Handoff Technique For Multi-point To Multi-UE Coordinated Transmissions

Coordinated Multi-point technology as one of IMT-Advanced system’s keytechnologys, due to its effective improvement of cell-edge user’s performance andsystem throughput, more attention has been attracted in recent years. However, theintroduction of “cooperate”, resulting in a high complexity, a higher handoff delay anda larger signal overhead. Therefore, how to design efficient algorithms of cooperativehandoff is a key problem of mobility management. Most of the exsiting work aresupport the cooperation at one end, in order to meet the needs of next-generationwireless communication systems, there is the urgent need of handoff scheme which issupporting the cooperate at both ends.To solve this problem, this paper considered IMT-Advanced system as the studybackground. The existing work of cooperative handoff are summarized, further moretraditional handoff schemes and LTE system’s handoff scheme are analyzed. Thenbased on distributed BS network architecture, a handoff scheme for multi-point tomulti-user coordinated (MP2MUC) transmission is proposed. The proposed schemecombines the cooperative soft handoff with the cooperative hard handoff; introduce thetime-frequency synchronization and channel-energy maximization as cooperativehandoff criterion. It support the cooperation at both ends, but also compatible with thecooperation at one end, and even the traditional non-cooperative model.To verify the validity of the proposed handoff algorithm for MP2MUC systems, theprobability of successful handoff, the number of execution for handoff and the ratio ofpingpang handoff are presented. Simulation results demonstrate that the efficiency ofhandoff and the probability of successful handoff can be improved.