The Research On The Simulation Of 3G Communication Channel And The Performance Of Communication System

As we all know, 3G has many great functions, and it must be the developing direction of communication system. This article researches the simulation of 3G communication channel and the performance of communication system. It contains five parts:It's introduced in the first part that the brief history and present status of mobile communication system. One of the key technique of 3G is the research on the simulation of 3G communication channel and the performance of communication system.The second part summarizes basic transmitting circumstance of 3G. It introduces the three main influences come from the communication channel: path loss in free space, shadowing fading and mul-tipath eclipse. It also give the three model of communication channel. Through analysis and experiments, the detailed models are given in the article.There are three main techniques to improve the performance of 3G. the third part discusses the two of them: diversity and equalization techniques. There five kinds of diversity techniques and each of them has been studied in this paper. The RAKE receiver looked as the deputy has been paid more attention to. As usual, equalization technique can be divided into frequency field and time field equalization. Viterbi arithmetic is introduced at first and then an improved Viterbi arithmetic is proposed. The method can complete search efficiently.The method of channel coding is researched in the four part. Firstly, it's introduced IS-95 coding and given the frame and gridding figures of it. Then it gives more attention to Turbo coding. Based on the structure of Turbo, the theory and arithmetic of coding and decoding are also be discussed. At last, the article analyzes the fixed-point implementation of Turbo code. The optimizations for fixed-point implementation presented at here lead to significant reduction inhardware resource. By reducing the soft input quantization to 4-bit, the buffer size for TTI based operation is saved by 33%. If the clipping and stopping method is applied, the computation of each iteration can be further reduced by 20%. The fifth part sums up the whole article.