ETSI TS 101 376-5-7 V2.3.1 (2008-08)

ETSI TS 101 376-5-7 V2.3.1 (2008-08)
Technical Specification


GEO-Mobile Radio Interface Specifications (Release 2);
General Packet Radio Service;
Part 5: Radio interface physical layer specifications;
Sub-part 7: Radio Subsystem Synchronization;
GMPRS-1 05.010

---------------------- Page: 1 ----------------------
GMPRS-1 05.010 2 ETSI TS 101 376-5-7 V2.3.1 (2008-08)




Reference
RTS/SES-00303-5-7
Keywords
GMPRS, GMR, GPRS, GSM, GSO, interface,
MES, mobile, MSS, radio, satellite, S-PCN,
synchronization, terminal
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
Individual copies of the present document can be downloaded from:
http://www.etsi.org
The present document may be made available in more than one electronic version or in print. In any case of existing or
perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF).
In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive
within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
http://portal.etsi.org/chaircor/ETSI_support.asp
Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2008.
All rights reserved.

TM TM TM TM
DECT , PLUGTESTS , UMTS , TIPHON , the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered
for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
ETSI

---------------------- Page: 2 ----------------------
GMPRS-1 05.010 3 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

Contents
Intellectual Property Rights.5
Foreword.5
Introduction .6
1 Scope.7
2 References.7
2.1 Normative references.7
2.2 Informative references.8
3 Definitions and abbreviations.8
3.1 Definitions.8
3.2 Abbreviations.9
4 General description of synchronization system.9
4.1 System timing structure.9
4.2 Timebase counter.9
4.3 General requirement.9
4.3.1 Timing and frequency reference point.9
4.3.2 MES requirement.9
4.3.3 Network requirement.9
4.3.4 Measurement conditions.10
5 Timing synchronization, TtG/GtT call.10
5.1 General description.10
5.2 Timing of forward link common channels .10
5.2.1 FCCH/BCCH timing.10
5.2.2 CCCH timing.10
5.3 Idle mode timing synchronization .10
5.3.1 Initial timing acquisition.10
5.3.2 Paging mode .10
5.3.3 Alerting mode.10
5.4 Synchronization at initial access .10
5.4.1 Synchronization process.10
5.4.2 RACH timing pre-correction .11
5.4.3 Description of parameters.11
5.4.4 Timing accuracy.11
5.5 Dedicated mode synchronization .11
5.5.1 In-call timing relationship.11
5.5.2 In-call synchronization scenario.11
5.5.3 Transmission timing drift rate.11
5.5.4 RX/TX guard time violation .12
5.5.5 Packet transfer mode time slot synchronization.12
5.6 Packet transfer mode synchronization.12
5.6.1 Packet transfer mode timing relationship.12
5.6.2 Time synchronization for Packet switched channels .13
5.6.3 Transmission timing drift rate.14
6 Frequency synchronization, TtG/GtT call.14
6.1 General description.14
6.2 Frequency of common channels.14
6.3 Idle mode frequency synchronization.15
6.3.1 Initial frequency acquisition .15
6.3.2 Paging mode .15
6.3.3 Alerting mode.15
6.4 Synchronization at initial access .15
6.4.1 Frequency compensation strategy.15
6.4.2 Parameter description.15
ETSI

---------------------- Page: 3 ----------------------
GMPRS-1 05.010 4 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

6.5 Dedicated mode synchronization .15
6.6 Frequency synchronization for the packet switched channels.15
7 Frame and message synchronization, TtG/GtT call .16
7.1 Frame synchronization.16
7.1.1 Frame number definition .16
7.1.2 Frame synchronization scenario .16
7.2 Message synchronization.17
7.2.1 Power control message synchronization .17
7.2.1.1 Synchronization in master-to-slave direction.17
7.2.1.2 Synchronization in slave-to-master direction.17
7.2.2 SACCH message synchronization, TCH6/TCH9 call .17
8 Synchronization for TtT call .17
9 Aeronautical terminal synchronization scheme.17
Annex A (informative): Worst-case delay and Doppler features .18
Annex B (informative): Range of timing correction factor .19
Annex C (informative): Differential Doppler frequency.20
Annex D (informative): SACCH message synchronization, TtG/GtT call.21
Annex E (normative): Timer T3202 for packet mode of operation.22
Annex F (normative): PTCCH/U and PTCCH/D scheduling.23
Annex G (informative): Bibliography.24
History .25

