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1. Quality of Service (QoS) Modelling Project A Communications networks which integrate data, video and voice are characterized by various forms of stochastic input traffic flows, limited network bandwidth and limited buffer availability. Delivery of Quality of Service (QoS) in such integrated networks normally takes the form of guaranteed bounds on specific metrics such as packet loss or delay. Traditionally, QoS services, are described in terms of deterministic QoS metrics - so called guaranteed service within the Internet framework. Such services are not applicable to the wireless domain, where the variability of the wireless channel requires QoS to be of a statistical nature. In this research program the effect of mobility on the delivery of QoS in variable quality wireless networks will be investigated. Particular emphasis on the physical location of devices in the wireless network will be investigated. Opnet will be used to model different protocols and their working. Opnets Modeler and Wireless Module have been used to develop an intelligent MAC layer capable of delivering multimedia traffic (in particular VoIP) effectively in the WLAN environment. We first study the various alternatives to achieve service differentiation and their corresponding effects on multimedia traffic. Secondly, the backoff algorithm, virtual contention, direct link protocol and other aspects of 802.11e are being implemented on top of the legacy 802.11 standard. This work will act as a baseline for more advanced features that we are investigating, such as location-based QoS, large scale wireless simulation with high speed underlying 802.11g/n physical layer. 2. Quality of Service (QoS) Modelling Project B It is the main thrust of this project to develop and prototype software for a communication system which uses Quality of Service (QoS) measurements of a wireless channel - seamlessly embedding this information in the devices of new potential users on the channel. The user’s devices will utilize the acquired channel QoS in order to ascertain the suitability of the channel to their ongoing and requested applications. In the event of potential conflicts, embedded intelligent software within the device will make the appropriate decisions so as to optimize the QoS for priority applications. Opnet will be used to model multiple access on the channel using WLAN 802.11 protocols 3. Smart antennas in a mobile ad hoc network The use of smart antennas in a mobile ad hoc network hasn't been prevalent until now. This is due to the complex issues of finding the desired directions when we use directional antennas. This issue is particularly critical in an ad hoc network which has no centralized control and the mobile terminals may have limitations of size and the complexity/cost of communication hardware. Thus, in my project I present a novel MAC protocol to address these problems such as hidden terminal problem and how to track mobile users, in order to increase the system performance of ad hoc networks. 4. Adaptive Bandwidth Reservation for High-Speed Multimedia Wireless Networks Carrying Multimedia Traffic Next generation high-speed wireless networks are expected to support multimedia applications. It is therefore important for these networks to provide Quality of Service (QoS) guarantee. Also, with the enormous growth of portable computers equipped with networking capabilities, it is important to develop real time protocol for wireless LAN (WLAN) technologies, such that real time video communication services can be extended to the mobile terminals, with acceptable QoS. Real time video transmission over unreliable wireless link demands particularly for an efficient and fast bandwidth reservation scheme such that QoS is maintained. This project will design and implement an adaptive bandwidth reservation scheme for efficient video transmission over WLANs. 5. Adaptation of ATM ABR service to 10GbE WANs There is some speculation that ATM networks will be phased out and new ATM networks will not be deployed after several years. As it appears to be, 10 Gbit/s Ethernet (10GbE) is the most dangerous competitor that could replace ATM in WANs. As such, we have investigated the possibility of adapting the congestion control algorithms that we developed for ATM ABR service to the 10GbE WANs. To this end, we have been able to develop a flow control mechanism for the 10GbE . Apart from the ON/OFF control prescribed by the standard, there are a few recent flow control mechanisms developed for the 10GbE networks in the literature. However, they do not comply with the present standard as they require other quantities such as queue level to be included in the control frame. In contrast, our algorithm complies with the standard. However, if the standards evolve further to include a control frame with a field to carry the explicit rate, we can use our algorithms developed for ABR congestion control directly. We have used OPNET to verify the performance of our scheme. 6. STDMA (Spatial TDMA) in the presence of location
errors. 7. Undergraduate Teaching of OPNET Currently students in their final year of undergraduate study are undertaking full year thesis projects using OPNET on the following topics:
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