5.2a Training sequences

3GPP45.001General descriptionGSM/EDGE Physical layer on the radio pathRelease 17TS

5.2a.1 General

As shown in Figure 1, all burst types except the frequency correction burst contain a training sequence (also referred to as a synchronization sequence). Its purpose is to facilitate synchronization, channel estimation and blind detection of modulation on the radio interface.

For normal bursts (NB) and higher symbol rate bursts (HB) a set of eight training sequences is defined for each modulation (GMSK, 8PSK, 16QAM and 32QAM for NB, and QPSK, 16QAM and 32QAM for HB) to facilitate training sequence planning, i.e., avoiding that strong interfering bursts have the same training sequence as the wanted signal bursts.

For access bursts (AB) seven different synchronization sequences are defined for use on the RACH and EC-RACH CC1 to CC4. For extended synchronization sequence burst (ESAB) one long synchronization sequence is defined for use on EC-RACH CC5. The synchronization sequence used indicates the channel request type and MS modulation capability.

All training sequences are defined in 3GPP TS 45.002.

5.2a.2 VAMOS

For VAMOS, a second set of eight training sequences (TSC Set 2) is defined for GMSK modulated normal bursts (see 3GPP TS 45.002). Two GMSK training sequences are used to form the AQPSK training sequence (see 3GPP TS 45.002) for the downlink VAMOS modulation, see subclase 13.3.

5.2a.3 Extended TSC Sets

When using extended TSC Sets, additional sets, each of eight training sequences, are defined for the different modulations when using normal bursts. The number of additional TSC Sets depends on the domain (circuit switched or packet switched) they operate in.

For the circuit switched domain, two new GMSK sets, referred to as GMSK TSC Set 3 and GMSK TSC Set 4 are defined.

For the packet switched domain, including EGPRS and EGPRS2-A, one additional set of eight training sequences is defined for each of GMSK, 8PSK, 16QAM and 32QAM normal bursts, referred to as TSC Set 2 for 8PSK, 16QAM and 32QAM modulation, while for GMSK, TSC Set 3, which is identical to TSC Set 3 used for circuit switched channels, is used.

An MS indicating support for Extended TSC Sets (see 3GPP TS 24.008) shall support all additional TSC Sets applicable to its modulation capabilities for both circuit switched and packet switched channels. Especially, if such an MS supports GMSK modulated circuit switched channels, it shall support GMSK TSC Set 1, GMSK TSC Set 2, GMSK TSC Set 3 and GMSK TSC Set 4 regardless of its support for VAMOS (see 3GPP TS 24.008).

5.2a.4 EC-GSM-IoT

For EC operation, an EC-CCCH/D block designated to MSs in the lower coverage class (CC1) only shall use a TSC from the TSC Set 1 for GMSK corresponding to the BCC (see 3GPP TS 45.002) and EC-CCCH/D blocks designated to at least one MS in a higher coverage class (CC2 to CC4) shall use the paired TSC with the same TSC number from the TSC Set 2 for GMSK (see 3GPP TS 45.002).

For EC-RACH a set of five synchronization sequences are defined, denoted TS3, TS5, TS6, TS7, and TS8. Different synchronization sequences are used to indicate the UL CC selected to assist the BTS in detecting the MS access and separate accesses from different CCs. TS3 is used for CC1, TS5 is used for CC2, TS6 is used for CC3 and TS7 is used for CC4. EC-RACH uses the single timeslot format for CC1 (i.e. 1 TS EC-RACH) and may use either the single or dual timeslot format (i.e. 1 TS EC-RACH or 2 TS EC-RACH) for CC2 to CC4. For CC5 using ESAB in two consecutive timeslots TS8 is used. The synchronisation sequence to be used for CC5 using EDAB is defined in 3GPP TS 45.002.