Hop status estimation algorithm based on coherent demodulation of CPM

A hop status estimation algorithm and its error recovery scheme combined with RS (Reed-Solomon) codes are proposed for enhancing the error correcting performance of coherent demodulation of Continuous Phase Modulation (CPM) signal in mobile radio frequency hopping channels. The algorithm provides an accurate hop status estimation by fully exploiting the metric weights rendered after recursively searching through the phase trellis of CPM. As a result, the algorithm requires no extra pilot bits and delay. Both simulation and analytical results show that an average of 98.6% accurate estimation probabilities can be achieved for CPM with modulation index h = 1/2. When combined with RS codes, corrupted hops are indicated as erasures. The residual bit error rate is reduced 38.82% and 36.34% under different channel corrupted hop rate (CHR) by fully utilizing the extrinsic information signaled from the demodulator.