IEEE Communications Magazine • December 2009 84 0163-6804/09/$25.00 © 2009 IEEE 1 There is no strict differ- ence between WBAN and WPAN in their defini- tions. In this article WBAN refers to a network of wireless devices in or on a human body, while WPAN refers to a network of wireless peripherals in proximity to a person. INTRODUCTION With the growing needs in ubiquitous communi- cations and recent advances in very-low-power wireless technologies, there has been consider- able interest in the development and application of wireless networks around humans. A wireless body area network (WBAN) is a radio frequen- cy (RF)-based wireless networking technology that interconnects tiny nodes with sensor or actuator capabilities in, on, or around a human body. Typically, the transmissions of these nodes cover a short range of about 2 m. Complement- ing wireless personal area networks (WPANs), 1 in which radio coverage is usually about 10 m, WBANs target diverse applications including healthcare, athletic training, workplace safety, consumer electronics, secure authentication, and safeguarding of uniformed personnel. A WBAN can also be connected to local and wide area networks by various wired and wireless communication technologies, as illustrated in Fig. 1. WBANs will play an important role in enabling ubiquitous communications, creating a huge potential market. In the area of healthcare, according to the World Health Organization’s statistics, millions of people suffer from obesity or chronic diseases every day, while the aging population is becoming a significant problem. Both the current situation and future trend call for new technologies such as WBANs to facili- tate first-hand health monitoring and medical care (point of care). From the consumer elec- tronics perspective, short-range wireless tech- nologies for human-computer interaction (HCI) and entertainment are booming. Take Bluetooth Low Energy technology as an example; a recent report predicts the initial market volume of those ultra-low-power products to be in the bil- lions. Unlike conventional wireless sensor networks (WSNs), WBANs have their own characteristics, as discussed below, which distinguish them from WSNs and also create new technical challenges. Architecture: A WBAN consists of two cate- gories of nodes: sensors/actuators in or on a human body, and router nodes around WBAN wearers or second-tier radio devices equipped on the wearers, functioning as an infrastructure for relaying data. In WSNs, however, every node functions as a sensor node as well as a router node. Density: The number of sensors/actuators deployed on the wearer depends on use cases. Typically, they are not deployed with high redun- dancy to tolerate node failures as in convention- al WSNs, and thus do not require high node density. Data rate: Most WSNs are applied for event- based monitoring, where events can happen irregularly. In contrast, WBANs are employed for monitoring human physiological activities, which vary in a more periodic manner. As a result, the application data streams exhibit rela- tively stable rates. Typical WBAN sensors are summarized later. Latency: For both healthcare and consumer applications, latency resulting from the underly- ing network such as a WBAN should be mini- mized. While power saving is definitely beneficial, replacement of batteries in WBAN nodes is much easier than in WSNs, in which nodes may be physically unreachable after deployment. Therefore, it may be necessary to maximize battery life in a WSN at the expense of higher latency. Mobility: Wearers of WBANs may move around. WBAN nodes affiliated with the same wearer move together and in the same direction. In contrast, WSN nodes are usually considered to be stationary, and any node mobility does not occur in groups. ABSTRACT A wireless body area network is a radio-fre- quency-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 func- tionalities for applications varying from health- care 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 cov- erage. Finally, a number of open research issues are discussed. CONSUMER COMMUNICATIONS AND NETWORKING Huasong Cao and Victor Leung, University of British Columbia Cupid Chow and Henry Chan, The Hong Kong Polytechnic University Enabling Technologies for Wireless Body Area Networks: A Survey and Outlook