In this paper, coordination and communication problems in wireless sensor and actor networks (WSANs) are jointly addressed in a unifying framework. A sensor-actor coordination model is proposed based on an event-driven partitioning paradigm. Sensors are partitioned into different sets, and each set is constituted by a data-delivery tree associated with a different actor. The optimal solution for the partitioning strategy is determined by mathematical programming, and a distributed solution is proposed. In addition, a new model for the actor-actor coordination problem is introduced. The actor coordination is formulated as a task assignment optimization problem for a class of coordination problems in which the area to be acted upon needs to be optimally split among different actors. An auction-based distributed solution of the problem is also presented. Performance evaluation shows how global network objectives, such as compliance with real-time constraints and minimum energy consumption, can be achieved in the proposed framework with simple interactions between sensors and actors that are suitable for large-scale networks of energy-constrained devices.

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Communication and Coordination in Wireless Sensor and Actor Networks

Incorporating the environment-sensing capability of wireless sensor networks into video- based surveillance systems can provide advanced services at a lower cost than traditional surveillance systems.The integrated mobile surveillance and wireless sensor system (iMouse) uses static and mobile wireless sensors to detect and then analyze unusual events in the environment.

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iMouse: An Integrated Mobile Surveillance and Wireless Sensor System

Wireless sensor networks make possible many new applications in a wide range of application domains. One of the primary applications of such networks is the detection and tracking of continuously moving objects, such as wild fires, biochemical materials, and so forth. This study supports such applications by developing a continuous object detection and tracking algorithm, designated as CODA, based on a hybrid static/dynamic clustering technique. The CODA mechanism enables each sensor node to detect and track the moving boundaries of objects in the sensing field. The numerical results obtained using a Qualnet simulator confirm the effectiveness and robustness of the proposed approach.

CODA: A Continuous Object Detection and Tracking Algorithm for Wireless Ad Hoc Sensor Networks

One important goal of surveillance systems is to collect information about the behavior and position of interested targets in the sensing environment. These systems can be applied to many applications, such as fire emergency, surveillance system, and smart home. Recently, surveillance systems combining wireless sensor networks with video cameras have become more and more popular. In traditional video surveillance systems, the system performance and cost is proportional to the number of deployed video camera. In this paper, we propose a real time video surveillance system consisting of many low cost sensors and a few wireless video cameras. The system allows a group of cooperating sensor devices to detect and track mobile objects and to report their positions to the sink node in the wireless sensor network. Then, the sink node uses the IP cameras deployed in the sensing area to record these events and display the present situations. We also propose a camera control scheme to initialize the coverage distribution of cameras and support the inter-task handoff operations between cameras. We have implemented the proposed system with 16 sensor nodes and two IP cameras, and evaluated the system performance. The result shows that our surveillance system is adaptable to variant environments and provides real time information of the monitored environment.

Design and Implementation of a Real Time Video Surveillance System with Wireless Sensor Networks

Wireless Heterogeneous Sensor Network (WHSN) facilitates ubiquitous information acquisition for Ambient Intelligence (AmI) systems. It is of great importance of power management and topology control for WHSN to achieve desirable network performances, such as clustering properties, connectivity and power efficiency. This paper proposes a game theoretic model of topology control to analyze the decentralized interactions among heterogeneous sensors. We study the utility function for nodes to achieve desirable frame success rate and node degree, while minimizing the power consumption. Specifically, we propose a static complete-information game formulation for power scheduling and then prove the existence of the Nash equilibrium with simultaneous move. Because the heterogeneous sensors typically react to neighboring environment based on local information and the states of sensors are evolving over time, the power-scheduling problem in WHSN is further formulated into a more realistic incomplete-information dynamic game model with sequential move. We then analyze the separating equilibrium, one of the perfect Bayesian equilibriums resulted from the dynamic game, with the sensors revealing their operational states from their actions. The sufficient and necessary conditions for the existence of separating equilibrium are derived for the dynamic Bayesian game, which provide theoretical basis to the proposed power scheduling algorithms, NEPow and BEPow. The primary contributions of this paper include applying game theory to analyze the distributed decision-making process of individual sensor nodes and to analyze the desirable utilities of heterogeneous sensor nodes. Simulations are presented to validate the proposed algorithms and the results show their ability of maintaining reliable connectivity, reducing power consumption, while achieving desirable network performances.

Game-Theoretic Modeling of Joint Topology Control and Power Scheduling for Wireless Heterogeneous Sensor Networks

Wireless ad-hoc sensor networks are being developed to carry out tasks such as target detection and tracking, environment monitoring, and data collection across the area of deployment. We explore the problem of using sensor networks to detect and track continuous objects, such as wild fire and bio-chemical material. The continuous objects are different from traditional one or many individual targets in that they are continuously distributed across a region and usually occupy a large area. These continuous objects tend to diffuse, increase in size, change in shape, or even split into multiple relatively smaller continuous objects. The fusion and dissemination of local boundary information becomes a very challenging problem. In the paper, we propose a dynamic cluster-based structure to track the movement of boundaries and facilitate the fusion and dissemination of boundary information in a sensor network.

Xiang ji

Papers

Dynamic cluster structure for object detection and tracking in wireless ad-hoc sensor networks