Research On Resource Allocation Of Multicast Service In EMBMS

eMBMS(evolved Multimedia Broadcast Multicast Service)use the same wireless communication resources to send the same service data in the form of point to multipoint,it can improve the efficient utilization of the system resources.However,due to radio characteristics of wireless signal transmission,and the dynamics of the wireless communication environment,the link states of each multicast users are different.Traditional multicast transmission rate depends on the user with the least channel gain,which restricts the improvement of the system capacity and can't guarantee the fairness among users.So studying reasonable strategy of resource allocation has been a hot topic in the field of multicast,considering both the different channel qualities and various demands of users.The problems of resource allocation are usually be solved through mathematical modeling,in the form of optimization model with one or several constraints.This article fisrt sorts the research actuality into 4 types,provides their corresponding models,and then gets down to research based on aforementioned survey.There are several multicast groups in eMBMS,and each of them requests different services with different transmission rates.According to current multicast resource allocation methods,the BS will allocate the majority resources to the group with more users,and it's difficult for the groups with less users to get their demanding resources.In this article,we do research on multicast resource allocation with the constraint of rate ratio,and the simulation results prove that our method can meet the requirements of fairness among multicast groups.In addition,we simulate the relation between the rate ratio and throughput loss.Considering different channel conditions of users in a single multicast group,to provide users differentiated services,this paper continues to study the layered transmission resource allocation algorithm with QoS(Quality of Service)guarantee.Service data is modulated and coded into base layer data stream and enhancement data stream,First subcarriers are allocated by conservation allocation strategy,to meet the basic needs of all users for multicast service,and then remaining subcarriers will be allocated to enhancement layer multicast data,to provide userswith good channel quality of higher business experience,finally through power adjustment to further increase the system throughput.But when SNR is low,the transmission power can not make multicast service successfully received by users.To settle this problem,we propose a transmission mechanism,combining layered multicast transmission and cooperation communication.Finally,we realize the resource allocation method of layered multicast transmission and the proposed mechanism by MATLAB simulation.