Turbo detection of coded continuous-phase modulations

Abstract

Iterative (turbo) decoding of a coded, interleaved continuous-phase modulated (CPM) waveform is presented. The transmitter consists of a rate-2/3 convolutional encoder followed by an interleaver, and an 8-ary continuous phase modulator. At the receiver, soft output a posteriori probability algorithms for the convolutional code and the CPM waveform iteratively refine their probability estimates. Current simulation results show a 2.5 dB SNR improvement (at 10/sup -5/ bit-error rate) over trellis-coded CPM (TCCPM) with a 99% bandwidth efficiency of 1.24 bps/Hz. The detector has a complexity of approximately 4.5 times that of the TCCPM system.