ETSI TS 145 010 V13.5.0 (2019-05)

ETSI TS 145 010 V13.5.0 (2019-05)






TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
GSM/EDGE Radio subsystem synchronization
(3GPP TS 45.010 version 13.5.0 Release 13)

R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS

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3GPP TS 45.010 version 13.5.0 Release 13 1 ETSI TS 145 010 V13.5.0 (2019-05)



Reference
RTS/TSGR-0645010vd50
Keywords
GSM
ETSI
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3GPP TS 45.010 version 13.5.0 Release 13 2 ETSI TS 145 010 V13.5.0 (2019-05)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables 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 (https://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.
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
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Foreword
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
http://webapp.etsi.org/key/queryform.asp.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

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3GPP TS 45.010 version 13.5.0 Release 13 3 ETSI TS 145 010 V13.5.0 (2019-05)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
1.1 References . 6
1.2 Definitions and abbreviations . 6
2 General description of synchronization system . 8
3 Timebase counters . 9
3.1 Timing state of the signals . 9
3.2 Relationship between counters . 9
4 Timing of transmitted signals . 9
5 BTS Requirements for Synchronization . 10
5.0 General . 10
5.1 Frequency source . 11
5.2 Timebase counters . 11
5.3 Internal BTS carrier timing . 11
5.4 Initial Timing advance estimation . 11
5.5 Maximum timing advance value . 11
5.6 Delay tracking . 12
5.6.1 For circuit switched channels. 12
5.6.2 For packet switched channels . 12
5.6.3 Delay assessment error . 12
5.6.4 Pico-BTS and Local Area multicarrier BTS delay tracking . 12
5.7 Timeslot length . 12
5.7.0 Implementation options . 12
5.7.1 Regular implementation with timeslot lengths of non-integral symbol periods . 13
5.7.2 Implementation option for reduced symbol period bursts when integral symbol period option is used
for normal symbol period bursts . 14
5.8 Range of Timing advance . 15
6 MS Requirements for Synchronization . 15
6.0 General . 15
6.1 MS carrier frequency . 16
6.2 Internal timebase . 16
6.3 Assessment of BTS timing . 16
6.4 Timing of transmission . 16
6.5 Application of Timing Advance . 16
6.5.1 For circuit switched channels. 16
6.5.2 For packet switched channels . 17
6.6 Access to a new BTS . 17
6.7 Temporary loss of signal . 18
6.8 Timing of channel change . 18
6.9 Application of new Timing Advance value . 19
6.10 Definition of "ready to transmit within x ms" . 19
6.11 Definition of additional reaction times for GPRS mobile stations . 19
6.11.1 Uplink and downlink assignment reaction times . 19
6.11.2 Change in channel coding scheme commanded by net work . 20
6.11.3 Contention resolution reaction time . 20
6.11.4 Reaction time in response to other commanding messages . 21
6.11.5 PAN related reaction times . 21
6.11.6 DTR related reaction times . 21
6.12 Observed Frequency Offset (OFO) reported by the CTS-MS . 22
ETSI

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6.13 Timing of inter-RAT channel change from GSM to UTRAN . 22
6.13a Timing of inter-RAT channel change from GSM to E-UTRAN . 23
6.14 Timing of combined intracell channel change and packet assignment . 23
7 CTS-FP Requirements for Synchronization . 24
7.1 Frequency source default requirements . 24
7.2 Frequency source for a CTS-FP assisted by a CTS-MS . 24
7.3 Internal CTS-FP carrier timing . 24
7.4 Timeslot length . 24
7.5 Assessment of CTS-MS delay . 24
Annex A (normative): Additional requirements for pseudo-synchronization, synchronized
handovers and pseudo-synchronized handovers . 25
A.1 General descriptions and definitions . 25
A.1.1 Conventions . 25
A.1.2 Definitions . 25
A.1.3 Details of operations . 25
A.2 BTS requirements . 26
A.2.1 The pseudo-synchronization scheme . 26
A.2.1.1 BTS a time difference estimate . 26
A.2.1.2 The reception epoch criterion . 26
A.2.1.3 Pseudo-synchronized handover . 26
A.2.2 The synchronization scheme . 26
A.3 MS requirements . 27
A.3.1 Provision of time difference information . 27
A.3.2 After each successful circuit-switched handover . 27
A.3.3 Synchronized or a pseudo synchronized handover . 27
Annex B (informative): CTSBCH timeslot shifting properties for CTS-MS synchronization . 28
B.1 Determination of TN by the CTS-MS when CTSBCH shifting is not active . 28
B.2 Determination of TN by the CTS-MS when CTSBCH shifting is active . 28
Annex C (informative): BTS frequency source stability and E-OTD LMU reporting periods
for LCS . 29
C.1 BTS frequency source stability and E-OTD LMU reporting periods . 29
C.2 Frequency source stability . 29
C.3 Relationship to E-OTD reporting periods . 29
Annex D (informative): Change history . 31
History . 35

