Richard Tynan

Autonomic wireless sensor networks

This paper seeks to demonstrate that autonomic behaviour is not restricted to resource-rich system, as typified by large servers, but can be incorporated into distributed and computationally challenged devices. Methods regarding how wireless sensor networks can benefit from the use of autonomic techniques without being overburdened with additional computing costs will be discussed. This will be achieved through the use of multi-agent systems (MAS). The discussion is grounded in the development of an autonomic wireless sensor network aimed at environmental sensing, an environmental nervous system. Finally, we provide empirical evidence of self-management via the use of distributed agents.

Agents for wireless sensor network power management

The primary function of wireless sensor networks is data acquisition or monitoring of some medium, such as temperature. In many instances these networks are deployed throughout inaccessible or hazardous regions meaning frequent maintenance such as battery replacement is undesirable and in some cases impossible. Intelligent power management for these devices is critical in maximizing the networks life span and ultimately will dictate the success of such deployments. This longevity must, however, be achieved while maintaining the integrity of the sensory data harvested by the network. Due to the inherent distributed nature of wireless sensor networks, intelligent software agents lend themselves to performing this power management in such a distributed domain. In this paper we examine some of the potential decisions an agent may face regarding intelligent power management and we look at how the stronger notion of agency could be employed to allow a richer deliberation regarding potential decisions. Allowing more adaptive control of WSNs in light of their computationally challenged nature.

Intelligent agents for wireless sensor networks

Interpolation is a technique used to estimate the value of a function at a given location, assuming that the values of the function are known for surrounding locations. A Wireless Sensor Network (WSN) is a spatially distributed set of sensor platforms usually with a range of sensory modalities e.g. temperature or light intensity. Interpolation can be used to intelligently activate nodes of a WSN for power conservation. In this paper we argue that this can form the basis for a distributed agent-based power management scheme and we propose an algorithm for achieving this. As a corollary to this approach we will also demonstrate the feasibility of using distributed, intelligent agents on computationally challenged devices such as the sensor nodes.

Protocol assessment issues in low duty cycle sensor networks: the switching energy

Energy assessment of MAC protocols for wireless sensor networks is generally based on the times of transmit, receive and sleep modes. The switching energy between two consecutive states is generally considered negligible with respect to them. Although such an assumption is valid for traditional wireless ad hoc networks, is this assumption valid also for low duty cycle wireless sensor networks? The primary objective of this work is to shed some light on relationships between node switching energy and node duty cycle over the total energy consumption. In order to achieve the target, initially, we revisit the energy spent in each state and transitions of three widespread hardware platforms for wireless sensor networks by direct measurements on the EYES node. Successively, we apply the values obtained to the SMAC protocol by using the OmNet++ simulator. The main reason for using SMAC is that it is the protocol normally used as a benchmark against other architectures proposed

Agent Migration and Communication in WSNs

Intelligent agents offer a viable paradigm for enabling AmI applications and services. As WSN technologies are anticipated to provide an indispensable component in many application domains, the need for enabling the agent paradigm to encompass such technologies becomes more urgent. The resource-constrained ad-hoc nature of WSNs poses significant challenges to conventional agent frameworks. In particular, the implications for agent functionality and behaviour in a WSN context demand that issues such as unreliable message delivery and limited power resources, amongst others, be considered. In this paper, the practical issues of agent migration and communication are considered in light of WSN constraints. The discussion is illustrated through a description of approaches adopted by Agent Factory Micro Edition (AFME).

Interpolation for wireless sensor network coverage

One of the primary issues for any wireless sensor network (WSN) deployment is that of longevity of the network. The lifespan of the network must be maximized while maintaining the quality of the sensory data received from the network. Most current solutions for achieving this require the definition of a sensing radius for each sensor together with a coverage level k. The sensed area is covered if every point within the area is inside the sensing radius of at least k sensors. When some points are covered by more than k sensors, it may be possible to instruct the surplus sensors to enter a low power sleep mode. This will conserve the energy of the network while maintaining the required coverage level. In. this paper we propose a novel alternative to this approach based on interpolation. If the sensor network is capable of interpolating the sensed medium at a given sensors location to a specified accuracy or higher, then we propose that this sensor is redundant and can be put into sleep mode. We demonstrate our approach using live sensory data.

MERLIN: A Synergetic Integration of MAC and Routing Protocol for Distributed Sensor Networks

Notoriously, energy-efficient MAC protocols cause high latency of packets. Such delays may well increase when a routing protocol is applied. Therefore, quantifying the end-to-end delay and energy consumption when low duty cycle MAC and routing protocols are jointly used, is of particular interest. In this paper, we present a comprehensive evaluation of the MERLIN (MAC and efficient routing integrated with support for localization) protocol. MERLIN integrates MAC and routing features into a single architecture. In contrast to many sensor network protocols, it employs a multicast upstream and multicast downstream approach to relaying packets to and from the gateway. Simultaneous reception and transmission errors are notified by using asynchronous burst ACK and negative burst ACK. A division of the network into timezones, together with an appropriate scheduling policy, enables the routing of packets to the closest gateway. An evaluation of MERLIN has been conducted through simulation, against both the SMAC and the ESR routing protocols,which is an improved version of the DSR algorithm. The results illustrate how both SMAC and ESR, jointly used in low duty cycle scenarios, can cause an impractical and very high end-to-end delays. MERLIN, as an integrated approach, notably reduces the latency, resulting in nodes that can operate in a very low duty cycle. Consequently, an extension of the operative lifetime of the sensor network is achieved.

Garment-based monitoring of respiration rate using a foam pressure sensor

Comfortable body monitoring is crucial to many wearable devices. However, many traditional sensors impede wearability by their physical structure or functional requirements. This paper presents the application of a novel garment-integrated foam-based pressure sensor used for monitoring the wearers respiration rate. The sensor was evaluated in a torso garment during a 10-minute treadmill test. Results were accurate within one breath per minute, as compared to a standard airflow breathing test.

An energy-efficient and low-latency routing protocol for wireless sensor networks

Recent advances in wireless sensors network (WSN) technology have made possible the manufacturing of tiny low-cost, low-power sensors with wireless multi-hop communication and sensing capabilities. Energy conservation for WSNs is a primary objective that needs to be addressed at all layers of the networking protocol stack. In many applications latency is another crucial factor to be addressed. However this must be done in the context of the energy constraints imposed by the network. In this paper we present an experimental evaluation of two node scheduling regimes within MERLIN (MAC energy efficient, routing and localization integrated), an energy-efficient low-latency integrated protocol for WSNs. In particular we contrast the X and V scheduling family schemes with respect to the following properties: network setup time, network lifetime and message latency. We conduct our experiments within the OmNet++ simulator.

Multi-agent system architectures for wireless sensor networks

Traditionally Multi-Agent Systems have been thought of in terms of devices that possess a relatively rich set of resources e.g. power, memory, computational ability and communication bandwidth. This is usually necessary due to the complex deliberation and negotiation processes they require to fulfil their goals. Recently, networked devices have become available on the millimeter scale called Wireless Sensor Networks (WSNs), which pose new challenges because of their constrained resources. However what these devices lack in resources they make up for in numbers due to their small inexpensive nature. In this paper we identify some of the existing MAS architectures for WSNs, and we propose some novel architectures of our own.