Hala M. Mokhtar

Fault management in wireless sensor networks

Wireless sensor networks (WSNs) have gradually emerged as one of the key growth areas for pervasive computing in the twenty-first century. Recent advances in WSN technologies have made possible the development of new wireless monitoring and environmental control applications. However, the nature of these applications and harsh environments also created significant challenges for sensor networks to maintain a high quality of service in potentially harsh environments. Therefore, efficient fault management and robust management architectures have become essential for WSNs. In this article, we address these challenges by surveying existing fault management approaches for WSNs. We divide the fault management process into three phases: fault detection, diagnosis, and recovery and classify existing approaches according to these phases. Finally, we outline future challenges for fault management in WSNs.

A Cellular Approach to Fault Detection and Recovery in Wireless Sensor Networks

In the past few years wireless sensor networks have received a greater interest in application such as disaster management, border protection, combat field reconnaissance and security surveillance. Sensor nodes are expected to operate autonomously in unattended environments and potentially in large numbers. Failures are inevitable in wireless sensor networks due to inhospitable environment and unattended deployment. The data communication and various network operations cause energy depletion in sensor nodes and therefore, it is common for sensor nodes to exhaust its energy completely and stop operating. This may cause connectivity and data loss. Therefore, it is necessary that network failures are detected in advance and appropriate measures are taken to sustain network operation. In this paper we extend our cellular architecture and proposed a new mechanism to sustain network operation in the event of failure cause of energy-drained nodes. In our solution the network is partitioned into a virtual grid of cells to perform fault detection and recovery locally with minimum energy consumption. Specifically, the grid based architecture permits the implementation of fault detection and recovery in a distributed manner and allows the failure report to be forwarded across cells. The proposed failure detection and recovery algorithm has been compared with some existing related work and proven to be more energy efficient.

A Fault Management Architecture for Wireless Sensor Network

Advancement in wireless communication and electronics has made possible the development of low cost sensor networks. Wireless sensor networks (WSNs) facilitate monitoring and controlling of physical environment from remote location with better accuracy. They can be used for various application areas (e.g. health, military, home). Due to their unique characteristics, they are offering various research issues that are still unsolved. Sensors energy cannot support long haul communication as changing energy supply is not always possible in WSN. Also, failures are inevitable in wireless sensor networks due to inhospitable environment and unattended deployment. Therefore fault management is an essential component of any network management system. In this paper we propose a new fault management architecture for wireless sensor networks. In our solution the network is partitioned into a virtual grid of cells to support scalability and perform fault detection and recovery locally with minimum energy consumption. Specifically, the grid based architecture permits the implementation of fault detection in a distributed manner and allows the failure report to be forwarded across cells. A cell manager and a gateway node are chosen in each cell to perform management tasks. Cell manager and gateway nodes coordinate with each other to detect faults with minimum energy consumption. We assume a homogeneous network where all nodes are equal in resources. The architecture has been evaluated analytically and compared with different proposed solutions.

Mobile Event Monitoring Protocol for Wireless Sensor Networks

Among wireless sensor networks applications, event monitoring is an application that has attracted a lot of attention in the recent years. As a physical event may be mobile, communication protocols should be designed to support mobility and allow the user to track the mobile event continuously, in energy-efficient way. In this paper, we present a new mobile event monitoring protocol for wireless sensor networks. Once the tracked event detected, the protocol builds a cluster that contains all nodes that detect this event with a certain threshold. In order to save energy, we propose to use a cluster membership update mechanism to update the cluster status when the event changes its position, instead of forming a new cluster each time the event moves. We evaluate the proposed protocol by simulations and show that our protocol results in much more energy saving than other monitoring protocols for average and high speed mobile events.

