MULTIPLE DIFFERENTIAL DETECTION OF PARALLEL CONCATENATED CONVOLUTIONAL (TURBO) CODES IN CORRELATED FAST RAYLEIGH FADING

A new technique for iterative decoding of parallel concatenated convol utional (turbo) codes (PCCC's) for the correlated fast Rayleigh fading channel is proposed and evaluated, This technique is based upon the u se of a multiple differential detector (MDD) receiver structure which exploits the statistical characteristics of the fading process to over come the effects of the rapid phase and amplitude variations, Since tr aditional MDD receivers cannot be used with PCCC's because they do not produce soft output and are not compatible with channel interleaving, a novel MDD receiver structure is derived which overcomes these short falls, In addition, with careful use of extrinsic information related to the a posteriori probability distribution function of the transmitt ed symbols, the receiver is designed in such a fashion as to allow cha nnel estimation to improve with each iteration, Evaluation of the prop osed receiver by means of computer simulation has shown dramatic perfo rmance improvements in fast Rayleigh fading channels as compared to lo ng constraint-length conventional convolutional codes using both singl e and traditional MDD receiver structures.