A coherent detector for some MCPFSK schemes operating in fast fading channels

We present a coherent detection technique for M-level continuous phase frequency shift keying (MCPFSK) signals, with modulation index of W, transmitted over Rayleigh fast fading channels. The technique is based on the idea of inserting data dependent pilot symbols that forces the MCPFSK signal to pass through known phase states periodically. The pilot insertion rule, in conjunction with a properly designed channel estimation, enables the receiver to accurately estimate the channel state information (CSI). If so desired, the accuracy of the CSI can be further refined by adopting a multiple-pass decoding approach. We also include a precoding technique that can essentially reduce the bit error rate of minimum shift keying (MSK) by half