Active Wideband DAS to ‘carve out’ WMTS frequency interference from US hospitals
By Jeffery Fuller, Zinwave
Wireless medical telemetry devices have been implemented into healthcare facilities and hospitals as a way of remote monitoring patients' health through radio technology. Such devices can be used to measure patients' vital signs, such as pulse, heart and respiratory rates by simply transferring data from a transmitter worn by a patient to a specialized radio receiver in a central monitoring station. Advances in wireless medical telemetry have helped lead to greater medical efficiencies within healthcare industries. By removing the need to be connected to restrictive hospital monitors; wireless telemetry provides increased comfort and mobility to patients and in turn, also allows medical facilities to manage limited resources more effectively. Ultimately this cuts costs because in theory, several patients can be monitored simultaneously.
However, radio interference has long plagued the operation of wireless medical telemetry devices. Prior to the introduction of the Wireless Medical Telemetry Service (WMTS) by the Federal Communications Commission (FCC) in 2000, medical telemetry devices operated in an unlicensed and/or secondary basis to TV broadcast and Private Land Mobile Radio (PLMR) bands. Devices such as wireless heart rate and blood pressure monitors were only allowed to operate within the free available portion of the 174 to 216 MHz and 470 to 688 MHz spectrum and would consequently be subject to interference from the primary users in these frequency bands.
Addressing Bandwidth Interference
In June 2000, the FCC took essential steps to address the growing concerns about this bandwidth interference from new Digital Television (DTV) transmitters and increased traffic from PLMR equipment. The FCC allocated a 'protected' bandwidth spectrum specifically for WMTS. The WMTS bands include 608-614 MHz, 1395-1400 MHz, and 1427-1432 MHz, and were opened to all types of communications apart from voice and video, in both a bi-directional and unidirectional basis, on the condition that all devices are related to medical care. With a radio spectrum dedicated solely to medical telemetry use, the FCC successfully enabled medical telemetry devices to operate without interference from non-medical operations and resolved the potential conflict from new DTV and PLMR services.
However, despite the efforts that have been made to reduce RF interference, without a dedicated wireless coverage system, larger health facilities like hospitals will struggle to sustain reliable quality of service for WMTS due to coverage black spots caused by building infrastructure. This is a widespread problem and in reality, is dangerous for patients as it leads to lapses in patient monitoring, putting patients at high risk.
WMTS Causes a Big SurgeThe introduction of WMTS in 2000 caused a big surge in upgrading and replacing medical telemetry equipment within healthcare institutions to comply with bandwidth regulations. Nine years on, hospital officials are once again faced with the challenge of improving quality of service for these devices by investing in enhancing in-building wireless coverage with dedicated equipment.
US Frequency Bands
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In the US, the issue is more complex as priority in frequency bands for WMTS differs geographically. For the most part, WMTS is granted priority status over non-medical telemetry devices in the 1427-1432 MHz band. However, WMTS has priority status in the 1429-1431.5 MHz band in Pittsburgh, Washington D.C., Richmond/Norfolk, Austin/Georgetown, Battle Creek, Detroit and Spokane. These seven areas are now known as 'carve out' districts.
There is a growing need to find a future-proof, in-building solution to guarantee improved, wider and most importantly, reliable wireless coverage within hospitals in the US - irrespective of which portion of the WMTS spectrum each state operates in and irrespective of which wireless service is being used. Active distributed antenna systems are recognized globally as a key enabler in improving in-building coverage. This technology offers huge potential in resolving the aforementioned coverage and WMTS reliability issues caused by signal attenuation from building infrastructure as well as interference from non-medical transmissions.
The geographical variation in frequency bands in the US presents a particular problem in that an Active Distributed Antenna System (DAS) solution needs to be able to support a multitude of wireless services, and more importantly, needs to do so simultaneously. For example, we have been working with our clients to develop a 'true wideband' in-building coverage system that is able to support the full wireless spectrum from 136 MHz to 2.7 GHz and provide simultaneous support for multiple services whether it be medical telemetry, Cellular 2G, 3G through to LTE, PMR/Tetra, Wi-Fi, WiMAX etc. Today, Wideband Active DAS technology can support all medical telemetry frequencies effectively.
Because new wireless services can be added without the need for additional components or costly upgrades to infrastructure, such systems also future-proof initial investments in in-building coverage. Fundamentally, a Wideband Active DAS ensures greater reliability when using medical telemetry devices by providing improved quality of service and wider coverage. It promotes enhanced medical care and helps save lives.
Jeffery Fuller, is president of Zinwave, www.zinwave.com.
Wireless Design & Development
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2010
Advantage Business Media
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