Research On Access Control In Heterogeneous Cellular Networks

With the development of mobile Internet,the global mobile data traffic presents an explosive growth trend,and the performance requirement of wireless communication network is further improved so that the traditional isomorphic cellular network has been unable to meet the growing demand for communication.With more forms of communication nodes have been introduced into the network scenario,heterogeneous cellular network gradually formed,the application of this network form can effectively enhance the overall performance of the network at the system level,so it has become a hot topic in mobile communication research in recent years.Although the use of heterogeneous cellular network can effectively improve the network transmission capacity and the quality of user communication,it is also facing a series of problems and challenges,the most notable problem is the interference in the network,including the same-tier interference and the cross-tier interference,etc.In this paper,for the uplink and downlink of the heterogeneous cellular network scenario consisting of macro and micro base stations respectively,we propose a research method based on user access control,which takes the system capacity as an optimization goal.(1)In the downlink of heterogeneous cellular network,traditional user access algorithms are mostly proposed only based on the distance between the user and the base station,or the received signal strength of the user,which did not make a detailed analysis for the interference of the network.In this paper,we firstly propose a user access algorithm based on SINR(signal-to-interference-plus-noise ratio),to make the user access the base station which can make the user get greatest SINR.Then,we further do an allocation of frequency resources and power using the user clustering algorithm,so that all the users of network can be divided into multiple user clusters based on the interference level,and the subchannel allocation among the user cluster can effectively avoid the same frequency interference that caused by the users in the same cellbeing allocated to the same subchannel,and which can also further improve the system capacity.Finally,we proposed a power allocation algorithm to adjust the power of the base station on subchannels.(2)In the uplink,we propose a user access control method based on cell range expansion technology,designing a user access algorithm to dynamically adjust the bias of base station to optimize the user access issues,and to make the user access the best appropriate base station which can make the system average SINR optimal.Moreover,to a certain extent,this algorithm also can balance the load between base stations.As same as the downlink method we proposed,we also optimize the frequency allocation and the power allocation on the uplink.In the allocation of subchannel,we use the way of traversal optimization,assign every user one or more optimal subchannels to get the largest rates.In the power allocation,we use a power allocation algorithm to adjust the user equipment power on subchannels,through the repeated iteration and find the optimal result,we can obtain an approximate optimal system total capacity for uplink.Through the simulation analysis,the user access control methods for the uplink and the downlink which we proposed in this paper can both improve the system capacity.And the research in this paper can provide a reference for the future research of access control and the actual network deployment of heterogeneous cellular networks.