ETSI

---------------------- Page: 4 ----------------------
GMPRS-1 05.010 5 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Satellite Earth Stations and
Systems (SES).
The contents of the present document are subject to continuing work within TC-SES and may change following formal
TC-SES approval. Should TC-SES modify the contents of the present document it will then be republished by ETSI
with an identifying change of release date and an increase in version number as follows:
Version 2.m.n
where:
• the third digit (n) is incremented when editorial only changes have been incorporated in the specification;
• the second digit (m) is incremented for all other types of changes, i.e. technical enhancements, corrections,
updates, etc.
The present document is part 5, sub-part 7 of a multi-part deliverable covering the GEO-Mobile Radio Interface
Specifications (Release 2) General Packet Radio Service, as identified below:
Part 1: "General specifications";
Part 2: "Service specifications";
Part 3: "Network specifications";
Part 4: "Radio interface protocol specifications";
Part 5: "Radio interface physical layer specifications";
Sub-part 1: "Physical Layer on the Radio Path: General Description";
Sub-part 2: "Multiplexing and Multiple Access; Stage 2 Service Description";
Sub-part 3: "Channel Coding";
Sub-part 4: "Modulation";
Sub-part 5: "Radio Transmission and Reception";
Sub-part 6: "Radio Subsystem Link Control";
Sub-part 7: "Radio Subsystem Synchronization";
Part 6: "Speech coding specifications";
Part 7: "Terminal adaptor specifications".
ETSI

---------------------- Page: 5 ----------------------
GMPRS-1 05.010 6 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

Introduction
GMR stands for GEO (Geostationary Earth Orbit) Mobile Radio interface, which is used for mobile satellite services
(MSS) utilizing geostationary satellite(s). GMR is derived from the terrestrial digital cellular standard GSM and
supports access to GSM core networks.
The present document is part of the GMR Release 2 specifications. Release 2 specifications are identified in the title
and can also be identified by the version number:
• Release 1 specifications have a GMR-1 prefix in the title and a version number starting with "1" (V1.x.x.).
• Release 2 specifications have a GMPRS-1 prefix in the title and a version number starting with "2" (V2.x.x.).
The GMR release 1 specifications introduce the GEO-Mobile Radio interface specifications for circuit mode mobile
satellite services (MSS) utilizing geostationary satellite(s). GMR release 1 is derived from the terrestrial digital cellular
standard GSM (phase 2) and it supports access to GSM core networks.
The GMR release 2 specifications add packet mode services to GMR release 1. The GMR release 2 specifications
introduce the GEO-Mobile Packet Radio Service (GMPRS). GMPRS is derived from the terrestrial digital cellular
standard GPRS (included in GSM Phase 2+) and it supports access to GSM/GPRS core networks.
Due to the differences between terrestrial and satellite channels, some modifications to the GSM standard are necessary.
Some GSM specifications are directly applicable, whereas others are applicable with modifications. Similarly, some
GSM specifications do not apply, while some GMR specifications have no corresponding GSM specification.
Since GMR is derived from GSM, the organization of the GMR specifications closely follows that of GSM. The GMR
numbers have been designed to correspond to the GSM numbering system. All GMR specifications are allocated a
unique GMR number. This GMR number has a different prefix for Release 2 specifications as follows:
• Release 1: GMR-n xx.zyy.
• Release 2: GMPRS-n xx.zyy.
where:
- xx.0yy (z = 0) is used for GMR specifications that have a corresponding GSM specification. In this case,
the numbers xx and yy correspond to the GSM numbering scheme.
- xx.2yy (z = 2) is used for GMR specifications that do not correspond to a GSM specification. In this
case, only the number xx corresponds to the GSM numbering scheme and the number yy is allocated by
GMR.
- n denotes the first (n = 1) or second (n = 2) family of GMR specifications.
A GMR system is defined by the combination of a family of GMR specifications and GSM specifications as follows:
• If a GMR specification exists it takes precedence over the corresponding GSM specification (if any). This
precedence rule applies to any references in the corresponding GSM specifications.
NOTE: Any references to GSM specifications within the GMR specifications are not subject to this precedence
rule. For example, a GMR specification may contain specific references to the corresponding GSM
specification.
• If a GMR specification does not exist, the corresponding GSM specification may or may not apply. The
applicability of the GSM specifications is defined in GMPRS-1 01.201 [8].
The clause numbering and the table and figure numbering in the present document are aligned to the numbering of the
corresponding Release 1 specification GMR-1 05.010 [6] as far as possible. The table and figure numbering in the
present document has been adjusted in order to maintain this alignment as follows:
• A table that uses the same table number replaces the corresponding table in GMR-1 05.010 [6];
• A table that uses a different table number is a new additional table.
ETSI

