ETSI TS 101 376-5-7 V3.3.1 (2012-12)

GEO-Mobile Radio Interface Specifications (Release 3); Third Generation Satellite Packet Radio Service; Part 5: Radio interface physical layer specifications; Sub-part 7: Radio Subsystem Synchronization; GMR-1 3G 45.010

RTS/SES-00328-5-7

General Information

• Status: Published
• Publication Date: 20-Dec-2012
• Technical Committee: SES SCN - Satellite Communications and Navigation
• Current Stage: 12 - Completion
• Due Date: 02-Jan-2013
• Completion Date: 21-Dec-2012
• Mandate: M/496

Standards Content (Sample)

Technical Specification
GEO-Mobile Radio Interface Specifications (Release 3);
Third Generation Satellite Packet Radio Service;
Part 5: Radio interface physical layer specifications;
Sub-part 7: Radio Subsystem Synchronization;
GMR-1 3G 45.010
GMR-1 3G 45.010 2 ETSI TS 101 376-5-7 V3.3.1 (2012-12)

Reference
RTS/SES-00328-5-7
Keywords
3G, GMPRS, GMR, GPRS, GSM, GSO,
interface, MES, mobile, MSS, radio, satellite,
S-PCN, synchronization, terminal, user
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© European Telecommunications Standards Institute 2012.
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ETSI
GMR-1 3G 45.010 3 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 7
1 Scope . 9
2 References . 9
2.1 Normative references . 9
2.2 Informative references . 10
3 Definitions and abbreviations . 10
3.1 Definitions . 10
3.2 Abbreviations . 11
4 General description of synchronization system . 11
4.1 System timing structure . 11
4.2 Timebase counter . 12
4.3 General requirement . 12
4.3.1 Timing and frequency reference point . 12
4.3.2 MES requirement . 12
4.3.3 Network requirement . 13
4.3.4 Measurement conditions . 13
5 Timing synchronization, TtG/GtT Session. 13
5.1 General description. 13
5.2 Timing of forward link common channels . 14
5.2.1 FCCH/BCCH timing. 14
5.2.2 CCCH timing . 14
5.3 Idle mode timing synchronization . 15
5.3.1 Initial timing acquisition . 15
5.3.2 Paging mode . 15
5.3.3 Alerting mode . 15
5.4 Synchronization at initial access . 15
5.4.1 Synchronization process . 15
5.4.2 RACH timing pre-correction . 16
5.4.3 Description of parameters . 18
5.4.4 Timing accuracy . 19
5.5 Dedicated mode synchronization (A/Gb mode only) . 19
5.5.1 In-call timing relationship (A/Gb mode only) . 19
5.5.2 In-call synchronization scenario (A/Gb mode only) . 20
5.5.3 Transmission timing drift rate (A/Gb mode only) . 21
5.5.4 RX/TX guard time violation (A/Gb mode only) . 22
5.6 Packet transfer mode synchronization . 22
5.6.1 Packet transfer mode timing relationship. 22
5.6.2 Time synchronization for Packet switched channels . 24
5.6.3 Transmission timing drift rate . 27
5.6.4 RX/TX guard time violation . 27
5.6.5 Packet transfer mode timing relationship for handover to dedicated packet channel (Iu mode only) . 27
5.6.6 Packet transfer mode timing for handover to shared packet channel (Iu mode only) . 28
6 Frequency synchronization, TtG/GtT call . 28
6.1 General description. 29
6.2 Frequency of common channels . 29
6.3 Idle mode frequency synchronization. 29
6.3.1 Initial frequency acquisition . 29
6.3.2 Paging mode . 29
6.3.3 Alerting mode . 29
6.4 Synchronization at initial access . 29
ETSI
GMR-1 3G 45.010 4 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
6.4.1 Frequency compensation strategy . 30
6.4.2 Parameter description . 31
6.5 Dedicated mode synchronization (A/Gb mode only) . 31
6.6 Frequency synchronization for the packet switched channels . 33
7 Frame and message synchronization, TtG/GtT call . . 35
7.1 Frame synchronization . 35
