
TCU Panel
TCU
CDA
GWRDB
SPCC Router
TCU
SS7
VME Cage
FL Cabinet
Server
GPS Rcvr
FL Shelf
(40)
5/polarize/ant
FL
ls ta
VME Cage
NIS
CSU
Patch Panel
(Gateway RF System)
GWC
SSA
T1
Patch Panel
LHCP
OMC
E1
Trunks
Patch Panel
GRS
Cabinets
(up to 13)
SS7
GSM
MSC
SS7
SBSShelf
Interface
Card
BY
Digital
Cabinets
(up to 13)
Demod
Cards
AL
Router
Common
Card
Receive
Controller
Card
IT
Cabinet
Cabinet
(2)
(2)
BSCI
SBS
1/96 calls
Receiver
Cards
TFU
TFU
RHCP
LNA
(DISCO)
RL
Splitters
Splitters
DIG
(up to 4)
CIS
RL
Down
Converter
OFF
VLR
11 12 1
10
7 6 5
GTS
Antennas
LHCP
TFU
Selector
Cards (12)
ΣΣ
GSM
HLR
VME Cage
VME
Backplane
GCU
Modulator
Cards
ba
Upconverter
Cards
Up Converter
RHCP
SSPA
G lo
IS-41
HLR
SS7
VLR
CCP
T1/E1
Trunks
PSTN
T1
GCS
Trunk Set Combinations
VIP
(Gateway CDMA System)
( m o s t l i k e l y: )
· IS-41 territory:
· GSM territory:
Figure 5-2 Gateway Connections to the PSTN - Flexible Interface
Physical Interface: The Gateway will connect to telecommunications networks via standard T1/E1.
This is accomplished by the Service Switching Adjunct (SSA) shown in the upper right of Figure 5.1-2.
This is also called Service Switching Point (SSP) in intelligent networks.
PSTN Interface Protocols: The Gateway provides an Integrated Service Digital Network (ISDN)
interface and will connect to the PSTN via Primary Rate Interface (PRI).
5-3
Description of the Globalstar System
GS-TR-94-0001
Revision E
5.2 Registration Process
10
Registration is the process by which the User Terminal notifies the Gateway of its location, status,
identification, User Terminal type, and paging slot being monitored. Under normal circumstances, the
Globalstar Gateway only contains a Visitor Location Register which is used in conjunction with external
GSM or IS-41 Home Location Registers. Registration with an external HLR will be supported through
the Gateway VLR. Registration while roaming involves the exchange of information between system
types (GSM to IS-41 or visa versa). The messages and procedures for exchange of authentication data
with the AuC/HLR is currently being reviewed by TIA for inclusion in IS-41D, and is summarized in
TSB-51, Cellular Radio Telecommunications Inter systems Operation: Authentication, Signaling
Message Encryption and Voice Privacy.
11
There are two registration processes that will be supported.
12
13
User Terminal
User ID
HLR
VLR
IS-95 Modified
ESN/MIN
IS-41
Globalstar
IS-95 Modified
GSM/IMSI
GSM
Globalstar
IS-41 HLR Registration: Figure 5-3 illustrates the process of registration of an IS-95 User Terminal
within an IS-41 HLR.
3. The visited Gateway sends
a data message that
includes the phone ESN/MIN
to the HLR across the
signaling network.
2. Home sys tem SPC is
determined from
ESN /M IN
Gatew ay
Gateway (Visited)
IS-41 M ap
Data
GAI
Globals tar
Air Interface
CDM A
4. T he Cus tomer Pr ofile is
sc anned for an ID match
and the present GW
address is updated in
the HLR.
Home Location Register
ANSI
SS7
IS-41 M AP
messages
ANSI
SS7
IS-41 Map
Data
ANSI
SS7
Signaling
Networ k
Visitor
Location
Register
(VLR)
Home
Location
Regis ter
(HLR)
Notes:
ESN = Electronic Serial Number
MIN = Mobile Identification Number
Us er
Ter mi nal
(Visiting)
1. Data M essage
includes ESN /M IN
or IMEI
14
15
File: Reg IS-41
Rev: 10/ 14/95
6. A r ecord is created in the Visi tor
Location Register (VLR) and
stored with profile information.