---------------------- Page: 6 ----------------------
GMPRS-1 05.010 7 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

1 Scope
The present document presents the requirements for synchronizing timing and frequency between the MES and the
Gateway Station (GS) in the GMR-1 Mobile Satellite System for circuit switch and packet switch modes of operation.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably,
the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore, the
reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the
method of access to the referenced document and the full network address, with the same punctuation and use of upper
case and lower case letters.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
[1] ETSI TS 101 376-1-1: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 1: General specifications; Sub-part 1: Abbreviations and acronyms;
GMPRS-1 01.004".
[2] ETSI TS 101 376-4-8: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 4: Radio interface protocol specifications; Sub-part 8: Mobile Radio Interface
Layer 3 Specifications; GMPRS-1 04.008".
[3] ETSI TS 101 376-5-2: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 5: Radio interface physical layer specifications; Sub-part 2: Multiplexing and
Multiple Access; Stage 2 Service Description; GMPRS-1 05.002".
[4] ETSI TS 101 376-5-5: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 5: Radio interface physical layer specifications; Sub-part 5: Radio
Transmission and Reception; GMPRS-1 05.005".
[5] ETSI TS 101 376-5-6: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 5: Radio interface physical layer specifications; Sub-part 6: Radio Subsystem
Link Control; GMPRS-1 05.008".
ETSI

---------------------- Page: 7 ----------------------
GMPRS-1 05.010 8 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

[6] ETSI TS 101 376-5-7 (V1.3.1): "GEO-Mobile Radio Interface Specifications (Release 1);
Part 5: Radio interface physical layer specifications; Sub-part 7: Radio Subsystem
Synchronization; GMR-1 05.010".
NOTE: This is a reference to a GMR-1 Release 1 specification. See the introduction for more details.
[7] ETSI TS 101 376-4-12: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 4: Radio interface protocol specifications; Sub-part 12: Mobile Earth Station
(MES) - Base Station System (BSS) interface; Radio Link Control/Medium Access Control
(RLC/MAC) protocol; GMPRS-1 04.060".
[8] ETSI TS 101 376-1-2: "GEO-Mobile Radio Interface Specifications (Release 2) General Packet
Radio Service; Part 1: General specifications; Sub-part 2: Introduction to the GMR-1 family;
GMPRS-1 01.201".
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
Not applicable.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in GMPRS-1 01.201 [8] and the following
apply:
Frequency Correction (FC): in-call frequency correction sent over FACCH channel
frequency offset: frequency correction sent over AGCH channel
guard time violation: message to indicate the violation of Rx/Tx burst guard time
MAC_FORWARD_TS_OFFSET: offset in number of timeslots of MAC-slot 0 or D-MAC-slot 0 relative to the start
of the downlink frame
MAC_RETURN_TS_OFFSET: offset in number of timeslots of MAC-slot 0 or D-MAC-slot 0 relative to the start of
the uplink frame
Precorrection Indication (PI): timing delay pre-compensated by the MES in the RACH transmission
RACH_TS_OFFSET: RACH window offset relative to the start of BCCH window within the same frame, measured in
number of timeslots
RACH_SYMBOL_OFFSET: RACH timing offset in symbols
NOTE: The offset between RACH window and the start of the reference frame seen from the MES. Measured in
number of symbols.
SA_BCCH_STN: BCCH window offset relative to the start of the frame, in number of timeslots
SA_FREQ_OFFSET: twice of the downlink beam center Doppler due to satellite motion only
SA_SIRFN_DELAY: within each multiframe, the first FCCH channel frame number relative to the start of the
multiframe
SB_FRAME_TS_OFFSET: offset between downlink frame N and uplink frame N + 7 at the spot-beam center,
measured in number of timeslots
ETSI

