Study Of New Cooperative Multicast Technology

With the rapid development of mobile Internet,service of mobile communication has shown explosive growth,which puts forward higher requirements for high-speed and high-quality transmission technology.Multimedia Broadcasting Multicast Technology(MBMS)which proposed in Long Term Evolution(LTE)can effectively utilize the network resources of mobile communications to achieve efficient point-to-multipoint transmission.The MBMS needs to divide users into multicast groups in cellular cells,and the users in multicast groups can receive data from the base station uniformly to realize resource sharing.Although MBMS consumes less system resources,it also faces a balance between user fairness and system throughput.First of all,the basic theory of LTE resource scheduling and MBMS is introduced.Then several classical multicast scheduling algorithms are analyzed,and some problems in users' fairness or system throughput are pointed out.To solve this problem,a new two-stage cooperative multicast scheme,NTSCM,is proposed.The scheme firstly keeps the base station working continuously in two stages of transmission,and sends new multicast data in each stage.Then in cooperative transmission,two types of relays are used to complete data forwarding alternately.NTSCM scheme greatly improves the efficiency of base station and the utilization rate of system resources,strengthens the role of relay in two-stage cooperative transmission.In addition,the scheme can significantly improve the edge throughput and the overall system throughput.In order to further improve the quality of data reception of mobile users and eliminate interference between them,and solve the problems caused by channel quality differences,this paper introduces NOMA technology,and proposes an improved NOMA-based cooperative multicast scheme,namely INCM scheme.Firstly,the scheme uses the characteristics of NOMA to distinguish the users with different channel quality from the power domain,and then uses SIC to effectively remove the interference between the users which act as mobile relays in the second phase of cooperative transmission.The INCM scheme not only achieves the continuous and efficient work of the base station,but also achieves a great increase in the throughput of users,effectively improves the quality of data reception of users with poor channel link quality and the overall performance of the system.In order to evaluate the performance of the proposed schemes,the cooperative multicast schemes are analyzed from the aspects of user outage probability,throughput gain and user fairness.The traditional multicast scheme and the existing cooperative multicast scheme are compared,and the results are obtained through LTE simulation platform.The simulation results show that the NTSCM scheme achieves improvements in throughput and the efficiency of resource utilization,while the INCM scheme can greatly improve the situation of user's signal reception,and has the advantage of overall performance while providing high quality of service for the edge users of the cell.