1、3404583 01i05520 493 Released: 15 February 1994 GSM 05.10 Version: 4.4.0 Date: 21 January 1994 Source: ETSI TC-SMG Reference: GSM 05.1 O UDC: 621.396.21 Key words: European digital cellular telecommunications system, Global System for Mobile communications (GSM) European digital cellular telecommuni
2、cations system (Phase 2); Radio subsystem synchronisation (GSM 05.10) ETSI European Telecommunications Standards Institute ETSI Secretariat Postai address: 06921 Sophia Antipolis Cedex - FRANCE Office address: Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE Tel.: + 33 92 94 42 O0 - Fax: +
3、33 93 65 47 16 European Telecommunications Standards Institute 1 994. All rights reserved. No part may be reproduced except as authorised by written permission. The copyright and the foregoing restriction on reproduction extend to all media in which the information may be embodied. 3404583 Oit05521
4、32T Page 2 GSM 05.1 O version 4.4.0: January 1994 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Standards Approval Dept.“
5、at the address shown on the title page. _ 3404583 0105522 266 Page 3 GSM 05.1 O version 4.4.0 January 1994 Contents Foreword 5 1.1 scope 7 1.2 Normative references 7 1.3 Definitions and abbreviations . 7 2 . General Description of Synchronization System 8 3 . TimebaseCounters . 8 4 . Timing of Trans
6、mitted Signals . 8 5 . BS Requirements for Synchronization . 9 6 . MS Requirements for Synchronization . 9 Annex A (normative): Additional requirements for pseudo-synchronisation . 12 General descriptions and definitions . 12 Al . 1 Conventions 12 Al . 2 Definitions 12 Al . 3 Details of operations 1
7、2 A2 BS requirements . 13 A3 MS requirements . 13 Al 3404583 0305523 IT2 Page 5 GSM 05.1 O version 4.4.0: January 1994 Foreword This space is reserved for the foreword of future versions of this document. Previous page is blank = 3404583 0305524 039 = Page 7 GSM 05.1 O version 4.4.0 January 1994 1.1
8、 Scope This technical specification defines the requirements for synchronization on the GSM radio subsystem. (However, it does not define the synchronization algorithms to be used in the BS and MS. These are up to the manufacturer to specify.) 1.2 Normative references This E incorporates by dated an
9、d undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this ETC only when incorpor
10、ated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies. GSM 01.04: “European digital cellular telecommunication system (Phase 2); Definitions, abbreviations and acronyms“. GSM 04.08: “European digital cellular telecommunication system (
11、Phase 2); Mobile radio interface layer 3 specification. GSM 05.02: “European digital cellular telecommunication system (Phase 2); Multiplexing and multiple access on the radio path. GSM 05.05: “European digital cellular telecommunication system (Phase 2); Radio transmission and reception“. GSM 05.08
12、: “European digital cellular telecommunication system (Phase 2); Radio subsystem link control“. GSM 03.30: “European digital cellular telecommunication system (Phase 2); Radio network planning aspects. Definitions and abbreviations In addition to those below, definitions and abbreviations used in th
13、is specification are listed in GSM 01.04. Timing Advance: Quarter bd number: Timeslot number: TDMA frame number: Current Serving BS: Timebase counters: MS timing offset: A signal sent by the BS to the MS which the MS uses to advance its timings of transmissions to the BS so as to compensate for prop
14、agation delay The timing of quarter bit periods (la13 s) within a timeslot The timing of timeslots within a TDMA frame The count of TDMA frames relative to an arbitrary start point The BS on one of whose channels (TCH, DCCH or CCCH) the MS is currently operating A set of counters which determine the
15、 timing state of signals transmitted by a BS or MS The 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 bit, and reported once per SACCH or after a RACH as required (e at the s
16、ame rate as timing advance). For example, for an MS with a round trip propagation delay of P bits, but with a timing advance of T bits, the reported timing offset will be P-T quantized to the nearest bit. Previous page is blank 3404583 0305525 T75 Page 0 GSM 05.10 version 4.4.0: January 1994 2. Gene
17、ral Description of Synchronization System This section gives a general description of the synchronization system. Detailed requirements are given in Sections 3 to 6 below. The BS sends signais on the BCCH to enable the MS to synchronize itself to the BS and if necessary correct its frequency standar
18、d to be in line with that of the BS. The signals sent by the BS for these purposes are (a) Frequency correction bursts (b) Synchronization bursts The timings of timeslots, TDMA frames, TCH frames and control channel frames are ail related to a common set of counters which run continuously whether th
19、e MS and BS are transmitting or ncrt. Thus, once the MS has determined the correct setting of these counters, all its processes are synchronized to the current serving BS. The MS times its transmissions to the BS in line with those received from the BS. The BS sends to each MS a “timing advance“ par
