Spatially coupled repeat-accumulate codes over half-duplex relay channel

In this paper we study the design and analysis of spatially coupled repeat-accumulate (SC-RA) codes over a three-terminal half-duplex relay channel. The channels between the terminals are considered binary input additive white Gaussian noise (BIAWGN) channels, while decode-and-forward (DF) relaying is considered at the relay. We present low complexity density evolution analysis for the SC-RA code based relay code, which leads to simple code design procedure. For a wide range of design rates, we show that SC-RA code based relay code asymptotically approaches the capacity of a given relay channel. We observe that this relay code outperforms existing channel codes optimized for half-duplex DF relaying protocol. We also show the finite-length performance of the presented code through simulation results.