LDPC coded two-way MIMO relay networks with physical layer network coding

Low-density parity-check (LDPC) codes offer a very powerful error correction technique which allows data transmission in wireless networks with arbitrarily low probability of error. This paper studies LDPC-coded wireless networks with a two-way relay scheme. Two techniques have been developed to increase the throughput of relay networks. First, only two time slots are used to perform one round of information exchange, by exploiting the concept of physical layer network coding. The sources transmit simultaneously their independent messages to the relay in slot 1, while the relay broadcasts the processed signal to the sources in slot 2. Secondly, to reduce the processing time at the relay, we have proposed an estimate-and-forward strategy for LDPC-coded two-way relay networks, where no LDPC decoder is required at the relay. The proposed estimate-and-forward strategy simplifies the processing at the relay, especially when the sources change the encoding parameters. Finally, an effective decoding algorithm has been developed at each source, by subtracting self-interference from the received signals. The simulation results indicate that the proposed LDPC-coded relaying network achieves extremely reliable transmission at very low signal-to-noise ratios.