User is deregi stered on shutdown
or REGC ANC from HLR
SPC = Switching Point Code
Authenticati on
IMEI = International Mobi le
Equipment Identi fi er
Center (Futur e)
5. The subscr iber profi le is
returned to the Gateway.
IS 41 Authenticates Equipment
User is der egis tered fr om
previ ous VLR ( REGCANC )
Figure 5-3 Registration of a U.S. based User with an IS-41 HLR
5-4
Description of the Globalstar System
GS-TR-94-0001
Revision E
If IMEI are used in the User Terminals, ESN will not be stored. ESN is computed from the IMEI. The
IMEI also incorporates the type approval code.
GSM HLR Registration: Here, all of the network components (MSC, HLR, VLR and AuC) should
be able to communicate as in the normal system. The challenge is reduced to a protocol inter working
task on the Gateway-VLR and Gateway-MSC interfaces, and transport of GSM authentication data to
and from the SIM. Figure 5-4 illustrates the registration process.
2. Home system SPC
is determined from
the User ID
3. The visited Gateway sends
a data message that
includes the User ID to the
HLR across the signaling
network.
Gateway (Visited)
Gateway
GAI
Globalstar
Air
Interface
Home Location Register
ITU
C 7
GSM - MAP
Data
GSM-A
MSC
Mobile
Switching Center
Home
Location
Register
(HLR)
Kc Triplet
MAP = Mobile Application Protocol
SPC = Switching Point Code
Authentication
Center
ID = Identification
6. A record is created in the Visitor
Location Register (VLR) and
stored with profile information.
5. The subscriber profile is
returned to the Gateway.
GSM Authenticates Subscriber
User is deregistered on shutdown
Figure 5-4 Registration of a European User in a GSM HLR
5-5
GSM - MAP
Data
Notes:
SIM Card
File: Reg GSM
Rev: 10/14/95
ITU
C 7
ITU
C 7
Signaling
Network
Visiting
GSM User
Terminal
GSM MAP
messages
Visitor
Location
Register
(VLR)
CDMA
1. Data Messaage
includes User ID
4. The Customer Profile is
scanned for a User ID
match and the present
location is updated in
the Home Location
Register (HLR).
User is deregistered from
previous VLR.
Description of the Globalstar System
GS-TR-94-0001
Revision E
3. The visited Gateway sends
a data message that
includes the phone ID to the
HLR across the signaling
network.
2. Home system SPC is
determined
Gateway
GAI
Globalstar
Air
Interface
4. The Customer Profile is
scanned for an ID match
and the present GW
address is updated in
the HLR.
Gateway (Visited)
Home Location Register
ITU
C 7
IS-41 MAP
ITU SS-7
ANSI
SS7
IS-41 MAP
Data
ITU-ANSI
SS-7
Protocol
Converter
CDMA
Home
Location
Register
VLR
Notes:
IS-41 Call
Control Processor
(HLR)
ESN = Electronic Serial Number
MIN = Mobile Identification Number
1. Data Message
includes ESN/MIN
or IMEI
File: Reg IS-41 GSM
Rev: 10/14/95
Authentication
SPC = Switching Point Code
Visiting
User
Terminal
Center (Future)
ID = Identification (MIN & ESN)
6. A record is created in the Visitor
Location Register (VLR) and
stored with profile information.
User is deregistered on shutdown
or upon command from the HLR.
5. The subscriber profile is
returned to the Gateway.
User is deregistered from
previous VLR.
Figure 5-5 Registration of a U.S. User in a GSM Environment
5-6
Description of the Globalstar System
GS-TR-94-0001
Revision E
2. Home system SP C is
d etermined
3. The visited Ga teway send s
a data me ssag e that
i ncludes the User ID to the
HLR acro ss th e sig naling
ne twork.
4.
Th e Cu sto mer Profi le is
scanned for an ID match
and the presen t GW
address is u pd ated in
the HLR.
Ga teway
Ga teway (Visited)
G AI
Globalstar
Ai r
In te rface
Home Lo catio n
A NSI
S S7
G SM - MAP
Visito r
Location
Reg ister
(VLR)
G SM-A
MSC
Mobile
S witchin g Ce nter
10
Kc Tri plet
Authentica tion
Center
ID = Id en tificatio n
6. A re cord is create d in the Vi sitor
L ocation Register (V LR) an d
stored with profile infor mation .
