Joint source channel decoding of circular non binary turbo codes

Non binary turbo codes are gaining a lot of attention since the recent adoption of duo binary circular turbo codes by the Digital Video Broadcasting (DVB) community. In this paper, a Joint Source Channel Decoding (JSCD) scheme is proposed for circular non-binary turbo codes. With a view to exploit a-priori probabilities from source statistics, a symbol level trellis is incorporated into the circular trellis of the non-binary turbo decoder. Reversible Variable Length Codes (RVLC) are used as the input source in all simulations. Results show that with JSCD, circular duo binary turbo codes provide an average gain of 0.4 dB at Bit Error Rate (BER) of 10^-5 as compared to conventional decoding of circular duo binary turbo codes. With circular triple binary turbo codes, JSCD provides a striking average gain of 3.5 dB at a BER of 10^-6 compared to conventional decoding of circular triple binary turbo codes.