| The real-time and accurate location information for the User Equipment(UE)is required in the key technologies for the 5th Generation(5G)mobile communication system,including Millimeter wave communication,massive Multiple-Input Multiple-Output(m MIMO)system and Ultra Dense Network(UDN).Such a requirement can be satisfied when the location information is obtained based on the measurement of uplink reference signals.Therefore,uplink reference signals can be widely utilized in 5G mobile communication system,especially in mobility management.The application of uplink reference signals is studied.Firstly,the potential application of uplink reference signals in 5G system is described.In addition,the existing research on uplink measurement issues,mobility management schemes and location management schemes for UE are summarized.Furthermore,the network architecture in 5G system and the downlink measurement based mobility management schemes are introduced.Secondly,the deployment scenarios of cellular mobile communication system are described,and the concept of uplink reference signal based mobility management is introduced.Additionally,the mathematical model for the deployment scenarios of cellular mobile communication system is developed.Moreover,an uplink reference signal for mobility management is designed,and the basic scheme of uplink based mobility management is studied.Thirdly,the enhanced scheme of uplink reference signal based mobility management in Radio Resource Control(RRC)inactive state is studied.Based on the Radio access network based Notification Area(RNA),an enhanced scheme of uplink reference signal based mobility management is proposed,and its performance is analyzed by simulation in two deployment scenarios.As shown in the simulation results,the signaling overhead among the camped cell,neighbor cells and the last serving cell of UE of the enhanced scheme is lower than that of the basic scheme,while the paging miss rate and UE power consumption of both schemes are similar.Finally,the enhanced scheme of uplink reference signal based mobility management in RRC connected state is studied.By applying the uplink reference signal to the pre-handover scheme,an uplink reference signal based pre-handover scheme is proposed.Moreover,its performance is analyzed by simulation.As shown in the simulation results,the signaling overhead of the uplink reference signal based pre-handover scheme is lower than that of the downlink measurement based pre-handover scheme.On the other hand,the handover failure rate of the uplink reference signal based pre-handover scheme is lower than that of the basic scheme of uplink reference signal based mobility management. |
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