U ser is d er eg ister ed on shu td ow n
o r u po n co mma nd from the HLR
5.
GSM Authenticates Subscriber
The sub scrib er pr ofile is
retu rn ed to the Gateway.
User i s de registe red from
pre vio us V LR.
Figure 5-6 Registration of a European User in an IS-41 Environment
5.3 Authentication Process
Authentication verifies that the User Terminal is authorized to use the Globalstar resources. The
Gateway will support authentication of the User Terminals; but, authentication is the responsibility of the
home PLMN operator. The Gateway will transport authentication messages in the form required by the
home PLMN operator. The Gateway will incorporate facilities to challenge, examine and update the
authentication signature in the User Terminals.
To achieve a consistent authentication scheme, the system adopted must be able to deal with each of the
following situations:
a. GSM User in GSM System
12
b. IS-41 User in IS-41 System
13
c. GSM User in IS-41 System
14
d. IS-41 User in GSM System
16
Note s:
SPC = Switchi ng P oint Code
11
15
Home
Location
Re giste r
(HLR)
MAP = Mobile A pp lication P rotocol
Visiting
GSM User
Te rmin al
Data
Co nver ter
S IM Ca rd
1. Data M essa age
inclu des User ID
G SM - MAP
ANSI-ITU
Protoco l
CDMA
Reg GS M I S -41
Rev: 10/ 14/9 5
SS -7
Da ta
ITU
C7
Where IS-41 User indicates a user whose Home system is based upon the IS-41 model and protocols
(i.e. AMPS, IS-54, IS-95 and PSTN systems), and a GSM or IS-41 System indicates a serving
5-7
Description of the Globalstar System
GS-TR-94-0001
Revision E
10
11
12
Globalstar system where the mobility management facilities (HLR, VLR etc.) are GSM or IS-41-based,
respectively.
GSM User in GSM System: Here, all of the network components (MSC, HLR, VLR and AuC)
should be able to communicate as in the standard GSM system. The challenge is reduced to a protocol
inter working task on the Gateway-VLR and Gateway-MSC interfaces, and transport of GSM
authentication data to and from the SIM. GSM roamers do not require a protocol converter. GSM
uses the same SS-7 as the international signaling.
IS-95 user in IS-95 (IS-41) System: All of the network components and protocols will operate in an
IS-41 system. IS-41D supports and authentication center. Some networks may not support
authentication.
GSM User in IS-95 (IS-41) System: In this scenario, the various network components belong to
different systems, as summarized in the following table:
Component
System
SIM
GSM
Gateway/MSC
IS-41
VLR
IS-41
HLR/AuC
GSM
13
16
The task that needs to be solved in this scenario is the retrieval and storage of authentication data from
the HLR/AuC. For example, the triplets could be both requested and stored by the Gateway and the
RAND and SRES parameters carried on the air interface to/from the SIM.
17
The general message exchange is illustrated in Figure 5-7:
14
15
5-8
Description of the Globalstar System
GS-TR-94-0001
Revision E
Subscriber
Unit
SIM
HLR/AuC
Gateway
Inser t Subscriber D ata
Authentication C hallenge
RAND
SRES
Authentication Challenge Response
Authentication C hallenge
RAND
SRES
Send Parameters
Send Parameters Response
Authentication Challenge Response
File: GSM in IS41
Figure 5-7 Authentication for a GSM User in IS-41 System
IS-95 User in GSM System: In this scenario, the various network components belong to different
systems, as summarized in the following table:
Component
System
User Terminal
IS-95/Globalstar
Gateway/MSC
GSM
VLR
GSM
HLR/AuC
IS-41
10
11
12
In the IS-41 system, authentication is done mainly by the Gateway, with updates to authentication
parameters periodically being retrieved from the AuC. The Gateway just has to recognize that the user
understands IS-41 authentication, and not GSM and process messages appropriately.
The messages and procedures for exchange of authentication data with the AuC/HLR is currently being
reviewed by TIA for inclusion in IS-41C, and is summarized in TSB-51, Cellular Radio
Telecommunications Inter systems Operation: Authentication, Signaling Message Encryption and Voice
Privacy.
