Introduction to Body Area Networks

The rise of interest in wearable technologies like watches and glasses has meant an increased focus on wireless networking. The term body area networks has been coined to refer to wireless network technology used in conjunction with wearables.

The primary purpose of body networks is to transmit data generated by wearable devices outside to a wireless local area network (WLAN) and/or the Internet. Wearables may also exchange data directly with each other in some cases.

Body area networks are particularly of interest in the medical field. These systems include electronic sensors that monitor patients for a variety of healthcare-related conditions. For example, body sensors attached to a patient can measure whether they have suddenly fallen to the ground and report these events to monitoring stations. The network can also track heart rate, blood pressure and other patient vital signs. Tracking the physical location of doctors within a hospital also proves useful in responding to emergencies.

Military applications of body area networking also exist, including monitoring the physical locations of field personnel. Soliders’ vital signs can also be tracked similar to healthcare patients as part of monitoring their physical well-being.

Google Glass advanced the concept of wearables for mediated and augmented reality applications. Among its features, Google Glass provided voice-controlled picture and video capturing and Internet searching. Although Google's product did not achieve mass adoption, it paved the way for future generations of these devices.

Technologies used in body area networking continue to evolve quickly as the field remains in early stages of maturity.

In May 2012, the U.S. Federal Communications Commission assigned the regulated wireless spectrum 2360-2400 MHz for medical body area networking. Having these dedicated frequencies avoids contention with other kinds of wireless signals, improving the medical network’s reliability.

The IEEE Standards Association established 802.15.6 as its technology standardization for wireless body area networks. 802.15.6 specifies various details for how low-level hardware and firmware of wearables should work, enabling makers of body network equipment to build devices capable of communicating with each other.

BODYNETS, an annual international conference for body area networking, assembles researchers to share technical information in areas such as trends in wearable computing, medical applications, network design and use of the cloud.

The personal privacy of individuals requires special attention when body networks are involved, particularly in healthcare applications. For example, researchers have developed some new network protocols that help thwart people from using transmissions from a body network as a way to track people’s physical locations (see Location Privacy and Wireless Body Area Networks).

Consider these three factors that together specially distinguish wearable networks from other kinds of wireless networks:

1. Wearable devices tend to feature small batteries, requiring the wireless network radios to run at significantly lower power levels than for mainstream networks.  That’s why Wi-Fi and even Bluetooth often can’t be used on body area networks: Bluetooth commonly draws ten times as much power as desired for a wearable, and Wi-Fi requires much more.
2. For some wearables, particularly those used in medical applications, reliable communications are a must. While outages on public wireless hotspots and home networks inconvenience people, on body area networks they can be life threatening events. Wearables also face outdoors exposure to direct sunlight, ice and generally more extreme temperatures that traditional networks do not.
3. Wireless signal interference between wearables and other kinds of wireless networks also poses special challenges. Wearables may be positioned in very close proximity to other wearables and, being naturally mobile, are brought into many diverse environments where they must co-exist with all kinds of other wireless traffic.