A Modification of Accumulate-Repeat-Accumulate Code Structure via Spatial Coupling
Shady M. Ibraheem1, M. M. Abd Elrazzak, Salwa M. Serag Eldinm, W. Saad, Atef E. Aboelazm
Journal of Data Processing, Vol. 3, No. 4, 2013.
DOI: 
Link: http://www.dline.info/jdp/fulltext/v3n4/1.pdf
Abstract:
In this paper a new family of accumulate repeat accumulate codes are established by a collection of interconnected proto-graphs in a spatially coupled manner. A little modification in the repeater-combiner stage of an accumulate repeat accumulate code emphasizes this development. Spatially coupled low density parity check (SCLDPC) codes appear to approach the capacity universally across the binary-input memoryless (BMS) channels. However, the maximum degree distribution is unbounded and this leads to computational complexity problems at encoders and decoders. Accumulate repeat accumulate (ARA) codes could introduce bounded complexity ensembles that asymptotically achieve capacity on the binary erasure channels (BEC). So, we provide a density evolution (DE) analysis for systematic SC-ARA proto-graphs over the binary erasure channels (BEC). We also discuss the stability conditions for them. Simulation results show that over the BEC spatially coupling of ensembles of ARA codes drives the message-passing belief propagation decoding threshold (BP) to be closed to the maximum a posterior (MAP) threshold of the underlying codes.