Dual-signal receiver structures for simultaneous reception of two BPSK modulated co-channel signals using signal cancellation

Abstract

In this paper a dual-signal receiver concept is proposed for simultaneous reception of two narrowband Binary Phase Shift Keying (BPSK) modulated co-channel signals, e.g. two desired signals of different strength. The principle of the proposed receiver concept is based on signal separation and cancellation, by decorrelation of the large signal using the estimated data, followed by demodulation of the small signal. A possible implementation of the receiver concept is presented in detail. The Bit Error Rate (BER) for both signals is derived and numerical and simulation results are presented for two receiver structures with different second demodulator: (1) the coherent BPSK demodulator; (ii) the differentially coherent (DPSK) demodulator. The channel is assumed to be an Additive White Gaussian Noise (AWGN) channel without fading. Comparison of the BER performance of the small signal to the optimum result when only AWGN is present, shows that nearly optimum demodulation of the small signal is possible when the signal strength difference is not too small.