The pan‐European mobile radio system: Part I

Following the launch of the Pan‐European digital mobile radio (GSM) system its salient features are summarised in this tutorial review [1,8]. Time Division Multiple Access (TDMA) with eight users per carrier is used at a multi‐user rate of 271 kbit/s, demanding a channel equaliser to combat dispersion. The error protected chip‐rate of the full‐rate traffic channels is 22.8 kbit/s, while in half‐rate channels is 11.4 kbit/s. There are two speech traffic channels, five different‐rate data traffic channels and 14 various control and signalling channels to support the system's operation. A moderately complex, 13 kbit/s Regular Pulse Excited speech codec with long term predictor (LTP) is used, combined with an embedded three‐class error correction codec and multi‐layer interleaving to provide sensitivity‐matched unequal error protection for the speech bits. An overall speech delay of 57.5 ms is maintained. Slow frequency hopping at 217 hops/s yields substantial performance gains for slowly moving pedestrians.