Research And FPGA Implementation On Two-Dimensional Peak-to-Average Ratio Reduction Technology

With the rapid development of modern wireless communication systems,spectrum resources are increasingly scarce.In order to improve spectrum utilization efficiency,OFDM modulation technology has been widely used.However,the OFDM signal is a non-constant envelope signal with a high peak-to-average ratio.When it passes through the power amplifier,it will generate in-band distortion and out-of-band spectrum leakage,which will cause a serious bit error rate at the receiving end.Therefore,in practical applications,the power amplifier often needs to take a larger power back to reduce the distortion caused by the nonlinearity,which will cause the power amplifier efficiency to decline.On the other hand,in order to solve the problem of base station size and excessive power consumption effectively,it has become a trend to use a single power amplifier to support multi-band parallel transmission signals in the transmitter,and as the core component in the transmitter structure,the power amplifier is also the largest source of energy consumption.Therefore,the peak-to-average ratio of concurrent multi-band signals has become one of the key technologies of wireless communication systems.This paper studies the two-dimensional peak-to-average ratio technology in the single-amplifier concurrent dual-band scenario,analyzes the advantages and disadvantages of the traditional two-dimensional peak-to-peak average ratio method and the differential two-dimensional peak-to-peak average ratio method,and proposes iterative noise filtering clipping method.In this method,the two band signals are processed jointly,and the difference in the instantaneous amplitude of the two band signals is considered.The non-proportional peak clipping method is adopted to avoid clip peak by mistake effectively;at the same time,the second iteration processing is introduced to reduce the peak regeneration situation effectively.In order to reduce the order of the filter,it is used by interpolating and cascading the filter,which makes the method easy to implement in hardware.In this paper,a 70MHz dual-band OFDM signal is used to evaluate the peak-to-average ratio performance.The results show that when the EVM is less than 7%,the signal PAPR can be reduced by 2.9dB through using the method proposed in this paper,the peak-cutting efficiency and EVM performance has been improved significantly compared with the differential two-dimensional reduction.Aiming at the proposed iterative noise filtering clipping method,this paper used the"top-down" design idea to divide the hardware implementation of the method into modules according to different functions,and completed the hardware logic design and RTL simulation verification of each module in System Generator,and finally implemented the method on FPGA.When we use the same dual-band OFDM signal as MATLAB simulation on the actual measurement of the hardware platform,the results show that the signal PAPR is reduced by 2.8dB when the EVM value is less than 7%,which is basically consistent with the MATLAB simulation results and verifies the correctness of the hardware design.