The Research On Reducing The Peak To Average Power Ratio Of The Orthogonal Frequency Division Multiplexing System

With the rapid development in wireless communication, more and more higher data transmission rate was required in many fields. The conventional communication system with single carrier is difficult to meet the desired performance of the system. Orthogonal Frequency Division Multiplexing (OFDM) is regarded as the key technology of the physical layer in the next generation mobile communication system, because of its good performance on anti multi-path effect and higher spectrum efficiency, It has been adopted by many communication systems and standard protocals. However, a major drawback of OFDM technology is its high Peak-to-Average Power Ratio (PAPR), which can lead to high requirement for High Power Amplifier(HPA) at transmitter, low efficiency of transmission and also high complexity of system. So the research on how to effectively reduce the PAPR of the OFDM system is quite meaningful.This thesis firstly introduces the basic theory of OFDM system and its advantages and disadvantages, and then analyzes the reasons of high PAPR and concludes the main techniques of reducing the PAPR home and abroad. Besides according to the properties of the Reed-Muller code, it proposes a simple quasi-optimum coding scheme which gives a way to find the good codewords and proves the property that the peak envelope power is invariant for codewords'cyclic shifting and inversing, The results demonstrate the proposed coding scheme can achieve the reliable performance and has a certain improvement in code rate. The paper emphasizes on analyzing the conventional Partial Transmit Sequence(PTS) method and makes a research on the parameters which are corresponding with complexity of the system, and then proposes a quasi-optimum method based on m-sequence to reduce the complexity of PTS scheme. The simulations demonstrate that it can not only reduce the complexity of PTS system effectively, but also improve the PAPR performance.The core problem of PAPR research is to find the ways that not only can reduce PAPR effectively, but also has moderate calculation complexity. Thus there is a tradeoff between the performance and complexity.