5-9
Description of the Globalstar System
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Revision E
5.4 GSM - A Interface in Globalstar
The Globalstar Gateway will interface with and MSC in the GSM environment in much the same way
that any base station interfaces with the MSC. Figure 5-8 illustrates a typical GSM DTAP on Mobile
Terminated Calls.
UT
GW (BSS)
GSM MSC
UDT
CR (PAGE RESP)
Signalling Channel Request
Request for Service
DT1 (CPH MOD CMD)
CDMA
Radio
Processing
Events
DT1 (CPH MOD COM)
DT1 (SETUP)
Activates Encryption, Service
Option at Selector
DT1 (CALL CONFIRM)
DT1 (ASS REQ)
Activates Traffic Voice Path
DT1 (ASS COM)
DT1 (ALERT)
DT1 (CONNECT)
DT1(CONNECT ACK)
Stable 2-way Call
Figure 5-8 GSM DTAP on Mobile Terminated Call
Figure 5-9 Illustrates GSM DTAP on a typical mobile originated call in Globalstar.
5-10
Description of the Globalstar System
GS-TR-94-0001
Revision E
UT
GW (BSS)
GSM MSC
Signalling C hannel Request
CDMA
Radio
Processing
Events
CR (CM SERV REQ)
CC (AUTH REQ )
R equest for Service &
Authentication
DT1 (AUTH RESP)
DT1 (CPH MOD CMD)
DT1 (CPH MOD COM)
DT1 (SETUP)
Activates Encryption, Service
O ption at Selector
DT1 (CALL PROCEED)
DT1 ( ASS REQ)
Activates Traffic Voice Path
DT1 (ASS CO M)
DT1 (ALERT)
DT1 ( CONNECT)
DT1( CONNECT ACK)
Stable 2 -way Call
Figure 5-9 GSM DTAP on Mobile Originated Call
5-11
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5-12
Description of the Globalstar System
GS-TR-94-0001
Revision E
6. CALL PROCESSING
6.1 Call Processing between Globalstar and PLMN
This section discusses call processing between Globalstar and other PLMN systems. In Globalstar all
User Terminals are treated as roaming from their terrestrial PLMN home system.
Globalstar Only User Terminals: There are a series of User Terminals that are Globalstar Only. In
these cases the service provider will incorporate the Globalstar Only User Terminals in the local Home
Location Register (HLR). This applies to GSM or IS-41 HLRs. The Gateway will treat Globalstar
Only UTs as Roamers.
10
No Existing HLRs: In areas where there is no existing HLR, Globalstar may set up an HLR and
function as the Service Provider.
11
Emergency Calls: Globalstar will comply with the regulations for delivery of emergency calls.
12
Mobile Originated Call: Figure 6-1 illustrates how a mobile originated call is processed.
Gateway
CDMA
VLR
S witch
or MSC
Origination
Request
From User
ORIGREQ
or igreq
Call E stablishment
13
14
15
File: UT Ori gin
Figure 6-1 Mobile Originated Call
The following steps are performed:
16
1. An Origination Request (ORIGREQ) is received from a User Terminal.
17
2. An Origination Request INVOKE is sent from the Gateway (GW) to the VLR.
6-1
Description of the Globalstar System
GS-TR-94-0001
Revision E
3. The Mobile is currently registered in this Visitor Location Register (VLR). The VLR
responds with the Origination Request RETURN RESULT parameters.
4. The call is established with the terrestrial system.
Mobile Terminated: There are two scenarios for roaming call delivery. The first one is for a
successful call (i.e. the user is idle). In the second case, the user is busy - this case is used to illustrate
the possible invocation of a supplementary service such as Call Forward on Subscriber Busy.
Roaming Call Delivery - Idle Case: Figure 6-2 illustrates a successful call connection.
Originating
System
Switch
or MSC
GW
Serving
System
VLR
call
1 origination
HLR
VLR
GW
LOCREQ
ROUTREQ
ROUTRE Q
routreq
locreq [TLDN]
routreq [TLD N]
Call Setup
Figure 6-2 Roaming Call Delivery - Successful
10
11
12
13
14
15
The following steps are performed:
1. The switch attempts to deliver a call to the home Gateway of a mobile. In this scenario, the
mobile is roaming, and so is not registered at the VLR of the home system.
