A Study On Spectrum Resource Allocation Algorithms For Small Cell Networks

Small cell is formed by the base station with lower transmission power and smaller coverage,is an important part of future mobile communication system.The introduction of small cell in traditional mobile cellular network can optimize network coverage,greatly improve the system capacity,and provide better communication services for users.However,the introduction of small cell will inevitably bring some new problems,especially the problem of communication interference between users,posing new challenges to the design of mobile cellular network.Related research has shown that efficient and reasonable spectrum resource allocation is one of the effective means to solve the problem of communication interference.This thesis studies the small cell spectrum resource allocation in mobile cellular networks,proposes three small cell spectrum resource allocation algorithms,to reduce the communication interference in the system and improve the system performance of the network.Firstly,this thesis proposes a clustering-based spectrum resource allocation(CSRA)algorithm for a system scenario with a single macro cell and multiple small cells with the objective to minimize both intra-tier and inter-tier interferences in the system and maximize the system capacity.It consists of three phases,namely small cell clustering,determination of small cell priority and spectrum resource allocation.In small cell clustering,according to clustering principles,building a series of small cell clusters,and an upper limit for the cluster size is set in for clustering to avoid the formation of a too large cluster,which otherwise would consume a large number of physical resource blocks(PRBs)and thus affect the system capacity;In determination of small cell priority,according to corresponding principle,determining the priority of small cells in the system;In spectrum resource allocation,according to allocation principles,perform spectrum resource allocation for all users in the system.To increase spectrum utilization,all PRBs are allowed to be used by all users in the system.Simulation results show that the proposed CSRA algorithm can significantly increase the system capacity as compared with an existing CDRA algorithm.Secondly,this thesis proposes a two-tier clustering based downlink resource allocation(TCRA)algorithm for a system scenario with a single macro cell and multiple small cells with the objective to minimize intra-tier interference in the system and maximize the system capacity.It consists of three phases,namely small cell clustering,user clustering and spectrum resource allocation.In small cell clustering,all small cells in the system are partitioned into a set of small cell clusters based on graph coloring,and those small cells with the same color are partitioned into the same cluster;In user clustering,all SUEs in each smallcell cluster are further partitioned into a set of user clusters based on the interference graph of each small cell cluster;In spectrum resource allocation,PRB allocation is performed based on the user clusters obtained.Simulation results show that the proposed TCRA algorithm can significantly improve the system performance in terms of the total system capacity as compared with an existing FCRA algorithm.Finally,based on the two-tier clustering based downlink resource allocation(TCRA)algorithm,the inter-tier interference is further considered while the intra-tier interference is reduced,this thesis proposes an advanced two-tier clustering based downlink resource allocation(ATCRA)algorithm for a system scenario with a single macro cell and multiple small cells with the objective to maximize the system capacity.It consists of three phases,namely small cell clustering,user clustering and spectrum resource allocation.In small cell clustering,all small cells in the system are partitioned into a set of small cell clusters based on graph coloring,and those small cells with the same color are partitioned into the same cluster;In user clustering,according to the resource allocation strategy adopted by the system,the corresponding user clusters are established.If adopting orthogonal assignment,the user clusters of macro and small cell are established respectively.If adopting co-channel assignment,a series of user clusters(including macro user equipment and small cell user equipment)are established;In spectrum resource allocation,PRB allocation is performed based on the user clusters obtained.Simulation results show that the proposed ATCRA algorithm can significantly improve the system performance in terms of the total system capacity as compared with CSRA algorithm.