On pilot symbol assisted detection of MSK and GTFM in fast fading channels

We present in this paper a coherent detection technique for binary continuous phase modulation (CPM), with modulation index of 1/2, operating in the Rayleigh flat fading channel. The technique is based on the idea of inserting data dependent pilot symbols that forces the CPM signal to pass through known phase states periodically. When coupled with an appropriate front end filter and interpolation filter, very accurate channel state information (CSI) can be estimated at the receiver for fading compensation. Moreover, the accuracy of the CSI can be further refined by adopting a multiple-pass decoding approach. Finally, a precoding technique capable of essentially reducing the bit-error-rate (BER) by half is introduced.