Efficient Concatenated Coding Schemes With Turbo Codes

Turbo codes are a class of high-performance forward error correction codes closely approaching the Shannon limit, as the important topics in research field of communications, and are applied to many wireless transmission scenarios. However, at high signal-to-noise ratios(SNRs), with the increase of SNR, the obtained performance gain decreases gradually, i.e., the error probability curve declines very slowly, which called “error floor”. For some high reliable communication systems which require very low error probability, like digital TV broadcasts, optical fiber communication systems, turbo codes can't be applied.To lower the error floor of turbo codes and satisfy the requirement of high reliability of communication systems, based on the turbo coding scheme, this paper presents the product coding scheme, which uses a matrix structure to combine the inner code and outer code and to tune the error property. Firstly, the reasons leading error floor of turbo codes are analyzed. Secondly, the statistical distribution characteristics of the residual errors of turbo codes and the error correction capability of the outer code needed to match turbo codes are studied. Then, an effective processing method, i.e., the outer coding scheme of product code that can lower the error floor, is selected for correcting the residual errors of turbo codes. Finally, the product coding scheme is designed. The outer code for proposed product code is high-rate BCH code.Simulation results show that compared with the traditional turbo codes and product codes, the product codes can lower error floor significantly, and can achieve bit error rate of 810-. Compared with conventional concatenated codes, the proposed scheme can obtain lower decoding complexity and higher coding rate.