20、ameter according to the perceived round trip propagation delay BS-MS-BS. The MS advances its timing by this amount, with the result that signals from different MSs arriving at the BS and compensated for propagation delay. This process is called “adaptive frame alignment Additionally, synchronisation
21、 functions may be implemented in both the MS and the BS to support the so- called pseudo synchronisation scheme. 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 p
22、seudo-synchronisation scheme are included in Annex A. 3. Timebase Counters 3.1 The timing state of the signals transmitted by a BS or MS is defined by the following counters: - Quarter bit number QN (O - 624) - Bit number BN (O - 156) - Timeslot number TN (O - 7) - TDMA frame number FN (O to (26 x 5
23、1 x 2048) - 1 = 271 5647) 3.2 The relationship between these counters is as follows: * QN increments every 1 Y1 3 s BN = Integer part of QN/4 * M increments whenever QN changes from count 624 to O * FN increments whenever TN changes from count 7 to O 4. Timing of Transmitted Signals The timing of si
24、gnais transmitted by the MS and BS are defined in GSM 05.02. The MS can use the timing of receipt of the synchronization burst to set up its timebase counters as follows: QN TN = O when the synch burst is received FN is set by the timing of the training sequence = 51 (T3T2) mod (26) i T3 + 51 x 26 x
25、 TI when the synch burst is received, (where T3 = (10 x T3) + 1, T1, T2 and T3 being contained in information fields in synchronization burst) Thereafter, the timebase counters are incremented as in section 3.2 (When adjacent BSs are being monitored for handover purposes, the MS may choose to store
26、the values 3404583 0105526 901 Page 9 GSM 05.10 version 4.4.0: January 1994 of QN, TN and FN for all the BSs whose synchronization bursts have been detected relative to QN, TN and FN for its current serving BS) 5. BS Requirements for Synchronization The conditions under which the requirements of sec
27、tions 5.4 and 5.6 must be met shall be 3 dB below the reference sensitivity level in GSM 05.05 and 3 dB less carrier to interference ratio than the reference interference ratios in GSM 05.05. 5.1 The BS shall use a single frequency source of absolute accuracy better than 0.05 ppm for both RF frequen
28、cy generation and clocking the timebase. The same source shall be used for ail carriers of the BS. 5.2 It is optional whether the timebase counters of different BSs are synchronized together. 5.3 The channels of different carriers transmitted by a BS shall be synchronized together, ie controlled by
29、the same set of counters. The timing difference between the different carriers shall be less than 1/4 bit periods, measured at the BS antenna 5.4 When the BS detects a random access CCCH transmission or a message with a long guard time (eg handwer acknowledgement) on a ICH, it shall measure the dela
30、y of this signal relative to the expected signal from an MS at zero distance under static channel conditions. This delay, called the timing advance, shall be rounded to the nearest bit period and included in a response from the BS when applicable 5.5 The maximum timing advance value shall be 63. If
31、the BS measures a value larger than this, it shall set the timing advance to 63. (GSM 03.30 defines how the PLMN deals with MSs where the delay exceeds timing advance value 63.) 5.6 The BS shall thereafter continuously monitor the delay from the MS. If the delay changes by more than one bit period,
32、the timing advance shall be advanced or retarded 1 and the new value signalled to the MS. The delay shall be assessed in such a way that the assessment error (due to noise and interference) is less than 1/2 bit periods for stationary MS. For MS moving at a speed up to 500 km/h the additional error s
33、hall be less then 1/4 bit period. The control loop for the timing advance shall be implemented in such a way that it will cope with MSs moving at a speed up to 500 km/h. Restricting the change in timing advance to 1 bit period at a time gives the simplest implementation of the BS. However the BS may
34、 use a larger change than this but great care must then be used in the BS design. 5.7 Optionally, the BS may use a timeslot length of 157 bit periods on timeslots with TN = O and 4, and 156 bit periods on timeslots with TN = I, 2, 3, 5, 6, 7, rather than 156.25 bit periods on ail timeslots. 5.8 The
35、timing advance shall be in the range O to 63. The value O corresponds to no timing advance, e. the MS transmissions to the BS are 468.75 bits periods behind (see section 6.4). The value 63 corresponds to maximum timing advance, e. the MS transmissions are 405.75 bit periods behind. 6. MS Requirement
36、s for Synchronization The MS shall only start to transmit to the BS if the requirements of sections 6.1 to 6.4 are met. The conditions under which the requirements of sections 6.1 to 6.4 must be met shall be 3 dB below the reference sensitivity level in GSM 05.05 and 3 dB less carrier to interferenc
37、e ratio than the reference interference ratios in GSM 05.05. In discontinuous reception (DRX), the MS should meet the requirements of sections 6.1 to 6.3 during the times when the receiver is required to be active. - - . - - - - Page 10 GSM 05.1 O version 4.4.0: January 1994 = 3404583 0205527 848 6.
