The Application Of PLVA To The Third Generation Mobile Communication System

When transmitting digital signal in mobile communication system,the receiving digital signal by receiver will inevitably error due to the effect of unideal channel transmission characteristics and additive noise.In order to achieve certain Bit Error Rate under known Signal-to-Noise power Ratio,firstly,we should design baseband signal rationally,choose modulation and demodulation ways,adopt time-domain or frequency-domain equalisation technologies to reduce Bit Error Rate as much as possible.If the Bit Error Rate can not meet the requirements, it is necessary to adopt error control coding techniques to reduce the Bit Error Rate furtherly to meet the requirements.All coding technologies are adopted in mobile communication system, convolutional code is both theory and practice superior to block codes. Convolutional code is a very promising method of coding which is provided by Elias and others in 1955, it is an usual error control coding technology in the depth space communication system and wireless communication system. Convolutional code is different from block codes, its check symbol is not only related with information symbol of the symbol group,but also with the previous symbol group. In the process of coding, convolutional code makes full use of the relevance between symbol words, and its information symbol and check symbol are also smaller than block codes. Under the same symbol rate and the complexity of equipments, both in theory and in practice, convolutional code has been proved that its performance is not worser than block codes; at the same time, convolutional code is more easily than block codes in achieving the best decoding. So from the channel coding theorem, convolutional code is a very promising code.As an effective FEC code, convolutional code will play a more prominent role in the 3G and B3G era. Therefore, based on the conventional decoding algorithm, it is necessary to find a new conventional decoding algorithm.On the background of the 3^rd Generation mobile communication system, the thesis discusses the application of Viterbi decoding with theoretical analysis and simulation to the 3G mobile communication system especially WCDMA. The main fruits are summarized as follows: three main 3G mobile communication techniques are briefly summarized firstly; the coding process about WCDMA is summarized and analyzed particularly; the characters for decoding method of convolutional code are systematically summarized.Based on the conventional viterbi decoding algorithm,the author provides a kind of improved algorithm—Parallel List Viterbi Algorithm, which is tied up with Huawei scientific research,Parallel List Viterbi Algorithm improves the decoding performance of convolutional code effectively. At the same time,performance simulations are presented at particular testing instrument.According to the result,comparing with conventional viterbi decoding algorithm,the Parallel List Viterbi Algorithm can improve about 0.2～0.4dB.