Abstract
In this article, we discuss an extensive class of channel codes called turbo codes. These error correction methods will achieve very good results in terms of error rates, which may be close to the bandwidth limit of the Shannon channel. The article begins with a brief discussion on the coding of the turbo, and then describes the form of the iterative decoder most often used to decode the turbo codes. This article proposes a new optimal modification of the log-MAP-log decoding algorithm. This method (PL-log-MAP) is based on a partial linear approximation of the correction function in the Jacobean logarithm. Using the proposed approximation, the complex functions of ln (.) I exp (.) In the log-MAP algorithm can be estimated with high accuracy and lower computational complexity. The effectiveness of the proposed approximation is tested and demonstrated by applying it to the digital communication system for transmission images in MatLab. It seems that the performance of the PL-log-MAP algorithm has the closest efficiency to the original log-MAP solution.