PAPR Reduction Based On Tone Reservation Method In OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) techniques is the key technologies of the 4G mobile communication.OFDM has high data rate transmission capability with high bandwidth efficiency in coping with multipath fading and have been successfully applied to many areas. 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.In this thesis, several celebrated techniques are introduced and analysed to reduce PAPR, such as clipping,μ-law companding,selective mapping (SLM),partial transmit sequence (PTS) and tone reservation (TR).The method of clipping,μ-law companding and tone reservation are introduced mainly in this paper,and two improved method are proposed in this paper,too.First,the signal pre-distortion technology and probability technology of PAPR reduction are analysed and summaried by accessing to relevant information.Then, an improved scheme of tone reservation based on FFT/IFFT in OFDM system is proposed. According to this method, we can receive better PAPR by using the cancellation signal which is required by pre-set threshold and clipping. This improved scheme can get the better performance of computational complexity reduction, and simultaneously make the PAPR performance remain unchanged. According to the simulation results, the PAPR reduction is about 6dB when the number of iteration is 5. The number of complex multiplication and addition can get 88.73% reduction when the number of iteration is 10.At last, by analysing theμ-law companding algorithm and TR algorithm, a combined algorithm base on the TR algorithm andμ-law companding algorithm is proposed. Simulation results indicate that the PAPR can be reduced about 6.3dB by this new mehod.