Ask any wireless engineer what their ideal environment would be for deploying a network of wirelessly-connected devices, and you’ll get an answer that doesn’t exist in the real world: A completely open space…with clear sight lines to every nook and cranny…where you can place the wireless nodes exactly where you want them…with connected devices that stay put…where there is little to no conflicting signal traffic to create interference and complexity….and so forth.
Most real world spaces where IoT/M2M networks are deployed fall far short of that ideal, and many of the most important environments where wireless will be used don’t check a single one of those boxes. That doesn’t mean that wireless IoT deployments are impossible. It just means that you have to work around those obstacles, which sometimes happen to be a reinforced concrete wall, or a hornets’ nest of other wireless signals, or a device that simply can’t stay in one place.
These complex environments take many shapes:
- Industrial settings where issues such as electrical interferences, and sub-optimal physical layout can wreak havoc
- Urban areas where the dense concentration of conflicting signals and the quirky geometry of buildings are enormous challenges
- High-traffic public environments where the number of Wi-Fi users and the competing demands for signals so often affect performance of IoT deployments
Those are all very difficult settings for teams that are implementing Wi-Fi-based networks of connected devices, but for the purpose of this article we will talk about a setting that combines all of these challenges and more: hospitals and medical buildings. The specifics of these examples may narrowly relate to the realm of people wearing scrubs, but the challenges and the lessons for overcoming them are universal to all complex environments where IT teams and wireless engineers are being asked to enable wirelessly-connected devices using the Wi-Fi protocol.
Why is wireless so difficult in a hospital? It’s difficult for all the same reasons that wireless is indispensable. The physical layout of hospitals, the real-time data linkages required by healthcare applications, and the constant motion of nurses, doctors, patients, and the technologies deployed to monitor and treat them all make traditional wired connectivity a relic of the past in hospital and medical settings. If you’ve been in a hospital recently, it’s an obvious point: The only way this non-stop, 24/7 environment of constantly-moving personnel, patients, and equipment could possible work today is with as many devices as possible being wireless and providing real-time data to everyone and everything that interacts with patients. Wireless is absolutely vital in a setting like this…
…but the same things that makes wireless so crucial also make it very difficult to deploy IoT in a connected hospital setting:
- The byzantine layout of medical facilities with an infinite number of corners and reinforced walls posing signal challenges left and right
- The mobility of devices, which constantly moves from one wireless zone to another while requiring no hiccups in the transmission of real-time patient data
- The high number of competing wireless signals, which create interference issues galore
- And the regulatory requirements and IT policies that also impose strict rules about the security of these wireless signals
Whether the complex environment is a hospital, an industrial setting, a high-traffic public area or some other environment, the following 5-step methodology will ensure that the team setting up the IoT network successfully overcomes those challenges.
Step 1: Measure It…Two Ways
In woodworking, the most common saying you will hear is “Measure twice, cut once.” The importance of measuring (and getting the geometry right) is equally important in implementing wireless in a complex setting like hospitals. But the measurement is not simply about spatial dimensions. In a hospital, just as important is taking the time to do detailed spectral measurements that assess how signals travel in that space, how much interference there is, and more.
This kind of measurement is particularly important in hospitals because not all spaces are created equal. Common areas like waiting rooms where families gather are relatively “easy” areas in wireless terms, due to their open site lines and the prevalence of devices that don’t depend on truly uninterrupted signals. A few yards away, though, may be the radiology department where x-ray and MRI rooms have equipment and lead-lined walls that have a completely different spectral blueprint.
A truly connected hospital requires the wireless network to work regardless of whether specific areas are “friendly” or “unfriendly” to Wi-Fi-connected devices. That is why a comprehensive survey of the facility—both in terms of physical layout and spectral topography—is so important. The process is charmingly old-fashioned: an engineer with an armful of obtuse-looking equipment walks slowly through every room and hallway in a given building, paying no attention to the people he/she passes, paying very close attention to signal strength and interference on the meter, and making notations on a blueprint of the facilities every step of the way. That person is laying the foundation for an effective IoT network by mapping out exactly where wireless access points (APs) should be located to work around the physical and spectral quirks of the hospital.
Step 2: Location, Location, Location…and GHz
Using the detailed blueprint of the hospital created in the step above, the next step is to install the Wi-Fi APs, which will create a consistent web of connectivity for all the constantly-moving people and devices in the facility. Just as with real estate, location is key…but there is something else that will play just as big a role in the success of the installation. It’s the frequency.
The most common wireless frequency used by Wi-Fi APs—not only in hospitals, but in all other environments—is 2.4 GHz. The problem is that the 2.4 GHz frequency is woefully overloaded in most environments, with congestion issues that make it poorly suited for the avoid-signal-interruptions-at-all-costs needs of the medical devices in a hospital setting. It is therefore important for IT managers and wireless engineers to seek the right blend of 2.4 GHz and 5 GHz apps to balance the strengths and weaknesses of each. Wireless communications at 5 GHz will sidestep the congestion of the 2.4 GHz band with a broader set of bands to operate on, but their shorter signal range must be factored in. Conversely, 2.4 GHz can compensate for those distance limitations if used in a smart way.
