DPSK exact bit error rates with unsynchronized slowly fading interferers

We derive a new closed-form expression for the exact bit error probability for the detection of a noncoherent binary phase shift keying signal experiencing a multiple cochannel asynchronous interferers in nonselective Rayleigh-fading channels. The analysis accounts for the effect of the timing offset of the different interfering signals as well as the correlation between two adjacent bit intervals. It is valid for general waveshaping pulses and allows interfering signals to have unequal power levels. The results are used to assess the accuracy of the Gaussian interference approximation for diversity receivers.