ETSI

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Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI

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3GPP TS 45.010 version 13.5.0 Release 13 6 ETSI TS 145 010 V13.5.0 (2019-05)
1 Scope
The present document defines the requirements for synchronization on the radio sub-system of the digital cellular
telecommunications systems GSM. However, it does not define the synchronization algorithms to be used in the Base
Transceiver Station (BTS), CTS Fixed Part (CTS-FP) and Mobile Station (MS). These are up to the manufacturer to
specify.
1.1 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. 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 the same
Release as the present document.
[1] 3GPP TR 21.905: “Vocabulary for 3GPP Specifications”.
[2] 3GPP TS 25.123: “Requirements for support of radio resource management (TDD)”.
[3] 3GPP TS 25.133: “Requirements for support of radio resource management (FDD)”.
[4] 3GPP TR 43.030: “Radio network planning aspects”.
[5] 3GPP TS 43.052: “Lower layers of the Cordless Telephony System (CTS) Radio Interface; Stage
2”.
[6] 3GPP TS 43.059: “Functional stage 2 description of Location Services (LCS) in GERAN”.
[7] 3GPP TS 43.064: “Overall description of the GPRS radio interface; Stage 2”.
[8] 3GPP TS 44.018: “Mobile radio interface layer 3 specification, Radio Resource Control Protocol”.
[9] 3GPP TS 44.060: “General Packet Radio Service (GPRS); Mobile Station (MS) - Base Station
System (BSS) interface; Radio Link Control/ Medium Access Control (RLC/MAC) protocol”.
[10] 3GPP TS 45.002: “Multiplexing and multiple access on the radio path”.
[11] 3GPP TS 45.005: “Radio transmission and reception”.
[12] 3GPP TS 45.008: “Radio subsystem link control”.
[13] 3GPP TS 45.050: “Background for RF Requirements”.
[14] 3GPP TS 45.056: “CTS-FP Radio Sub-system”.
[15] 3GPP TS 45.004: “Modulation”.
[16] 3GPP TS 36.133: “Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for
support of radio resource management”.
[17] 3GPP TS 36.211: “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and
Modulation”.
1.2 Definitions and abbreviations
In addition to those below, abbreviations used in the present document are listed in 3GPP TR 21.905.
BTS: Base Transceiver Station.
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BTTI: Basic TTI.
Coverage Class: see definition in 3GPP TS 43.064.
CTS-FP: CTS Fixed Part.
CTS-MS: MS operating in CTS mode.
Current Serving BTS: BTS on one of whose channels (TCH, DCCH, CCCH or PDCH) the MS is currently operating.
Current Serving CTS-FP: CTS-FP on one of whose channels (TCH or CTS control channels) the CTS-MS is
currently operating.
EC: Extended Coverage, see definition in 3GPP TS 43.064.
EC operation: see definition in 3GPP TS 43.064.
EC-GSM-IoT: Extended Coverage GSM for Internet of Things.
FANR (Fast Ack/Nack Reporting): Fast Ack/Nack Reporting enables the use of a PAN field within an RLC/MAC
block for EGPRS data transfer or for EGPRS2 data transfer. FANR enables the mobile station to transmit in the uplink
direction a PAN field corresponding to a downlink TBF. Similarly FANR enables the network to transmit in the
downlink direction a PAN field corresponding to an uplink TBF.
MS timing offset: delay of the received signal relative to the expected signal from an MS at zero distance under static
channel conditions with zero timing advance. This is accurate to ± 1 symbol, and reported once per SACCH or after a
RACH as. required (i.e. at the same rate as timing advance). For example, for an MS with a round trip propagation
delay of P symbols, but with a timing advance of T symbols, the reported timing offset will be P-T quantized to the
nearest symbol. For GPRS the MS timing offset is not reported.
Normal Symbol Period: duration of a symbol for bursts using a modulating symbol rate of 1625/6 ksymb/s (see 3GPP
TS 45.004); it is equal to 48/13 µs. This symbol duration is used for transmission of GMSK, 8PSK, 16QAM and
32QAM modulated bursts on downlink and GMSK, 8PSK and 16QAM modulated bursts on uplink (see 3GPP TS
45.004).
Observed Frequency Offset (OFO): difference of frequency of signals received by a CTS-MS from a CTS-FP and a
BTS. The Observed Frequency Offset is measured and reported by the CTS-MS on CTS-FP requirement. The Observed
Frequency Offset is expressed in ppm with an accuracy of 1/64 ppm (i.e. about 0,016 ppm).
PAN: Piggy-backed Ack/Nack.
Quarter symbol number: timing of quarter symbol periods (12/13 µs or 10/13 µs depending on the actual symbol
period used) within a timeslot. A symbol can represent 1 to 5 bits depending upon modulation.
Reduced Latency: refers to the use of FANR either in BTTI configuration or in RTTI configuration for EGPRS and
EGPRS2.
Reduced Symbol Period: duration of a symbol for bursts using a modulating symbol rate of 325 ksymb/s (see 3GPP
TS 45.004); it is equal to 40/13 µs. This symbol duration is used for transmission of QPSK, 16QAM and 32QAM
