Timing recovery for continuous phase modulation transmitted over fast flat-fading channels

The problem of deriving symbol synchronization information from the received signal for a class of bandwidth efficient continuous phase modulation (CPM) schemes transmitted over a fast flat-fading channel is studied. The modulation class considered is M-ary CPM with a modulation index h = 1/M. A particular synchronizer structure which generates a tone at the symbol rate in a manner which automatically cancels the fading phase effects is proposed and analyzed in detail. The practical aspects of implementing this synchronizer using digital signal processing methods are discussed. Finally, simulation results showing the root mean square jitter produced by this synchronizer for a few well-known cases of modulation and fading channel parameters are presented to illustrate the performances of the system.