Research On Handover Mechanism Of Multicast Broadcast Single Frequency Network Based Trunking System User

The Third Generation Partnership Project(3GPP) introduced the Multicast Broadcast Fingle Frequency Network(MBSFN) transmission technology in Evolved Multimedia Broadcast Multicast Service(E-MBMS) in Long Term Evolution(LTE) network. A MBSFN based Trunking Communication System can take the advantages of the cellular network, like wide range of coverage and high penetration of user equipments, and can guarantee a required efficient usage of radio resources and steady high-speed service delivery.However, when refers to the continuity of E-MBMS services while moving, no special strategy is designed in 3GPP standard. Users moving between cells in a single frequency network can continue to receive the E-MBMS services from multicast channel. Whereas, it is necessary to handover to the target cell using unicst transmission carriers to continue receiving E-MBMS services when the user leaves the SFN. When a user hands over to the target cell, there may be other users needing to hand over to the same cell or beginning a new call in the target cell. Too many demands to access to the target cell in a short time may lead to a lackage of resources, which may cause handover call dropped or new call blocked. Moreover, even if the user hands over to the target cell successfully, the QoS requirement of the service also depends on the resource scheduling strategy in the target cell. Because of the delay-sensitive properties of the real-time multimedia multicast services in Trunking System, if the allocation strategy of the radio resource fails to take the delay-sensitive nature of the Trunking System services into account, it is possible to lead to a large latency when Trunking System users receiving multicast services and affect the user experience.In order to solve these problems, an admission control algorithm based on resource reservation of the target cell at the edge of the single frequency network for handover is designed. The target cell decides whether to be part of the SFN when the user trying to handover to the target cell, if it can reduce the resource occupancy of the target, the target cell joins in the SFN and provide multicast service for Trunking System users through multicast channel. Otherwise, a resource reservation algorithm based on service and call type hierarchical will be applied to reserve resources to the Trunking System services and handover calls in priority to guarantee handover success rate of the Trunking System users. The simulation for the designed algorithm proves that it does reduce the handover drop rate of Trunking System users.A Delay Sensitive Proportion Fair(DSPF) scheduling algorithm is designed by importing delay factor into Proportion Fair scheduling algorithm. A handover target cell resource scheduling strategy at the edge of SFN is also designed based on DSPF, which assigns a higher priority to make Trunking System users have a chance to dispatch latency and optimize QoS when the latency is too large for the Trunking System users receiving the delay sensitive real-time multimedia services. The simulation proves the algorithm does reduce the overall delay and the short-term delay of Trunking System users.