用于异构网络的差值门限模糊切换算法

Difference threshold based fuzzy handover algorithm for heterogeneous networks

为了提高用户在异构网络中进行垂直切换的准确度,减少"乒乓效应",提出了一种差值门限模糊切换算法(Difference Threshold based Fuzzy Handover,DTFH).DTFH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信噪比差值,根据该信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;然后,采用模糊逻辑方法得到用户当前网络与目标网络的模糊判决值,根据两个网络的模糊判决值之差与设定的切换判决门限的对比结果进行切换判决.以LTE和WiMAX异构网络为仿真场景,仿真结果表明,与传统切换算法相比,DTFH算法能在减少"乒乓效应"的同时,提高用户吞吐量,从而提高垂直切换的性能.

In order to improve the accuracy of vertical handover and to reduce the ＂Ping-Pong effect＂, a difference threshold based fuzzy handover （DTFH） algorithm is proposed for heterogeneous networks. The handover trigger and handover decision are considered for DTFH. The signal to noise ratio （SNR） gap between the target network and the current network is obtained by the mobile station （MS）, and the SNR gap between the two networks is compared with a predefined trigger threshold for handover trigger. Then based on the method of fuzzy logic, the MS gets the fuzzy decision values of the target network and the current network, and the gap between the fuzzy decision values of these two networks is compared with a predefined decision threshold for handover decision. In simulation, a heterogeneous network comprising LTE and WiMAX is used. Compared with traditional handover algorithms, the simulation results show that the DTFH algorithm can reduce the ＂PingPong effect＂, increase the throughput of MS, and improve the performance of vertical handover.