modulated bursts on uplink and downlink (see 3GPP TS 45.004).
RTTI: Reduced TTI.
Symbol Period: symbol period is the duration of a symbol and shall refer to normal symbol period unless explicitly
clarified to be the reduced symbol period.
TDMA frame number: count of TDMA frames relative to an arbitrary start point.
Timebase counters: set of counters which determine the timing state of signals transmitted by a BTS or MS.
Time group (TG): used for compact, time groups shall be numbered from 0 to 3 and a particular time group shall be
referred to by its time group number (TG) (see 3GPP TS 45.002).
Timeslot number (TN): timing of timeslots within a TDMA frame.
Timing Advance: signal sent by the BTS to the MS which the MS uses to advance its timings of transmissions to the
BTS so as to compensate for propagation delay.
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Timing Advance Index: Timing Advance Index TAI used for GPRS, which determines the position of the subchannel
on PTCCH (see 3GPP TS 45.002) used by the MS to send an access burst, from which the network can derive the
timing advance.
TTI: Transmission Time Interval.
2 General description of synchronization system
This clause gives a general description of the synchronization system. Detailed requirements are given in clauses 3 to 7.
The BTS sends signals on the BCCH carrier or, for COMPACT on the CPBCCH carrier, to enable the MS to
synchronize itself to the BTS and if necessary correct its frequency standard to be in line with that of the BTS. The
signals sent by the BTS for these purposes are:
a) Frequency correction bursts;
b) Synchronization bursts.
The timings of timeslots, TDMA frames, TCH frames, control channel frames, and (for COMPACT) the rotation of
time groups are all related to a common set of counters which run continuously whether the MS and BTS are
transmitting or not. Thus, once the MS has determined the correct setting of these counters, all its processes are
synchronized to the current serving BTS.
The MS times its transmissions to the BTS in line with those received from the BTS. The BTS sends to each MS a
"timing advance" parameter (TA) according to the perceived round trip propagation delay BTS-MS-BTS. The MS
advances its timing by this amount, with the result that signals from different MS's arriving at the BTS and compensated
for propagation delay. This process is called "adaptive frame alignment".
Additionally, synchronization functions may be implemented in both the MS and the BTS to support the so-called
pseudo synchronization scheme for circuit-switched handovers. The support of this scheme is optional except that MS
shall measure and report the Observed Timing Difference (OTD), which is a mandatory requirement. The detailed
specifications of the pseudo-synchronization scheme for circuit-switched handovers are included in annex A.
While in dual transfer mode an MS performs all the tasks of dedicated mode. In addition, upper layers can require the
release of all the packet resources, which triggers the transition to dedicated mode, or the release of the RR resources,
which triggers the transition either to idle mode and packet idle mode or, depending upon network and MS capabilities,
to packet transfer mode.
When handed over to a new cell, the MS leaves the dual transfer mode, enters the dedicated mode where it switches to
the new cell, may read the system information messages sent on the SACCH and may then enter dual transfer mode in
the new cell (see 3GPP TS 44.060).
In CTS, the CTS-FP sends signals on the CTSBCH to enable the MS to synchronize itself to the CTS-FP and if
necessary correct its frequency standard to be in line with that of the CTS-FP.
The signals sent by the CTS-FP for these purposes are:
a) Frequency correction bursts;
b) Synchronization bursts.
The timings of timeslots, TDMA frames, CTSBCH, CTSARCH, CTSAGCH and CTSPCH frames are all related to a
first common set of counters which run continuously whether the CTS-MS and CTS-FP are transmitting or not. Thus,
once the CTS-MS has determined the correct setting of these first counters, the CTS-MS is able to attach to the current
serving CTS-FP. In addition, during CTS-MS attachment, the CTS-FP sends to the CTS-MS the remaining counters for
SACCH and TCH frames. Then, all processes of the CTS-MS are synchronized to the current serving CTS-FP.
The CTS-MS times its transmissions to the CTS-FP in line with those received from the CTS-FP. The timing advance
parameter is set to zero for CTS.
Additionally, the CTS-FP may be assisted by a CTS-MS to adjust its frequency source. When required by the CTS-FP,
the CTS-MS estimates if possible and reports the Observed Frequency Offset of the CTS-FP with a specified BTS. The
CTS-FP may then adjust its frequency source according to this value.
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3 Timebase counters
3.1 Timing state of the signals
The timing state of the
...