Research And Implementation Of Broadband Transmission Technology Based On Software Radio

The structure of STBC is simple,the complexity of coding and decoding is low,and it can get better diversity gain in practical application,so it is widely concerned.Orthogonal frequency division multiplexing?OFDM?technology can well solve the intersymbol interference and multipath interference in the communication system.Applying space-time block coding to a multiple-input multiple-output orthogonal frequency division multiplexing system can effectively improve the anti-interference performance of the system.This dissertation mainly studies the space-time block coding algorithm and the peak to average power ratio?PAPR?reduction algorithm of OFDM.Based on the existing algorithm,an improvement is proposed,and the improved algorithm scheme is designed and implemented by using software radio technology.The specific contents are as follows:1.A single input single output orthogonal frequency division multiplexing communication system based on real air channel is built by using universal software radio peripheral and experimental virtual instrument engineering platform.Modulation and demodulation,OFDM modulation and demodulation,OFDM synchronization,signal equalization,video transmission and reception are realized in software radio.In order to suppress the peak to average power ratio of the constructed OFDM system,in this dissertation,the traditional partial transmit sequence is used,On the basis of PTS algorithm,an improved PAPR scheme for OFDM suppression is proposed,and the improved scheme is successfully designed and implemented by using software radio.The improved scheme uses the maximum norm method to reduce PAPR.The experimental results show that the PAPR of OFDM is effectively reduced compared with the traditional PAPR scheme.2.A set of multi input multi output orthogonal frequency division multiplexing communication system based on air real channel is built by using universal software radio peripheral and experimental virtual instrument engineering platform.In software radio,cyclic coding and decoding,modulation and demodulation,space-time coding and decoding,OFDM modulation and demodulation,OFDM synchronization,signal equalization,video transmission and reception are realized.In order to improve the transmission reliability of MIMO system,this dissertation proposes an improved space-time block coding scheme based on the traditional space-time block coding,and successfully designs and implements the improved space-time block coding scheme by using software radio.The improved space-time block coding scheme uses Hadamard matrix to merge two constellation points into one symbol,and the new symbol generated by the combination is used for the input of the traditional space-time block coding scheme.Experimental results show that the performance of the improved coding scheme is better than that of the traditional coding scheme.At the same time,in order to verify the feasibility of building the system,this dissertation uses software radio to realize the transmission and reception of video.Experimental results show that the system can transmit video normally,and the bit error rate reaches 10^-6 level.