Recent years have witnessed the emergence of machine-to-machine (M2M) networks as an efficient means for providing automated communications among distributed devices. Automated M2M communications can offset the overhead costs of conventional operations, thus promoting their wider adoption in fixed and mobile platforms equipped with embedded processors and sensors/actuators. In this paper, we survey M2M technologies for applications such as healthcare, energy management and entertainment. In particular, we examine the typical architectures of home M2M networks and discuss the performance tradeoffs in existing designs. Our investigation covers quality of service, energy efficiency and security issues. Moreover, we review existing home networking projects to better understand the real-world applicability of these systems. This survey contributes to better understanding of the challenges in existing M2M networks and further shed new light on future research directions.

With the rapid development of hardware and embedded systems, wireless sensor networks (WSNs) are being developed for surveillance applications. While meriting more in-depth research and development, deploying a practical WSN for surveillance is challenging due to the limited power and bandwidth of the battery-operated sensor nodes. In this paper, we first propose an energy-efficient image transportation strategy through motion detection. In case of data delivery over long distance, this paper further investigates the use of cooperative communications to design a reliable image transmission scheme over WSN, and demonstrates its effectiveness in improving network reliability in wireless multimedia sensor networks.

We present a new scheme to automatically identify the locations of wearable sensor nodes in a wireless body area network (WBAN). Instantaneous atmospheric air pressure readings are compared to map nodes in physical space. This enhancement enables unassisted sensor node placement, providing a practical solution to obtain and continuously monitor node locations without anchor nodes or beacons. To validate this localization scheme, a statistical analysis is conducted on a set of air pressure sensors and a prototype WBAN to examine the performance and limitations. Based on a 60 cm separation between nodes, indicative of the expected separation between limbs and placement positions along a patient's body, the measurements consistently exceeded p -value reliability within a 95% confidence interval. We also present and experimentally demonstrate an enhancement aiming to reduce false-positive (Type I) errors in conventional accelerometer-based on-body fall detection schemes. Our statistical analysis has shown that by continuously monitoring the patient's limb positions, the WBAN would be better able to discriminate “fall-like” motions from actual falls.

Body area network (BAN) technology has emerged in recent years as a subcategory of wireless sensor network technology targeted at monitoring physiological and ambient conditions surrounding human beings and animals. However, BAN technology also introduces a number of challenges seldom seen before due to the scarcity of hardware and radio communication resources and the special properties of the radio environment under which they operate. In this chapter, we review the foundations of BANs along with the most relevant aspects relating to their design and deployment. We introduce current, state-of-the-art applications of BAN, as well as the most challenging aspects concerning their adoption and gradual deployment. We also discuss issues pertaining to sensor node communications, trade-offs, and interfacing with external infrastructure, in addition to important aspects relating to wearable sensor technology, enabling software and hardware, as well as future trends and open research issues in BANs.

We present a new approach to identifying and verifying the location of wearable wireless sensor nodes (W2SNs) placed on a body by inferring differences in altitudes using atmospheric air pressure sensors. This technique is aimed at long-term, in-home monitoring applications of the elderly and patients with chronic conditions, where the user has the freedom to install and remove the W2SNs as required without caregiver assistance. Our prototype shows that each IEEE 802.15.4-capable W2SN, employing pressure sensors, is capable of detecting altitude changes sufficient to distinguish between the relative elevation of a patient's arm and leg, and recognize which W2SN is placed on which limb; preliminary results show detection in altitudes down to 39cm apart.

This paper advances a novel approach that facilitates the location of services and/or digital assets advertised by directories in a Mobile Ad hoc Network. The proposed Service Directory Placement Protocol (SDPP) improves scalability and reduces packet traffic overhead by advancing a multi-directory extension of an earlier approach that relied on the migration of a single directory through the network. This investigation demonstrates that modelling the directory replication problem as a Semi-Markov Decision Problem solved by means of a Reinforcement Learning technique known as Q-learning improves the performance of SDPP. Computer simulations validate the feasibility of the proposed scheme that enables packet overhead reductions between 15 and 75 %, whereas the directory location success rate improves by up to 11% when compared with pure broadcast flooding and other existing approaches in wireless networks where hosts move at walking speeds.

