Principal component combining with differential detection for DPSK signals over Rayleigh fading channels
A principal component combining with differential detector (PCC–DD) is proposed to demodulate M-ary DPSK signals in diversity systems. Exact average bit error probability (BEP) of binary DPSK signals over Rayleigh fading channels for the PCC–DD is obtained in closed form and is shown to agree with the results of simulations. Approximate average BEP of quadrature and octal DPSK signals over Rayleigh fading channels for the PCC–DD are also derived and are shown to be close to those from simulations. It is also shown that PCC–DD outperforms the well known DPSK demodulator that contains a set of differential detectors followed by equal gain combining (DD–EGC) over Rayleigh fading channels in terms of low-average BEP. The performance gain of the PCC–DD over the DD–EGC is large when the signal is binary DPSK, and is very small when the signal is either quadrature or octal DPSK.