Performance Analysis And Topology Optimization Of A3 Handover Algorithm Based On LTE-X2 Interface

In view of the existing problems in LTE/LTE-A network that hot areas are lack of communication coverage abilities and throughputs,the feasible solution is to increase the deployment of small base stations.But the deployment of a large number of small base stations will make the network handover times increase significantly and than leading to network performance declines in throughputs,delay and jitter.This situation is also the problem that the future 5G network will face.So how to set the topologies and maximize the use of the base stations' coverage capacities and then reducing the network handover times is necessary.Previous researchers' studies on the handover performances were mainly focused on the reduction of handover times,reducing the ping-pong effect and enhancing the successful handover rate of network.They improved the handover performances of network by adjusting the decision factors,adding intelligent handover algorithm,adjusting the access layer's scheduling strategies and so on.However,most previous researches ignored three kinds of facts that:(1)the A3 handover algorithm had obvious switching boundaries;(2)the paths had limitations to the users' moving behaviors;(3)the topology shape affected the number of switches.In fact,there were amounts of researches on square topology and cellular topology in wireless sensor networks,which improved the performance of networks by changing topology.Considering the shortcomings of previous studies,this paper has done some work and get results as follows:(1)by analyzing the A3 handover conditions and the propagation loss models,this paper solved the handover boundaries of square and diamond topologies with MATLAB tool;(2)by doing statistical analysis and comparison of handover times in cellular and square networks in NS3 simulation environment,this paper found that the reasonable relative position could make the handover times in square networks less than that in cellular networks obviously;(3)by introducing the thought of weighted path and making the high weighted path locate in a more reasonable position,this paper reduced the whole handover times in hot areas;(4)by comparing and analysing on the performances of the A3 handover algorithm and A2A4 handover algorithm,this paper pointed out the superiorities of A3 handover algorithm in reducing handover times.Also the A3 handover algorithm had stronger communication coverage abilities and was less likely to cause ping-pong effects;(5)by proposing a optimization scheme of A3 handover algorithm based on terminal types for hot areas,this paper reduced the network jitter and delay significantly;(6)by establishing the indoor scene model,simulating and analysing in double layer network,it found that using A3 handover algorithm and square topology could also make the switching frequency of the overall system reducing.And the wireless environment map could provide further guidance for indoor femtocell deployments.