Source compression in two-way two-relay network using compute-and-forward relaying

In this paper, the performance of relaying network that employs vector quantization with Compute-and-Forward (CF) relaying technique in AWGN and Rayleigh fading channel is analyzed. Radio relaying is needed when the source and destination cannot directly communicate with each other. Source compression techniques of optimum vector quantization and lattice quantization is employed at source nodes. Physical layer network coding (PNC) with compute and forward relaying is an ingenious relaying scheme that exploits the broadcast nature of wireless channel and forwards the linear combination of signals received from multiple nodes. On the reception of linear combination of messages from the relay nodes, source nodes are capable of extracting the data intended for them. The end-to-end error performance at the source nodes is analyzed. As the performance of CF relaying is sensitive to channel estimation error, we estimate the channel using Least Square Estimation (LSE) and Minimum Mean Square Estimation (MMSE) channel estimation algorithms. The sum-rate of nearly 7 bits/s/Hz for AWGN channel at 20 dB SNR in compute-and-forward relaying is achieved which is only 3.75 bits/s/Hz for decode-and-forward relaying (DF). Thus source compression techniques with efficient CF relaying in PNC is a promising technique to improve the efficiency in wireless relaying networks.