Distributed Network Channel Coding for Multiple Access Relay Interference Channels

In this paper, we consider a multi-access relay interference channel (MARIC), where multiple groups of source nodes communicate with multiple respective destinations, respectively, through a common multi-hop relay network. A joint distributed network-channel coding (DNCC) scheme is proposed to explore both network and channel coding gains. In DNCC, each relay performs a linear network coding and a graph code is formed at each destination. However, multiple groups of source nodes interfere with each other at each destination as each code graph contains bits sent from all other groups of source nodes. To eliminate the inter-group interference, DNCC employs a code-nulling process, so that the graph code at each destination is only the code of its own group of source nodes and does not contain the bits from other group of source nodes. This converts a MARIC into multiple independent multi-access relay channels (MARCs), for each of which a group of source odes communicate with a single destination. Furthermore, for the systematic graph code, such as low density generate matrix (LDGM) code, with respect to each group of source nodes, the LDGM code formed in each decomposed MARC is essentially the same as that formed in the original MARIC. This significantly relax the system design as we can design the distributed LDGM code for each group of source nodes independently as if other group of source nodes does not exist.