Selected Mapping Method Based On OFDM System PAPR Reduction Technique

Orthogonal Frequency Division Multiplexing (OFDM) techniques have received a great deal of attention due to its high data rate transmission capability with high bandwidth efficiency in coping with multipath fading and has been widely used in digital audio (DAB), Digital Video Broadcasting (DVB), wireless local area network (WLAN) and other technical fields. As a result, OFDM is considered as the key technologies of the 4G mobile communication.However, one major drawback of OFDM is the high peak-to-average power ratio (PAPR) of the output signal. High PAPR at the transmitter can cause the high power amplifier (HPA) to go into non-linear regions and cause nonlinear output, and degrade the performance of OFDM system seriously.PAPR is a key problem of OFDM system, many reserches have been made home and abroad. However, existing methods are not perfect and have such-and-such disadvantage. In this paper, causes of high PAPR problem are analysed and methods which can reduce PAPR efficiently are proposed, main works done in this paper is listed as follow:First, investigation about existing methods to reduce PARR of OFDM system is made. Simulation analysis is made using the software MATLAB.Then, methods of Selected Mapping(SLM) and Tone Reservation(TR) are mainly analysed. Based on the analysis, a betterment method combined these two methods is proposed. The combined method, TR_SLM method reduces the PAPR of the system efficiently and this is verified by simulation.At last, a betterment method is proposed. Although the TR_SLM method efficiently reduce PAPR, it import webbing redundancy information. To eliminate the webbing redundancy information, method proposed in last chapter is optimized at last. One of the chaos list, the Logistic Mapping is imported into SLM and TR respectively at first and simulation analysis is made. The simulation result shows that the import of the chaos list can not only eliminate the webbing redundancy information but can also reduce the PAPR of the system. A lot of simulation result prove that new united arithmetic can reduce the PAPR efficiently, and because of the import of the chaos list in the new arithmetic, the webbing redundancy information is reduced, and the usable ratio of the system frequency band is proved.