Turbo Codes for Noncoherent Channels

Eric K. Hall and Stephen G. Wilson University of Virginia Charlottesville, VA 22903 Abstract In this work, the application of turbo codes to communications systems using noncoherent FSK and DPSK is considered for the AWGN channel. For both cases, the turbo decoder is formulated employing the appropriate channel metrics. For DPSK, a Gaussian metric is formed while FSK utilizes two decision statistics per received symbol having Rayleigh and Rician statistics respectively. Simulation results are shown to illustrate the coding gains achievable by turbo codes. Comparisons are made to coherent BPSK performance as well as channel capacity limits. Also illustrated is the e ect of code rate and the noncoherent combining penalty.