More than you probably want to know about MICS.
Established in 1999, the MICS rules apply to transmitters that support the diagnostic and/or therapeutic functions associated with implantedmedical devices to enable individuals and medical practitioners to utilize potential life-saving medical technology without causing interference to other users in the spectrum - that's the official text from the original Order.
The Commission set aside the 402-405 MHz bandbecause the signal propagation characteristics in the band are particularly well suited for implantable applications due to signal propagation characteristics in the human body, the relative dearth of other users in the band, and the ability to stake out the band internationally. The MICS use of this band is secondary to the primary users of this spectrum - Meteorological Aids Service (Medaids), the Meteorological Satellite Services, and the Earth Satellite Service.
Technical rules were established to minimize interference and ensure safe coexistence of multiple MICS devices. The MICS band is broken into 300 kHz wide channels. The rules specify that devices must "listen" for other devices before transmitting, called Listen Before Talk (LBT). If interference is encountered, the radio switches channels and listens again - known as "frequency agility." The rules also allow MICS devices to transmit without prior frequency monitoring in response to a non-radio frequency actuation signal generated by a device external to the body (i.e., manual activation), or in response to a medical implant event (i.e., alert or alarm condition).
You can read more about MICS here (FCC Deals with MICS - Vendors Help and Hinder), here (FCC Announces Regulatory Changes for Wireless Medical Devices) and here (Medtronics Brags on New Wireless ICD).
I respect you opinions on WTMS. I’ve been a CBET and a radio guy for over 20 yrs and remember the old days too. The FCC, ASHE, and FDA worked on the telemetry problem and came up with WTMS. Its not perfect, but 802.11 isn’t either. 802.11 is just as susceptibe to interferance and equipment failures as any other wireless device.
The idea of people portioning part of the 802.11x band for medical is basicly an adhoc WMTS band without the security the FCC gives to “Primary” users.
WMTS is classified by the FCC as the â€œPrimaryâ€ protected user of those frequencies, and by law, any interference must be corrected by the
entity causing the interference to the primary user.
There is no “primary” users in the 802.11x band… and nobody has any special privilages or restrictions on what part of 802.11 they decide to use.
Thanks for your thoughtful comment. I agree 100% that neither WMTS or 802.11a/b/g is ideal for wireless medical devices.
With the growing number of wireless medical devices in hospitals — first telemetry/patient monitors, then infusion pumps, and someday POCT devices, ventilators, IABPs, dialysis, etc. — there are two limitations to WMTS the preclude broad use of that spectrum.
The first issue with WMTS is bandwidth: there just isn’t that much of it. The other issue is that the FCC never designated any technical standards to ensure coexistence and efficient use of the spectrum.
I’m sure you remember the coexistence issues between GE and Philips telemetry systems when they first came out — neither vendor could demo their telemetry at a hospital with the other’s system due to interference (I’m not sure they saw this as a feature or a bug ;->). GE and Philips do coexist now, but I’ve not looked at how they’ve arrived at that coexistence and if it, in fact, maximizes the bandwidth. When you consider a hospital with wireless devices from say Cardinal Alaris, Covidien Puritan Bennett, Abbot Point of Care, Masimo to the mix — there’s not even a mechanism for all those vendors to work out a coexistence scheme.
The 802.11a/b/g spectrum is huge compared to WMTS, orders of magnitude bigger. Admittedly you can say pretty much the same about 802.11a/b/g regarding coexistence (heck, it’s even a problem on Ethernet) as you can WMTS.
The sad truth is that these days both pieces of spectrum require active management by users, and active collaboration among vendors. The golden age of installing something wireless and having it “just work” are gone.
The next few years, especially when IEC 80001 hits, will be interesting.
The big problem with 402 to 406 MHz is that it is satellite primary.
My “Low Power” transmitter (Portable Earth Station) runs around 30 watts peak and 7 watts average depending on what it is doing.
We use 398 to 399 MHz for voice as well for ground ops and 420 to 440 MHz for radar, voice, video, etc.
406 to 420 is trunking radio.
Remember that a 100 watt transmitter at 406 MHz will emit more noise at 405 MHz than your transmitter puts out on frequency.
My talkie runs 4 watts average, 30 to 512 MHz range AM or FM analog and several Digital modes as well.
It is a (RF) jungle out there!