On Prolonging Network Lifetime through Load-Similar Node Deployment in Wireless Sensor Networks

This paper is focused on the study of the energy hole problem in the Progressive Multi-hop Rotational Clustered (PMRC)-structure, a highly scalable wireless sensor network (WSN) architecture. Based on an analysis on the traffic load distribution in PMRC-based WSNs, we propose a novel load-similar node distribution strategy combined with the Minimum Overlapping Layers (MOL) scheme to address the energy hole problem in PMRC-based WSNs. In this strategy, sensor nodes are deployed in the network area according to the load distribution. That is, more nodes shall be deployed in the range where the average load is higher, and then the loads among different areas in the sensor network tend to be balanced. Simulation results demonstrate that the load-similar node distribution strategy prolongs network lifetime and reduces the average packet latency in comparison with existing nonuniform node distribution and uniform node distribution strategies. Note that, besides the PMRC structure, the analysis model and the proposed load-similar node distribution strategy are also applicable to other multi-hop WSN structures

A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks

In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs

Overlapping layers for prolonging network life time in multi-hop wireless sensor networks

Wireless sensor networks have been proposed as a practical solution for a wide range of applications due to their benefits of low cost, rapid deployment, self-organization capability, and cooperative data-processing. Many applications, such as military surveillance and habitat monitoring, require the deployment of large-scale sensor networks. A highly scalable and fault-tolerant network architecture, the Progressive Multi-hop Rotational Clustered (PMRC) structure has been proposed, which is suitable for constructing large-scale wireless sensor networks. However, similar to other multi-hop structures, the PMRC structure also suffers from the bottleneck problem; This thesis is focused on solving the bottleneck problem existing in the PMRC structure. First, the Overlapping Neighbor Layers (ONL) scheme is proposed to balance the energy consumption among cluster heads at different layers. Further, the Minimum Overlapping Neighbor Layers (MONL) scheme is proposed wherein the overlapped area between neighbor layers is gradually increased through network life time to achieve load balance and energy efficiency in the whole network area. Simulation results show that the MONL scheme significantly prolongs network life time and demonstrates steady performance on sensor networks with uniformly distributed sensor nodes. To further prolong the network life time, traffic-similar sensor nodes distribution combined with the MONL scheme is studied; The proposed overlapped layers schemes are proven to be effective in solving the bottleneck problem and prolonging network life time for PMRC-based networks. They can also be applied for other multi-hop cluster-based sensor networks. The traffic-similar nodes distribution concept can be applied in optimizing sensor network deployment to achieve desired network life time

A Finite Queue Model Analysis of PMRC-based Wireless Sensor networks

In our previous work, a highly scalable and fault- tolerant network architecture, the Progressive Multi-hop Rotational Clustered (PMRC) structure, is proposed for constructing large-scale wireless sensor networks. Further, the overlapped scheme is proposed to solve the bottleneck problem in PMRC-based sensor networks. As buffer space is often scarce in sensor nodes, in this paper, we focus on studying the queuing performance of cluster heads in PMRC-based sensor networks. We develop a finite queuing model to analyze the queuing performance of cluster heads for both non-overlapped and overlapped PMRC-based sensor network. The average queue length and average queue delay of cluster head in different layers are derived. To validate the analysis results, simulations have been conducted with different loads for both non- overlapped and overlapped PMRC-based sensor networks. Simulation results match with the analysis results in general and confirm the advantage of selecting two cluster heads over selecting single cluster head in terms of the improved queuing performance

Load-Similar Node Distribution for Prolonging Network Lifetime in PMRC-Based Wireless Sensor Networks

In this paper, the energy hole problem in Progressive Multi-hop Rotational Clustered (PMRC)-based wireless sensor networks (WSNs) is studied. We first analyze the traffic load distribution in PMRC-based WSNs. Based on the analysis, we propose a novel load-similar node distribution strategy combined with the Minimum Overlapping Layers (MOL) scheme to solve the energy hole problem in PMRC-based WSNs. Simulation results demonstrate that the load-similar node distribution strategy significantly prolongs network lifetime than uniform node distribution and an existing nonuniform node distribution strategies. The analysis model and the proposed load-similar node distribution strategy have the potential to be applied to other multi-hop WSN structures

A Software Architecture for Adaptive Modular Sensing Systems

In this thesis, a novel software architecture and knowledge representation scheme is described that facilitates the combination and reconfiguration of modular sensor and actuator components, termed transducer interface modules (TIMs), to produce flexible modular sensor systems. Each TIM provides a core sensing or actuation functionality. A composite sensor is able to automatically determine its overall geometry and assume an appropriate collective identity, and if reconfigured, may then assume a different identity to match its new geometry. In current practice, a fixed combination of sensors and actuators is typically utilized, and is tailored to a specific application. Such systems cannot be cheaply or quickly reconfigured to handle a change in process requirements. Domains that may benefit from easily reconfigurable modular sensing systems include flexible inspection, mobile robotics, surveillance, and even space exploration. The software architecture is distributed, and is comprised of six layers where the implementation of each layer is encapsulated from the layer above, to which it provides service. The use of a distributed and layered architecture promotes scalability, mitigates against a single point of failure, and enables each layer to be easily implemented, modified, and debugged independently of the others. The modularization of the software architecture is further facilitated through the utilization of a pre-emptive real-time operating system, which enables the concurrent execution of the various software components specific to the architecture that implement the services provided within most of its layers. Among the layers comprising the software architecture is a virtual machine layer, which implements a lightweight, architecture-specific version of Sun Microsystems’ Java Virtual Machine that runs on top of the real-time operating system. The integration of a virtual machine enables the platform-independent template algorithms utilized at the composition layer to be written once and executed on any TIM irrespective of its underlying hardware architecture. These template algorithms are unique to this software architecture and provide intelligence to a set of heterogeneous TIMs, enabling them to collaborate and behave as a single entity termed a logical module. The evaluation of the software architecture consists of performing multiple runs of two tests in which select sensors and actuators are associated with TIMs that are then allowed to interact in order to form a logical entity. The first test evaluates the behaviour of a logical module in which the constituent TIMs interact entirely through wireless communication. The second test evaluates the behaviour of a logical module in which the constituent TIMs are physically connected in various orientations, and interact through both wireless communication as well as through their physically connected faces. In both tests, correct behaviour was exhibited. However, the performance and scalability of the architecture was somewhat restricted by the limited processing and memory resources present in the current implementation of the TIMs. The design of the software architecture facilitates easy portability between embedded platforms and scales with increasing hardware capability. Therefore, utilization of future TIM hardware variations possessing increased processing and memory resources will reduce the latencies introduced throughout the architecture and lead to tangible improvements in its performance