Overview of Medical Body Area Networks
Written By: Bob Buckiewicz
Bob is the Director of Hardware Development at LSR. He has over 30 years of experience in the development of low power wireless communication systems. Bob is a graduate of the University of Illinois (BSEE 1980) holds four patents, has two patents pending, and is a winner of Electronic Design News (EDN) magazine's "Excellence in Design" award for development of the world's first frequency synthesized walkman portable radio.
FCC Dedicates Spectrum to Medical Body Area Networks (MBAN)
Washington, D.C.—The Federal Communications Commission (FCC) has advanced its wireless health care agenda by adopting rules that will enable Medical Body Area Networks (MBAN), low-power wideband networks consisting of multiple body-worn sensors that transmit a variety of patient data to a control device. MBAN devices free patients from cumbersome cables that tether them to their hospital beds. MBAN devices provide a cost effective way to monitor every patient in a healthcare institution, so clinicians can provide real-time and accurate data, allowing them to intervene and save lives. Wireless devices that operate on an MBAN spectrum can be used to actively monitor a patient’s health, including blood glucose and pressure monitoring, delivery of electrocardiogram readings, and even neonatal monitoring systems. MBAN devices will be designed to be deployed widely within a hospital setting and will make use of inexpensive disposable body-worn sensors. MBAN technology will also make it easier to move patients to different parts of the health care facility for treatment and can dramatically improve the quality of patient care by giving health care providers the chance to identify life-threatening problems or events before they reach critical levels.
Figure 1 - MBAN Device (courtesy FCC photostream)
Currently almost 50% of all patients in U.S. hospitals are not monitored. FCC Chairman Julius Genachowski stated that MBAN systems will enable patient monitoring in real time that is both accurate and cost-effective. “A monitored patient has a 48% chance of surviving a cardiac arrest. Unmonitored patients have a 6% chance of survival.” By allowing for continuous monitoring of patients, MBAN enabled devices can help doctors respond more quickly in emergency situations and improve overall in-home patient care as well. According to the FCC, this action “represents an improvement over traditional medical monitoring devices,” as it makes it easier to move a patient, allows for increased patient comfort, and could represent annual savings of $1.2 billion in expenses accrued after relocating patients to different clinics and departments.
FCC Rules and Regulations for MBAN
This final ruling sets aside 40 MHz of protected spectrum in the 2360-2400 MHz band specifically for wireless medical devices. Dedicated spectrum should help alleviate the interference problems normally associated with Wi-Fi and other high-powered devices used in hospitals. The 2360-2390MHz frequency range is available on a secondary basis. The FCC will expand the existing Medical Device Radio communication (MedRadio) Service in Part 95 of its rules. MBAN devices using the band will operate under a ‘license-by-rule’ basis, which eliminates the need to apply for individual transmitter licenses. Usage of the 2360-2390MHz frequencies are restricted to indoor operation at health-care facilities and are subject to registration and site approval by coordinators to protect aeronautical telemetry primary usage. Operation in the 2390-2400 MHz band is not subject to registration or coordination and may be used in all areas including residential.
The MBANs Advantage
Small, wearable sensors monitor patients’ vital signs and collect real-time clinical information such as temperature, blood glucose levels, blood pressure, pulse and respiratory function, and aggregate it over an MBAN at a nearby device for local processing and forwarding to centralized displays and electric medical records. Body sensors can also be used to deliver medical therapy to particular areas of the body.
Key advantages include:
- Allowing patient monitoring throughout the entire hospital which increases comfort and mobility
- Patients can be monitored before they reach the hospital and after they are sent home
- Enhanced patient safety, care and comfort by eliminating the need for cables that restrict patients by tethering them to hospital beds
- Ease of transport: allowing patients to be easily relocated in different clinics
- Medical-equipment makers employing wireless monitoring should rid hospital rooms of nests of cables and let patients move out of expensive intensive-care wards
- Infection control: eliminating wires could help reduce the risk of infection
Figure 2 - MBAN Devices (courtesy of GE Healthcare)
FCC and FDA Regulatory Status
- Beginning October 1, 2012 devices are permitted under the FCC’s “license by rule” standards under which healthcare providers must register their devices and coordinate how and when they are used.
