Current Research (November 2009-present):

PhD Research (2005-2009):

Thesis Abstract:

Delay Tolerant Networks (DTNs) challenge the operation of protocols used in terrestrial networks at the physical, medium access control (MAC), and transport layers of the protocol stack. Deep space, the most extreme DTN, is an environment where transmission reliability, accuracy, and timeliness may be more difficult to achieve than in terrestrial networks due to harsh and dynamic conditions. Transport protocols are being developed for use on the long-distance Interplanetary backbone, however, each has advantages and disadvantages in different scenarios. Future protocols developed must maximise link utilisation when connectivity exists, minimise communication attempts and wasted resource consumption when connectivity does not exist, and accommodate network congestion. Furthermore, performance should be achieved autonomously to minimise operating costs and optimise decision-making responses.

Our approach, the Context-Aware Brokering (CAB) algorithm, is an autonomous middleware with context-aware capability which resides alongside any protocol stack between application and transport layers. It has capabilities to enable communication over both long- and short-distance links, and the version executed is optimised depending on the scenario. The CAB selects the most appropriate protocol for each transmission by comparing application requirements against environment constraints, intelligently configures it to maximise performance, and takes intermediary action when network dynamics compromise QoS levels. Its overall objective is to allow transmission reliability, accuracy, latency, or sustainability QoS to be achieved, or enable a balance to be maintained between each, depending on the transmission scenario.

Positive results are produced in a range of scenarios from an implementation of the CAB algorithm in ns-2.30. These are observed primarily when the CAB identifies environment constraints in relation to application requirements in advance of transmission beginning, and/or when the environment is dynamic and the CAB takes intermediary action to autonomously accommodate changes. A cost-benefit impact of the CAB architecture exists, and its positive impact on performance is most significant in dynamic environments which are long-distance and/or mobile when network conditions change in ways which are accommodated in the policy rules, and for applications without real-time and interactive transmission requirements. In a limited selection of scenarios, the CAB introduces overheads to the transmission without parallel improvements in performance. This is the case when pre-transmission assistance from the CAB is not required and the network remains stable until the transmission completes. Overhead costs are therefore incurred without any additional positive impacts from the CAB. The importance of deploying a CAB in all scenarios, however, is in the ability to exploit the potential of achieving a minimum level of service in the unpredictable and dynamic DTN.

MSc Research (2004-2005):

This MSc dissertation, completed alongside BT who were involved in a 21st Century Network Upgrade Strategy in Northern Ireland, was designed to aid the decision-making process concerning Digitial Subscriber Line (xDSL) technology and potentially fiber optic cable. The project involved classifying the population, estimating bandwidth requirements until 2010 based on their personal characteristics, measuring the capabilities of the current network and assessing the potential of redesigning the network to achieve the estimated maximum bandwidth requirements. The conclusion reached was that, while satisfactory for most, DSL will not be a suitable technology for all customers in Northern Ireland by 2010, and that fibre-to-the-home (FTTH) will be required in a number of cases.

Dissertation Abstract:

Bandwidth requirements from the network of the future Digital Subscriber Line (DSL) is an example of a rapidly advancing technology offering various bandwidth choices to the customer. However, the infrastructure upon which it is delivered sometimes raises bandwidth constraints in regions. To survive in this competitive industry, UK operators must provide maximum coverage and service, requiring considerable investment by some. Many are waiting until the future of the industry is secured and the opportunity to recover costs is assured. However, they must avoid waiting too long. The question of when, how and where to upgrade is pertinent.

This dissertation has investigated the layout of a network in Northern Ireland, revealing its inability to cope with future demand. The length of the local loop has been gradually extended as the population relocate to the suburbs. As a result, the deployment of faster-speed, but shorter-reaching DSL technologies is currently not possible. This fact becomes increasingly important when bandwidth requirements continue to increase.

The relocation of network components has been tested in collaboration with deployments of developing DSL technologies. While performance increases have been seen, the proposed bandwidths are not sufficient for all customers. This discovery has resulted in the conclusion that, while a complete fibre network roll-out is not economically feasible, such deployments must be made in areas. DSL technologies will, however, be sufficient for most.