An Iterative Unified Decoding for Decode-Quantize-Forward Relaying

This paper proposes a design strategy for decode- quantize-forward (DQF) relaying in which two relay nodes parallelly forward quantized a-posteriori loglikelihood ratio (LLR) after channel decoding. A primary focus is on cross correlation among quantized bits. When the source signal is received by plural relays and they are transmitted independently, the parallel streams can be regarded as an imperfect parallel repetition streams, and the final destination can detect the concatenated code sequences. In the proposed scheme, taking into account this feature, we have designed its iterative unified decoding modules, in which we have a novel iterative unified decoding schemes that consists of vertical and horizontal iterations. We have demonstrated that the iterative unified decoding is capable of obtaining large iterative gain in terms of bit error rate (BER).