A practical forwarding scheme for wireless relay channels based on the quantization of log-likelihood ratios

This paper considers a wireless relay network with one source, one relay, and one destination. We propose a low-complexity quantize-and-forward (QF) scheme in which the relay calculates log-likelihood ratios (LLRs) for the code bits transmitted by the source and passes quantized versions of these LLRs on to the destination. The destination combines the LLRs from the source-destination link and the quantized LLRs from the source-relay link to obtain improved information bit estimates. We verify the usefulness of the proposed scheme via numerical simulations in block and fast fading.