We present a simple but effective handoff protocol that enables continuous monitoring of ambulatory patients at home by means of resource-limited sensors. Our proposed system implements a 2-tier network: one created by wearable sensors used for vital signs collection, and another by a point-to-point link established between the body sensor network coordinator device and a fixed access point (AP). Upon experiencing poor signal reception in the latter network tier when the patient moves, the AP may instruct the sensor network coordinator to forward vital signs data through one of the wearable sensor nodes acting as a temporary relay if the sensor-AP link has a stronger signal. Our practical implementation of the proposed scheme reveals that this relayed data operation decreases packet loss rate down to 20% of the value otherwise obtained when solely using the point-to-point, coordinator-AP link. In particular, the wrist location yields the best results over alternative body sensor positions when patients walk at a 0.5 m/s.

Advances in wireless communication technologies, such as wearable and implantable biosensors, along with recent developments in the embedded computing area are enabling the design, development, and implementation of body area networks. This class of networks is paving the way for the deployment of innovative healthcare monitoring applications. In the past few years, much of the research in the area of body area networks has focused on issues related to wireless sensor designs, sensor miniaturization, low-power sensor circuitry, signal processing, and communications protocols. In this paper, we present an overview of body area networks, and a discussion of BAN communications types and their related issues. We provide a detailed investigation of sensor devices, physical layer, data link layer, and radio technology aspects of BAN research. We also present a taxonomy of BAN projects that have been introduced/proposed to date. Finally, we highlight some of the design challenges and open issues that still need to be addressed to make BANs truly ubiquitous for a wide range of applications.

We examine the applicability of mobile software codes to perform networking tasks in wireless and mobile computing environments. We contend that the advent of wireless technologies during the past decade has turned computer networks increasingly complex to manage. In particular, factors such as context awareness and user mobility are now crucial in the design of communications protocols used by portable devices with moderate to severe bandwidth and battery power limitations. Unlike hard-coded communication protocols that fulfill a specific need, mobile software agents can be deployed to deal with a range of tasks and can be designed to efficiently adapt to diverse circumstances. We present our latest advancements in the areas of mobile ad hoc networking and wireless sensor networks using mobile agents (MAs). We also elaborate on the importance of engineering an efficient migration strategy as the single most distinctive proceeding that an MA performs to operate efficiently. In addition, we describe the Wiseman system for scripting MAs that can perform networking tasks in both homogeneous and heterogeneous wireless network environments. Monitoring, tracking, and E-healthcare applications are discussed and evaluated at length.

We describe the initial design, implementation and testing of a wearable sensor system employed for human motion analysis. Our proposed system is part of an ongoing investigation aimed at efficiently timing the self-administration of prescription drugs in Parkinson's disease patients by using wireless sensors to capture distinctive motion patterns that indicate the onset of dyskinesia lapses as the prescription drug wears off. Our prototype incorporates three pairs of accelerometer/gyroscope sensors, each connected to a wireless node equipped with an IEEE 802.15.4 radio. Sensor data are transmitted to a computer that is employed for visualization. We describe practical experience encountered during the initial development of our prototype, and outline the potential battery and bandwidth conservation benefits introduced by employing popular signal processing methods.

As software entities that migrate among nodes, mobile agents (MAs) are able to deliver and execute codes for flexible application re-tasking, local processing, and collaborative signal and information processing. In contrast to the conventional wireless sensor network operations based on the client-server computing model, recent research has shown the efficiency of agent-based data collection and aggregation in collaborative and ubiquitous environments. In this paper, we consider the problem of calculating multiple itineraries for MAs to visit source nodes in parallel. Our algorithm iteratively partitions a directional sector zone where the source nodes are included in an itinerary. The length of an itinerary is controlled by the angle of the directional sector zone in such a way that near-optimal routes for MAs can be obtained by selecting the angle efficiently in an adaptive fashion. Simulation results confirm the effectiveness of the proposed algorithm as well as its performance gain over alternative approaches.