2. The VLR sends a Locate Request (LOCREQ) INVOKE to the Home Location Register
(HLR) requesting the location of the mobile.
6-2
Description of the Globalstar System
GS-TR-96-0021
Revision E
3. The HLR determines the serving system for the User Terminal and sends a Routing Request
INVOKE to the serving VLR.
4. The VLR sends a Routing Request (ROUTREQ) INVOKE to the Gateway to request the
allocation of a Temporary Local Directory Number (TLDN) for the mobile.
5. The Gateway allocates a TLDN and returns the result in a Routing Request RETURN
RESULT.
6. The VLR returns this TLDN to the HLR in the Routing Request RETURN RESULT.
7. The HLR sends the TLDN to the originating VLR via Locate Request RETURN RESULT.
10
11
12
13
8. The Gateway forwards the call to the destination Gateway (using the TLDN) and call setup is
initiated with the serving Gateway.
Roaming Call Delivery - Busy Case: This scenario illustrates the case where the called number is
busy in a roaming system. The message exchange would be similar if features such as call forwarding
were activated. Figure 6-3 is a case where the called number is busy.
Originating
System
Switch
or MSC
GW
call
origination
Serving
System
VLR
HLR
VLR
GW
LOC REQ
ROUTRE Q
ROUTREQ
routreq 5
locr eq [busy]
busy
routreq [busy]
14
15
Figure 6-3 Roaming Call Delivery - Subscriber Busy
6-3
Description of the Globalstar System
GS-TR-94-0001
Revision E
The following steps are performed:
1. The switch attempts to deliver a call to the home Gateway of a mobile. In this scenario, the
mobile is roaming, and so is not registered at the VLR of the home system.
2. The VLR sends a Locate Request (LOCREQ) INVOKE to the HLR requesting the
location of the mobile.
3. The HLR determines the serving system for the User Terminal and sends a Routing Request
INVOKE to the serving VLR.
4. The VLR sends a Routing Request INVOKE to the Gateway to request the allocation of a
Temporary Local Directory Number (TLDN) for the mobile.
11
6. The Gateway determines that the mobile is busy in another call and returns the result in a
Routing Request RETURN RESULT.
12
6. The VLR returns this notification to the HLR in the Routing Request RETURN RESULT.
10
14
7. The HLR sends the result to the originating VLR via Locate Request RETURN RESULT,
and the VLR forwards the result to the Gateway.
15
8. The Gateway returns a busy indication to the network.
13
16
17
Note that in the case of other call setup failures e.g. if Call Forwarding has been activated, the same
scenario applies in principle, but the indication contained within the messages are different.
6-4
Description of the Globalstar System
GS-TR-96-0021
Revision E
6.2 TIA and ETSI Call Flow Examples
This is an informative appendix which contains examples of call flows. The diagrams follow these
conventions:
• All messages are received without error
• Receipt of messages is not shown except in the handoff examples
• Acknowledgments are not shown
• Authentication procedures are not shown
• Encryption mode transitions are not shown
6-5
Description of the Globalstar System
GS-TR-94-0001
Revision E
User Terminal
Gateway
• Detects user-initiated call
• Sends Origination Message
Access Channel
• Sets up Traffic Channel
• Begins sending null Traffic
Channel data
• Sets up Traffic Channel
Paging Channel
• Sends Channel Assignment
Message
• Receives N5m consecutive valid
frames
• Begins sending the Traffic Channel
preamble
• Acquires the Reverse Traffic
Channel
• Begins transmitting null Traffic
Channel data
Forward Traffic
Channel
• Sends Gateway Acknowledgment
Order
• Sends Service Request Message for
Service Option 1
Reverse Traffic
Channel
• Allocates resources for Service
Option 1
• Begins processing primary traffic in
accordance with Service Option 1
Forward Traffic
Channel
• Sends Service Connect Message
• Sends Service Connect Completion >
Message
Reverse Traffic
Channel
Optional
• Sends Origination Continuation
Message
Optional
Reverse Traffic
Channel
Optional
• Applies ring back in audio path
Optional
Forward Traffic
Channel
Optional
• Removes ring back from
audio path
• Sends Alert With Information
Message (ring back tone)
