The Pan-European Mobile Radio System

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Description/Abstract

Abstract. Following the launch of the Pan-European digital mobile radio (GSM) system its salient features are surnrnarised in this tutorial review [I, 81. Time Division Multiple Access (TDMA) with eight users per carrier is used at a multi-user rate of 27 1 kbit/s, demanding a channel equaliser to combat dispersion. The error protected chip-rate of the full-rate traffic channels is 22.8 kbitls, while in half-rate channels is 11.4 kbitls. 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 kbitls 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.