The pan-European mobile radio system: Part I

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 [ I 61 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 91 5MHz uplink and 935 960 MHz downlink bands, respectively. At a transmission rate of 271 kbitls 1.35 bitlslHz 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 cochannel interferences are ensured by the combination of adaptive powerand 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 noiseand interference-ratios in excess of 10 12 dBs.