Andrew Jennings

Energy efficient cluster formation in wireless sensor networks

Energy optimized cluster formation for a set of randomly scattered wireless sensors is presented. Sensors within a cluster are expected to be communicating with a cluster head only. The cluster heads summarize and process sensor data from the clusters and maintain the link with the base station. The clustering is driven by the minimization of energy for all the sensors. Recent developments in clustering are used to support the work, and a cluster visualization interface is used to observe the simulation results.

Energy Efficiency of Intrusion Detection Systems in Wireless Sensor Networks

Security is a significant concern for many sensor network applications. Intrusion detection is one method of defending against attacks. However, standard intrusion detection is not suitable for sensor networks with limited battery power, memory and processing resources. This paper compares several approaches to intrusion detection in sensor networks. We investigate accuracy of detecting attacks, versus energy efficiency

A comparative study of mobility prediction in fixed wireless networks and mobile ad hoc networks

In this paper we have introduced a mobility prediction scheme that proposes the use of a new sector-based tracking of mobile users, with a sector-numbering scheme to predict user movements. The proposed scheme is applicable for both the fixed network and the ad hoc networking structures. Our study shows that accurate prediction is possible with reduced area of tracking for both types of networks.

RUNWAY WIDTH EFFECTS IN THE VISUAL APPROACH TO LANDING

The effect of changes in runway width on the perception of glide-slope has been the subject of extensive investigations. Despite considerable research, an explanation of this effect has been elusive. A mathematical model for glide-slope perception was published recently based on the premise that a desirable goal of perception is to form a perception with minimal uncertainty. One of the qualitative predictions of that model was that changes in the aspect ratio of the runway would affect the perceived glide-slope. In this article, the predictions of the model are quantified and are shown to be in close agreement with experimental results in the literature.

Robust Routing

In a network, traffic demands are known with a degree of uncertainty, traffic engineering should take into account the traffic variability. In this research work we focus on the robust routing under changing network conditions. Daily Internet traffic pattern shows that network is vulnerable to malicious attacks, denial of service attacks, worms and viruses. Oblivious routing has a substantially better performance than open shortest path first [OSPF] routing for different level of uncertainty. We propose a theoretical framework for Robust Routing aiming to improve online and offline traffic engineering approaches.

Relay Path Selection Approaches in Peer-to-Peer VoIP Systems

Multipath overlay routing technologies are seen as alternative solutions for VoIP because they inherit path diversity from peer-to-peer overlay networks. We discuss and compare the performances of two relay path selection approaches proposed for VoIP overlay systems through extensive simulations. We propose a new method for relay path computation that takes into account both path disjointness and other network quality factors (such as packet delay or loss). We further apply our method in different overlay network scenarios by varying the supernode distribution. It is found that there is a considerable improvement of path performance when relaying traffic through highly connected ASs using the new method.

Aggregated priority queueing as an efficient queueing mechanism to overcome effects of self-similarity

Differentiated Services (DiffServ) architecture is based on aggregation of traffic and, unlike the Integrated Services (lntServ) the resources are not reserved on a per flow basis. One of the current research issues is the provision of Quality of Service (QoS) guarantees to real time traffic in the DiffServ environment. The idea here is to achieve these guarantees without per flow resource allocation while safeguarding the best effort traffic from extremely high delays. The self-similar nature of Internet traffic that results in burstiness and very high delays has been identified in the recent past. The problem at hand is, what packet-scheduling scheme can be used to minimise delay to reasonable limits and the levels of control to be applied on the aggregated traffic to achieve such limits. We propose a class based aggregated Priority Queue with Lower Real time Traffic Utilisation (PQ-LRTU) as a packet-scheduling scheme that is capable of providing statistical delay guarantees for DiffServ networks. Since only a real time traffic utilization threshold is maintained at the entrance to the network to control traffic, it provides a simple mechanism. Overall queue efficiency is achieved by using different levels of delay tolerable lower priority traffic.

Analyzing the Key Distribution from Security Attacks in Wireless Sensor

As wireless sensor network (WSN) has limited resource, security function and operation must be simplified. So its defense is relatively weak comparing to PC or high-power server. This paper demonstrates key distribution for sensor networks that is resistant to brute force attack, known plain text attack, replay attack, man-in-the-middle attack and denial of service attack (DoS). This paper compares a proposed solution HKD with SPINS and ARIADNE protocols which are designed for WSN and ad hoc networks. The evaluation demonstrates that ARIADNE is the strongest protocol.. HKD can minimize the power consumption while SPINS balances both energy and security.

Relay node selection in large-scale VoIP overlay networks

Relay path selection is one of the critical components of VoIP overlay systems. This paper looks at the choice of relay nodes and its impact on the performance of VoIP overlay paths in interdomain environment. We model the network at the Autonomous System level and simulate different scenarios of relay path selection. For the optimal relay path performance, we recommend to select relay nodes whose distances are less than or equal to three hops away from the sources. Our analysis shows that the performance of relay paths in existing methods is influenced by the density of the relay nodes. There is a trade-off between delay and hop overlap performance objectives. We propose new algorithm for selecting relay nodes. Initial results show that the proposed method can improve performance.

Adaptive Intrusion Detection in Wireless Sensor Networks

Security is a significant concern for many sensor network applications. Intrusion detection is one method of defending against attacks. However, standard intrusion detection is not suitable for sensor networks with limited battery power, memory and processing resources. This paper compares several approaches to intrusion detection in sensor networks. We investigate accuracy of detection of attacks versus energy efficiency. Existing solutions are compared with a new adaptive protocol for distributed defense