Research GSM SCH Channel Coding

With the current wireless more widely applications, especially in the development of the video and audio broadcasting, the transmission quality requirements are higher, besides the wireless channel interference in addition to all kinds of noise, there are multipath and fading caused by various mobile etc., to make channel conditions much worse. Against adverse channel conditions, providing high-quality transmission quality, it is the advantages of formal Turbo codes. GSM system must adopt a more efficient coding scheme to adapt to high-speed data transmission requirements, so we can consider using Turbo codes.This paper first analyzes the GSM system, SCH channel coding translation program and its channel coding of the basic principles and requirements, and study the he inner coding channel coding of Shortened Cyclic group code and outer coding of convolutional code in detail; and then based on proposed GSM05.03, channel interference are Gaussian and burst interference, this article focused on the GSM system and its SCH channel code, decoding scheme, on the inner coding channel coding, outer coding, burst length, some of the features of each detection method in MATLAB platform, with achieve self-Model loop detection, convolutional decoding improvement of system performance testing, and the performance testing and analysis in Gaussian channel, Rayleigh Road and Rice channel with interference were detected. The results show that the channel encoding and decoding for correcting random errors have a good ability to improve the system bit error rate, but this improvement capacity is achieved by monitoring element, all the improvement is limited.Finally, according to the encoding and decoding Turbo codes principles and algorithms, this paper presents a system for high-speed GSM data transmission channel coding scheme, and its performance test. As a very good performance for the MAP algorithm but too complex, and in the actual communication system the performance is limited; SOVA algorithm relatively simple, but worse performance than the MAP algorithm, and the decoding performance is not very stable. The Turbo code is proposed to simplify the maximum number of MAP algorithm, by the recursive formula to get an approximation of the number of areas, thereby greatly reducing the complexity of MAP algorithm. Since the introduction of approximation, its performance is suboptimal compared to the MAP algorithm. Through system testing, performance improvement of its system is about0.73dB.