Millimeter Wave Beamforming In Communication And Disaster Detection For Hsr

The dedicated wireless communication system for train dispatching control and the broadband wireless communication system to access to the Internet for passengers on the train are two kinds of communication systems on HSR(High speed railway).GSM-R system is adopted for train dispatching control in most systems,and passengers on the train access to Internet with public mobile networks.However,the mobility performance in current systems cannot satisfy the information rate and quality requirements for passengers.Thus it is necessary to exploit new spectrum for HSR communication systems.The wireless communication system on HSR evolves to the next generation mobile communication system is inevitable,along with the massive update and replacement of current base station and other infrastructure.In addition,since HSR mostly travels through the mountainous area,the natural disasters such as landslide and debris flow threaten the safety of railway operation chronically.Therefore a disaster monitoring technology for HSR scenarios is needed.Millimeter wave has great potential in the next generation communication system because of its ability to achieve ultra-high-speed data rate,and it is also of great significance in the radar detection due to its high detection precision.The millimeter-wave communication and detection technology can be integrated into a base station,making the safety base station possess both high-speed wireless transmission capabilities and disaster monitoring functions.The radar and communication equipment share the site,the baseband as well as the back haul system,making the base station have advantages of low system cost,high detection efficiency and easy maintenance of equipment.Therefore,in this thesis,the research with the millimeter-wave characteristics and the millimeter-wave beamforming based on the C-RAN communication and detection integrated system has great theoretical and practical significance.In order to improve the performance of the communication and detection system in our thesis,the millimeter wave transmission characteristics and the beamforming as well as the scanning scheme are mainly researched.First,we introduce the communication and detection integrated system,and analyze the appropriate spectrum of the system.The relationship between the millimeter-wave communication coverage and the transmission power and the detection range are also analyzed.Due to the importance of beamforming in HSR communication,this thesis studies the opportunistic beamforming on HSR in detail.The theory of beamforming and the influence issues of beam width are analyzed.Besides,we research two kinds of opportunistic beamforming and analyze the influence of the beamforming performance brought by antenna number at base station and train as well as DOA estimation error.Moreover,the single and double flow beamforming switching assisted by location information is proposed in this thesis,and the proper switching position is analyzed according to the system capacity and the beam interference factor.Furthermore,in order to improve the disaster detection efficiency in this integrated system,the frequency division and multi-beam detection scheme and the adaptive beam scanning scheme are put forward based on the millimeter wave transmission characteristics and detection demands.Thus,different detection beamforming schemes are employed in different detection areas.By the analysis,we can see that the adaptive beamforming scheme can meet the detection demand in each area,and then can reduce the complexity of the system to some extent as well,which is an effective disaster detection beamforming scheme.