A Sensor Relocation Scheme for Wireless Sensor Networks

In the past few years wireless sensor networks have received a greater interest in application such as disaster management, border protection, combat field reconnaissance and security surveillance. Sensor nodes are expected to operate autonomously in unattended environments and potentially in large numbers. WSNs cannot be deployed manually in a hostile or harsh environment. Thus, WSNs can be formed by dropping them from the air. However, random deployment of sensor nodes can leave holes in terms of coverage in the sensing area. Moreover, sensor nodes failure may cause connectivity loss and in some cases network partitioning. The mobile devices can be used as an orthogonal method to address the network connectivity, coverage, and network life time problems in WSNs. Mobile sensors are useful as they can move to locations that meet sensing coverage requirements. In this paper we propose a novel sensor relocation scheme where redundant mobile nodes are moved to heal coverage holes in the network. We evaluate this work by simulations and show that our approach outperforms others in terms of relocation time and total energy consumption.

Self-Managed Fault Management in Wireless Sensor Networks

Wireless sensor networks usually deploy in the harsh operational environment where the physical presence of human administrators is impractical. Applications and systems of these networks are thus expected to operate with the minimum aid or supervision. Biologically-inspired behaviors, such as self-healing, self-adaptation, have already been recognized as the desirable features for these systems to self-adapt to various unpredicted changes occurred in the environment. In this paper, we address such biological feature in terms of fault management. We propose a hierarchical structure to properly distribute fault management tasks among sensor nodes by introducing more dasiaself-managingpsila functions. In addition, we also consider an alternate solution to self-reconfigure fault management function of sensor nodes adapting to various system requirements, such as replacement of a faulty node.

A new self-detection scheme for sensor network boundary recognition

One of the exigent problems in wireless sensor networks is the recognition of network boundary and the detection of holes within the network. In this paper, we propose an algorithm in which every node in the network self-detects whether it is a boundary node or an inner node by utilizing the available connectivity information and making no assumptions about the location awareness. The algorithm is efficient than existing schemes in terms of accuracy and energy consumption. It does not need high degree of connectivity as compare to other existing schemes. The simulation results prove the efficiency and accuracy of our algorithm.

A self-organised middleware architecture for Wireless Sensor Network management

In this paper, we propose a lightweight middleware system that supports Wireless Sensor Networks (WSNs) to handle real-time network management using a hierarchical framework. The primary objective of this middleware is to provide standard management services for sensor applications to maintain network service quality with minimal human intervention. Middleware of sensor node also reconfigures its functionality autonomously to reflect changes of node resources expenditure or network environment. In addition, we propose an alternate power management solution to achieve energy efficiency of sensor networks via controlling management performance of sensor nodes. This approach reduces node energy consumption without frequent reconfiguration of network management structure.

Coordinate Magnetic Routing for Mobile Sinks Wireless Sensor Networks

Extending lifetime and energy efficiency are important objectives and challenges in wireless sensor networks (WSN). Mobile sinks have been proposed and recognized for efficient data dissemination, reduced latency, and energy efficiency for wireless sensor networks. However, Mobile sink wireless sensor networks (MSWSN) also introduce many challenges especially in high performance routing capability. To address these challenges, we propose a novel efficient data dissemination algorithm for mobile sinks wireless sensor networks. This algorithm, Coordinate Magnetic (CM), is based upon representing the network as a virtual grid and using coordinate conception and magnetic phenomenon for data dissemination in network. We have conducted a simulation study to our work using the Georgia Tech Network Simulator (GTNetS) simulator. Our simulation under evaluation although seems promising.

An effective bandwidth model for deterministic QoS guarantees of VBR traffic

Modern high speed integrated services networks have to support applications with diverse traffic characteristics and performance requirements. One of the most interesting approaches to integrate the different types of traffic is the theory of effective bandwidth. The effective bandwidth of a time varying source is the minimum amount of bandwidth required to satisfy its QoS. In this paper, we present a new deterministic traffic model that is based upon the effective bandwidth notion. The model is derived from a worst-case analysis of the traffic on a single-node basis. It uses a simple method to evaluate the minimum resources needed to guarantee the deterministic QoS requirements of a connection. The model is thoroughly analyzed and compared to other deterministic models available on literature. It achieves accuracy, simplicity of traffic characterization and of admission tests. Moreover, it simplifies the pricing process.