Design of network-coding based multi-edge type LDPC codes for a multi-source relaying system

In this paper we investigate a multi-source LDPC coding scheme for a Gaussian relay system, where M sources communicate with the destination under the help of a single relay (M - 1 - 1 system). More specifically, we propose a network coded LDPC coding scheme for the M - 1 - 1 system where network coding over all sources´ data is performed at the relay. A challenge in such a scheme is the code design for asymmetric channels where each source has different code rate. To address this issue, we present here a novel scheme named network coded multi-edge type LDPC code (NCMET-LDPC). Within NCMETLDPC we optimize the code profiles by EXIT charts, and show that the our coding scheme achieves better bit error rate (BER) performance relative to existing schemes.