Mangesh Chitnis

Wireless line sensor network for distributed visual surveillance

Wireless sensor networks (WSNs) play a crucial role in visual surveillance for automatic object detection, such as real-time traffic monitoring, vehicle parking control, intrusion detection,and so on. These online surveillance applications require efficient computation and distribution of complex image data over the wireless camera network with high reliability and detection rate in real time. Traditionally, such applications make use of camera modules capturing a flow of two dimensional images through time. The resulting huge amount of image data impose severe requirements on the resource constrained WSN nodes which need to store, process and deliver the image data or results within a certain deadline. In this paper we present a WSN framework based on line sensor architecture capable of capturing a continuous stream of temporal one dimensional image (line image). The associated one dimensional image processing algorithms are able to achieve significantly faster processing results with much less storage and bandwidth requirement while conserving the node energy. Moreover, the different operating modes offered by the proposed WSN framework provide the end user with different tradeoff in terms of node computation versus communication bandwidth efficiency. Our framework is illustrated through a testbed using IEEE 802.15.4 communication stack and a real-time operating system along with one dimensional image processing. The proposed line sensor based WSN architecture can also be a desirable solution to broader multimedia based WSN systems.

A Survey on Bandwidth Resource Allocation and Scheduling in Wireless Sensor Networks

Bandwidth resource allocation and scheduling has posed a challenging problem in wireless sensor networks. This paper provides a survey on the current state-of-the-art researches in this important area. Bandwidth reservation is considered in terms of time slot allocation in a pure TDMA or TDMA/CSMA based networks. We first overview different approaches for time slot allocation in a star network topology, and then elaborate the problem of time slot allocation and scheduling in a multihop wireless communication network in the presence of interference. Since the problem in multihop wireless network is proved to be NP-complete, most of the exiting solutions use different heuristics to resolve this problem. We address some of these heuristics and algorithms and their impact in wireless sensor networks. Finally, we provide some of the advantages, limitations and possible extensions in the context of IEEE 802.15.4 communications protocol which is being widely used for wireless sensor networks.

Simulating real-time aspects of wireless sensor networks

Wireless Sensor Networks (WSNs) technology has been mainly used in the applications with low-frequency sampling and little computational complexity. Recently, new classes of WSN-based applications with different characteristics are being considered, including process control, industrial automation and visual surveillance. Such new applications usually involve relatively heavy computations and also present real-time requirements as bounded end-to- end delay and guaranteed Quality of Service. It becomes then necessary to employ proper resource management policies, not only for communication resources but also jointly for computing resources, in the design and development of such WSN-based applications. In this context, simulation can play a critical role, together with analytical models, for validating a system design against the parameters of Quality of Service demanded for. In this paper, we present RTNS, a publicly available free simulation tool which includes Operating System aspects in wireless distributed applications. RTNS extends the well-known NS-2 simulator with models of the CPU, the Real-Time Operating System and the application tasks, to take into account delays due to the computation in addition to the communication. We demonstrate the benefits of RTNS by presenting our simulation study for a complex WSN-based multi-view vision system for real-time event detection.

A component-based architecture for adaptive bandwidth allocation in Wireless Sensor Networks

In this paper we investigate the problem of reactive on-line bandwidth allocation in adaptive Wireless Sensor Networks. In adaptive WSN for monitoring applications, nodes can react to physical events by adapting their behavior, for instance increasing the amount of computation to be performed, or reducing the amount of consumed energy. Accordingly, the nodes may increase or decrease their bandwidth requirements. Hence, a reconfiguration algorithm is needed to reallocate the bandwidth to the different nodes, to maximize a certain global quality index. To address this problem, we first present a component-based methodology to model nodes and cluster of nodes as components. Then, we use this methodology to decompose the global optimization problem into simpler local problems, so to enable the design of scalable heuristic algorithms. We propose two different heuristic algorithms, and we compare their performance by extensive simulations against a global optimization procedure based on the Simplex algorithm. We demonstrate that our proposed heuristics perform very well under almost all circumstances.

Traffic related observations by line sensing techniques

The use of Wireless Multimedia Sensor Networks (WMSNs) in Intelligent Transportation Systems (ITS) can offer cost effective solutions for gathering data on urban traffic, vehicle velocity, parking, etc. These applications demand real-time image acquisition and computational intensive processing in order to collect relevant information. We present our hardware and software solution for detecting moving objects and evaluating their velocity based on line sensor technology which guarantees fast processing, low storage and bandwidth requirements.

Rapid prototyping suite of IEEE 802.15.4-compliant Sensor Networks

This paper presents a toolsuite for rapid prototyping and implementation of real-time applications on Wireless Sensor Networks. The work is motivated by the need to use WSNs in industrial control contexts, where the sampling rate, the workload is much higher than typical current applications of WSNs, and the real-time constraints are much tighter. We present a simulator for early evaluation of the real-time behavior of a WSN application; and a realtime operating system that implement appropriate real-time scheduling policies to allow timing analysis and guarantee timing constraints. We provide a demo based on a simple but realistic network scenario showing that simulation is in agreement with experimental results.

IMPACT OF THE OPERATING SYSTEM ON THE QOS OFFERED BY AN IEEE 802.15.4-COMPLIANT SENSOR NETWORK

Abstract This paper presents a toolsuite for rapid prototyping and implementation of real-time applications on Wireless Sensor Networks. The work is motivated by the need to use WSNs in industrial control contexts, where the sampling rate, the workload and much higher than typical current applications of WSNs, and the real-time constraints are much tighter. We present a simulator for early evaluation of the real-time behavior of a WSN application; and a real-time operating system that implement appropriate real-time scheduling policies to allow timing analysis and guarantee timing constraints. After presenting the structure and the characteristics of both tools, we show that the results of the simulation are in line with experimental results of the implementation of a simple but realistic network scenario.