SIR weighting combining diversity using matched filter for personal communication systems

We propose a novel SIR weighting postdetection combining diversity scheme with a new accurate SIR estimation method. The SIR is estimated and used as the weighting factor to compensate severe cochannel interference, one of the most important issues for PCS in terms of frequency utilization. The improvement offered by the proposal depends on SIR estimation accuracy. The SIR is, in this paper, estimated by a matched filter where the auto-correlation between received signal and unique word is calculated. Computer simulations confirm that the SIR of each diversity branch can be estimated easily and accurately by the proposed SIR estimation method. The proposed diversity scheme achieves a performance very close to that of ideal SINR weighting diversity under Rayleigh fading with severe cochannel interference. When average SIR = 10 dB and the number of branches (L) = 4, the proposed diversity scheme lowers the required E_b/N₀ by 5 dB at BER = 1×10^-3 compared to conventional maximal ratio combining diversity. This paper also presents the unique word length required to realize adequate performance, i.e., robustness against high-pitch Rayleigh fading.