Research Of Resource Optimal Allocation In Coordinated Multipoint Transmission

With the fast development of mobile communication technology, people more and more rely on the convenient communication service, and with the fast development of data service and multimedia service, people have higher requirements on the data transmission speed of wireless communication system. As a result, International Telecommunication Union started the work plan of4G system-IMT-Advanced system. According to the objectives set by ITU, IMT-Advanced system must sustain the mobile application ranging from low speed to high speed and dependable seamless coverage, and meanwhile satisfy the dynamic data requirements of user and service in various environments, including100Mbps at high speed and1Gbps at low speed. Since IMT-Advanced system faces the challenges of data transmission speed, service application and network coverage, it not only calls for the evolution of present technology, but also needs to introduce new mobile communication technology.In order to further improve the system performance, IMT-Advanced introduces Coordinated Multipoint Transmission (CoMP). Based on MIMO-OFDM technology, CoMP introduces a collaboration mechanism between the BSs (base station), relays and RRUs (radio remote unit). Through the cooperation of multiple points, the original interference on cell-edge user is transformed into desirable signal, not only improving the performance of cell-edge user but not bringing much elevation of signal overhead and complexity. Since CoMP has changed the operating mode of traditional network, the problems of cluster partition and resource allocation in CoMP system emerge. Only when these problems properly solved can the advantages of cooperative transmission be fully exploited.As to the above problems in CoMP system, the paper proposed a distributed cluster combination method. Being different from the traditional cluster partition method, the novel method doesn’t need a network central entity. Every sector first calculates its cooperation gain with adjacent sector, and then the stable match theory is utilized to determine the best combination selection. The simulation results show that the proposed method achieves the optimal system performance at low cost and time delay. Regarding the resource allocation problem in CoMP, the paper proposed a novel resource allocation algorithm based on proportional fairness algorithm. First in the cluster, cell-edge user and centric user respectively estimate the transmission speed with CoMP mode and traditional mode and report the statistics to the central entity of the cluster. The central entity of the cluster calculates the priorities of Cell-edge UE and Cell-center UE on every resource block based on the statistics, and compares their priorities to determine whether to implement CoMP transmission or not. The simulation results show that the proposed algorithm realizes the flexible selection between CoMP transmission and single node transmission, not only improving the system performance but also effectively guaranteeing the equity between cell-edge user and centric user.In addition, a3G-LTE system-level simulation platform was built with modularization design and C++&matlab hybrid programming technology. With strong expandability, it not only supports the system-level simulation of3G-LTE system, but also sustains the simulation of coordinated multipoint transmission in SU-CoMP, MU-CoMP scenario, which indeed offers a complete simulation environment for3G-LTE and the following revolutionary technologies.