Research On Novel High-reliable Index Modulation In Vehicular Communication Network

As a key technology to promote the development of modern intelligent transportation system,the vehicular communication network(VCN)is expected to shape and completely change the future transportation mode,and gradually becomes the research direction that the country attaches great importance to.Based on the inter-vehicle network,intra-vehicle network,and vehicle ad-hoc network,VCN making use of the wireless communication technologies,conducts wireless communication and information exchange between the vehicles to everything(V2X),which is an integrated network to realize intelligent transportation,information service,and vehicle intelligent control.With the development of VCN applications from basic applications such as road safety,traffic efficiency,and information services to enhanced applications such as intelligent transportation and self-driving,the subcarrier frequency will evolve from sub-6GHz to a higher band or even millimeter wave(mm Wave)band.Due to the highly complex mobile environment and the highly dynamic network topology,the existing wireless communication technology can not effectively meet the ultra-reliability requirements for the mentioned VCN applications.As a new modulation technology,index modulation(IM)maps part of the information bits to the modulation domain for symbol information transmission.The other part is mapped to some resources(such as antenna/subcarrier/beamspace)using the active state of the resource for index information transmission.Compared with the traditional multi-antenna technology,the index information bit transmitted by IM does not need to consume additional transmission power,which makes IM more energy efficient.Secondly,because only activating part of the resources,the transmitted signal is sparse,which will reduce the adjacent channel interference and make IM have strong anti-jamming ability.Based on these advantages,IM technology has a good application prospect in the next generation of VCN.To this end,this thesis has carried out the research on novel ultra-reliable IM technologies suitable for high-speed mobile scenarios to better support future diversified VCN applications.The major efforts can be summarized as:1.Aiming at the sub-6GHz high-speed mobile scenarios,the non-coherent spacefrequency modulation technique with low-complexity and high-reliability is proposed to avoid the performance loss caused by inaccurate channel state information(CSI)estimation.1)The phase shift keying(PSK)-based differential spatial frequency modulation(DSFM)technology is proposed.At the transmitter(Tx),the Kronecker product is used to fuse the differential-coded space-time information matrix and time-frequency information matrix,and differential detection is performed at the receiver(Rx)to avoid CSI.2)The angle rotate quadrature amplitude modulation(ARQAM)scheme is proposed for DSFM.At the Tx,the transmitted ARQAM constellation is transmitted by layered differential coding through the compound phase shift method,where each layer is constant modulation.Simulation results show that,compared with the amplitude phase shift keying,star-QAM non-constant modulation schemes,the DSFM system with ARQAM shows better bit error rate(BER)performance under the high-order constellation modulation condition.2.Aiming at the mm Wave high-speed mobile scenarios,two wideband beam index modulation techniques with high energy efficiency(EE)and ultra-reliability are proposed,which solves the problem of subcarrier interference caused by high Doppler shift.1)Wideband generalized beamspace modulation(wGBM)is proposed for the case that the number of radio frequency(RF)chains at the Tx is less than that at the Rx.By applying index mapping across the entire orthogonal frequency division multiplexing(OFDM)symbol,the multiplexing gain of the wGBM system is not limited by the number of RF chains at the transceiver,and thus further improves the spectrum efficiency and EE.Then an overall wGBM transceiver design has been provided and optimized.In addition,a Doppler frequency shift compensator is carefully designed to enhance the robustness of wGBM against Doppler.2)Wideband precoded beamspace modulation(wPBM)is proposed for the case that the number of RF chains at the Tx is greater or equal to that at the Rx.By applying IM to every single subcarrier,the hybrid mm Wave transceiver design of wPBM is designed and optimized.A geometric mean decomposition algorithm is designed at the Tx to improve the diversity gain;An effective Doppler frequency shift compensator is introduced to assist index modulation,such that the originally complicated joint-subcarrier-based maximum likelihood(ML)detection degenerates into the simple subcarrier-based ML detection,which effectively simplifies the Rx structure.Simulation results show that both wGBM and wPBM are superior to existing comparison schemes,and have strong Doppler resistance.3.Aiming at the centralized network application in mm Wave high-speed mobile scenarios,two multi-user(MU)wideband beam index modulation technology with high energy efficiency and ultra-reliability are proposed.1)Extend wGBM to the MU uplink access scenario.The user end(UE)improves EE based on a small number of RF chains.The joint optimization of multi-subcarriers and MUs is designed in the analog domain,and a low complexity linear minimum mean square error MU detection scheme is proposed at the base station(BS).2)Extend wPBM to downlink MU transmission scenarios.A hybrid block diagonalization scheme is designed at the BS to eliminate multi-user interference and further reduce the complexity of UE detection.Simulation results show that the BER performance advantages and anti-Doppler shift ability of wGBM and wPBM in the VCN mm Wave channels still exist in MU scenarios.4.Aiming at the ad-hoc application in mm Wave high-speed mobile scenarios,the ultra-reliability integrated sensing and communications(ISAC)IM technique is proposed.First,ISAC is introduced to vehicle-to-vehicle(V2V)networks,and formulates two types of problems by jointly optimizing system total transmission power and link selection to augment the end-to-end information delivery.Secondly,OFDM with IM(OFDM-IM)technology is introduced to ISAC-V2V to further improve the reliability of the multi-hop V2V communication links.Simulation results show that ISAC can improve the V2V multi-hop network performance from three dimensions: link selection,positioning,and information fusion.Compared with the non-sensing aided communication V2V system,ISAC-V2V significantly reduces the system total transmission power and the outage probability.In addition,the ISAC OFDM-IM outperforms the ISAC OFDM system in terms of BER performance.