38、1 The MS carrier frequency shall be accurate to within 0.1 ppm, or accurate to within 0.1 ppm compared to signals received from the BS (these signals will have an apparent frequency error due to BS frequency error and Doppler shift). In the latter case the signals from the BS must be averaged over s
39、ufficient time that errors due to noise or interference are allowed for within the above 0.1 ppm figure. The MS shall use the same frequency source for both RF frequency generation and clocking the timebase. 6.2 The MS shall keep its internal timebase in line with that of signals received from the B
40、S. If the MS determines that the timing difference exceeds 2 micro-seconds, it shall adjust its timebase in steps of 1/4 bit period. This adjustment shall be performed at intervals of not less than 1 second and not greater than 2 seconds until the timing difference is less than 1/2 bit periods. 6.3
41、In determining the timing of signals from the BS, the timings shall be assessed in such a way that the timing assessment error is less than 1/2 bit periods. The assessment algorithm must be such that the requirements of 6.2 can be met. 6.4 The MS shall time its transmissions to the BS according to s
42、ignais received from the BS. The MS transmissions to the BS, measured at the MS antenna, shall be 468.75-TA bit periods (.e. 3 timeslots-TA) behind the transmissions received from the BS, where TA is the last timing advance received from the current serving BS. The tolerance on these timings shall b
43、e +/- 1 bit period. The MS shall signal the used TA to the BS. 6.5 When the MS receives a new value of TA from the BS on the SACCH, it shall implement the new value of TA at the first TDMA frame belonging to the neh reporting period (as defined in GSM 05.08), after the SACCH frame containing the new
44、 TA value. 6.6 When the MS accesses a new BS, random access, or the serving BS is changed, handover, the MS shall change the TA as follows: Random access: The MS shall use a TA value of O for the Random Access burst sent. When a TA is received from the BS that TA shall be used. Synchronized handover
45、: After the Handover Access bursts which shall be sent with a TA value of O the MS shall use a TA derived from knowledge of the relative timing of the old and the new BS and the value of the TA for the old BS. When a TA is received from the new BS that TA shall be used. Non-synchronized handover: Th
46、e MS shall use a TA value of O for the Handover Access bursts sent. When a TA is received in a physical information message that TA shall be used. Before a TA is received from the new BS no valid “used TA“ shall be signalled to the new BS. Pseudo synchronized handover: After the Handover Access burs
47、ts which shall be sent with a TA value of O the MS shall use a TA as specified in Annex A. Pre-synchronized handover: After the Handover Access bursts which shall be sent with a TA value of O the MS shall use a TA as specified in the HO command by the old BS, or a default value oi 1, if the dd BS di
48、d not provide a TA value. 6.7 During a temporary total loss of signal, of up to 64 SACCH block periods, the MS shall update its timebase with a clock which is accurate to within 0.2 ppm, or to within 0.2 ppm of the signals previously received from the BS. 6.8 When the MS receives an intracell channe
49、l change command or a handover command (see GSM 4.08), it shall be ready to transmit on the new channel within 120 ms of the last timeslot of the message block containing the command, unless the access is delayed to an indicated starting time, in which case it shalt be ready to transmit on the new channel at the designated starting time, or 3404583 0305528 784 Page 11 GSM 05.1 O version 4.4.0: January 1994 within 120 ms, whichever is the later. The time between the end of the last complete speech or data frame or message block sent on the old channel and the time t
