Concatenated coding schemes and interleaving techniques over Rayleigh fading ionospheric channels

Abstract

SUMMARYIn this paper the performance of a concatenated coding scheme is evaluated over a slow Rayleigh fading HF ionospheric link with additive white Gaussian noise (AWGN). Well-known Ungerboeck TCM techniques onto an 8-PSK signal set are used as inner codes and Reed}Solomon block codes as outer codes. The coded/modulated signal is further di!erentially encoded before transmission to combat random phase changes. Block interleaving techniques are necessary to randomise long bursts of errors caused by the fading channel. The performance of the proposed concatenated coding system is investigated for various Doppler spreads. Signi"cant coding gains are achieved over uncoded, diversity or other conventionally coded systems with a small bandwidth expansion. Finally the interesting e!ects of interleaving on the behaviour of the proposed systems are analysed.