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.

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.

A wireless body area sensor network (WBASN) is a wireless networking technology that interconnects tiny nodes with sensing capabilities in, on or around a human body. The vital-sign information collected by these sensors can then be used by care-givers to assess the health of a patient. Therefore, it is necessary to provide reliable communication services to prioritized WBASN data streams with quality of service (QoS) guarantees. However, existing research has not devoted enough attention to this issue. This paper proposes a QoS provisioning framework for WBASN traffic employing the IEEE 802.15.4 super-frame structure in the beacon-enabled mode. A method of prioritizing WBASN traffic is proposed, along with algorithms for admission control and scheduling. Computer simulations reveal that our scheme is able to guarantee a 100% time constraint compliance ratio for traffic in contention access periods, and a 99.2% to 99.9% constraint compliance ratio for traffic in contention-free periods, while still admitting and accommodating tens of WBASN traffic streams.

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.

We present our Service Directory Placement Protocol (SDPP), a multi-directory scheme for service discovery in Mobile Ad-hoc Networks (MANETs). SDPP promotes the use of both fixed and mobile directories co-existing in a hybrid setting comprised of devices with different memory availability. Our proposed system is based on a heuristic approach, whose performance is optimized by formulating the directory-placement problem as a Semi-Markov Decision Process solved by Q-Learning. Performance evaluations reveal typical performance gains ranging between 15% and 75% of SDPP compared with a default broadcast approach for MANETs comprised of hosts moving at pedestrian speeds. A two-step process for practical implementation based on "off-line" computer simulations is also described.

We present the Service Directory Placement Algorithm (SDPA), a directory-placement scheme that leverages the performance of existing service discovery protocols over wireless ad-hoc networks. SDPA promotes the deployment of a nomadic service directory, whose current location in the network varies according to the dynamics of service-discovery queries driven by the users' applications and partial knowledge of the network's topology. SDPA is based on a heuristic approach, whose performance is optimized by formulating the directory-placement problem as a Semi-Markov Decision Process solved by means of a reinforcement-learning technique known as Q-Learning. Performance evaluations obtained through computer simulations of networks with up to 45 hosts moving at pedestrian walking speeds equal to or slower than 2 m/s reveal average bandwidth savings close to 50% over a default broadcast approach for service discovery once an efficient directory-placement policy is found.