Optimizing IEEE 802.11 Wireless Local Area Networks Performance in a Shared Spectrum
Emmanouil Panaousis · Research Repository (Kingston University London) · 2008
IEEE 802.11 WLAN is one of the most important access network technologies in the Internet today. IEEE 802.11 standards use the unlicensed spectrum for transmission and thus they must use spread spectrum techniques. These techniques decrease interference between multiple users and increase the ability to reuse the spectrum. Also, instead of treating spectrum as a scarce physical resource, we could make it available to all, an approach known as open spectrum. Moreover, the coexistence of wireless communication systems operating in the same environment has become a hot topic in recent years as more systems are choosing the unlicensed bands and they are forfeiting the need to purchase spectrum. From the perspective of the communication, cooperation embraces a number of techniques taking advantage of the synergetic interaction of more than one entity as well as the collaborative use of resources, all aiming to enhance performance. The benefit of cooperation in the wireless world is the enhancement of many fundamental performance figures of a wireless communication system. Another method to improve the performance of a wireless environment is the power control which is a technical mechanism used by some networking devices in order to prevent too much unwanted interference. In addition, the scientific area of game theory, which has revolutionized economics, may provide greater understanding of the wireless systems. The main problem of the today’s IEEE 802.11 WLAN is the small number of available channels. In this work we will focus on how to control the transmission power of pilot signals of IEEE 802.11 access points using game theory. First, we consider a non-cooperative power control game among different operators. Second, we assume that operators are cooperative. In the latter type of game, we assume the existence of a central authority called coordinator. In such a game there exists a Nash bargaining solution (NBS). Moreover, we examine the case of IEEE 802.11k enabled WLANs. IEEE 802.11k is an extension of the IEEE 802.11 specification for radio resource measurements. In an IEEE 802.11k-enabled wireless LAN, an access point or other network element