Huasong Cao

Enabling technologies for wireless body area networks: A survey and outlook

A wireless body area network is a radio-frequency- based wireless networking technology that interconnects tiny nodes with sensor or actuator capabilities in, on, or around a human body. In a civilian networking environment, WBANs provide ubiquitous networking functionalities for applications varying from healthcare to safeguarding of uniformed personnel. This article surveys pioneer WBAN research projects and enabling technologies. It explores application scenarios, sensor/actuator devices, radio systems, and interconnection of WBANs to provide perspective on the trade-offs between data rate, power consumption, and network coverage. Finally, a number of open research issues are discussed.

Body Area Networks

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.

Enabling low bit-rate and reliable video surveillance over practical wireless sensor network

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.

Employing IEEE 802.15.4 for Quality of Service Provisioning in Wireless Body Area Sensor Networks

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.

Wireless three-pad ECG system: Challenges, design, and evaluations

Electrocardiography (ECG) is a widely accepted approach for monitoring of cardiac activity and clinical diagnosis of heart diseases. Since cardiologists have been well-trained to accept 12-lead ECG information, a huge number of ECG systems are using such number of electrodes and placement configuration to facilitate fast interpretation. Our goal is to design a wireless ECG system which renders conventional 12-lead ECG information. We pro pose the three-pad ECG system (W3ECG). W3ECG furthers the pad design idea of the single-pad approach. Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals. We provide one example of pad placement and evaluate its performance by examining ECG data of four patients available from online database. Feasibility test of our selected pad placement positions show comparable results with respect to the EASI lead system. Experimental results also exhibit high correlations between synthesized and directly observed 12-lead signals (9 out of 12 cross-correlation coefficients higher than 0.75).

Performance Analysis of ZigBee Technology for Wireless Body Area Sensor Networks

A Wireless Body Area Sensor Network (WBASN) is a radio-frequency (RF) based wireless networking technology that interconnects tiny nodes with sensor or actuator capabilities in, on or around a human body. Complementing the coverage of Wireless Personal Area Networks (WPANs), WBASNs target diverse applications. This paper extensively evaluates the performance of ZigBee technology for WBASN-WPAN system by analysis and computer simulations. Specifically, we configure the system deployment, network structure, applicable data rates for WBASN sensor nodes, and underlying radio parameters. Average reception ratio, throughput and latency have been evaluated for the overall system performance; fairness across sensor nodes has been examined; preliminary results regarding mobility support of ZigBee for WBASN are also shown. After examining the performance of ZigBee network with our WBASN-WPAN configurations, we come to the conclusion that serveral optimizations should be done before applying ZigBee to such a system.

Demonstration of a novel wireless three-pad ECG system for generating conventional 12-lead signals

Wireless monitoring of a patients electrocardiogram (ECG) is a typical application in mobile healthcare area. Inspired by application of linear transformations to ECG signals obtained in a vectorcardiographic system, we propose the wireless three-pad ECG system (W3ECG). Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals. W3ECGs system-level design, pad placements and evaluations are presented in a separate paper. This paper details W3ECGs pad design, software implementation, and experimental studies.

Design and evaluation of a novel wireless three-pad ECG system for generating conventional 12-lead signals

Electrocardiography (ECG) is a widely accepted approach for monitoring of cardiac activity and clinical diagnosis of heart diseases. In order to make ECG systems portable, easy to setup, comfortable to patients and tolerant of artifacts, wireless single-pad ECG systems have been developed. To tackle the problems raised by wireless single-pad ECG systems, we propose an upgraded version, the wireless three-pad ECG system (W3ECG). W3ECG furthers the pad design idea of the single-pad approach. We add two more pads to the W3ECG to gain spatial variety of heart activity. Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals. We provide one example of pad placement and evaluate its performance by examining ECG data of four patients available from online database. Feasibility test of our selected pad placement positions show comparable results with respect to the EASI lead system. Experimental results also exhibit high correlations between synthesized and directly observed 12-lead signals (9 out of 12 cross-correlation coefficients higher than 0.75).

Cell link: Real-time data tracking of automobiles via cell phones

This paper explores the suitability and effectiveness of employing cell phones for real-time data collection and tracking on-board automobiles. We present a novel application that runs in a commercially available GPS-enabled cell phone to continuously log a vehicles driving and engine performance and geocode the collected data at regular intervals. Data are reported to a central server in real-time, stored in a database and displayed on map available on the Internet. This information is valuable for the estimation of the congestion status on the road as well as other travel information to provide appropriate timely warning in support of a green and safe dynamic transportation environment.

A Multi-Channel Approach for Video Forwarding in Wireless Sensor Networks

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.