Virtual Multi-AP Access for Transport-Level Quality Improvement in Wireless Local Area Networks with Hidden Stations

Koichi NISHIDE  Hiroyuki KUBO  Ryoichi SHINKUMA  Tatsuro TAKAHASHI  

IEICE TRANSACTIONS on Information and Systems   Vol.E93-D   No.12   pp.3251-3259
Publication Date: 2010/12/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E93.D.3251
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on Parallel and Distributed Computing and Networking)
wireless LAN,  hidden-station problem,  transport protocol,  throughput,  

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The demand of using applications that assume bidirectional communication such as voice telephony and peer-to-peer using wireless stations has been increasing and especially, the rapid increase of uplink traffic from wireless terminals is expected. However, in uplink WLANs, the hidden-station problem remains to be solved. In this paper, we point out this hidden-station problem and clarify the following unfairness between UDP and TCP uplink flows: 1) the effect of collision caused by hidden-station relationship on throughput and 2) the instability of the throughput depending on the number of hidden stations. To solve these problems, we propose a virtual multi-AP access mechanism. Our mechanism first groups stations according to the hidden-station relationship and type of transport protocol they use then assigns a virtually isolated channel to each group, which enables STAs to communicate as if STAs in different groups are connected to different isolated APs (virtual APs: VAPs). It can mitigate the effect caused by collisions between hidden stations and eliminate the contention between UDP and TCP uplink flows. Its performance is shown through simulation.