EXIT chart analysis of Repeat Accumulate Codes for Log-BCJR algorithm in iterative decoding

In this paper, a generic schematic design of turbo like codes known as Repeat Accumulate Codes is proposed. This type of codes is a subset of serial concatenated turbo codes executed as an outer code, while a convolutional code as an inner code having interleaver inserted between them. In the associated decoder, Log-BCJR algorithm is applied as it is found to perform very well for iterative decoding process. The main idea is to design a simple scheme in order to investigate the performance of repeat accumulate codes, by varying the sizes of frame length transmitted over Additive White Gaussian Noise (AWGN) channel and accomplishing eight decoding iterations at the iterative decoder. It is achievable in Bit Error Rate (BER) chart to investigate the overall performance of the turbo and turbo like codes, while Extrinsic Information Transfer (EXIT) chart is a very powerful analysis tool to portray the iterative decoding behaviour. Therefore, BER chart along with EXIT chart is presented, to provide a far accurate insight of the proposed system.