Wireless transceiver circuit enables low-power medical body area networks

February 12, 2014 // By Jean-Pierre Joosting
A wireless transceiver circuit for use in body area networks (BAN) for medical applications that adheres to the 400 MHz-band international standard has been developed by imec Holst Centre and Fujitsu Laboratories Ltd., the details of which were announced at the IEEE International Solid-State Circuits Conference 2014 (ISSCC 2014).

While the subject of high expectations for medical applications, wireless monitoring of brainwaves or other vital signs has in the past required over a dozen milliwatts (mW) of electric power. Now, however, by optimizing the architecture and circuitry, Fujitsu Laboratories and imec Holst Centre have succeeded in reducing the electric power requirements of wireless transceiver front-ends, to just 1.6 mW when receiving data and 1.8 mW when transmitting.

The various sensor nodes that make up the BAN all need battery power, and to make the system as convenient as possible for both the patient and medical practitioners, there is a need to extend battery run-times so the required frequency of battery replacement or recharging is held to a bare minimum.

The component in the sensor node that draws the most power is the wireless transceiver circuit, so to extend battery life, the power demands of that part need to be reduced. The challenge has been in developing a compact, low-power transceiver that can support the variations in transfer rates which medical systems require, without adding any new circuitry.

This technology extends by approximately ten-fold the battery life of conventional sensor products used for patient monitoring. This cuts the frequency of battery replacement or recharges, lightens the burden on patients, and increases the work efficiency of medical practitioners.

Based on this joint research into wireless transceiver technology, Fujitsu Laboratories plans to apply it to non-medical uses, as well, such as to the monitoring of societal infrastructure, thereby further enhancing network front-end interface technologies.

Figure 1: In the field of healthcare and medicine, BAN have attracted attention for their potential application in collecting patient-monitoring data via a wireless network of sensors placed on the patient’s body.

This research project stipulated a 400-MHz wireless specification compliant with IEEE 802.15.6, the international standard for BANs, and support for two independent modes: a 4.5 Mbps high-speed mode capable of transmitting brainwaves, images, and other data