Smart Antenna Beamforming Algorithm And Its Applied Research Of High-Speed Railway Wireless Communication

Railway wireless communication system is dedicated to the transmission of important information such as train control commands and dispatching commands,which requires higher reliability and low delay.The railway wireless communication system is prone to malicious or unintentional interference,which seriously threatens the safety of trains.Nowadays,high-speed rail is the first choice for people to travel.To ensure people’s safety,it is particularly important to study how to improve the performance of railway wireless communication system.In recent years,the introduction of smart antenna technology has brought new solutions for railway wireless communication system to solve these problems.Smart antenna beamforming can not only choose appropriate adaptive algorithm to adjust the weight vector of antenna array,but also track the target signal and suppress interference according to different requirements.In the scene of high-speed railway,smart antenna beamforming can improve the reliability and signal tracking ability of railway wireless communication system.Based on swarm intelligence algorithm,this thesis improves the classical adaptive algorithm.Then the universal software radio platform is used to build a beamforming system for verification.The main work of this thesis is as follows:Firstly,I study smart antenna and adaptive beamforming technology,analyze four optimal criteria of adaptive beamforming algorithm in this thesis.Then the universal software radio platform is introduced.Secondly,the classical beamforming algorithms such as least mean square(LMS),least square(RLS)and linear constrained minimum variance(LCMV)algorithm are studied theoretically.Aiming at the imbalance of convergence performance and error stability in classical algorithms,this thesis improves LMS algorithm with swarm intelligence algorithm.LMS algorithms have the advantages of global convergence.Swarm intelligence algorithm performs local optimization.Combining their advantages,improved algorithm can achieve efficient operation.The experimental results show that the anti-interference and convergence performance of the improved algorithm are obviously enhanced.Finally,USRP and software radio platform GNU Radio are used to model the wireless communication scene of high-speed train.The uniform linear array is installed at the base station side,and the classical algorithm and improved algorithm are programmed via GNU Radio platform to build an adaptive beamforming system.The result shows that the adaptive beamforming algorithm based on swarm intelligence algorithm has an obvious performance improvement,which is consistent with the simulation results.