In this paper, we consider the use of multiple mobile software agents to perform different tasks in wireless sensor networks (WSNs). To this regard, determining the number of mobile agents in the WSN remains an open issue in solving multi-agent itinerary planning (MIP) problem. We propose a novel scheme entitled MST-MIP based on minimum spanning tree, where each branch stemmed from the sink corresponds to a group of source nodes assigned for a mobile agent to visit. Furthermore, a balancing factor α is introduced to achieve a flexible trade-off control between energy cost and task duration, and the balancing MST-MIP algorithm is named BST-MIP. Extensive experiments show that MST-MIP has lower energy consumption than previous MIP proposals, while BST-MIP decreases the task duration up to 50

Radio frequency identification technology has received an increasing amount of attention in the past few years as an important emerging technology. However, the intrinsically passive features of existing RFID systems, to which we refer as first-generation RFID systems, render their adaptation to real-world dynamics in order to efficiently comply with up-to-date applicationspecific requirements difficult. To address this challenging issue, we propose an evolution to second-generation RFID systems characterized by the introduction of encoded rules that are dynamically stored in RFID tags. This novel approach facilitates the systems' operation to perform actions on demand for different objects in different situations, and enables improved scalability. Based on 2G-RFID-Sys, we propose a novel e-healthcare management system, and explain how it can be employed to leverage the effectiveness of existing ones. It is foreseeable that the flexibility and scalability of 2G-RFIDSys will support more automatic and intelligent applications in the future.

We present a simple but effective scheme that leverages the effective packet rate in multi-hop Wireless Sensor Networks (WSN) to forward constrained video feeds. The maximum packet rate observed in multi-hop WSN is seldom realized due to various factors. One limitation is that the implementing hardware may possess only one half-duplex radio interface. Additionally, most data forwarding schemes found in the WSNs literature employ a single radio frequency channel for their transmissions. Therefore, packet transmissions must be spaced out to avoid collisions in the wireless medium, decreasing the packet rate that can be attained. Our approach multiplexes the transmission of individual data packets through two separate paths, each of which employs a different subset of frequency channels, thus enabling packet rates closer to the maximum value. We demonstrate the practicality of our approach over commercial WSN devices to forward constrained video feeds, and conduct performance evaluations to gauge its efficiency.

In this paper we present a flexible middleware platform for re-tasking Wireless Sensor Networks (WSNs) that we coin WISEMAN. Based on our previous experiences with mobile agents in computer networks, we developed a lightweight interpreter of text-based codes that enables their deployment in order to implement diverse WSNs tasks. WISEMAN occupies 19Kbytes of TinyOS embedded code, and 3 Kbytes of memory to operate in commercially available sensor nodes. We examine different agent migration methodologies, and present performance evaluations to gauge their efficiency in terms of delay and bandwidth with aims to determine which approach works best depending on the intended agent application. Our results indicate that WISEMAN agents can migrate as fast as 235 mS per-hop, which is comparable to existing approaches, while supporting the necessary code execution flexibility needed for the rapid implementation and deployment of WSN re-tasking programs.

Recent years saw a significant number of efforts aimed at the efficient creation of Scatternets: multi-hop Wireless Personal Area Networks (WPAN) created by means of Bluetooth technology that allows users to seamlessly exchange information. We present a novel solution to the Scatternet formation problem by means of mobile programs that help realise our goal according to a predefined topology formation policy. We argue that this approach offers improved flexibility when compared with existing protocols that employ the message-passing communications model. The effectiveness of our proposed mobile processing scheme is demonstrated through computer simulations.