Showing papers by "Ilangko Balasingham published in 2008"

Dynamic Spectrum Allocation in Wireless Cognitive Sensor Networks: Improving Fairness and Energy Efficiency

Abstract: This paper considers the centralized spectrum allocations in resource-constrained wireless sensor networks with the following goals: (1) allocate spectrum as fairly as possible, (2) utilize spectrum resource maximally, (3) reflect the priority among sensor data, and (4) reduce spectrum handoff. The problem is formulated into a multi-objective problem, where we propose a new approach to solve it using modified game theory (MGT). In addition, cooperative game theory is adopted to obtain approximated solutions for MGT in reasonable time. The results obtained from numerical experiments show that the proposed algorithm allocates spectrum bands fairly with well observing each sensor's priority and nearly minimal spectrum handoffs.

A reinforcement learning based routing protocol with QoS support for biomedical sensor networks

Abstract: Biomedical sensor networks have been widely used in medical applications, where data packets usually contain vital sign information and the network used for communications should guarantee that these packets can be delivered to the medical center reliably and efficiently. In other words, a set of requirements for quality of services (QoS) must be satisfied. In this paper, RL-QRP, a reinforcement learning based routing protocol with QoS-support is proposed for biomedical sensor networks. In RL-QRP, optimal routing policies can be found through experiences and rewards without the need of maintaining precise network state information. Simulation results show that RL-QRP performs well in terms of a number of QoS metrics and energy efficiency in various medical scenarios. By investigating the impacts of network traffic load and sensor node mobility on the network performance, RL-QRP has been proved to fit well in dynamic environments.

A multi-agent reinforcement learning based routing protocol for wireless sensor networks

Abstract: In this paper, we present MRL-QRP, a multi-agent reinforcement learning based routing protocol with QoS support for wireless sensor networks. In MRL-QRP, sensor node cooperatively computes QoS routes using a distributed value function - distributed reinforcement learning algorithm (DVFDRL). Global optimization can be achieved by using locally observed network information and limited exchanging of state values with immediate neighboring nodes. We compare the network performance of MRL-QRP with QoS-AODV, an on demand QoS support routing protocol. The impact of network traffic load and sensor node?s mobility on the network performance are investigated, simulation results show that MRL-QRP performs well in respects of a number of QoS metrics and fits well in highly dynamic environments.

Threat Assessment of Wireless Patient Monitoring Systems

Abstract: We address issues related to threat assessment of mobile patient monitoring systems using a wireless infrastructure including body area biomedical sensor networks. Several user scenarios are presented. Patient sensitive data, mobile and wireless infrastructure, and resource-constraint sensor nodes provide a challenging task of fulfilling some minimum requirements for security, privacy, reliability of the data and availability of the system. We have therefore studied threats associated to both short range and long range mobile wireless communication infrastructures, where requirements for security recommendations for such systems are presented. Emphasis is given on applications that employ a wireless infrastructure, such as biomedical sensor networks. In this work we present an informal threat assessment of mobile patient monitoring systems used with several scenarios.

Are the wavelet transforms the best filter banks for image compression

Abstract: Maximum regular wavelet filter banks have received much attention in the literature, and it is a general conception that they enjoy some type of optimality for image coding purposes. To investigate this claim, this article focuses on one particular biorthogonal wavelet filter bank, namely, the 2-channel 9/7. As a comparison, we generate all possible 9/7 filter banks with perfect reconstruction and linear phase while having a different number of zeros at z = -1 for both analysis and synthesis lowpass filters. The best performance is obtained when the filter bank has 2/2 zeros at z = -1 for the analysis and synthesis lowpass filters, respectively. The competing wavelet 9/7 filter bank, which has 4/4 zeros at z = -1, is thus judged inferior both in terms of objective error measurements and informal visual inspections. It is further shown that the 9/7 wavelet filter bank can be obtained using gain-optimized 9/7 filter bank.

Use of MPEG-21 for Security and Authentication in Biomedical Sensor Networks

Abstract: Privacy and security are two major concerns in the ubiquitous deployment of wireless patient monitoring systems. Wireless sensor networks become an integral part of the monitoring process, where wireless sensors can enter or leave the monitoring situation randomly. As a tool to handle threats that may arise by the use of wireless sensors, we propose a new framework using MPEG-21. MPEG-21 is an architecture that can handle end-to-end management of content and network resources. In this paper we evaluate the use of the MPEG-21 architecture in a resource-constraint wireless sensor network, where different threats are evaluated and countermeasures are proposed.

Power control for mission critical wireless sensor networks using repeated coalitional games

Abstract: In this paper, we propose a coalitional game theoretic approach to the power control problem in resourceconstrained wireless sensor networks, where the objective is to enhance power efficiency of individual sensors while providing the QoS requirements. We model this problem as two-sided one-to-one matching game and deploy deferred acceptance procedure that produces a single matching in the core, which is the set of actions aN of all sensors such that no coalition of sensors has an action that all its members prefer to aN. Furthermore, we show that, by applying the procedure repeatedly, a certain stable state is achieved where no sensor can anticipate improvements in their power efficiency as far as all of them are subject to their own QoS constraints. We evaluate our proposal by comparing them with cluster-based coalescing and the local optimal solution obtained by maximizing the total system energy efficiency, where the objective function is non-convex.

Handling unknown NBI in IR-UWB system used in biomedical wireless sensor networks

Abstract: Impulse radio-ultra wideband (IR-UWB) communication technique is considered as a strong candidate for short range biomedical wireless sensor networks (BWSN). Coexistence with other systems in the ISM band is important, where narrow band interference (NBI) can become a threat to this system. This paper proposes a method to increase robustness of IR-UWB system in the existence of NBI. This method takes the advantage of using both FEC coding and frequency interleaving technique. One of the features of the proposed system is that it performs well in an environment with unknown NBI. Comparisons between single-band and multi-band signaling schemes are given. Simulation results show that the proposed multi-band scheme performs well in existence of NBI and provides about 3.5 dB gain in comparison to single-band scheme with the same configuration, where the NBI to AWGN energy ratio equals 30 dB.

On the use of the MPEG-21 framework in medical wireless sensor networks

Abstract: This paper proposes a system architecture for wireless sensor network (WSN) using the MPEG-21 multimedia framework in medical applications. It has been envisioned that future hospitals will have networks comprising WSNs for low rate medical sensors as well as other network nodes supporting high rate audiovisual content. The increasing collection and variety of media content (multimedia) in such a scenario, needs a framework for the interaction with the external users regarding data filtering, meta information tagging, authentication and data rights control. Furthermore due to different user terminals and network resources, media adaptation will become important to provide reliable and robust quality of services. The MPEG-21 standard seems to have potential to meet some of the mentioned requirements. In this paper, we argue for an extension of the MPEG-21 terminology for use in biomedical wireless sensor networks and incorporate the requirements needed for medical applications. We show the architecture of a demonstration prototype based on this extended MPEG-21 framework that is under development, capable of displaying selected biomedical sensor data. The deployment of such a system may become warranted in future healthcare enterprises.