An Integrated Framework For Enhancing User Experience For Different Data Services In Multi-rate Wireless Systems

Abstract

Technological advances in multi\--rate wireless systems have made wireless data services an intrinsic part of human life. An abundance of wireless devices, both in the wireless enabled home multimedia systems as well as in corporate offices, have trigerred an array of research in enhancing the wireless data services. The success and acceptance of these various rich data services Technological advances in multi\--rate wireless systems have made wireless data services an intrinsic part of human life. An abundance of wireless devices, both in the wireless enabled home multimedia systems as well as in corporate offices, have trigerred an array of research in enhancing the wireless data services. The success and acceptance of these various rich data services depends on satisfying the user experience derived from such services.\\ In this thesis, we first focus on identifying and exposing the important parameters, specfically network parameters pertaining to the multi\--rate wireless systems, which hinder user satisfaction for a wireless multimedia system. Subsequently, we provide an integrated framework which encapsulates channel estimation techniques, scheduling algorithms specifically catering to the issues in multi\--rate wireless systems and mobility solutions for improving user experience. We startoff by performing theoretical modeling of how user satisfaction for the various data services vary with different network impediments. The insights reveal that the traditional metrics \textit{throughput}, \textit{connectivity} and \textit{delay} constraints hold very much for the upcoming multi\--rate wireless multimedia systems. However, the intelligence lies in tackling these constraints at specific layers in the protocol stack. Experimental data reveals that loss and delay variations in the multimedia stream results in Audio\--Video Synchronization issues leading to severe degradation of the multimedia experience. We develop accurate channel estimation techniques specifically for multi\--rate wireless systems which enhance the throughput of the system. Thereafter couple the proposed channel estimation technique with scheduling algorithms specifically designed for multi\--rate wireless systems which vastly improves the performance of the system in terms of effective throughput and user satisfaction. Rate adaptation techniques are also proposed. Connectivity which completely breaks down the service is a serious issue with Wi\--Fi devices since the transmission range is limited ($<100$ meters) and wireless users tend to be inherently mobile. To ensure connectivity and honor the strict timing requirements demanded by streaming multimedia applications we have designed and implemented a client\--end handoff framework for Wi\--Fi systems using the Madwifi driver. In case of throughput constraint, we have focussed on determining a theoretical upper bound to the number of satisfied users in comparison to existing schemes. All the proposed mechanisms jointly enhance the performance of the data services for multi\--rate wireless systems and consequently maximize the number of satisfied user.