异构网络中基于门限和AHP的TOPSIS垂直切换算法

为提高异构网络系统吞吐量,减少乒乓效应,提出一种基于门限和层次分析法的切换算法(different threshold and AHP based TOPSIS vertical handoff algorithm,DTAT).DTAT算法考虑异构网络中的切换触发与切换判决两个方面.用户获得当前网络和目标网络的SINR(信干噪比)差值,根据该信干噪比差值与设定的切换触发门限的比较结果进行切换触发;利用层次分析法中的特征向量法来决定各个属性之间的权重关系,根据属性矩阵和权重向量,利用逼近理想值的排序方法(TOPSIS)得到用户当前网络与目标网络的判决值,选取最佳网络.仿真结果表明,DTAT算法能够根据各业务特点综合考虑各属性间关系,从而提高垂直切换的性能.

Threshold-and AHP-based TOPSIS vertical handoff algorithm for heterogeneous networks

In order to improve the throughput capacity of heterogeneous network system,and reduce its ’ping-pong’ effect,a threshold-and AHP(analytic hierarchy process)-based TOPSIS vertical handoff algorithm(DTAT) was proposed.The handover trigger and handover decision were considered in DTAT.The signal to interference plus noise ratio(SINR) difference between the target network and current network was obtained by mobile station(MS),and the SINR gap between the two networks was then compared with a predefined trigger threshold to conduct handover trigger.The weight relations among all attributes were determined by using eigenvalue method in AHP.Finally,TOPSIS algorithm was used to make network decision by virtue of the attribute matrix and weight vector.The MS would get the TOPSIS decision values of the target network and current network and select the optimal network.The simulation result showed that the DTAT algorithm could comprehensively take the attribute relationship into consideration by virtue of the characteristics of all traffics and improve the performance of vertical handoff.