NCFSK error performance on slow fading channels in the presence of unsynchronized interferers

An expression for the bit error rate (BER) of noncoherent frequency shift keying (NCFSK) modulation with a non-faded desired signal and a single Rayleigh-faded unsynchronized co-channel interferer (UCCI) is derived. This is used to obtain the BER, P_f, for a Rayleigh-faded desired signal. It is found that P_f is not sensitive to the number, n_I of UCCI´s. It is shown that the BER with UCCI is smaller than that with synchronized co-channel interference (SCCI). For a Rayleigh-faded desired signal, the difference is about 0.8 dB for large signal-to-interference ratios (SIR). Simulation is used to obtain the block error rate (BKER) with UCCI as a function of n_I, number of errors corrected and Doppler frequency. It is found that the BKER with no error correction increases with n_I. The BKER with UCCI is generally smaller than that with SCCI. With error correction, the improvement in BKER tends to be larger as n_I increases