Design And Performance Analysis Of New Sensing Reference Signals For 5G-A And 6G Mobile Communication Systems

The future 5th generation advanced(5G-A)and 6th generation(6G)will support machine-type communications,immersive services,and so forth,which have given rise to the demand for powerful communication and sensing capabilities.With the rapid development of the wireless communication industry,the frequency band and antenna of the wireless communication system are becoming similar to the radar system.In order to reduce the hardware cost and save the spectrum,the sensing and communication functions will be mutually beneficial in the same system,which makes the joint sensing and communication(JSC)technology feasible and promising.Waveform design is the fundamental to the JSC technology.At present,the communication centric JSC designs have received extensive attention.The orthogonal frequency division multiplexing(OFDM)signal has been widely applied in the design of communication centric JSC waveforms due to its high frequency spectral efficiency,low complexity and robustness against multipath fading.In addition,the pilot or reference signals in wireless communications usually have good passive detection performance,strong anti-noise capability and good auto-correlation characteristics,hence they bear the potential for applying in radar sensing.Starting with the design of new sensing reference signals for 5G-A and 6G,this dissertation first proposes a sensing reference signal approach scheme based on 5G positioning reference signal(PRS),which can be quickly compatible with the 5G systems.The signal model and radar signal processing algorithm based on 5G PRS are derived,and the range and velocity estimation performance is analyzed.On this basis,a method that improves the accuracy of velocity estimation by using multiple frames is proposed.In addition,the Crámer-Rao lower bound(CRLB)of the range and velocity estimation for PRS based radar sensing is derived.The simulation results show that PRS has the feasibility and superiority over other pilot signals in radar sensing.In addition,a JSC signal design method with flexible structure is proposed for the differentiated demand of communication and sensing requirements of diverse scenarios.Then,to satisfy the high-precision sensing requirements inspired by 6G emerging services,this dissertation exploits the advantages of large time-bandwidth product of linear frequency modulation(LFM)and high spectral efficiency of OFDM,and introduces the signal model and system implementation based on OFDM-LFM JSC signal.Then,a JSC waveform design combining triangular frequency modulation(TFM)and OFDM is proposed,and the delay-Doppler decoupling radar signal processing scheme is proposed to achieve high resolution range sensing.The simulation results show that the proposed scheme can significantly improve the accuracy of range and velocity estimation compared with the OFDM based and the OFDM-LFM based ISAC scheme.Finally,this dissertation designs a new sensing reference signal based on the OFDMTFM waveform system,which can be used in the scenarios with high sensing performance requirements.