Research On The Peak-to-Average Power Ratio Reduction Techniques For OFDM Systems

Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier transmission technique, which can achieve the high speed serial data into parallel transmission by frequency division multiplexing. Because of its high bandwidth efficiency and good anti-multipath fading, OFDM technology has become the key technology of the fourth generation mobile communication system. However, OFDM technology has some drawbacks, such as having a high peak to average ratio (PAPR), sensitive to frequency deviation, difficult to synchronize between sub-carriers and other issues. Among them, how to reduce the high peak-to-average power ratio of OFDM signal is the important issue. Reducing PAPR efficiently is important to reduce the linear range requirements to D/A converter and high power amplifier, also to lower power consumption and increase high power amplifier efficiency, to cut operating costs for mobile networks. To solve this problem, the thesis focuses on effectively reducing the PAPR, the content is organized as follows:Firstly, the thesis describes the development and application of OFDM technology, and explains the basic principles of OFDM technology and system model, and gives the parameters of the OFDM system selection criteria and research focus. After the analysis of high PAPR OFDM system causes, the thesis explains the definition and distribution of PAPR.Secondly, this thesis focuses on the inhibition of OFDM systems PAPR limiting class technology. By simulation analysis of limiting the traditional class technology, we found that although the value can reduce the PAPR, but it is difficult to solve the peak growth. Clipping and Filtering algorithm (CAF) can be a good solution to this problem. By simulation analysis of CAF, we found, CAF algorithm can effectively reduce the PAPR value, and reducing the error rate performance is also improved. In order to better suppress the signal of the peak re-growth, CAF algorithm has been improved to Repeat Clipping and Filtering algorithm (RCAF), the simulation found that the higher the number of iterations, the lower PAPR value is, the better the performance of PAPR. But with the number of iterations increasing, the rate of reducing the PAPR value is low.Finally, the thesis proposed a new PAPR suppression algorithm for OFDM systems, the mean signal power algorithm. Simulation show that the algorithm can effectively reduce the PAPR value, while the algorithm has low complexity, and it can reduce the transmit power and computing time.