Research On The Method Of Reducing The Peak-to-average Power Ratio Of Ofdm System In Vehicle Channel

In recent years,with the integration and development of communication technology and transportation technology,the application of vehicle wireless communication in intelligent transportation has been promoted.Vehicle communication is gradually becoming a key technology for reliable communication.The total number of cars continues to climb lead to urban traffic jams.In the case of high-density traffic flow,factors such as limited radio frequency communication and shortage of spectrum resources lead to reduce communication quality.Vehicle channel Orthogonal Frequency Division Multiplexing(OFDM)system can be used as the basic technology of smart transportation,which can not only solve the shortage of spectrum resources,but also effectively deal with the problem of radio frequency communication interference reducing communication quality.Vehicle channel OFDM has important value of research for vehicle networking communication.But the one of disadvantages of OFDM is Peak to Average Power Ratio(PAPR).The traditional clipping method can simply and effectively reduce the PAPR,while the clipping method will put in clipping noise and reduce the bit error rate performance of the system.Therefore,this paper mainly focuses on how to suppress the PAPR of vehiclemounted communication channel OFDM systems and how to reduce clipping noise to improve the bit error rate performance of the vehicle-mounted communication channel OFDM systems.The main work and achievements are as follows:1.We have studied the problem of high peak-to-average power ratio(PAPR)in vehicular channel orthogonal frequency division multiplexing(OFDM)systems and investigated the suppression of PAPR using a combination of generalized precoding and nonlinear companding techniques.We qualitatively analyzed the bit error rate(BER)performance of vehicular channel OFDM systems after applying this method and concluded that precoding can reduce the BER of vehicular channel OFDM systems by averaging the signal-to-noise ratio per subcarrier.However,we did not derive a specific BER formula from the theoretical analysis.We conducted simulation experiments in a vehicular channel OFDM system to validate the effectiveness and reliability of the proposed joint method.The simulation results demonstrate that the proposed joint method can effectively reduce PAPR in vehicular channel OFDM systems.The BER aspect also verifies the conclusions drawn from theoretical analysis.2.In response to the problem of reduced bit error rate(BER)performance in vehicular channel orthogonal frequency division multiplexing(OFDM)systems caused by clipping noise introduced by the clipping method,we have conducted research on a method based on compressed sensing to iteratively reduce the clipping noise.To validate the effectiveness and reliability of this method,experiments were conducted in a simulated vehicular channel OFDM system.The proposed method initially models the signal after clipping.At the receiver end,the signal is subjected to maximum likelihood estimation.Then,an iterative relationship is established among the observed clipping noise,the clipped noise recovered through compressed sensing,and the demodulated signal.Iterations are performed with a set threshold to ultimately reduce the clipping noise and obtain the demodulated signal.Simulation experiment results demonstrate that the proposed method effectively reduces clipping noise.Additionally,compared to the Decision-Aided Reconstruction(DAR)algorithm and the traditional Orthogonal Matching Pursuit(OMP)algorithm,the proposed method achieves a significant reduction in the bit error rate,as confirmed by the simulation experiment results.Finally,we summarized the whole paper,including the problems existing in the research and the future research direction.