The world of wireless LANs

With wireless networks playing an important role in hospitals and health centers, Vaduvur Bharghavan, founder and CTO of Meru Networks, explains how wireless LANs will be able to provide the levels of service required by tomorrow’s healthcare applications.

“The capacity given to each user has to be stable so that nurses and clinicians know their applications will work every time”
-Vaduvur Bharghavan

Wireless LANs improve patient care with applications like mobile nurse call; reduce errors through EMR systems; and increase utilization of limited resources by tracking equipment like IV pumps, wheelchairs and defibrillators. As dependency on the network increases, wireless LAN technology must evolve to ensure availability and application predictability.

Once wireless LANs are deployed, various requirements still remain to ensure high levels of performance. Because healthcare is a 24/7 operation, network access has to be available 24/7 too. Changes within a healthcare environment such as new equipment and physical modifications will affect network performance. As well as tracking users, devices and applications, the network management system needs to be aware of changes in the physical environment and new, non-WLAN devices that can interfere with the network. The system must verify if the coverage and performance levels are maintained, ensuring that the network is available and operating at the appropriate service level.

Assuring application performance is the most significant challenge facing IT when managing wireless LANs in healthcare organizations. Healthcare staff need to trust the wireless network will be there when they need it and that it will provide an acceptable level of performance. That doesn't just mean making sure that a signal is available; it means monitoring all the network's vital signs to ensure that the IT infrastructure remains healthy and up to specification.

The capacity given to each user has to be stable so that nurses and clinicians know their applications will work every time. The round-trip latency has to be predictable too, to prevent downtime in voice and other real-time applications. And this assurance has to extend beyond the wireless part of the network. Users need acceptable performance from all components working together - application servers, security infrastructure and backend wired links too.

Just like patient monitoring, we need to be proactive in assuring users that the network is healthy by continuously checking the network's vital signs to make sure that everything is running smoothly. We can do this by injecting test traffic into the network, sending real packets over the airwaves and then through the backend network infrastructure. By behaving like a real client, the monitoring system gets a real client's eye view of the network. And just like patient monitoring, if the level falls below an acceptable limit, an alarm is sent.

Fortunately, the traditional approach of IT staff having to walk around with laptops and running applications from every corner of the hospital no longer scales: technicians can't be everywhere at once and they don't want to work 24/7. A better approach is to create a virtual client on each access point. That virtual client can then connect to other nearby access points in exactly the same way as a real client, going through the same airlink, the same controllers and the same authentication servers.

The virtual client can inject test traffic that measures every performance metric, so network administrators can see exactly how real clients perform - anywhere and at any time.

It can support and assure the availability of any application, but it's particularly useful for applications that don't tolerate poor connectivity. Many EMR applications eat a lot of bandwidth, so proactive monitoring will verify that the capacity they need is always available for them. It's critical for the phones and communicator badges used by nurses and other staff too. Although these are fairly low bandwidth, they need constant connectivity and low latency because even a few microseconds delay can be noticeable in conversation or lead to dropped calls.

Dr. Vaduvur Bharghavan, co-founder of Meru Networks, is a credited innovator in wireless networking, specifically wireless medium access protocols and QOS architectures. He holds MS and PhD degrees in Computer Science from UC Berkeley and a BTech Degree in Computer Science from the Indian Institute of Technology at Madras.