Optional
Forward Traffic
Channel
(User conversation)
• Sends Alert With Information
Message (tones off)
(User conversation)
Figure 6-4 Simple Call Flow, User Terminal Origination Example Using Service Option 1
(TIA Call Control Procedures)
(Part 1 of 2)
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Description of the Globalstar System
GS-TR-96-0021
Revision E
User Terminal
Gateway
• Detects user-initiated call
• Sends Channel Request Message
indicating call origination and
service option requested
• Sets up Traffic Channel
Access Channel
• Sets up Traffic Channel
• Begins sending null Traffic
Channel data
Paging Channel
• Sends Channel Assignment
Message
• Receives N5m consecutive valid
frames
• Begins sending the Traffic Channel
preamble
• Acquires the Reverse Traffic
Channel
• Begins transmitting null Traffic
Channel data
Forward Traffic
Channel
• Sends Gateway Acknowledgment
Order
• Sends ETSI Layer 3 Transport
Message containing CC Setup
message
Reverse Traffic
Channel
• Starts setting up a call
•
Forward Traffic
Channel
• Sends ETSI Layer 3 Transport
Message containing CC CallProceeding message
See the note below
Note: The gateway and the user terminal follow the call establishment procedures as defined in section 5.2.1 of
ETS 300 557, GSM 04.08.
Forward Traffic
Channel
• Sends Service Connect Completion >
Message
Reverse Traffic
Channel
• Begins processing primary traffic in
accordance with Service Option 1
(User conversation)
• Sends Service Connect Message
(User conversation)
Figure 6-5 Simple Call Flow, User Terminal Origination Example Using Service Option 1
(ETSI Call Control Procedures)
(Part 2 of 2)
6-7
Description of the Globalstar System
GS-TR-94-0001
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User Terminal
• Sends Page Response Message
Gateway
Paging Channel
• Sends General Page Message
Access Channel
• Sets up Traffic Channel
• Begins sending null Traffic
Channel data
• Sets up Traffic Channel
Paging Channel
• Sends Channel Assignment
Message
• Receives N5m consecutive valid
frames
• Begins sending the Traffic Channel
preamble
• Acquires the Reverse Traffic
Channel
• Begins transmitting null Traffic
Channel data
Forward Traffic
Channel
• Sends Gateway Acknowledgment
Order
• Allocates resources for Service
Option 1
Forward Traffic
Channel
• Sends Service Request Message for
Service Option 1
• Sends Service Response Message
accepting Service Option 1
Reverse Traffic
Channel
• Begins processing primary traffic in
accordance with Service Option 1
Forward Traffic
Channel
• Sends Service Connect Completion >
Message
Reverse Traffic
Channel
Forward Traffic
Channel
Reverse Traffic
Channel
• Starts ringing
• Sends Service Connect Message
• Sends Alert With Information
Message (ring)
• User answers call
• Stops ringing
• Sends Connect Order
• Begins sending primary traffic
packets from the Service Option 1
application
(User conversation)
(User conversation)
Figure 6-6. Simple Call Flow, User Terminal Termination Example Using Service Option
1 (TIA Call Control Procedures)
(Part 1 of 2)
6-8
Description of the Globalstar System
GS-TR-96-0021
Revision E
User Terminal
Gateway
Paging Channel
• Sends General Page Message with
service option requested
• Sends Channel Request Message
indicating paging response
Access Channel
• Sets up Traffic Channel
• Sets up Traffic Channel
• Begins sending null Traffic
Channel data
Paging Channel
• Sends Channel Assignment
Message
• Receives N5m consecutive valid
frames
• Begins sending the Traffic Channel
preamble
• Acquires the Reverse Traffic
Channel
• Begins transmitting null Traffic
Channel data
Forward Traffic
Channel
• Sends ETSI Layer 3 Transport
Message containing RR Paging
Response message
Reverse Traffic
Channel
• Starts alerting
Forward Traffic
Channel
• Sends ETSI Layer 3 Transport
Message containing CC Setup
message
• Sends ETSI Layer 3 Transport
Message containing CC
Call_Confirmed message
Reverse Traffic
Channel
• See note below
• Sends Gateway Acknowledgment
Order
Note: The gateway and the user terminal follow the call establishment procedures as defined in section 5.2.2 of
ETS 300 557, GSM 04.08.
