Analysis of Near-Capacity Iterative Decoding Schemes for Wireless Communication Using EXIT Charts

This article proposes and compares the performance of three flexible and bandwidth efficient transceivers. The terminology of Over-Complete Mapping (OCM) is introduced in the first two schemes. All of the schemes, namely Non-Convergent Serial Concatenated OCM Coding (NCSCOC), Convergent Serial Concatenated OCM Coding (CSCOC) and Self-Concatenated Convolutional Coding (SECCC); are simulated for the Rayleigh channel and employing iterative decoding to attain the refined output stream for feeding the video decoder. Specifically, the iterative decoding is beneficial in acquiring the convergence of EXtrinsic Information Transfer (EXIT) curves by repeatedly sharing of the mutual information. The difference between the NCSCOC and CSCOC schemes lies in the inner and outer rates. This change reflects an improvement in the Bit-Error Rate (BER) and improved EXIT convergence of CSCOC scheme, with reference to NCSCOC scheme. Results show that NCSCOC scheme never reaches the point of perfect convergence despite iterative decoding. However, CSCOC and SECCC schemes succeed in securing perfect convergence. Investigating the BER curves, it is deducible that SECCC is the most desirable transceiver system, having the least BER. Furthermore, it is plausible that the overall performance of SECCC is much better than the preceding schemes. Explicitly, our experimental results show that the proposed CSCOC scheme outperforms its identical code rate counterpart NCSCOC scheme by about 3 dB at the Peak Signal-to-Noise Ratio (PSNR) degradation point of 1 dB. Additionally, an E-b/N-0 gain of 20 dB is attained using SECCC scheme relative to identical code rate NCSCOC benchmarked scheme.