SIR weighting combining diversity for digital mobile communications

Diversity reception is a powerful technique to reduce the degradation of transmission quality caused by fading. One of the techniques, postdetection maximal-ratio combiner (MRC), is not necessarily effective under cochannel interference, because received signal strength used as the weighting factor is not relative to the instantaneous signal-to-interference power ratio (SIR). The paper proposes an SIR estimation method using the matched filter and a diversity scheme using the estimated SIR as the weighting factor. The performance is evaluated theoretically and by means of computer simulations. The results show that the proposed SIR estimation method can estimate the accurate instantaneous SIR and that the BER characteristics of the proposed diversity scheme under cochannel interference realize better performances than those of MRC.