Forward Traffic
Channel
• Sends Service Connect Completion >
Message
Reverse Traffic
Channel
• Begins processing primary traffic in
accordance with Service Option 1
(User conversation)
• Sends Service Connect Message
(User conversation)
Figure 6-7 Simple Call Flow, User Terminal Termination Example Using Service Option 1
(ETSI Call Control Procedures)
(Part 2 of 2)
6-9
Description of the Globalstar System
GS-TR-94-0001
Revision E
User Terminal
Gateway
• Detects user-initiated disconnect
• Sends Release Order
Reverse Traffic
Channel
Forward Traffic
Channel
• Sends Release Order
• Enters the System Determination
Substate of the User Terminal
Initialization State
Figure 6-8. Simple Call Flow, User Terminal Initiated Call Disconnect Example (TIA Call
Control Procedures)
(Part 1 of 2)
User Terminal
Gateway
• Detects user-initiated disconnect
• Sends ETSI Layer 3 Transport
Message containing CC Disconnect
message
Reverse Traffic
Channel
• Initiates procedures to clear the
network connection
• Releases the MM connection
Forward Traffic
Channel
• Sends ETSI Layer 3 Transport
Message containing CC Release
message
• Sends ETSI Layer 3 Transport
Message containing CC Release
Complete message1
Reverse Traffic
Channel
• Releases the MM connection
• Releases the RR connection (Traffic
Channel)
Forward Traffic
Channel
• Sends Release Order
• Enters the System Determination
Substate of the User Terminal
Initialization State
Figure 6-9 Simple Call Flow, User Terminal Initiated Call Disconnect Example (ETSI Call
Control Procedure)
(Part 2 of 2)
1 For
more details see call release procedures defined in section 5.4.3 of ETS 300 557, GSM 04.08.
6-10
Description of the Globalstar System
GS-TR-96-0021
Revision E
User Terminal
Gateway
• Detects call disconnect
• Sends Release Order
Forward Traffic
Channel
Reverse Traffic
Channel
• Sends Release Order
• Enters the System Determination
Substate of the User Terminal
Initialization State
Figure 6-10. Simple Call Flow, Gateway Initiated Call Disconnect Example (TIA Call
Control Procedures)
(Part 1 of 2)
6-11
Description of the Globalstar System
GS-TR-94-0001
Revision E
User Terminal
Gateway
• Detects call disconnect
Forward Traffic
Channel
• Sends ETSI Layer 3 Transport
Message containing CC
Disconnect message
• Sends ETSI Layer 3 Transport
Message containing CC Release
message
Reverse Traffic
Channel
• Releases the MM connection
• Releases the MM connection
Forward Traffic
Channel
• Sends ETSI Layer 3 Transport
Message containing CC Release2
Complete message
• Releases the RR connection (Traffic
Channel)
Forward Traffic
Channel
• Sends Release Order
• Enters the System Determination
Substate of the User Terminal
Initialization State
Figure 6-11 Simple Call Flow, Gateway Initiated Call Disconnect Example (ETSI Call
Control Procedure)
(Part 2 of 2)
