Nikolaos A. Pantazis

A survey on power control issues in wireless sensor networks

ith the proliferation in sensor nodes and the development in wireless communication technologies, Wireless Sensor Networks (WSNs) have gained worldwide attention in recent years. They facilitate monitoring and controlling of physical environments from remote locations with great accuracy and represent a significant improvement over wired sensor networks. WSNs are employed in a vast variety of fields, such as: environmental monitoring (e.g., temperature, humidity), monitoring disaster areas providing relief, file exchange, conferencing, home, health (monitoring patients and assisting disabled patients), commercial applications including managing inventory and monitoring product quality and military purposes. Their function is to collect and disseminate critical data, while their position does need to be engineered or predetermined, in contrast to the wired ones. This allows random deployment in inaccessible terrains or disaster relief operations. On the other hand, this also means that WSN protocols and algorithms must possess self-organizing capabilities [1]. Realization of the wireless sensor network applications requires wireless ad-hoc networking techniques. Although a great number of protocols and algorithms have been proposed for wireless ad-hoc networks, they are not well-suited to the unique features and application requirements of WSNs for the following reasons: • The topology of a WSN changes very frequently. • The number of sensor nodes in a WSN can be several orders of magnitude higher than the number of sensor nodes in a wireless ad-hoc network. • Sensor nodes are densely deployed in a sensor field • Sensor nodes mainly use a broadcast communication paradigm, whereas most wireless ad-hoc networks are based on point-to-point communications. • Sensor nodes may not have global identification due to their large amount of overhead and large number of sensors in the WSN. • Sensor nodes are limited in power, computational capacity and memory. This last requirement is the primary limitation of the WSNs. Their survivability, as it has already been mentioned, depends on power control and power management of the consumed energy, as well as on network connectivity. Considerable research has been focused at overcoming the deficiencies of energy consumption of the sensor nodes, guaranteeing the sensor networks existence and increasing the sensor networks lifetime in such energy-constrained environments through more power control schemes regarding resource allocation, routing and low-energy consumption. This survey attempts to provide an overview of these issues as well as the solutions proposed in recent literature. ABSTRACT A Wireless Sensor Network (WSN) is actually composed of a large number of very small …

Energy efficiency in wireless sensor networks using sleep mode TDMA scheduling

Power saving is a very critical issue in energy-constrained wireless sensor networks. Many schemes can be found in the literature, which have significant contributions in energy conservation. However, these schemes do not concentrate on reducing the end-to-end packet delay while at the same time retaining the energy-saving capability. Since a long delay can be harmful for either large or small wireless sensor networks, this paper proposes a TDMA-based scheduling scheme that balances energy-saving and end-to-end delay. This balance is achieved by an appropriate scheduling of the wakeup intervals, to allow data packets to be delayed by only one sleep interval for the end-to-end transmission from the sensors to the gateway. The proposed scheme achieves the reduction of the end-to-end delay caused by the sleep mode operation while at the same time it maximizes the energy savings.

Energy-efficient route selection strategies for wireless sensor networks

Wireless Sensor Networks (WSNs) facilitate monitoring and controlling of physical environments from remote locations with the best possible accuracy. Sensor networks are wireless networks consisting of groups of small, inexpensive nodes, which collect and disseminate critical data. Also, sensor nodes have various energy and computational constraints due to their inexpensive nature and ad hoc method of deployment. Considerable research has been focused on overcoming these deficiencies through low-energy consumption schemes. Among other factors, the route selection strategy may have an impact on the sensors lifetime, and following on the network lifetime. In this paper, we study various route selection strategies that aim at prolonging the lifetime of WSNs. Also, a new route selection scheme is proposed, that increases further the network lifetime. The performance of these schemes is analyzed through simulation.

Power control schemes in wireless sensor networks for homecare e-health applications

Power control is an important research topic for ad-hoc Wireless Sensor Networks (WSNs). In todays sophisticated and competitive wireless environment, the control of the energy consumption in a WSN for homecare e-health makes it possible to guarantee basic levels of system performance, such as connectivity, throughput, delay, QoS and survivability in the presence of both mobility-immobility and a large number of sensor nodes. Recent advances in sensor fabrication technology, low-power digital and analogue electronics, and low-power wireless communication systems have made it possible to develop low-cost, robust and survivable WSNs to support activities such as assisted living and ambient intelligence (Aml). A large variety of approaches for intelligent energy-efficient schemes have been simulated over different performance metrics. In this paper, various decision support schemes are proposed evaluating the selection of different network infrastructures in terms of routing optimization and signal strength selection.