7.1.1 Frame number definition . 35
7.1.2 Frame synchronization scenario . 35
7.2 Message synchronization . 36
7.2.1 Power control message synchronization . 36
7.2.1.1 Synchronization in master-to-slave direction (A/Gb mode only). 36
7.2.1.2 Synchronization in slave-to-master direction (A/Gb mode only). 37
7.2.1.3 DCH power control message synchronization in forward direction . 37
7.2.1.4 DCH power control message synchronization in return direction . 38
7.2.2 SACCH message synchronization, TCH6/TCH9 call (A/Gb mode only) . 38
8 Synchronization for TtT call (A/Gb mode only) . 38
8.1 Timing synchronization . 39
8.1.1 General description . 39
8.1.2 Initial access. 40
8.1.2.1 Synchronization procedure . 40
8.1.2.2 Basic requirement . 41
8.1.3 TtG channel synchronization . 41
8.1.3.1 Basic requirement . 41
8.1.4 Transition from TtG-to-TtT channel . 41
8.1.4.1 Synchronization procedure . 42
8.1.4.2 Basic requirement . 42
8.1.5 TtT channel synchronization. 42
8.1.5.1 Synchronization procedure . 43
8.1.5.2 Basic requirement . 43
8.1.6 Effect of the half symbol offset (TtT call) . 43
8.2 Frequency synchronization . 43
8.2.1 General description . 43
8.2.2 Synchronization at initial access . 44
8.2.2.1 Synchronization procedure . 45
8.2.2.2 Basic requirement . 45
8.2.3 TtG channel synchronization . 45
8.2.3.1 Basic requirement . 45
8.2.4 Transition from TtG-to-TtT channel . 46
8.2.4.1 Synchronization procedure . 46
8.2.4.2 Basic requirement . 46
8.2.5 TtT channel synchronization. 46
8.2.5.1 Synchronization procedure . 46
8.2.5.2 Basic requirement . 47
8.3 Frame synchronization . 47
9 Aeronautical terminal synchronization scheme . 48
9.1 MES special features . 48
9.1.1 Speed . 48
9.1.2 Worst-case delay and Doppler features . 48
9.1.3 Frequency offset . 48
9.2 Frequency synchronization . 49
9.2.1 Frequency synchronization general description . 49
9.2.2 Idle mode frequency synchronization . 49
9.2.2.1 Initial frequency acquisition . 49
9.2.2.2 Paging mode . 49
9.2.2.3 Alerting mode . 49
9.2.3 Synchronization at initial access . 49
9.2.3.1 Frequency compensation strategy . 49
9.2.3.2 Parameter description . 50
9.2.4 Dedicated mode synchronization . 50
9.2.4.1 Frequency compensation strategy . 50
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GMR-1 3G 45.010 5 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
9.2.4.2 Parameter description . 51
9.3 Timing synchronization . 51
9.3.1 Timing synchronization general description . 51
9.3.2 Idle mode timing synchronization . 51
9.3.2.1 Initial timing acquisition . 51
9.3.2.2 Paging mode . 52
9.3.2.3 Alerting mode . 52
9.3.3 Synchronization at initial access . 52
9.3.4 Dedicated mode synchronization . 52
9.3.4.1 Doppler-based timing adjustment . 52
9.3.4.2 Standard timing synchronization procedure . 52
9.3.4.3 Parameter description . 52
Annex A (informative): Worst-case delay and Doppler features . 53
A.1 L-band . 53
A.2 S-band. 54
Annex B (informative): Range of timing correction factor . 55
Annex C (informative): Differential Doppler frequency . 56
Annex D (informative): SACCH message synchronization, TtG/GtT call (A/Gb mode only) . 57
D.1 SACCH message synchronization scenario . 57
D.2 SACCH message-round trip delay . 57
Annex E (normative): Timer T3202 for packet mode of operation . 60
Annex F (normative): PTCCH/U and PTCCH/D scheduling (A/Gb mode only) . 61
Annex G (informative): Bibliography . 62
History . 63

ETSI
GMR-1 3G 45.010 6 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
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://ipr.etsi.org).
