Iterative array detection of CPM over continuous-time Rayleigh fading channels

A multiple-antenna receiver is proposed for achieving a diversity effect that partly overcomes the severity of continuous-time frequency-flat Rayleigh fading channels, and fast fading channels in particular. The error performance is also improved by bit interleaving and channel coding, where the encoders/channel is viewed as a serially concatenated system: a convolutional code constitutes the outer code, whereas a differential encoder and the fading channel (having truncated memory) form a joint inner code. In order to obtain a feasible detector structure it is desirable to perform iterative decoding by applying some a posteriori probability (APP) algorithms. For this purpose, we derive a novel generalization of the well known BCJR (due to Bahl, Cocke, Jelinek, and Raviv 1974) algorithm that calculates the APPs for fading channels-or for channels having memory. Numerical results indicate that iterative decoding becomes more powerful when the exploited channel memory depth is extended, but the chief performance gain is achieved by introducing multiple antennas.