Research On Cooperative Relay Technology For Vehicular Communication Network

As one of the key technologies to form the information backbone of intelligent transportation system,vehicle-to-everything(V2X)communication technology can support the allround connection scenario between “Pedestrian-vehicle-road-cloud”.In order to meet the requirements of expanding the signal coverage of V2 X and improving the quality of communication services in the 5G Ultra-Reliable and Low Latency Communications(URLLC)scenario,Vehicleto-Vehicle(V2V)cooperative relay communication technology has been included in the standardization work of the 3rd Generation Partnership Project(3GPP).Cooperative relay communication technology can effectively improve the reliability,spectrum efficiency and signal coverage of V2V communication in complex and dynamic vehicle networking scenarios by sharing the antenna resources of cooperative relay nodes,so it has important research significance and application prospects.However,due to the high dynamics of vehicle movement and the time-varying characteristics of non-stationary channels caused by multipath fading,it is easy to cause transmission reliability degradation,spectral efficiency deterioration,link interruption and other problems in the actual networking of vehicles.Recent studies show that although the fusion of relay network and multi-input multi-output technology can enhance the spectral efficiency,inter-relay interference is not conducive to reliable communication.Therefore,it is necessary to study the cooperative transmission technology of highly reliable relay network in V2V communication.In order to improve the reliability and spectral efficiency of V2V communication in nonstationary dynamic channels,based on the cooperative transmission theory of wireless relay network,the principle of generalized spatial modulation,and the principle of signal detection,this paper analyzes V2V communication in non-stationary dynamic channels.How to enhance the effective relay selection,suppress the relay transmission interference,control the relay transmission error propagation,the signal detection quality of imperfect relay and other problems are carried out indepth research.A flexible,efficient and reliable double hop relay network cooperative transmission protocol and an efficient relay joint signal detection algorithm are proposed.The transmission structure of the relay network,the theoretical model of signal transmission,the system spectrum efficiency,bit error rate and diversity gain are modeled and analyzed,and the optimization method of the system performance parameters is obtained.Finally,the optimization design rules of system reliability and spectrum efficiency are given through Matlab simulation optimization design and comparison experiment.The innovative contents and contributions are as follows:(1)In view of the influence of non-stationary channel characteristics of V2V communication on the reliability and spectral efficiency of cooperative communication,Cooperative Butson Hadamard matrix-aided generalized Space Shift Keying relay network cooperation transmission structure and protocol are proposed,including broadcast,relay double hop relay network cooperation signal processing.In the broadcast process,a cyclic redundancy error check mechanism is adopted to reduce the transmission of relay demodulation errors.In the relay collaboration process,a joint activation relay signal transmission vector is synthesized from the activation relay combination selection vector and symbol selection vector according to the BHSSK principle,and then forwarded to the destination node.The transmission vector constructed by Butson Hadamard matrix has orthogonality and expansibility,which effectively improves the communication quality of activated relay collaboration.(2)Further,based on the Markov birth-and-death model of dynamic V2V channels,the signal transmission theoretical model of CBHSSK relay network collaboration system in nonstationary channels is constructed.Under the ideal receiving condition,spectral efficiency,theoretical upper bound of bit error rate and system diversity gain are derived theoretically.Theoretical analysis shows that the frequency spectrum efficiency and reliability of the system can be improved by optimizing the activation relay ratio and the number of receiving antennas on the destination node of the relay network.(3)Aiming at the joint signal Detection quality of the destination receiver of the relay network under imperfect relay conditions such as relay interruption,a joint detection algorithm based on Outage Probability Order Detection(OPOD)is proposed.By sorting the interrupt probability distribution of the relay,the detection signal search space is reconstructed to improve the joint signal detection performance,so that the CBHSSK system can still maintain the reliable receiving quality of low bit error rate under the condition of poor interrupt conditions.The CBHSSK system can maintain the reliable receiving quality with low bit error rate under the condition of poor interrupt conditions.Finally,a V2V relay cooperative network communication simulation experiment system is built based on MATLAB,and Monte Carlo method is used to carry out simulation design and comparison experiments.The results show that the spectral efficiency of CBHSSK is improved by22 bit/s/Hz,18 bit/s/Hz and 5 bit/s/Hz,respectively,compared with the existing CSSK,DSM or DGSM systems.In addition,CBHSSK has a lower bit error rate than DGSM even under imperfect relay conditions with the same scale and interrupt probability.CBHSSK can provide highly reliable,efficient and flexible V2V communication,and has a good application prospect.