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 3.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 3); Third Generation Satellite 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; GMR-1 3G 45.001";
Sub-part 2: "Multiplexing and Multiple Access; Stage 2 Service Description; GMR-1 3G 45.002";
Sub-part 3: "Channel Coding; GMR-1 3G 45.003";
Sub-part 4: "Modulation; GMR-1 3G 45.004";
Sub-part 5: "Radio Transmission and Reception; GMR-1 3G 45.005";
Sub-part 6: "Radio Subsystem Link Control; GMR-1 3G 45.008";
Sub-part 7: "Radio Subsystem Synchronization; GMR-1 3G 45.010";
Part 6: "Speech coding specifications";
Part 7: "Terminal adaptor specifications".
ETSI
GMR-1 3G 45.010 7 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
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 3 specifications. Release 3 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).
• Release 3 specifications have a GMR-1 3G prefix in the title and a version number starting with "3" (V3.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.
The GMR release 3 specifications evolve packet mode services of GMR release 2 to 3rd generation UMTS compatible
services. The GMR release 3 specifications introduce the GEO-Mobile Radio Third Generation (GMR-1 3G) service.
Where applicable, GMR-1 3G is derived from the terrestrial digital cellular standard 3GPP and it supports access to
3GPP core networks.
Due to the differences between terrestrial and satellite channels, some modifications to the GSM or 3GPP standard are
necessary. Some GSM and 3GPP specifications are directly applicable, whereas others are applicable with
modifications. Similarly, some GSM and 3GPP specifications do not apply, while some GMR specifications have no
corresponding GSM or 3GPP specification.
Since GMR is derived from GSM and 3GPP, the organization of the GMR specifications closely follows that of GSM
or 3GPP as appropriate. The GMR numbers have been designed to correspond to the GSM and 3GPP numbering
system. All GMR specifications are allocated a unique GMR number. This GMR number has a different prefix for
Release 2 and Release 3 specifications as follows:
• Release 1: GMR n xx.zyy.
• Release 2: GMPRS n xx.zyy.
• Release 3: GMR-1 3G xx.zyy.
where:
- xx.0yy (z = 0) is used for GMR specifications that have a corresponding GSM or 3GPP specification. In
this case, the numbers xx and yy correspond to the GSM or 3GPP numbering scheme.
- xx.2yy (z = 2) is used for GMR specifications that do not correspond to a GSM or 3GPP specification. In
this case, only the number xx corresponds to the GSM or 3GPP numbering scheme and the number yy is
allocated by GMR.
- n denotes the first (n = 1) or second (n = 2) family of GMR specifications.
ETSI
GMR-1 3G 45.010 8 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
A GMR system is defined by the combination of a family of GMR specifications and GSM and 3GPP specifications as
follows:
• If a GMR specification exists it takes precedence over the corresponding GSM or 3GPP specification (if any).
This precedence rule applies to any references in the corresponding GSM or 3GPP specifications.
NOTE: Any references to GSM or 3GPP 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 or 3GPP specification.
• If a GMR specification does not exist, the corresponding GSM or 3GPP specification may or may not apply.
The applicability of the GSM and 3GPP specifications is defined in TS 101 376-1-2 [8].
ETSI
GMR-1 3G 45.010 9 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
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 3G 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 specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
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 necessary for the application of the present document.
In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly
refers to the latest version of that document in Release 7 or to the latest version of that document in the latest release
less than 7.
In the case of a reference to a GMR-1 3G document, a non-specific reference implicitly refers to the latest version of
that document in the same Release as the present document.
[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".
NOTE: This is a reference to a GMR-1 Release 2 specification. See the introduction for more details.
[2] ETSI TS 101 376-4-8: "GEO-Mobile Radio Interface Specifications (Release 3); Third Generation
Satellite Packet Radio Service; Part 4: Radio interface protocol specifications; Sub-part 8: Mobile
Radio Interface Layer 3 Specifications; GMR-1 3G 44.008".
