The pan-European mobile radio system: Part I

Abstract

Having considered the mapping of logical traffic and control channels onto physical channels, speech and error correction coding, interleaving as well as the TDMA hierarchy and synchronisation problems in Part I of this contribution, here mainly transmission issues are addressed [1–6] and some performance figures are provided. Constant envelope partial response Gaussian Minimum Shift Keying (GMSK) with a channel spacing of 200 kHz is deployed to support 125 duplex channels in the 890 - 915MHz uplink and 935 - 960 MHz downlink bands, respectively. At a transmission rate of 271 kbit/s 1.35 bit/s/Hz spectral efficiency is achieved. The controlled GMSK-induced and un-controlled channel-induced inter-symbol interferences are removed by the channel equaliser. The set of standardised wide-band GSM channels is introduced in order to provide bench-markers for performance comparisons. Efficient power budgeting and minimum co-channel interferences are ensured by the combination of adaptive power- and handover-control based on weighted averaging of up to eight uplink and downlink system parameters. Discontinuous transmissions (DTX) assisted by reliable spectral-domain voice activity detection (VAD) and comfort-noise insertion further reduce interferences and power consumption. Due to ciphering, no unprotected information is sent via the radio link. As a result, spectrally efficient, high-quality mobile communications with a variety of services and international roaming is possible in cells of up to 35km radius for signal to noise- and interference-ratios in excess of 10 - 12 dBs.