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

Kazuya TSUKAMOTO  Takeshi YAMAGUCHI  Shigeru KASHIHARA  Yuji OIE  

Publication
IEICE TRANSACTIONS on Communications   Vol.E90-B   No.12   pp.3579-3590
Publication Date: 2007/12/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.12.3579
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
Keyword: 
wireless LAN handover,  handover decision criterion,  signal strength,  frame retransmission,  FTP,  VoIP,  

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Summary: 
In ubiquitous networks, Mobile Nodes (MNs) often suffer from performance degradation due to the following two reasons: (1) reduction of signal strength by the movement of an MN and intervening objects, and (2) radio interference with other WLANs. Therefore, handover initiation based on quick and reliable detection of the deterioration in a wireless link condition arising from the above two reasons is essential for achieving seamless handover. In previous studies, we focused on a handover decision criterion and described the problems related to the two existing decision criteria. Furthermore, we showed the effectiveness of the number of frame retransmissions through simulation experiments. However, a comparison of the signal strength and the number of frame retransmissions could not be examined due to the unreliability of the signal strength in simulations. Therefore, in the present paper, by employing FTP and VoIP applications, we compare the signal strength and the number of frame retransmissions as a handover decision criterion with experiments in terms of (1) and (2) in a real environment. Finally, we clarify the problem of the signal strength in contrast to the effectiveness of the number of frame retransmissions as a handover decision criterion.