[3] ETSI TS 101 376-5-2: "GEO-Mobile Radio Interface Specifications (Release 3); Third Generation
Satellite Packet Radio Service; Part 5: Radio interface physical layer specifications;
Sub-part 2: Multiplexing and Multiple Access; Stage 2 Service Description; GMR-1 3G 45.002".
[4] ETSI TS 101 376-5-5: "GEO-Mobile Radio Interface Specifications (Release 3); Third Generation
Satellite Packet Radio Service; Part 5: Radio interface physical layer specifications; Sub-part 5:
Radio Transmission and Reception; GMR-1 3G 45.005".
[5] ETSI TS 101 376-5-6: "GEO-Mobile Radio Interface Specifications (Release 3); Third Generation
Satellite Packet Radio Service; Part 5: Radio interface physical layer specifications;
Sub-part 6: Radio Subsystem Link Control; GMR-1 3G 45.008".
[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.
ETSI
GMR-1 3G 45.010 10 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
[7] ETSI TS 101 376-4-12: "GEO-Mobile Radio Interface Specifications (Release 3); Third
Generation Satellite 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; GMR-1 3G 44.060".
[8] ETSI TS 101 376-1-2: "GEO-Mobile Radio Interface Specifications (Release 3); Third Generation
Satellite Packet Radio Service; Part 1: General specifications; Sub-part 2: Introduction to the
GMR-1 family; GMR-1 3G 41.201".
[9] ETSI TS 101 376-4-13: "GEO-Mobile Radio Interface Specifications (Release 3); Third
Generation Satellite Packet Radio Service; Part 4: Radio interface protocol specifications;
Sub-part 13: Radio Resource Control (RRC) protocol; Iu Mode; GMR-1 3G 44.118".
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
Not applicable.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in TS 101 376-1-2 [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 centre 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 centre,
measured in number of timeslots
SB_SYMBOL_OFFSET: additional offset between downlink frame N and uplink frame N + 7 at the spot beam centre,
measured in number of symbols
ETSI
GMR-1 3G 45.010 11 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
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 TS 101 376-1-1 [1] apply.
4 General description of synchronization system
The GEO-Mobile Radio 1 (GMR-1) satellite system is a multi-spot beam, multicarrier, synchronous system where the
timing and frequency on the satellite serve as the reference to synchronize the TDMA transmissions for the MESs, the
network GSs and other network elements.
For A/Gb mode only, the satellite may include a switch designed to provide single-hop, TtT connectivity. Such a
TDMA satellite switch permits the selection of connection patterns between any slot in the TDMA frame of a return
carrier in one spot beam to any other slot in the TDMA frame of a forward carrier in the same spot beam or any other
spot beam.
Synchronization in the GMR-1 system is composed of four major tasks:
• timing synchronization;
• frequency synchronization;
• frame synchronization;
• message synchronization.
A master oscillator onboard the GMR-1 spacecraft is the primary reference for all synchronization processes. The
fundamental goal of synchronization is to have gateways and mobile earth stations alike operate such that all bursts
arrive at the satellite synchronized in timing and frequency.
The above description applies to S and L band mobile link operations.
4.1 System timing structure
The GMR-1 satellite system is a TDMA system. Timing configuration in the system is composed of hyperframe,
superframe, multiframe, frame, timeslot, symbol and bit. A hyperframe is the longest repetition time period and
1/40 symbol duration is the smallest measurable and adjustable unit in the system.
A hyperframe has a duration of 3 h 28 min 53 s 760 ms, it contains 4 896 superframes, 19 584 multiframes or
313 344 TDMA frames. One superframe equals to 2,56 s, including four multiframes or 64 TDMA frames. One
multiframe includes 16 TDMA frames and each TDMA frame has 24 timeslots. The TDMA frame duration is 40 ms,
one timeslot duration is approximately 1,67 ms. In each timeslot, there are 39 symbols, each symbol corresponds to
2 bits. The complete timeframe structure can be seen from the graph shown in TS 101 376-5-2 [3].
A superframe always starts from the frame that meets FN mod 64 = 0. Within the superframe, the first frame is also the
beginning of the first multiframe with multiframe number 00.
