1 Scope

3GPP45.010GSM/EDGE Radio subsystem synchronizationTS

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".

[18] 3GPP TS 49.031: "Location Services (LCS); Base Station System Application Part, LCS Extension (BSSAP-LE)".

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.

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.

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.