| With the construction and improvement of urban communication and transportation networks,more and more radar application scenarios have emerged in wireless communication application scenarios.For example,in the fifth generation mobile communication technology(5G),the Internet of Vehicles(IoV)technology needs to provide both localization services and information-sharing services for vehicles.Therefore,integrated sensing and communication(ISAC),which combines wireless communication with radar sensing,has become an important technology in IoV applications.However,previous low-frequency sub-6 GHz wireless systems cannot meet the requirements of IoV for high-speed communication and high-precision sensing.Compared to low-frequency sub-6 GHz communication systems,millimeter wave(mm Wave)communication systems operating at higher frequencies have greater available bandwidth,providing users with higher-rate communication services.On the other hand,the large bandwidth of millimeter waves makes the duration of symbols shorter.This provides higher ranging accuracy for radar sensing.At the same time,mm Wave radar can also achieve higher angle sensing accuracy with the same antenna aperture area.Therefore,how to apply mm Wave ISAC system to IoV has become a problem of concern.This paper will study the relevant issues encountered by mm Wave ISAC systems in IoV in urban traffic scenarios:Firstly,for a common straight-lane scenario,to meet the needs of vehicle localization and information sharing,this paper investigates an ISAC scheme implemented by vehicles.The communication-centric scheme uses a hybrid analog and digital(HAD)architecture.In this scheme,vehicles equipped with the HAD mm Wave ISAC system will respectively perform forward longrange and panoramic close-range sensing to obtain information about their own surroundings,and actively establish communication connections with forward targets to exchange relevant vehicle parameters.In order to enable vehicles to simultaneously perform forward sensing and communication,this paper uses multi-beam technology.Compared to the traditional sensing-firstcommunication-later scheme,the considered ISAC scheme can achieve higher communication throughput while maintaining acceptable radar performance.Secondly,this paper expands the scenario to crossroads.In this scenario,the base station(BS)locates vehicles at crossroads and provides communication services.Due to the poor penetration of mm Waves,signals are easily blocked,and the coverage of the system is limited.Therefore,this paper introduces a reconfigurable intelligent surface(RIS)help system to expand coverage at a lower cost.In the considered system,BS generates two signals,which are used to directly search for targets and indirectly search for targets through RIS.At the same time,using a time of arrival(TOA)ranging algorithm is difficult to avoid the impact of BS clock synchronization errors.Therefore,in this article,the system uses the time difference of arrival(TDOA)to calculate the target distance to avoid the impact of clock synchronization errors on the calculation results.In order to reduce the time spent on target search,this paper also uses a Kalman filter(KF)algorithm to track the target state.This paper verifies the feasibility of the above schemes through simulation experiments,and analyzes the numerical results. |
