Quality of service support for wireless networks
This dissertation addresses the issue of Quality of Service (QoS) support for wireless networks, especially IEEE802.11 wireless LANs, having time-varying capacity which makes the QoS support problem difficult. To provide guarantees of QoS parameters such as delay violation probability, packet loss probability due to buffer overflow, etc., for the wireless networks, we need to take into account not only input traffic characteristics, but also time-varying wireless channel characteristics.
Considering the wireless channel characteristics, with the theoretical tool of large deviation theory we analyze the wireless Generalized Processor Sharing (GPS) scheme to provide stochastic performance guarantees for wireless LANs through the PCF mode which is based on a polling scheme, and propose connection admission schemes to admit as many connections as possible while satisfying QoS requirements of each connection.
To increase the throughput and delay performance of the best-effort traffics such as the TCP traffics flowing through the wireless LANs we propose the H∞ AQM scheme for the congested queue which resides in the AP station, facing the wireless networks with time-varying channel capacity. We show superior performance of the proposed scheme in comparison with the ABED scheme through ns simulation results.
For the cases where traffic or channel models are not available, we propose the adaptive bandwidth allocation scheme and the relative differentiated service architecture for wireless LANs, and show the experimental results obtained from the testbed in which the proposed schemes were implemented.
0984: Computer science