Theoretical analysis of BER in DPSK/OFDM systems with postdetection diversity reception

In OFDM systems with differential phase shift keying (DPSK), it is possible to apply differential modulation in either the time or frequency domain, depending on fading channel conditions, such as Doppler frequency shift and delay spread. Meanwhile, postdetection diversity for DPSK is attractive because the cophasing function necessary in predetection combiners is not required. The paper proposes a simple calculation method, that is an approximate closed-form equation of the bit error rate (BER) in DPSK/OFDM systems with postdetection diversity over both time and frequency selective Rayleigh fading channels. The validity of the proposed method is demonstrated by the fact that the BER performances given by the derived equation coincide with those by Monte Carlo simulation.