QoS enabled IP based wireless networking : design, modelling and performance analysis

Abstract

Quality of service differentiation has never achieved much attention and relevance until the advent of the convergence of mobile wireless network and the fixed Internet, that is, Internet Protocol ( IP ) based mobile wireless networks, or wireless Internet. These networks are poised to support multimedia applications ' traffic with diverse QoS sensitivities. To date, most traffic transferred over the Internet still undergo best - effort forwarding, which does not guarantee whether or not traffic sent by a source gets to the intended destination, let alone loss and timing bounds. The major contribution of this thesis is three - fold. First, the thesis proposes a QoS - enabled wireless Internet access architecture, which leverages the micromobility in wireless standards to reduce mobile IP weaknesses, such as long handoff delay, to achieve effective interworking between mobile wireless networks and the global, fixed Internet. Although the idea here is applicable to any wireless standard, the design examples in this thesis are based on the IEEE 802.11b wireless local area network ( WLAN ) standard. Second, it proposes a framework for a class of wireless channel state dependent packet scheduling schemes, which consider the QoS requirements of the applications ' traffic ; the wireless channel state ( reflected in instantaneous data rate or noise level ) ; and optimises the usage of the expensive wireless resource. The operation of the QoS - enabled, channel state - dependent packet scheduler is analysed using optimisation theory, eigenanalysis and stochastic modelling. Third, the thesis analyses the effects of wireless channel properties on differentiated QoS ( DQoS ) schemes, using two - dimensional, channel - state - dependent queuing theory, matrix analytic methods to stochastic modelling and eigenanalysis. The ana - lytical model of DQoS schemes, especially models accounting for user scenarios such as speed of motion and wireless channel properties, such as fading, spatio - temporarily varying quality and low rate, is not properly covered in the open literature, and hence was a motivation for this part of the thesis. The wireless channel is discretized into discrete - time Markovian states based on the received signal - to - noise plus interference ratio ( SNIR ), which also reflects on the instantaneous link quality. The link quality, in turn, influences the QoS experienced by the transported applications sitting on top of the ISO / OSI protocol hierarchy. The parameters of the Markovian states are evaluated using realistic physical channel noise models and transceiver characteristics, such as modem. [ Different modems ( modulator / demodulator ) yields different transceiver properties such as sensitivity. The analysis in the thesis adopts QPSKand BPSK modulation. ] Source traffic models are used in the analysis. Lastly, the thesis provides an extensive introduction to, and provides a detailed background material for the new area of mobile wireless Internet systems, upon which considerable future research can be based.