Distributed Turbo Coding Scheme with Punctured Soft Systematic-bit Repeat in Relay Systems over Quasi-static Rayleigh Fading Channels

In order to mitigate the error propagation and achieve diversity gain, an enhanced distributed turbo coding (DTC) with soft information relaying (SIR) scheme is proposed for relay systems in practical fading channels. For the proposed scheme, not only the soft information of the additional parity bits but also the soft information of the systematic bits are regenerated and repeated at the relay. To avoid the penalty of spectrum efficiency loss due to the repeat of information on systematic bits, puncturing is employed. Bit error probability performance of the proposed DTC-SIR scheme is analyzed via distance spectrum and union bound method. Both the theoretic analysis and the numerical simulation show that the proposed scheme outperforms the traditional DTC scheme in practical fading channels.