Experimental Evaluation of Decision Criteria for WLAN handover:Signal Strength and Frame Retransmission

In ubiquitous networks, Mobile Nodes (MNs) may often sufferfrom performance degradation due to the following two reasons: (1)reduction of signal strength by an MN’s movement and intervening objects,and (2) radio interference with other WLANs. Therefore, quickand reliable detection of the deterioration of a wireless link condition isessential for avoiding the degradation of the communication quality duringhandover. In our previous works, we focused on a handover decisioncriterion allowing MNs to maintain communication quality and statedthe problems of existing decision criteria. Furthermore, we showed theeffectiveness of the number of frame retransmissions through simulationexperiments. However, a comparison between signal strength and thenumber of frame retransmissions could not be examined due to the unreliabilityof signal strength in simulations. Therefore, in this paper, byemploying FTP and VoIP applications, we compare signal strength andthe number of frame retransmissions as a handover decision criterionwith experiments in terms of (1) and (2) in a real environment. Finally,we show the problems of signal strength in contrast to the effectivenessof the number of frame retransmissions as a handover decision criterion