Study On Channel Coding Algorithm In IEEE802.16e

WiMAX is a broadband wireless technology based on the wireless metropolitan area network IEEE 802.16 standard. It can provide high speed data transmission, voice and video services under fixed or mobile environment, so WiMAX has a broad application prospect. IEEE802.16e is the standard of air interface for fixed and mobile broadband wireless access systems working on 2~6GHz. In the physical layer of IEEE 802.16 standard, the data is divided into frames for transmitting, and FEC is used to enhance the reliability. In the newest standard, it is clearly pointed out that the support of convolutional code is mandatory and the support of convolutional turbo code is optional.In this article, broadband wireless technology and the development of channel coding technology are introduced firstly, then encoding and decoding principles of convolutional code are introduced, and encoding and decoding algorithm of tail-biting convolution code supported in 802.16e is emphasized. In view of the problem of decoding under the uncertain original coding state, one feasible decoding method is given. In the following principle of convolutional turbo code is introduced. Convolutional turbo codes constructed via parallel concatenation of two circular recursive systematic convolutional encoder linked by an interleaver. Convolutianal turbo codes are very flexible codes, easily adaptable to a large range of data block sizes and coding rates. The determination method of circular state in coding process is derived in the thesis. For emphasis several kinds of decoding algorithm as MAP algorithm, Log-MAP algorithm, Max-Log-MAP algorithm are introduced and performance and complexity of these decoding algorithm are compared. Finally performance of convolutional code and convolutional turbo code under different parameters is simulated and their performance under the same modulation and the same coding rate is compared.Overall, after a lot of theory study and understanding, this project focuses on the algorithm inference of convolutional code and convolutional turbo code supported in IEEE802.16e and system performance simulation, and gets several achievements.