Wi-Fi® connects providers with patients across a variety of environments
Already widely deployed for traditional networking throughout the healthcare vertical, Wi-Fi is driving new improvements the flexibility and efficiency of clinical services in healthcare environments. The market for Wi-Fi healthcare services will grow to $1.34 billion by 2016. Wi-Fi is well suited for these dynamic environments because it offers high performance, government-grade WPA2™ security, has a large installed base, and offers a ubiquitous ecosystem. Not just for use in hospitals and clinical settings, Wi-Fi also offers a solution to the growing personal health and fitness market.
There are a variety of applications that use and rely on Wi-Fi. Those include infusion pumps, oxygen monitoring devices, and smart beds, alongside mission-critical information applications such as access to electronic medical records (EMRs) and real-time access to X-rays and MRI scans. Medical telepresence delivered via Wi-Fi helps scale provision of high-quality health care to remote and underserved areas.
Wi-Fi helps healthcare IT managers eliminate the struggle associated with onboarding of new devices, and the technology is well suited to meet the growing connectivity demands from patients and their families in waiting rooms and lobbies. As the number of Wi-Fi devices connecting to healthcare networks grows, use of Wi-Fi CERTIFIED™ equipment helps ensure widespread interoperability and a good user experience.
A continuous roadmap of advancements bring new capabilities to healthcare
The latest version of Wi-Fi, Wi-Fi CERTIFIED ac, offers healthcare facilities a significant performance leap, without sacrificing core competencies like interoperability, security and ease of use. Wi-Fi CERTIFIED devices are backward compatible, so newer devices will seamlessly interoperate with current devices. Wi-Fi CERTIFIED ac devices are also expected to include Wi-Fi CERTIFIED n, and dual-band networks will enable more capacity, higher throughput, better coverage and lower latency in healthcare environments.
- What is mobility in a healthcare setting?
Mobility is used to describe continuous network connectivity, providing the user with anytime, anywhere access to social media, clinical, or business application data. When Wi-Fi® client devices and the hospital network to which they connect properly support mobility, a wireless device can access the network and hospital information systems (HIS) while on the move anywhere in the building and sometimes outside of the building (e.g. walkways between buildings). To properly support mobility in hospitals, adherence to best practices in the design, installation, and management of the Wi-Fi network and devices is essential.
- What is a mobile Wi-Fi device, and how is it different from a non-mobile Wi-Fi device?
Wireless client devices can be stationary, nomadic, or mobile. A stationary device stays connected to the same access point (AP) during an entire connection session. Examples of stationary devices are wireless desktop phones, security cameras, HVAC controls, card readers, infusion pumps and bedside patient monitors. These rely on an external power source and only require connectivity when stationary.
A nomadic device may move from one AP to another, but the applications on the device do not depend on a persistent network connection and may be buffering data during the transition between access points. A nomadic example is a spot check monitor that is used to gather data on a nurse’s rounds or an infusion pump in ambulatory settings. These devices send data on a semi-periodic basis when in use.
With a mobile device, an end user moves about the hospital or healthcare facility and requires a persistent connection. Examples are patient-worn telemetry devices that continuously monitor the vital signs of an ambulatory patient, or a smart phone that provides a physician attending to a patient instant access to all of the clinical systems required to provide care.
While the movement of a device is the most common trigger for roaming, it is possible for a stationary device to roam. Suppose that a stationary device is within range of two APs and connected to one of them. If a patient or healthcare professional positions his or her body between the device and the AP to which it is connected, then the clinician’s body may block enough of the Wi-Fi signal that the patient monitor is forced to roam to the second AP to avoid losing its connection.
- Why does a Wi-Fi client roam from one AP to another?
There are many reasons why a client will roam from one AP to another, the most common one being when a client moves from the radio frequency (RF) boundary of one AP to another AP. Healthcare environments are often very challenging from an RF planning standpoint, due to their physical structure, with long hallways, isolated patient rooms, and shielded radiology areas. These physical challenges can create abrupt transitions between AP coverage areas and inhibit fast and efficient roaming performance. With the strict performance and availability requirements of medical devices, significant emphasis on establishing a robust and reliable Wi-Fi network is important.
- How does a client roam?
The decision to roam from a connected access point to a new access point is generally the responsibility of the wireless client device. The roaming algorithms used by wireless client devices vary from vendor to vendor, but almost always involve the evaluation of the received signal strength indicator (RSSI). As a user moves away from the connected AP, the signal degrades. The client compares the received signal strength to a pre-defined threshold and determines if a roam is required. Once the signal drops below this threshold, the wireless client performs an off-channel scan, scanning all available channels for a candidate AP, selects one with acceptable signal strength, and completes the roaming process by connecting or associating to the new AP. Some more sophisticated clients utilize additional parameters such as AP neighbor lists or capacity load on an AP to help optimize the roaming process.
