SPATIAL-TEMPORAL EQUALIZATION FOR IS-136 TDMA SYSTEMS WITH RAPID DISPERSIVE FADING AND CO-CHANNEL INTERFERENCE

摘要

Spatial-temporal equalization for IS-136 Time Domain Multiple Access (TDMA) cellular/Personal Communication Services (PCS) systems is used to suppress intersymbol interference and co-channel interference, and improve communication quality. The present invention emphasizes channels with large Doppler frequency (up to 184 Hz), delay dispersion under one symbol duration, and strong co-channel interference. Since the channel can change within an IS-136 time slot, the spatial-temporal equalizer requires parameter tracking techniques. The present invention includes two parameter tracking algorithms: the 2-stage tracking algorithm, which uses diagonal loading in combination with a reduced complexity architecture, and the simplified 2-stage tracking algorithm, which further reduces complexity to one MxM and one 3x3 matrix inversion for weight calculation with M antennas. For a 4-antenna system, the simplified 2-stage tracking algorithm can sustain a 10-2 BER when the channel delay spread is half of the symbol duration and the signal-to-interference ratio (SIR) of the system is as low as 5 dB, making it a computationally feasible technique to enhance system performance for IS-136 TDMA systems.