Research On PAPR Suppression Technology Of Indoor Visible Light Communication Based On HACO-OFDM

Because of the popularity of the rapid development of mobile Internet technology and the shortage of wireless access network spectrum resources,the traditional access network technology is facing great challenges.Today's world is calling for a wide spectrum of resources,low energy consumption,removable access,so visible light communication technology came into being.Visible light communication technology,which based on the LED light bearing the high-speed bright and dark flashing signal to transmit information,adapts to a variety of indoor access scene.Because of the lack of electromagnetic pollution,low energy consumption,information security,visible light communication has become one of the hot issues.However,the limited modulation bandwidth of LED has become the bottleneck of the development of visible light communication.The solution is to use orthogonal frequency division multiplexing(OFDM).However,OFDM modulation has a high peak average power ratio(PAPR)defect,which makes the signal through the non-linear devices in visible light communication distortion.Therefore,it is necessary to use the appropriate method to suppress PAPR.Because there is no negative signal in visible light communication,the traditional OFDM peak ratio suppression technology can not be directly copied.It need to be improved.In this paper,I improve a new HACO-OFDM hybrid modulation,and give the corresponding PAPR suppression algorithm for OFDM signals.Specific work is as follows:Firstly,the difference between visible-type communication and traditional wireless communication in information bearing form and signal detection mode is analyzed.According to the original ACO-OFDM modulation data only in the odd subcarrier transmission,resulting in low spectrum utilization defects,it is proposed to use CAP modulation on the even carrier,and the odd carrier continues to follow ACO-OFDM modulation.Secondly,in the OFDM signal peak-to-average ratio suppression method,the direct slicing method has the problem of in-band signal distortion,resulting in degradation of BER performance,so it must be improved if applied to HACO-OFDM.The improved algorithm uses the TR-Clipping method to reduce the PAPR by preserving the peak-reduced audio PRT to cancel the OFDM peak signal.The simulation results show that the improved TR-Clipping algorithm has a gain of 3.7 dB and 1 d B compared to the original signal and the direct filtering method.Finally,PTS technology is a distortion-free PAPR suppression technique,but there is a drawback that the sideband information occupies the system resources to cause the transmission rate to fall and the computational complexity is too high.It can be found that the improved algorithm is a suboptimal iterative algorithm,and the computational complexity of IFFT operation is lower than that of the original PTS algorithm.