Fujitsu Laboratories and Holst Centre, a European R&D initiative by imec (Belgium), have developed low-power wireless transceiver circuit for use in body area networks (BAN) for potential medical applications that meet the 400MHz-band international standard.
Fujitsu Laboratories and imec Holst Centre have succeeded in reducing the electric power requirements of wireless transceiver front-ends by optimising the architecture and circuitry.
For instance, the wireless monitoring of brainwaves or other vital signs requires more than 12MW of electric power, but this ultra-low-power wireless transceiver reduces the power requirements to just 1.6MW when receiving data and 1.8MW when transmitting.
These ultra-low power wireless transceiver would decrease the overall power consumption of the complete sensor system and open opportunities to add much more functionality to the device.
In addition, as the battery size is decisive in determining the size of battery-operated systems today, low-power circuits could enable smaller batteries and lead to smaller devices.
Specifically, this technology has been designed to extend the battery life of conventional sensor products used for patient monitoring by approximately tenfold.
It also reduces the burden on patients, increases the work efficiency of medical practitioners by cutting the frequency of battery replacement or recharges.
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.
A major challenge in developing a compact, low-power transceiver that can support the variations in transfer rates, required by medical systems, was lowering the power demands to extend battery life without adding any new circuitry.
Fujitsu Laboratories and Holst Centre were able to achieve this by utilising digitally controlled receiver technology and high-speed digital three-point modulation technology.
This research project stipulated a 400MHz wireless specification compliant with IEEE 802.15.6, the international standard for BANs, and support for two independent modes. These comprise a 4.5Mbps high-speed mode capable of transmitting brainwaves, images, and other data needed in medicine, in addition to an 11.7kbps low-speed, low-power mode for low-power operations when sensor nodes are on standby.
In addition to patient monitoring, this transceiver circuit has potential applications in healthcare where it could be used as a sensing front-end interface for medical-device management.
Image: Schematic view of BAN System. Photo: courtesy of Holst Centre.