Capacity performance analysis of coherent detection in correlated fading channels using finite state Markov models

In this paper, an information theoretic approach is taken to the problem of joint channel estimation and coherent data detection in time varying flat fading channels. At the receiver side, the fading phase process is partitioned or mapped into a finite state Markov channel (FSMC). Using simulation-based capacity analysis of FSMC models, accurate capacity calculation of time varying fading channels is carried out and the effect of number of channel phase partitions on the channel capacity performance is studied. In the BPSK scheme, the capacity is saturated beyond 8 to 16 channel phase partitions. In QPSK signalling, the channel capacity gap between 16/32 channel phase partitions and 128 channel phase partitions is less than 0.3 dB. Moreover, the capacity performance of BPSK and QPSK in unknown correlated fading is compared. The comparison reveals that to maintain the superior QPSK capacity performance, care must be taken in the choice of average transmitted power and symbol duration.