Hierarchical energy efficient routing in Wireless Sensor Networks

The domain of wireless sensor networks (WSNs) is one of the most rapidly growing scientific fields. This is because not only the technological advances have enabled the development of advanced sensor nodes with extremely low cost but the potential applications of such structures are ever growing too. WSNs differ from traditional wireless communication networks in several of their characteristics. One of them is power awareness, due to the fact that the batteries of sensor nodes have a restricted lifetime and are difficult to be replaced. Therefore, all protocols must be designed in such a way as to minimize energy consumption and preserve the longevity of the network. That is why, routing protocols in WSNs aim mainly to accomplish power conservation while in traditional networks they focus primarily on the quality of service (QoS). Recent advances in WSNs have led to many new protocols specifically designed for sensor networks where energy awareness is an essential issue. This work suggests the development of such hierarchical routing protocol, named SHPER (scaling hierarchical power efficient routing), which proves to be particularly effective.

Increasing Intelligent Wireless Sensor Networks Survivability by Applying Energy-Efficient Schemes

Intelligent Energy efficiency is an important research topic for ad-hoc Wireless Sensor Networks (WSN). Power saving makes it possible to guarantee basic levels of system performance, such as connectivity, throughput and delay, in the presence of both mobility-immobility and a large number of sensor nodes. A large variety of approaches for intelligent energy-efficient schemes have been proposed in the literature focusing on different performance metrics. This article presents a comprehensive survey of recent energy-efficient schemes in ad-hoc wireless sensor networks, the application of which increases nodes’ lifetime and thus, network connectivity and survivability.

Energy-efficient routing protocols in wireless sensor networks for health communication systems

Wireless Sensor Networks (WSNs) have their own unique nature of distributed resources and dynamic topology. This introduces very special requirements that should be met by the proposed routing protocols for the WSNs. A Wireless Sensor Network routing protocol is a standard which controls the number of nodes that come to an agreement about the way to route packets between all the computing devices in mobile wireless networks. Today, wireless networks are becoming popular and many routing protocols have been proposed in the literature. Considering these protocols we made a survey on the WSNs energy-efficient routing techniques which are used for Health Care Communication Systems concerning especially the Flat Networks Protocols that have been developed in recent years. Then, as related work, we discuss each of the routing protocols belonging to this category and conclude with a comparison of them.

Enhanced route selection for energy efficiency in wireless sensor networks

Wireless Sensor Networks (WSNs) facilitate monitoring and controlling of physical environments from remote locations with the best possible accuracy. Sensor networks are dense wireless networks consisting of groups of small, inexpensive nodes, which collect and disseminate critical data. Thus, sensor nodes have various energy and computational constraints, due to their inexpensive nature and ad hoc method of deployment. Considerable research has been focused at overcoming these deficiencies through low-energy consumption schemes. Among, other factors, the route selection strategy may have an impact on the network lifetime. In this paper, we present a lifetime prolonging route selection strategy for wireless sensor networks, namely Low Cost Min-Max Energy Routing (LCMMER). The proposed algorithm tries to avoid the least-energy nodes, while at the same time to maintain low energy consumption for each transmission. Simulation results confirm the superiority of the proposed strategy in terms of node lifetime and network connectivity in comparison with the Minimum Total Transmission Power Routing (MTPR) and the Min-Max Battery Cost Routing (MMBCR) route selection strategies.

Enhanced End-to-End TDMA for wireless ad-hoc networks

TDMA has increasingly been used as the MAC layer for ad-hoc networks. However, the use of TDMA in multi-hop networks leads to the problem of distributing the available slots among the wireless nodes in an effective manner. The exact way the slots are distributed among the transmitting nodes has an impact on various performance parameters of the network, such as the end-to-end delay and the capacity. In general, an increase of the end-to-end delay may lead to an increased network capacity. In this paper, we study two new end-to-end TDMA scheduling algorithms, and compare them in terms of end-to-end delay and network capacity.

An Automated System for Integrated Service Management in Emergency Situations

The integration of Wireless Communications and Computer Science can lead to the development of advanced systems and services. This paper presents the development of an automated management system for road traffic control in emergency situations. This system consists of a Wireless Sensor Network (WSN) and a centralized control system. The performance evaluation of the system is accomplished through various scenarios of use.