A medical body area network (MBAN) consists of one or more miniaturized, low power wireless devices called sensor nodes, which are worn or embedded in a person’s body to monitor their health. An MBAN uses a smartphone or other device to relay data and alerts from the sensor nodes to a central database, to be analyzed by medical personnel. MBANs are a specialized type of network developed specifically for medical use.
What is an MBAN?
MBANs evolved from the development and increasing popularity of commercial wearables, like Fitbit products that track a user’s activities and monitor their vital signs. MBANs allow medical practitioners to remotely monitor, diagnose and respond to a patient’s health status. For instance, if an ill patient is having trouble breathing and they are unable to phone emergency services, an MBAN would raise an alert and an ambulance would be dispatched automatically. MBANs are a cost-effective way to monitor patients’ medical conditions and create a reliable historical reference of their health. In 2019, Federal Communications Commission (FCC) chairman Julius Genachowski noted that, "A monitored patient has a 48% chance of surviving a cardiac arrest. Unmonitored patients have a 6% chance of survival.”
The technology enables patients to live a relatively routine life, free of repetitive doctor visits or more cumbersome monitoring technologies. MBANs are also common in residential health care centers, such as rehabilitation centers or nursing homes, where it is helpful to check on patients who are recuperating or might need intermittent medical care. The pharmaceutical industry opts for them when testing new products, so those scientists can fully understand effects. They also find use in niche cases where a person’s physiobiological metrics can provide insight on performance or safety. High performance athletes, astronauts or military members might be some of those users.
How do these devices work?
Communication methods, protocols, and security for MBANs are specified by the latest standard for WBANs, IEEE 802.15.6. The three PHYSICAL (PHY) layers used by MBANs to manage physical connectivity between devices and the data link layer in the OSI model are narrow band (NB), ultra-wide band (UWB) and human body communication (HBC). NB was designed to support wearables and can handle data rates of up to 1 Mbps. UWB can manage data rates of up to 20 Mbps and is used in high-priority, quality-of-service (QoS) applications. HBC is a non-radio frequency (RF) wireless system. Data is transmitted through the human body using electric field communication (EFC) technology. It can handle data rates of up to 2 Mbps.
MBAN communication architecture has three tiers based on the WBAN framework: intra-WBAN, inter-WBAN and beyond-WBAN. Intra-WBAN comprises the sensor nodes. Collected data is transferred to the inter-WBAN via ZigBee, Wi-Fi or Bluetooth. Inter-WBAN uses a PDA, smartphone, or other electronic device to transfer this information to the beyond-WBAN tier using 3G, 4G, 5G, or WLAN where healthcare professionals can access it via the internet.
MBAN terminology is still fluid. An MBAN is configured in a star topology with a central hub, usually a wearable device or master transmitter that connects sensor nodes. Sensor nodes are sometimes referred to as biosensors, motes or client transmitters. (A sensor simply senses data whereas a sensor node can perform some processing and communication functions.)
Sensor nodes comprise physical and chemical components that sense analytes, like chemical constituents in a patient’s body, and convert them into electronic signals. The master transmitter is connected to a central location monitored by medical personnel via a large area network (LAN), through Ethernet, Wi-Fi or a Wireless Medical Telemetry Service (WMTS).
40 MHz of protected spectrum in the 2,360 MHz to 2,400 MHz band has been specifically set aside for wireless medical devices by the FCC, with the spectrum between 2,360 MHz and 2,390 MHz restricted to indoor use. The transmit power is 1 mW over 1 MHz bandwidth primarily for indoor communications so as not to interfere with other applications using this band range. The 2,390 MHz to 2,400 MHz band has a transmit power of 20 mW over 5 MHz. These bands are Industry Science and Medical (ISM) bands, relatively quiet bands as opposed to other noisier Wi-Fi bands like the 2,400 MHz to 2483.5 MHz range.
MBANs are used by health professionals and medical researchers to monitor the health and well-being of patients. There are two types of applications: implantable, like cardioverter defibrillators (ICDs), and wearable, like electrocardiogram (ECG) devices. Sensor nodes measure, control and track parameters like temperature, motion, blood pressure, blood glucose, brain activity, digestion and heart rate. MBANs are used to monitor sleep patterns, pain, depression, asthma and location. For instance, they can track the whereabouts of elderly people who have fallen or gone missing.
What's next for MBANs
There are numerous opportunities for MBANs to provide cost-efficient medical monitoring in environments from the military to medical R&D. But the development of MBANs is still at an early stage and much of the literature focused on MBAN capabilities is speculative, indicating a need for further research and innovative solutions.
For instance, one of the two main challenges with MBANs was initially that because batteries were small and power-limited, energy consumption needed to be reduced to secure a long battery life. One possible solution: modern MBANs that use kinetic (body) energy instead of batteries. The second challenge was security. If an attacker could intercept and either alter or incapacitate a message between a sensor node and a doctor, it could threaten the patient’s life. Research continues into security options for modern MBANs, which include those specified by IEEE 802.15.6 and Wi-Fi Protected Access version 2 (WPA-2). Bluetooth and ZigBee too have their own security services, standardized respectively by IEEE 802.15.3 and IEEE 802.15.4.
Securing the collection of biosensor data, identifying lines of responsibility if networks malfunction, hardening power supplies, mitigating operator errors, the need for self-testing sensor nodes, further miniaturization of sensor nodes, and network scalability are just some of the challenges still facing the modern MBAN.