Why Medical Device Makers Love/Hate Wi-Fi

Why Medical Device Makers Love/Hate Wi-Fi

In this post we’re going to lift the window shade a bit on why many manufactuers love Wi-Fi, and why they also hate it with equal passion.

You see, I’m often asked by manufacturers about alternatives to Wi-Fi for wireless medical devices. And I’ve done a number of wireless technology surveys for manufacturers, looking for attractive alternatives. There are no attractive alternatives, at least for most medical device applications at this point in time.

Before we dive into this sordid tale of passion and betrayal, let’s frame the discussion. The wireless application I’m referring to is the connection between a portable or mobile medical device and the enterprise wired network. While the examples in this post come from hospitals, there is much here that is applicable to ambulatory settings. Applications that are not considered are cable replacement applications (Bluetooth or wireless USB) or wireless sensors in body area networks (BANs) that are, by their nature, low power and short range, are a different animal.

Share
Read More

Scalabilility Challenges Wireless LANs

When thinking about wireless networks in hospitals, most people think about coverage, and coverage is certainly an important requirement. A network performance metric that is less obvious but perhaps even more important is capacity. Capacity refers to the number of clients associated with an access point (AP) and the total bandwidth that’s available in a given location.

All of this was once again brought into focus for me during a conversation with Phil Belanger, founder and chief marketing officer for consulting firm Novarum. Phil has been in the wireless LAN market a long time, starting with Zilog and Corvus and served as co-chair for the IEEE work group that defined part of the initial 802.11 wireless LAN standard. He ended up at Cisco when they acquired Aironet.

As more medical devices incorporate connectivity, the number of potential WiFi clients around a patient increases. For example, let’s imagine a patient with 5 B Braun infusion pumps, each with its own WiFi radio. Add to this a Dash patient monitor and a ventilator; the Dash has embedded WiFi and the vent has a third party wireless module. Besides these 7 wireless clients, each caregiver has a wireless VoIP phone and most physicians also have WiFi devices (PDAs or smart phones).

Now imagine that there are similar patients in just 3 near by rooms. What happens when a code is called in one of those rooms and 3 caregivers, and a bit later a couple physicians respond. Let’s see, that’s 7 wireless devices times three patients, for 21 active associations with the network. Of the 5 people responding to the code, say 2 of them are having wireless VoIP conversations (say with specialist, or looking for a STAT diagnostic test result) and 1 is charting the code on a COW. That’s 24 associations.

What happens if an acute care patient being transferred goes by, adding 3 more associations and another wireless VoIP call? Or another code is called in the same vicinity? Do calls get dropped and the means to receive urgent information is lost? Are associations with the network lost by medical devices? Which ones? Could it be a device connected to a lone patient in a private room? Might life critical alarms be missed?

Share
Read More

IEEE Completes 802.11r Fast Wi-Fi Roaming Standard

Just what we needed (really), another letter in the alphabet soup of 802.11 standards. This one, 802.11r, is also known as Fast Basic Service Set Transition (more details on the standard here).

The 802.11 standard was originally conceived to operate around individual access points (APs). This is a far cry from the high density AP network designs increasingly being installed in hospitals – and the wireless medical devices and other mobile applications they support.

In a conventional WiFi network it takes about 100 ms to re-associate with a new AP, and several seconds to re-authenticate connections using 802.1x (a common security requirement in many hospitals). This time lag can potentially result in several second gaps in patient monitoring waveforms, missed alarms, and dropped wireless VoIP phone calls. Another problem fixed in 802.11r is that a client radio does not know if the required quality of service (QoS) resources are available in the new AP until after it has associated with the new AP.

Share
Read More

Wi-Fi Device Drivers for Medical Devices

When you buy a Wi-Fi infrastructure device such as an access point or router, you do not pay extra for the software; it is included with the purchase price of the product. The same is true when a device maker buys a Wi-Fi radio module or card that is embedded or used in the device. Even though there is no extra charge for Wi-Fi software, that software provides most of a Wi-Fi product’s functionality in areas such as connectivity, roaming, security, quality of service, and management. Software also enables a Wi-Fi vendor to differentiate its offering by implementing features that address specific market and device requirements better than competitive products do.

Reference Driver: Not Enough

The core software component of a Wi-Fi product is the device driver for the Wi-Fi radio that operates in the device. That driver provides the interface between the device’s operating system and the radio. Intel, Atheros, Broadcom, Marvell, and other silicon providers may be known for making Wi-Fi chips out of silicon, but they employ teams of software engineers that develop device drivers for APs, routers, laptops, and other devices that use the radios with those chips inside.

While drivers from silicon providers (often called reference drivers) are sufficient for mainstream client devices such as laptops, they are not designed for mobile medical devices. For starters, a driver may not run on a medical device because the driver was written for a different operating system than the one that runs on the device. Even when it runs on a mobile medical device, a driver may not address the requirements of that device, especially requirements for reliable connectivity when the device is in motion.

Share
Read More

Distributed Antenna Systems – No Replacement for Wireless Strategy

MobileAccess-antenna

I received the following blog post from Stephen Olsen, Principal at Integra Systems. Steve has spent more than 20 years in the wireless industry in engineering, sales and business development. Steve’s wireless experience extends beyond health care to include public safety, cellular and 802.11.

In the past I’ve extended an invitation to a few select industry experts and thought leaders to post their writing. Steve is the first to take me up on my offer. Enjoy:

Over the last few years, MobileAccess and InnerWireless have generated considerable interest in broadband Distributed Antenna Systems (DAS) for the healthcare market. These systems can support a wide range of applications (WiFi, cell phones, mobile radios, pagers, WMTS) and frequency ranges (400/800 MHz up to 6 GHz).

The appeal to providers is the idea that a broadband DAS will remove all wireless headaches: no more cell phone complaints, WiFi will work better, no more dead spots for mobile radios, no more tricky RF interference problems, etc. Disappointment ensues when the DAS does not live up to its promise.

Share
Read More