Differential turbo coded modulation with APP channel estimation

A serially concatenated coding system which can operate without channel state information (CSI) with use of a simple channel estimation technique is presented. This channel estimation technique utilizes the inner decoder’s a posteriori probability (APP) information about the transmitted symbols to form a channel estimate for each symbol interval, and is termed APP channel estimation. The serially concatenated code (SCC) is comprised of an outer rate 2/3 binary error control code, separated by a bit interleaver from an inner code consisting of an 8-PSK bit mapping and differential 8-PSK modulation. Coherent decoding results in performance 0.6 dB from 8-PSK capacity for large interleaver sizes. APP channel estimation decoding without CSI over constant, random walk and linear channel phase models shows near-coherent results, with fractions of a dB loss in turbo cliff for the random walk phase model