2 For more details see the call release procedures as defined in section 5.4.4 of ETS 300 557, GSM 04.08.
6-12
Description of the Globalstar System
GS-TR-96-0021
Revision E
User Terminal
Gateway
(User conversation)
(User conversation)
• Detects request for third party to be
added to conversation
• Sends Flash With Information
Message (dialed digits)
Reverse Traffic
Channel
Optional
• Applies ring back in audio path
• Mutes speech
Optional
Forward Traffic
Channel
• Sends Alert With Information
Message (ring back tone)
(Called party answers)
Optional
• Removes ring back tone from audio
path
Optional
Forward Traffic
Channel
• Sends Alert With Information
Message (tones off)
• Unmutes speech from added party
(Two-way conversation with added
party; original party
held)
(Two-way conversation with added
party; original party held)
• Detects user request to establish
three-way conversation
• Sends Flash With Information
Message
Reverse Traffic
Channel
(Three-way conversation)
• Reconnects original party
(Three-way conversation)
Figure 6-12. Simple Call Flow, Three-Party Calling Example (TIA Call Control
Procedures)
6-13
Description of the Globalstar System
GS-TR-94-0001
Revision E
User Terminal
Gateway
(User conversation with first party)
(User conversation with first party)
• Detects incoming call
Optional
• Applies call waiting tone in audio
path
Optional
Forward Traffic
Channel
• Sends Alert With Information
Message (call waiting tone)
Reverse Traffic
Channel
• Mutes speech path to first party,
connects second party
• Detects user request to change
parties
• Sends Flash With Information
Message
(User conversation with second party;
first party held)
(User conversation with second
party; first party held)
• Detects user request to change
parties
• Sends Flash With Information
Message
Reverse Traffic
Channel
(User conversation with first party;
second party held)
• Mutes speech path to second
party, connects first party
(User conversation with first party;
second party held)
Figure 6-13. Simple Call Flow, Call-Waiting Example (TIA Call Control Procedures)
Figure 6-14 illustrates call processing operations during a soft handoff from pilot A to pilot B. Figure 615 illustrates call processing operations during a sequential soft handoff in which the user terminal is
transferred from a pair of pilots A and B through a pair of pilots A and C to pilot C. All the handoff call
processing procedures described below are the same for both the TIA and the ETSI call control and
mobility management procedures.
6-14
Description of the Globalstar System
GS-TR-96-0021
Revision E
User Terminal
Gateway
(User conversation using A)
• Sends Pilot Strength Measurement
Message
(User conversation using A)
Reverse Traffic
Channel
• Receives Pilot Strength
Measurement Message
GW decides to begin handoff to
channel B.
• Begins transmitting traffic on the
Forward Traffic Channel on B
• Receives Handoff Direction
Message
Forward Traffic
Channel
• Sends Handoff Direction Message
to use A and B
Reverse Traffic
Channel
• Receives Handoff Completion
Message
Reverse Traffic
Channel
• Receives Pilot Strength
Measurement Message
• Acquires B; begins using Active
Set {A,B}
• Sends Handoff Completion
Message
• Handoff drop timer of pilot A
expires
• Sends Pilot Strength Measurement
Message
GW decided to cancel channel A
• Receives Handoff Direction
Message
Forward Traffic
Channel
• Sends Handoff Direction Message
to use B only
Reverse Traffic
Channel
• Receives Handoff Completion
Message
• Stops diversity combining; begins
using Active Set {B}
• Sends Handoff Completion
Message
• Stops transmitting on the Forward
Traffic Channel using A
(User conversation using B)
(User conversation using B)
Figure 6-14. Call Processing During Soft Handoff
6-15
Description of the Globalstar System
GS-TR-94-0001
Revision E
User Terminal
Gateway
(User conversation using
A and B)
• Sends Pilot Strength Measurement
Message
(User conversation using
A and B)
Reverse Traffic
Channel
• Receives Pilot Strength
Measurement Message, determines
that new Active Set should contain
B and C
• Begins transmitting traffic on the
Forward Traffic Channel using C
• Receives Handoff Direction
Message
Forward Traffic
Channel
• Sends Handoff Direction Message
to use B and C
Reverse Traffic
Channel
• Receives Handoff Completion
Message
• Stops diversity combining A and B;
starts diversity combining B and C
• Sends Handoff Completion
Message
• Stops transmitting on the Forward
Traffic Channel using A
• Sends Pilot Strength Measurement
Message
Reverse Traffic
Channel
(Continues)
• Receives Pilot Strength
Measurement Message
(Continues)
Figure 6-15. Call Processing During Sequential Soft Handoff
(Part 1 of 2)
6-16
Description of the Globalstar System
GS-TR-96-0021
Revision E
User Terminal
Gateway
(Continues)
(Continues)
• Receives Handoff Direction
Message
Forward Traffic
Channel
• Sends Handoff Direction Message
to use C only
Reverse Traffic
Channel
• Receives Handoff Completion
Message
• Stops diversity combining; begins
using Active Set {C}
• Sends Handoff Completion
Message
• Stops transmitting on the Forward
Traffic Channel using B
(User conversation using C)
(User conversation using C)
Figure 6-16 Call Processing During Sequential Soft Handoff
(Part 2 of 2)
6-17

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