ETSI
GMR-1 3G 45.010 12 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
4.2 Timebase counter
The timing state of the signals transmitted by the MES and satellite is defined by the following counters:
• bit counter BN (0 to 77);
• timeslot counter TN (0 to 23);
• TDMA frame counter FN (0 to 313 343).
The relationship between these counters is as follows:
• BN increments every 5 000/234 μs;
• TN increments whenever BN changes from count 77 to 0;
• FN increments whenever TN changes from count 23 to 0.
The MES can use the timing of the receipt of the BCCH burst to set up its timebase counters as follows:
• BN is set by the timing of the FCCH timing acquisition;
• TN is set by the timeslot number that is contained in the information fields of the BCCH burst;
• FN is set by the frame number derived from the information fields of the BCCH bursts.
The frame number field definition is given in TS 101 376-4-8 [2].
4.3 General requirement
4.3.1 Timing and frequency reference point
The satellite is selected to be the reference point for both timing and frequency. For downlink signals, the reference
point is the output of the satellite forward link antenna. For uplink signals, the reference point is the input of the satellite
return link antenna.
4.3.2 MES requirement
The following requirements shall apply to the MES side:
• Both transmitter and receiver timing shall be derived from the same timebase.
• Both transmitter and receiver frequency shall be derived from the same frequency source.
• The MES shall use the same source for both RF frequency generation and clicking the timebase.
• All return link signals (control channel and traffic channel) transmitted from the MESs shall achieve
frame/timeslot alignment on the satellite timing reference point, i.e. input of satellite antenna.
• In various operation modes, synchronization shall be maintained under the worst case timing and frequency
drift rate due to MES-satellite relative motion and MES master oscillator stability. The MES oscillator long
term stability shall be better than 5 ppm. The MES oscillator short-term stability shall maintain all timing
offset, frequency offset and symbol rate requirement specified in TS 101 376-5-5 [4] in the absence of
received signal up to 5 s. The maximum timing drift rate due to MES-satellite relative motion is 0,32 μs/s. The
maximum frequency drift rate due to MES acceleration is 24,6 Hz/s.
• 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 TS 101 376-5-5 [4].
ETSI
GMR-1 3G 45.010 13 ETSI TS 101 376-5-7 V3.3.1 (2012-12)
4.3.3 Network requirement
The following requirements shall apply to the network side:
• All forward link signals (control channel and traffic channel) transmitted from the network shall achieve
frame/timeslot alignment on the satellite timing reference point, i.e. output of satellite antenna.
• Both forward and return link signals shall be adjusted by the network to maintain a fixed frame and slot
relative timing on the satellite timing reference point. This adjustment shall be capable of handling the worst
case timing and frequency drift caused by satellite motion and user motion.
• Forward and return link timeslots shall be assigned by the network to meet the follows: A 1,0 ms guard time
shall be left for the MES to switch between transmit and receive frequencies. A 1,0 ms guard time shall be left
for the MES to switch between two different receive frequencies.
• At the initial call setup, the network shall be able to estimate the RACH signal arrival to the accuracy better
than 12,6 Hz 1-sigma in frequency, 3,6 μs 1-sigma in timing, under the condition of AWGN channel.
• 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.
4.3.4 Measurement conditions
• In the following, all timing and frequency related parameters are defined under the condition of AWGN
channel, with E / N = −0,5 dB .
b 0
• In the following, unless specifically specified, all timing and frequency related parameters are defined as
1-sigma value.
5 Timing synchronization, TtG/GtT Session
The general requirement for MES timing synchronization is that the MES shall transmit signals that are time aligned
and frame number aligned with the system timing on the satellite reference point.
The MES timing alignment is achieved by correcting transmission timing with factors provided by a Gateway
Station (GS). RACH timing is setup by factors provided over the BCCH. The GS transmits a frame number on the
BCCH which is received and used by the MES to establish its local frame numbering process.
For the case in which the MES operates in A/Gb dedicated mode, TCH or SDCCH timing is corrected with corrective
factors given over the AGCH. During a call, timing correction is
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