I have most recently heard in the field that “well WLAN medical devices should use 802.11a not 802.11g, simply because the 5.0GHz spectrum is less crowded”…interesting. We should note that physics plays into the equation here. The higher the frequency of a wireless signal the shorter the range. 2.4GHz (802.11g) covers a substantial larger range than that of 5.0GHz (802.11a) and the higher frequency signals of 5.0GHz do not penetrate solid objects nearly as well as do 2.4GHz signals. The smaller wavelength of 5.0GHz allows a higher absorption rate by solid objects. If we think and compare we should look at the cellular industry…early days PCS at 1900MHz, now LTE or 4G at 700MHz. What should also be considered here also is the site survey. Did the integrator or design team conduct the site survey inside the patient rooms to take into account where the actual medical device will be used, or did they simply “walk the hallway”? The majority of site survey’s were conducted and planned for 802.11a/b/g, with clients running 802.11b/g, not just 802.11a. So what if the network design was planned for 802.11b/g, and then if a 802.11a client is being used?…well I would expect a lot of signal drop out. Patient Monitoring data as well as infusion pump data (real time and batch), does not really impact the network load in a significant way. It is small amounts of data. The author recently finished up a design with www.vocera.com for probably the most challenging and unique RF environment in a mission critical and classified Department of Defense location. (They are using 802.11g). The voice solution by Vocera works great! (See infrastructure design guide). Go to pages 19-20 and 32-40.
