The Study Of Clipping Technology And Turbo Codes Based On Wimax

With the development of the communications technology, the new services, and the interaction of market and technology, some new features of the future communication gradually appearing. On the one hand, the user is no longer satisfied with traditional broadband fixed access, mobile services have become increasingly demanding; on the other hand, the traditional mobile users are no longer satisfied with simple voice, text messaging and low-speed data services, more and more eager to high-speed data services, such as multimedia. Therefore, the two trends are mobile broadband technology and broadband mobile technology, and complement each other.In this case, WiMax has naturally become the focus of attention. In this paper, some physical layer technology of WiMax: OFDM technology, channel coding and decoding techniques are studied in detail.In the area of OFDM technology, Because of the many outstanding advantages, it becomes one of the most critical technologies in the current wireless communication standards. In this paper, it presents the basic principles of OFDM technology, gives the formula why the OFDM signal amplitude into the complex Gaussian distribution and the simulation results, and gives a detailed analysis of signal distortion type algorithm on the problem of reducing the PAPR, and it improves some algorithms based on these analysis. Such as: with regard to the compression and expansion algorithm, according to the expansion of small-signal and the compression of large-signal theory, improving theμlaw algorithm, giving the general expression, analyze and summarize of the power function of compression and expansion algorithm. It gives the detailed analysis and summary of the window algorithm, and it gives the analysis and improvement of constrained clipping algorithm. In the end, it shows the simulation result.On channel coding, it details the CC(Convolution Code), RSCC(Reed-Solomon Convolution code) and the CTC(Convolutional turbo code) encoder of the WiMax standard, and discuss the decoder of the CTC, it gives the formula of the MAP algorithm, and it gives the simulation results of the MAP algorithm according to the principle of the MAP algorithm: different coding rate(1 / 3, 1 / 2, 2 / 3, 3 / 4, 5 / 6), iterative decoding of different times(2,4,6,8,12) and different modulation( BPSK, QPSK, 16QAM, 64QAM). For more, it analyzes the simulation results and summarizes the improvement of the MAP algorithm.