Iterative Decoding for Serial Concatenated System of VLEC and Recursive STTC

In this paper, we consider serially concatenated source and space time systems. Recursive space time Trellis code (Rec-STTC) with high order modulation is used to provide high bandwidth efficiency. Variable length error correcting code (VLEC) is adopted to provide error resilient capacity at the source coding side. We propose an iterative joint source and space time decoding scheme. The maximum a posteriori probability (MAP) decoding algorithm is adjusted to accommodate issues including the information in both bit and symbol domains and the inseparable systematic information. Systems with a fixed overall information rate but different coding rates in component codes are studied. Simulation results indicate that the proposed joint source space time decoding scheme achieves a significant decoding gain in both quasi-static and rapid fading channels. In addition, for a system with more redundancy dedicated to the source code and a higher order modulation of STTC, the joint decoding yields better performance, though with increased complexity.