- The FCC is expected to appoint a frequency coordinator by next June to determine how two users can share the spectrum without interfering with one another. Both GE Healthcare and Philips Healthcare Systems are recommending that this process be expedited. American Society for Healthcare Engineering (ASHE), which is now the WMTS coordinator, has expressed its interest in being the MBAN coordinator as well.
- MBAN devices will need to receive FCC and Food and Drug Administration (FDA) approval before they can be used in hospitals. The FCC and FDA, which has regulatory control over mobile medical devices, are working together to streamline the approval process. The process could call for FCC to review the technical aspects of a device, while FDA would review its medical features.
- The FCC's approval makes the U.S. the first country to allocate spectrum for MBANs.
- The 2360- 2400 MHz band holds potential for international harmonization. Both Texas Instruments and GE Healthcare note that the band is included in the technical requirements developed by a European standards group studying medical devices.
Wireless Device Technical Overview
- 40 MHz of protected spectrum in the 2360-2400 MHz band
- The 2360-2390 MHz portion of the band is range-restricted to indoor use at health care facilities and will be subject to registration with an MBAN coordinator and additional coordination if warranted by location. The maximum transmit power is 1 mW measured over 1 MHz bandwidth
- The 2390-2400 MHz band will not require registration and coordination, and may be used in any location – including in-home residential settings. The maximum transmit power is 20 mW measured over 5 MHz bandwidth
- Use is on a shared, secondary, non-interference basis with Aeronautical Mobile Telemetry (AMT) or flight test radios occupying the 2360-2395 MHz band
- MBANs require a clear channel and the Wireless Medical Telemetry Service (WMTS) does not have the spectrum to accommodate them
- Expected Transmission Range: short range, about one hospital room, similar to Bluetooth
- Limited Data rate: <2 Mbps
Figure 3 - Wireless Spectrum (courtesy of Modern Mobil Apps)
What is an MBAN network?
The FCC defines a Medical Body Area Network (MBAN) as a low power network consisting of a MedRadio programmer/control transmitter and multiple medical body-worn devices all of which transmit or receive non-voice data or related device control commands for the purpose of measuring and recording physiological parameters and other patient information or performing diagnostic or therapeutic functions via radiated bi- or uni-directional electromagnetic signals.
How does an MBAN system operate?
A typical MBAN consists of a master programmer/control transmitter (“hub device”), which is included in a device close to the patient, and one or more client transmitters (“body sensors”), which are worn on the body and only transmit while maintaining communication with the hub that controls the transmissions. The hub conveys data messages to the body-worn sensors to specify, for example, the transmit frequency that should be used. The hub and sensor devices will transmit in the 2360-2400 MHz band.
Figure 4 - MBAN Hub/Sensor Nodes
The hub aggregates patient data from the body-worn sensors under its control and transmits that information, using the health care facility’s local area network (LAN) (which could be, for example, Ethernet, WMTS or Wi-Fi links), to locations where health care professionals monitor patient data. The hub also connects via the facility’s LAN to a central control point that will be used to manage all MBAN operations within the health care facility. Neither body sensors nor programmer/control transmitters may communicate directly which other.
To protect AMT operations from harmful interference, MBAN and AMT frequency coordinators will work together to coordinate MBAN operations in the 2360-2390 MHz band. The control point serves as the interface between the MBAN coordinator and the MBAN master transmitters to control MBAN operation in the 2360-2390 MHz band. The control point will receive an electronic key which is a data message that specifies and enables use of specific frequencies by the MBAN devices. The control point, in turn, will generate a beacon or control message to convey a data message to the hub via the facility’s LAN that specifies the authorized frequencies and other operational conditions for that specific MBAN.
MBAN FCC Rules and Regulations in 2013, 2014 and beyond
As of October 1, 2012 devices are permitted under the FCC’s “license by rule” standards under which healthcare providers must register their devices and coordinate how and when they are used. However, the FCC is not expected to appoint a frequency coordinator until June, 2013 and according to GE Healthcare, “MBAN devices are expected to hit the market in about 2 years.” Several of the major semiconductor manufacturers have indicated their current 2400-2483.5 MHz ISM band chipsets used for ZigBee/Bluetooth can easily be modified or adapted to cover the 2360-2400 MHz MBAN spectrum. This should allow for rapid deployment of the technology.