A site survey that creates a blended map for installation of both types of APs is often the best strategy for ensuring the performance of wirelessly-connected smart devices.
It is also important to note that IT managers should use enterprise-grade infrastructure when implementing a wireless network in order to protect sensitive data. Enterprise APs offer better security, centralized control, and a larger feature set. The most important qualification to look for is Wi-Fi certification. The AP infrastructure must be controller-based and centralized for easier management of such a large number of APs. On top of those base requirements, when dealing with life-critical medical devices, redundancy and self-healing capabilities are important. Redundancy includes back-up controllers, back-up servers, and back-up APs; and self-healing capabilities detect coverage holes and change power as necessary to fill them.
Step 3: Let Them Roam Where They Want To
One of the most challenging aspects of a hospital environment is how much the wirelessly-connected devices move. They are in constant motion from one hospital room to the next, from one floor to the next, through long hallways, into and out of elevators, etc. A given medical device might literally move miles in a 24 hour period, and that is very difficult for a Wi-Fi network to support.
Each of these best practices deserves their own deep dive discussion in order to explore them in full, but for the sake of space in this article we can only cover them briefly. Each of these should be core guiding principles for how your wireless network is installed in a complex environment like a hospital:
- Create layers of separation for different traffic using multiple Virtual Local Area Networks (VLAN), which makes it possible for the combination of movement and security that is so important in a medical environment.
- Never use Dynamic Frequency Selection (DFS) in a hospital setting because of the instability that can occur, which will interfere with the needs of real-time data transfer in so many devices.
- Establish a hierarchy of prioritization for wireless transmissions using a Quality of Service (QoS), which will give priority right of way to the devices that need it most.
- Customize roaming settings for each device to optimize how each device utilizes the network while ensuring that the needs of each device is met.
- Conduct thorough roaming throughput tests to ensure that devices operate successfully and avoid RF traffic, signal noise, and signal interruptions.
Step 4: Don’t Forget Security
This is a redundant thing to say to anyone involved in hospital IT, since compliance and security are always of paramount importance. But it’s worth pointing out a few things here that should be top of mind as a wireless network is being implemented:
- There has been a consensus that Wi-Fi Protected Access II with Advanced Encryption Standard (WPA2-AES) is the preferred security protocol for Wi-Fi deployments.
- As a complement to using WPA2-AES, hospitals should incorporate Extensible Authentication Protocol (EAP) authentication with certificates, which require a user to provide credentials before gaining access to the network.
- There is no situation in a hospital where Temporary Key Integrity Protocol (TKIP) is acceptable because of its vulnerability to a variety of attacks.
- Using VLANs as a core element of the wireless network’s design will enhance security by isolating users to a segment of the overall network and preventing ne’er-do-wells from gaining broader access to data across the hospital’s network.
- And as more hospitals allow workers to use their personal devices at work, we recommend that the wireless network provide those users with a separate VLAN that maintains separation between those employee devices and the life-critical machines that are connected to patients.
Step 5: Testing Is Not a One-Time Thing
The last piece of advice we want to give is perhaps the most important: Testing must not be a finite event that takes place once the network is first set up before the flip is officially switched to make it live to usage by the medical staff. Testing should be a continuous process since changes to the network and how it is used will be a constant after it goes live.
In addition to a comprehensive test after the network is initially set up, it should also be tested each time a new device is added, each time new code is written/installed for a device on the network, any time there is a change to how the physical layout is used, and each time that a given piece of equipment is used differently.
For example, if the hospital gets a new patient monitor and places it in a stationary position in a recovery room, it should be tested under those parameters. Or if a previously stationary workstation for nurses to update medical records is converted into a mobile unit that roams the halls during rounds, that piece of equipment should be tested under those parameters.
That means a lot of testing, but it’s key to ensuring that all the hard work that went into Steps 1-4 above remains effective and keeps pace with the changes that are constantly happening in an environment like this. It will reveal emerging issues like channel overlap, security breaks and weakening signals just as they are revealing themselves, allowing your team to fix them before they impact hospital operations and patient care.
Complex Environments, No Problem
As we discussed above, these examples are about a hospital, but they are equally relevant for other complex environments where there are many overlapping, interwoven obstacles to deploying an IoT network using Wi-Fi. No, it’s not always simple, but deploying IoT/M2M in these environments is definitely worth it because of the dramatic new capabilities it can enable. In the case of a “Connected Hospital” it can literally mean the difference between life and death by enabling more medical devices to work together in real-time, allowing medical professionals to work with more accurate information, and allowing nurses and doctors to make smarter, faster decisions.
The immense value and impact of the power of IoT technologies are just as dramatic in other industries where complex environments might otherwise be an obstacle to wireless networks, including industrial settings where wirelessly-linked sensors can reduce pollution, reduce energy consumption, and save workers’ lives.
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