Research On Beam Management Of 5G Multi Antenna System In High Frequency And High Speed Scenario

In order to meet the increasing number of user equipment and the increasing demand of data transmission rate,the fifth generation(5G)mobile communication introduced millimeter Wave technology which is with rich frequency band resources,large-scale multiple input multiple output(massive MIMO)technology,and carrier aggregation technology which can effectively improve the data transmission rate as important means of network capacity and performance improvement.Among them,different from the low frequency which is limited by spectrum resources and mostly involve interference protection for other systems,millimeter Wave is located in high frequency and has rich spectrum resource,it is crucial to meet the demand for better,faster enhanced mobile broadband of 5G.However,millimeter wave has high path loss and fast signal attenuation,thus Massive MIMO technology which can generate beams with high gain is widely used in the millimeter wave communication system.Massive MIMO technology makes up for the path loss of high frequency by generating a large number of antennas,which means that there will be a large number of beam pairs in the future 5G high-frequency communication systems.Therefore,it will be of great research significance to do the beam management well in the 5G high-frequency communication scenario.At the same time,according to the White paper on 5G vision and requirement released by working group on propulsion of IMT-2020(5G),the highest speed supported by 5G can reach 500km/h,which means 5G's ability to support high-speed mobile scenarios will be further enhanced.However,due to the extremely narrow beam width of millimeter-wave Massive MIMO system,the problems and challenges related to beam management technology in high-speed scenario still need to be solved urgently.In addition,to better meet the requirements of high data rate for transmission in 5G,carrier aggregation technology was further enhanced in 5G NR,In the future,it is expected to further improve the data transmission rate by applying high frequency band to the auxiliary carrier,therefore,it is to of great significance study how to do the management of high frequency beam well in the carrier aggregation scenario.Based on the above background,this thesis carries out relevant research on 5G multi-antenna beam management technology under high frequency and high speed scenarios.The main work and innovations are as follows:Aiming at the beam handover issue in millimeter wave mobilecommunication system in high-speed rail scenario,this thesis takes the high-speed railway scenario as an example,constructs the user's mobile model and millimeter wave communication system in high-speed rail scenario,and then introduces the beam handover scheme based on the mechanism of multiple beam cooperation(MBC)and seamless inter beam handover(SIBH)for 5G millimeter wave communication system.After that,aiming at the balance optimization between the handover failure probability of beam handover and the occupancy rate of beam resources,this thesis proposes a joint optimized dynamic inter beam handover(JOD-IBH)algorithm.The weight function W is introduced to assist the user to dynamically adjust the number of beams in the multi-beam cooperative group,so as to meet the requirements of beam handover while saving resources as much as possible.System level simulation shows that compared with the traditional beam handover scheme,JOD-IBH scheme improves the success rate of beam handover greatly,and it has obvious advantages in the balance between beam handover performance and resource consumption.Aiming at the problem about low success rate of real-time beam handover mechanism in 5G high-speed mobile scenarios,this thesis introduces the Gray Model(GM)into the mobile communication system,and proposes a Gray Model based Beam Handover Prediction algorithm(GIBHP).In this algorithm,the quality of the received beam signal is modeled by Fine grained GM during the beam handover prediction window,and then the time of beam handover is predicted based on user's moving model,finally the decision of beam handover will be made based on the error probability distribution formula.The simulation results show that the GIBHP algorithm has high prediction accuracy in high-speed scenario,and compared with the traditional beam handover scheme,it improves the success rate of beam handover mechanism to some extent.Aiming at the issues about that beam failure recovery(BFR)mechanism of 5G NR doesn't support secondary cell's uplink feedback in carrier aggregation scenario and has a significant PRACH resource overhead,in this thesis,firstly,the connection model between the user and multiple cells in the carrier aggregation(CA)scenario is constructed by means of beam-forming technology,and then a group based beam failure recovery mechanism is proposed.Furthermore,the identification design of beam failure recovery request(BFRQ)is optimized,including the identification of beam failure cell and the identification of candidate beam.Among them,for the identification of beam failure cell in BFRQ,three failure cell indication schemes are proposed:global method,hierarchical grouping method and invisible mapping grouping method;for the identification of candidate beam indication in BFRQ,an improved candidate beam indication scheme based on PRACH and an overhead saving candidate beam indication scheme based on PUCCH are proposed.Simulation results show that the proposed scheme improves the ability of BFR to support CA scenarios,and effectively reduces the cost of PRACH resources in the process of beam failure recovery.