- What is off-channel scanning for Wi-Fi client devices?
Off-channel scanning is when a Wi-Fi client device tunes its radio to another channel to look for available APs or scans for APs on a channel to which it is not connected (hence “off-channel”). The client scans the off-channel APs looking for a suitable AP to connect to in case it needs to roam from its current ‘on-channel’ AP.
- What is off-channel scanning for Wi-Fi access points (APs)?
An access point (AP) can also perform off-channel scanning. This process is the same as off-channel scanning for Wi-Fi client devices and essentially allows the AP to tune its radio to a different channel for a finite amount of time. Off-channel scanning is typically used as a method to detect sources of interference, rogue or unauthorized ad-hoc Wi-Fi networks. The operation of performing off-channel scanning is highly dependent in terms of manufacturer implementation and configuration of the WLAN.
- What is the impact on clients when APs perform off channel scanning?
When an AP is performing an off channel scan, the client devices that are connected to it will not be able to send traffic to the network. This can be disruptive to real time streaming devices that rely on a persistent connection. Care should be taken in the configuration of off-channel scanning.
- What are passive and active scanning?
The reason for client scanning is to determine a suitable AP to which the client may need to roam now or in the future. A client can use two scanning methods: active and passive. During an active scan, the client radio transmits a probe request and listens for a probe response from an AP. With a passive scan, the client radio listens on each channel for beacons sent periodically by an AP. A passive scan generally takes more time, since the client must listen and wait for a beacon versus actively probing to find an AP. Another limitation with a passive scan is that if the client does not wait long enough on a channel, then the client may miss an AP beacon.
- What is dynamic frequency selection (DFS)?
In many countries, regulatory requirements may limit the number of 5 GHz channels available or place additional restrictions on their use because the spectrum is shared with other technologies and services. For instance, in the US and other countries, some of the Unlicensed National Information Infrastructure (U-NII) bands are used by radar systems. Wi-Fi networks operating in those bands are required to employ a radar detection and avoidance capability. The IEEE 802.11h standard addresses this requirement by adding support for DFS and transmit power control (TPC) on every DFS channel.
- How does DFS work?
If a Wi-Fi AP detects a radar system on a channel with DFS enabled, the AP must announce to associated client devices that it is vacating the channel on which the radar is detected and the new channel to which it is moving. The client devices must immediately vacate the channel and are expected to associate to an AP on a different channel.
- How does DFS affect mobility?
For the 5 GHz bands that include DFS channels, clients are forbidden from performing active scans and must only use passive scanning. This can increase the time required to identify and select candidate roaming targets. This increase in scanning time may prevent some clients from keeping their connection active while roaming across APs.
When an AP detects radar it is allotted a period of time to search for available channels. This time period may exceed the application connectivity threshold and cause a client to lose its connection even though the DFS rules were strictly followed.
In some environments, it may be preferable to restrict RF usage to channels in which DFS is not mandated. Consult the country-specific regulations to determine which channels are DFS mandated.
- What is the impact of security mechanisms on mobility?
The healthcare industry adheres to another layer of security requirements prescribed by laws addressing privacy and a patient’s clinical information (e.g. HIPAA (Health Insurance Portability and Accountability Act, PCI (Payment Card Industry)). Protecting electronic health information is an essential business need for hospital administrators. Fortunately, Wi-Fi has strong encryption and authentication capabilities in the form of WPA2™ to assist IT managers in implementing security policies.
The basic security principle in IEEE 802.11 is that each time a client connects to an AP it must complete the authentication process. The two main types of security used are WPA2-Personal and WPA2-Enterprise and each has a different impact on roaming behavior because WPA2-Enterprise requires more steps in the authentication process. When the Enterprise version of Wi-Fi Protected Access® 2 is used, the required authentication when roaming adds time to the authentication or re-authentication process. For mobile devices, this added time may impact real-time streaming client performance. For important clinical applications like telemetry, where mobility is a part of the clinical usage, the use of a fast roaming algorithm such as 802.11r is recommended. As an example, when high quality of service (QoS) applications such as VoIP are used on a properly implemented Wi-Fi network, the combination of WPA2-Enterprise and fast roaming techniques provide a secure and reliable connection. The Wi-Fi Alliance’s Voice-Enterprise certification incorporates these important capabilities and is a key enabler of a high-performing enterprise WLAN.