An investigation into PCF-DCF behaviour of 802.11b networks

[摘要] ENGLISH ABSTRACT: In recent years the demand for bandwidth has dramatically increased because ofnew applications for data and multimedia, and wireless technology has prevailed asa prominent technology for data connectivity, especially for home, office and lastmile services.As wireless communications are dependant upon spectrum availability, which iscommunal, this scarce commodity in communication has to be used as efficientlyas possible. Some aspects of this requirement are addressed in this project.We chose the IEEE 802.11b standard for this particular investigation because ofits widespread use, the vast amount of applicable literature, the variety of softwaresimulation tools and the ease with which equipment can be obtained.The IEEE 802.11 standard specified the Point Coordination Function as the de-terministic protocol. Recently research into this aspect has stagnated, and it was thepurpose of this project to investigate how existing infrastructure networks could beimproved by optimising some modes of the 802.11 protocol. The investigation alsohoped to determine when to change between Distributed Coordination Function(DCF) and Point Coordination Function (PCF), and to provide an adaptive protocolto do so.This thesis presents mathematical models for the operation of DCF and PCF modes,which is compared with results from a network simulator (ns2), for theoretical veri-fication. A protocol is also proposed to dynamically switch between DCF and PCF,to harness the advantages they present.

[发布机构] Stellenbosch University