Research On Sensing Performance Enhancement Method Of Communication And Sensing System

With the rapid development of information technology,emerging technologies applied in the field of transportation emerge in an endless stream.Joint Communication and Sensing(JCS)technology integrates communication and sensing functions into a hardware platform,and has become a mainstream technology to improve vehicle sensing and communication performance with its high data transmission rate and high spectrum utilization.Aiming at the problem of sensing performance degradation in the application of communication and sensing integration technology in the field of transportation,this thesis proposes to use the Intelligent Reflecting Surface(IRS)and Carrier Aggregation(CA)technology.The traditional Orthogonal Frequency Division Multiplexing(OFDM)waveform is improved to improve the system sensing performance.The main contents are as follows:First of all,the characteristics and application fields of JCS technology are investigated,and the possibility of using OFDM waveforms in the JCS system to be applied in the transportation field is clarified.Next,the two key technologies involved in this thesis,IRS and CA technology,are described in detail,the JCS system model based on these two technologies is analyzed,and the feasibility of improving perception performance is illustrated.In the JCS system,due to the hardware limitation of the transmitted signal,the transmission power is insufficient,the signal-to-noise ratio of the echo signal is low,and the final target detection fails.The IRS-assisted JCS system design scheme is proposed,which mainly enhances the sensing performance of the JCS system from three aspects.First,the IRS can increase the echo signal power by changing the reflection coefficient.Second,through the Constant False Alarm Rate(CFAR)detection algorithm,it is proved that the IRS-assisted JCS system has a great detection probability.Thirdly,by analyzing the Cramer-Rao Lower Bound(CRLB)of the target’s velocity estimation and distance estimation,it is proved that this scheme has lower velocity and distance estimation errors.Aiming at the problem that multiple vehicles perceive and communicate at the same time in the traffic field,resulting in the aliasing of echo signals and the inability to complete accurate target detection,a CA-based JCS signal design scheme is proposed,which uses comb pilot and block pilot aggregation.The method makes up for the ranging and speed measurement errors caused by the use of a single pilot structure.The simulation results show that,compared with the comb pilot and block pilot structures before CA,the scheme of aggregation of comb pilots and block pilots has the best speed estimation and distance estimation performance.