White space fillers are hospital system killers

Spectrum analysis

Hospitals in the USA fear plans to fill white space - unused TV frequencies - will have a knock-on effect on the systems they use to monitor patients wandering around their buildings. So they are lobbying the Federal Communications Channel to reserve some more frequency for them.

In the US, medical telemetry systems are supposed to operate in channel 37, otherwise known as around 608MHz. Ever since a local TV station knocked out systems in a Dallas hospital in 1998 the FCC has blocked out channel 37 for medical telemetry systems, although deployments were allowed to use other frequencies on the understanding they migrate to channel 37 in due course. But with so many frequencies lying empty there has been little incentive for them to do so. Until now.

Enter Google, Microsoft and allies in the Wireless Innovation Alliance (WIA), who want to fill those white spaces with intelligent radios that avoid colliding with TV signals - but they could end up colliding with medical systems.

"If a new white space application that's operating thousands of times more powerfully came online, either in the hospital or outside the hospital, it could very well directly interfere with the telemetry system and prevent patient monitoring," Tim Kottak, engineering general manager for GE Healthcare told CNET.

He wants the FCC to block off channels 36 and 38, just to be sure, and to block off channels 33 to 35, too, for a year or so, as many legacy systems operate in channel 34 (otherwise known as around 576MHz).

But with so many demands for available spectrum the FCC is unlikely to reserve great chunks of spectrum, even if the WIA has agreed that white-space kit will avoid channel 37. This means medical systems may have to find somewhere else to operate.

In the UK, and Europe, they generally hang around 2.4GHz, and make use of standard radio technologies such as Bluetooth and ZigBee. There has been an attempt to harmonise a band at 402-405MHz for very-low-power radio connections, although that is really for implanted transceivers rather than hospital-wide systems.

In the UK the transition to digital TV has seen wireless microphones struggle to find space, with the companies using them too poorly organised to jointly bid for spectrum. Hospital systems might seem more important, but their makers are equally lacking in funds or coordination and (in the US) may face problems as early as next February - when white space radio could be in operation. ®

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