---------------------- Page: 8 ----------------------
GMPRS-1 05.010 9 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

SB_SYMBOL_OFFSET: additional offset between downlink frame N and uplink frame N + 7 at the spot beam center,
measured in number of symbols
Timing Correction (TC): in-call timing correction sent over FACCH channel
timing offset: timing correction sent over AGCH channel
USF Delay Value: if an MES receives a USF in its receive downlink frame N, it applies the USF (i.e. transmits
corresponding to the received USF grant) on the uplink frame numbered (N + USF Delay Value)
NOTE: USF Delay Value is decoded from USF_DELAY and USF_DELAY Adjustment parameters in BCCH
System Information, and it can take values of 6, 7, 8, 9 or 10.
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in GMPRS-1 01.004 [1] apply.
4 General description of synchronization system
Same as clause 4 in GMR-1 05.010 [6].
4.1 System timing structure
Same as clause 4.1 in GMR-1 05.010 [6].
4.2 Timebase counter
Same as clause 4.2 in GMR-1 05.010 [6].
4.3 General requirement
4.3.1 Timing and frequency reference point
Same as clause 4.3.1 in GMR-1 05.010 [6].
4.3.2 MES requirement
Same as clause 4.3.2 in GMR-1 05.010 [6], with the addition of the following:
MES receiver's time and frequency search ranges (apertures) shall be large enough to accommodate the variations
(specified in clause 4.3.3) in the network transmit time and frequency in addition to the satellite-MES relative motion
induced time and frequency shifts (see annex A for an informative description), MES oscillator drifts, etc. The MES
receiver, operating with such values of time and frequency apertures, shall achieve the performance requirements
(i.e. BER, FER, time and frequency estimation accuracies, etc.) specified in GMPRS-1 05.005 [4].
4.3.3 Network requirement
Same as clause 4.3.3 in GMR-1 05.010 [6], with the addition of the following:
The network shall ensure that the maximum variation between the transmit time of a CCCH burst and the transmit time
of a PDCH burst does not exceed 12 μs. Similarly, the maximum burst-to-burst variation in the PDCH transmit time
shall not exceed 4 μs. Burst-to-burst variations in the network transmit frequency shall not exceed 10 Hz.
ETSI

---------------------- Page: 9 ----------------------
GMPRS-1 05.010 10 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

4.3.4 Measurement conditions
Same as clause 4.3.4 in GMR-1 05.010 [6].
5 Timing synchronization, TtG/GtT call
Same as clause 5 in GMR-1 05.010 [6], except for the addition of the next paragraph, which follows the second
paragraph.
For the case in which the MES operates in the packet mode, receive timing shall be corrected by monitoring BCCH,
PCH or PDCH and transmission timing shall be corrected with factors provided by the Gateway Station (GS). The GS
provides correction factors via AGCH or PACCH based on the MES mode and situation, which is explained here.
5.1 General description
Same as clause 5.1 in GMR-1 05.010 [6], except for the addition of the next paragraph, which follows the fifth
paragraph.
If packet transfer mode is initiated via the RACH then the procedure is identical to that described for circuit switched
service in clause 5.3.1. Packet switched time and frequency synchronization for the PDCH and the PRACH is described
in clause 5.6.
5.2 Timing of forward link common channels
Same as clause 5.2 in GMR-1 05.010 [6].
5.2.1 FCCH/BCCH timing
Same as clause 5.2.1 in GMR-1 05.010 [6].
5.2.2 CCCH timing
Same as clause 5.2.2 in GMR-1 05.010 [6].
5.3 Idle mode timing synchronization
5.3.1 Initial timing acquisition
Same as clause 5.3.1 in GMR-1 05.010 [6].
5.3.2 Paging mode
Same as clause 5.3.2 in GMR-1 05.010 [6].
5.3.3 Alerting mode
Same as clause 5.3.3 in GMR-1 05.010 [6].
5.4 Synchronization at initial access
5.4.1 Synchronization process
Same as clause 5.4.1 in GMR-1 05.010 [6].
ETSI

---------------------- Page: 10 ----------------------
GMPRS-1 05.010 11 ETSI TS 101 376-5-7 V2.3.1 (2008-08)

5.4.2 RACH timing pre-correction
Same as clause 5.4.2 in GMR-1 05.01
...