An Effective Data Transfer Method for IEEE 802.11 Wireless LANs

Kazuyoshi SAITOH  Yasuhiko INOUE  Tomoaki KUMAGAI  Masataka IIZUKA  Satoru AIKAWA  Masahiro MORIKURA  

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.3    pp.1266-1270
Publication Date: 2005/03/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.3.1266
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
CSMA/CA,  multirate control,  priority control,  slot time,  

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This paper proposes a new effective data transfer method for IEEE 802.11 wireless LANs by integrating priority control and multirate mechanism. The IEEE 802.11 PHY layer supports a multirate mechanism with dynamic rate switching and an appropriate data rate is selected in transmitting a frame. However, the multirate mechanism is used with the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) protocol, low rate transmissions need much longer time than high rate transmissions to finish sending a frame. As a result, the system capacity is decreased. The proposed method assumes the same number of priority levels as the data rates, and a data rate is associated to a priority level. Priority of a transmission goes up with the used data rate. For this purpose, we have modified the CSMA/CA protocol to support prioritized transmission. By selecting the appropriate priority depending on the data rate and giving more transmission opportunities for high rate transmission, the system capacity is increased. The effect of the proposed mechanism is confirmed by computer simulations.