Routing protocols performance and intelligent quality of service applied to MANETs.

The wireless revolution prompted by the success of IEEE 802.11 standard has pressed the research community to deal with requirements of new wireless networks. In particular, wireless ad-hoc networks which are, specifically, a collection of wireless mobile nodes dynamically forming a temporary network without the use of any preexisting infrastructure or centralised administration. Routing protocols used in ad-hoc networks must automatically and continually adjust to environments. Most emerging network services require specialised Quality-of-Service (QoS) functionalities that cannot be provided by the current QoS-unaware routing protocols.Despite the large amount of research in these areas, several issues still need further investigation. The following points have become main concerns: i) traditional use of the hop count metric does not capture the very nature of wireless paths, resulting in poor performance of wireless networks; ii) the lack of comprehensive simulation methods to effectively observed performance of networks in various conditions and iii) the complexity of multi-constraint routing decisions, resulting in poor service quality in the end-user's point of view.This study takes an experimental approach to the evaluation of ad-hoc routing protocols and focuses on routing parameters as well as multimedia application QoS performance. In this thesis, we tackle the above mentioned issues and implement an efficient solution for the multi-constraint problem based on network measurements of valid experiments set-up. This study is exclusively based on simulations using NS-2 network simulator. In order to obtain an overview of the limitations of current conventional routing protocols, AODV and DSR protocols are used and their limitations in terms of QoS are measured and discussed. Operating conditions vary greatly from a static, lightly loaded network to constantly moving nodes with up to 10 simultaneous transmission connections. The results show that network performance degrades quickly and that QoS requirement was hardly met by any of these protocols.To evaluate the overall network performance, a new fuzzy logic assessment approach was developed taking into account the QoS parameters requirement of the transmitted application. Critical parameters were obtained through detailed simulation experiments under demanding operating conditions. These parameters were used as input to the fuzzy logic system to allow the computation of a single metric to represent the input variables (i.e. delay, jitter and throughput). The end results show that without a complicated mathematical model, a QoS value can be computed. This study addresses both theoretical aspects of QoS performance and routing progress in ad-hoc networks as well as practical issues in the set-up of simulation based studies.Finally, this study indicated that intelligent techniques can be effective for processing multiple QoS metrics to obtain an overall parameter that represents the application QoS. They can be adapted, not only to QoS routing, but to various aspects of QoS provisioning techniques.