Research On EMBMS Layered Multicast Resource Allocation Scheme

In recent years,the explosive growth of mobile traffic,especially video traffic,has posed a severe challenge to the situation of limited bandwidth resources.Enhanced Multimedia Broadcast Multicast Services(eMBMS)transmits video data to users of the same multicast group in the manner of point-to-multipoint,which makes up for the shortcomings of the unicast mode and effectively improves the resource utilization.However,the transmission rate of a multicast group is often limited by the channel quality of the edge users.The groups with poor channel quality are often difficult to obtain enough resources to meet the basic demands of users in the group,which results in poor fairness.At the same time,for the intragroup allocation of each group,if the transmission is performed at the lowest rate,it will cause a lot of waste of resources and reduce the overall system throughput.Meanwhile,it cannot provide differentiated services for users in the group.Therefore,how to solve the problem of diversity of user channel quality and take a balance between system throughput and user fairness,is one of the current research priorities of eMBMS resource allocation.This paper studies the eMBMS multicast resource allocation mechanism,and focuses on the advantages and disadvantages of the resource allocation strategy within the multicast groups.Modeling and analysis are separately conducted for different multicast group scenarios,and an improved resource allocation scheme is proposed.During the inner-group resource allocation stage,this paper proposes a resource allocation scheme based on layered multicast.For the base layer data,the user with the worst channel quality in the group is used as a reference,and the extreme case where the channel conditions between users are too different is considered.In order to solve the problem of complex calculation of resource allocation in the enhancement layer,this paper introduces an improved gravitational search algorithm.The innovation is to effectively reduce the computational complexity of solving resource allocation schemes.It is ensured that the algorithm can more accurately find the optimal resource allocation scheme,thereby improving resource utilization efficiency through the manners of optimizing the population’s initialization mechanism and convergence judgment mechanism.The simulation results prove the effectiveness of the improved gravitational search algorithm proposed in this paper in the enhancement layer assignment problem.As for resource allocation between groups,only the overall channel quality of the users in the group is considered,which results in the deficiency of the fairness of resource allocation.This paper proposes a resource allocation scheme based on the priority of multicast groups.The innovation is to give priority to ensuring the transmission of basic layer data of all multicast groups.Then,the remaining resources are used to satisfy the transmission of each group of enhancement layer data.The multicast groups with better average channel quality,more users,and less consumed resources are given the priority.The simulation results prove that the solution proposed in this paper can meet the basic service experience of multicast users.The base station can fully consider the data transmission of each group when allocating resources,which avoids the situation that some multicast groups cannot allocate resources for a long time because of poor channel quality,and improves the fairness of resource allocation between groups.Meanwhile,the allocation strategy within the group also guarantees a certain system throughput.