Performance Analysis And Optimization Of The Moving Relay Working In Hybrid-duplex Mode

With both the development of the wireless communication technology and the improvement of the automobile industry,more and more people are enjoying a convenient communication service when traveling;on a public transport.Due to the closed construction of the vehicles,the signal transmitted from a base station(BS)to a user equipment(UE)in the vehicles will go through a vehicular penetration loss(VPL).which results in a severe signal attenuation.Thus,the received signal of the vehicular UEs are too weak to guarantee the communication quality.In order to solve this problem caused by the VPL,moving relays(MRs)have been introduced in the smart city scenario,which are mounted on the top of the vehicles to realize the signal retransmission between a BS and a vehicular UE without a VPL while making;the wireless communication service better.However,it will lead to an increment of the transmission slots by using a relay,which is a waste of time slot resource.Therefore,it is important to design an applicable scheme to improve the spectral efficiency of the relay systems.Based on the MR network,this thesis considered applying the hybrid-duplex technology to improve the spectral efficiency of the whole system.On the other hand,in consideration of the influence of MRs on the UEs outside the vehicles,the study on the performance of UEs which are by the roadsides and using the hybrid-duplex mode in a MR network is still deserved.The main resear-ches of this paper are as follows:1.Combining MR technology and hybrid-duplex technology together,the mobility model of a MR is proposed at first.Based on the mobility model,the hybrid-duplex work mode of the MRs is shown.Then,the coverage probability of any UE inside the vehicles working in the hybrid-duplex work mode is obtained by using the random geometry theory.Finally,the performance comparison between the proposed hybrid-duplex scheme and the traditional half/full duplex are shown by simulation results.From the simulation results,given a constant distance threshold of the mode switch,the coverage probability of a vehicular UE whose connected MR is using the hybrid-duplex mode is a little lower than that of a vehicular UE whose connected MR is using the traditional half duplex mode.Correspondingly,the spectral efficiency of a vehicular UE whose connected MR is using the hybrid-duplex mode is gsreatly higher than that of a vehicular UE whose connected MR is using the traditional half duplex mode,which is beneficial to improve the overall performance of a UE inside the vehicle.2.In the smart city scenario with MRs deployed,a hybrid-duplex scheme for the UEs outside the vehicles and by the roadside is proposed.Based on the scheme,the performance of any UE is analyzed mathematically by using the random geometry theory.Moving relay can offload data traffic from BSs and reduce the heavy burdens of BSs.On the other hand,when the distance between the UE and its connected BS is short,the spectral efficiency of the UE can be enhanced by using the full-duplex mode compared with the half-duplex mode.At last,simulation results show that the proposed hybrid-duplex scheme can guarantee the UEs' service quality and lead to a 20%spectral efficiency improvement.In conclusion,this paper has conducted a research on the performance analysis of UEs both inside a vehicle and outside a vehicle in a hybrid duplex MR network.According to the simulation results,the proposed schemes can bring performance gains for UEs both inside a vehicle and outside a vehicle.Thus,the above researches are meaningful to the development of moving relay and hybrid duplex technology in the future.