5 Multiple access and timeslot structure

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

The access scheme is Time Division Multiple Access (TDMA) with eight basic physical channels per carrier. The carrier separation is 200 kHz. A physical channel is therefore defined as a sequence of TDMA frames, a time slot number (modulo 8) and a frequency hopping sequence.

The basic radio resource is a time slot lasting  576,9 µs (15/26 ms) and transmitting information at a modulation rate of  270,833 ksymbol/s (1 625/6 ksymbol/s) when the symbol period is the normal symbol period (see 3GPP TS 45.010) or at a modulation rate of 325 ksymbol/s for when the symbol period is the reduced symbol period (see 3GPP TS 45.010) . This means that the time slot duration, including guard time, is 156,25 symbols long when the symbol period is the normal symbol period (see 3GPP TS 45.010) or 187,5 symbols long when the symbol period is the reduced symbol period (see 3GPP TS 45.010).

We shall describe successively the time frame structures, the time slot structures and the channel organization. The appropriate specifications will be found in 3GPP TS 45.002.