Design and Support for Today's Wireless Network
In many ways, a wireless local area network (WLAN) can be compared to a highway—the network can only accommodate what it was initially designed for. And therein lay the challenges in the design and support of a WLAN: They require not only consideration of current needs, but anticipation of how those needs will evolve as the business evolves.
In 1999, the 802.11b standard was ratified and healthcare institutions immediately identified the advantages in using Wi-Fi for their highly mobile clinical workforce. In fact, there has been tremendous growth in the use of 802.11-based devices in healthcare institutions over the last decade. Clinicians' demand for mobility and access to information, coupled with readily available, inexpensive equipment, has resulted in revenues for mobile devices, applications and services for healthcare institutions growing from $50 million in 2002 to an estimated $1.2 billion in 2006, according to a 2004 case study by the Spyglass Consulting Group Health. The reason is clear: Mobility eliminates the inefficiency of clinicians spending large amounts of time gathering the information they need to provide high-quality patient care. On average, 888 hours are recovered per nursing unit each year as a result of having mobility capabilities, according to the Journal of Nursing Administration.
As wireless use in healthcare has grown, so has the number of applications and products capable of using this shared IP network. As part of ROI, healthcare institutions are using wireless networks for a variety of reasons, including telemetry devices, workstations on wheels, voice infrastructure, tablet, and PDA use. Because of its popularity, this medium has advanced quickly—which makes it extremely challenging from a deployment and design perspective.
Design challenges: Questions to address
How will we use our wireless? Departmental applications and usage requirements are the most important considerations when planning a wireless deployment in a hospital. Staying abreast of potential products that various departments are using or considering that are Wi-Fi–enabled is critical.
To start, map out the vision of what the completed WLAN solution will entail. The more information gathered and documented at this stage, the better the position the institution will be in when it comes to creating an RFP, evaluating offerings, and working with a manufacturer. At the very least, an organization should plan on a future WLAN solution supporting employees and guests with voice and telemetry solutions.
There must be a focus on potential future user and application demands, especially the demand for 802.11n, PDA phones, dual mode phones, video-over-wireless applications and fixed mobile convergence.
After the short- and long-term requirements of the system are identified, design should focus on reliability, security, scalability, upgradeability, manageability, and last, but not least simplicity. Abiding by these design principles is essential, especially when looking beyond notebook connectivity at functions such as:
Seamless roaming for Wi-Fi–enabled voice devices (VoWLAN) and devices that support video over Wi-Fi;
Coexisting and sharing of the medium with a diverse array of systems, such as voice-, video-, and telemetry-capable devices and systems;
Providing wireless guest access for patients, vendors, and visiting clinicians;
Wireless real-time location services and location tracking of devices, assets, and people; and
Value-added workflow analysis over several months to identify bottlenecks.
Technical requirements are not the only considerations for molding the design—aesthetics play a role, as well. Ensuring that the physical enclosures and antenna types chosen meet requirements from an aesthetic perspective and for code compliance is extremely important.
What are our budget constraints? Typically departments run into budget constraints when faced with having to install a robust, highly redundant wireless network for custom applications. However, if the appropriate infrastructure exists, budget demands are less, projects are more feasible, and there is higher potential for an influx of wireless-related project requests that can be met.
How can we maximize performance? Take care to understand the various product and application design requirements and sensitivity to network performance when tackling a large-scale wireless network design. For example, some Citrix-based applications being used in hospitals are extremely sensitive to roaming and may malfunction if the roam boundaries are not designed properly.
The same applies for workstations on wheels (WoWs), also known as computers on wheels (COWs). (As a side note, one should be careful using the term COWs in front of patients and visitors since it can easily be misunderstood as to who or what is being called a COW.) Many WoWs are based on old designs for wired setups. Some of the security methods used to secure the laptop to the cart can, in fact, negatively affect the built-in wireless card's performance.
How can we promote security on the network? When evaluating security options for the wireless network, different classes of devices need to be treated differently based on utilization, the type of traffic they support, and their roaming capabilities. It is strongly recommended to use at least single-factor authentication in conjunction with 802.1x. That is, user names and passwords can be used to authenticate users onto the wireless network, allowing for accountability for laptop users in a domain. The devices outlined below may have unique requirements in this respect:
Shared workstations need to be set up with multifactor authentication.
Voice devices experience difficulties roaming when 802.1x authentication is enabled. These will sometimes a lesser form of security and encryption, like a WPA preshared key or a shared, static WEP encryption key.
Legacy devices may only support static WEP, which has been shown to be a vulnerable, insecure form of encryption capable of being cracked within a short amount of time. It is important to include additional security mechanisms such as sensors and firewall rules to protect these weaker systems.
Focus on having a well-defined strategy for the various types of devices on the network. As you know, the clinical community will judge your network based on its ease of accessibility.
Can we make a smooth transition to wireless? The trend to move away from locally managed traditional (sometimes called “fat”) access points to “thin/fit,” centrally managed APs is beneficial to organizations, as it enhances simplicity and scalability in the wireless network. It allows for a centrally managed and controlled wireless solution that could easily integrate with existing wired network infrastructure. This approach allows an organization to target for simplicity and scalability, and maintain flexibility in the design.
Most vendors now offer an upgrade or migration path for their older Wi-Fi products. Some important consideration points when comparing solutions include:
Migration planning for any existing legacy WLAN installations
Centralized management and ease of tie-in to existing infrastructure
Ability to introduce new apps with relative ease
Simplified voice integration and product certifications
Telemetry product certifications
Product roadmap, 802.11n, etc.
Capability to support redundancy
Support for Dynamic Radios Management and RF self-healing. This is the capability of an AP radio to dynamically adjust power settings based on the RF footprint of surrounding access points
Ease of integration of guest access/services
Anywhere wireless access points are installed should also have a wireless Intrusion Protection and Detection System (IPS/IDS). A wireless IPS/IDS system serves the purpose of continuously monitoring and defending the airspace around access points. Most RF- sensor solutions also provide valuable insight into radio performance of the surrounding wireless network. Some have the ability to also provide audit reports for HIPAA and other compliance requirements. It is important to evaluate how well independent sensor products can integrate into a single WLAN solution. Many are now sold as integrated options from AP manufacturers.
Considerations for deployment
Following the design phase, and after site surveys have been completed and cabling is being run, a number of factors should be taken into account. For example, avoid installing wireless access points and sensors in surgery suites and patient rooms, because these are particularly difficult to install.
Also, large-scale wireless deployment requires a high degree of diligence with regard to network documentation of VoWLANs, closets, updated floor plans, etc. This is essential to streamlining support processes. It also may be beneficial to have a key individual working with the cablers to ensure proper AP and sensor placement.
Finally, corporate communication is essential throughout the process. It must be clearly outlined how the network will be turned on. A communication plan from IT leadership should be put in place to inform end users about the new network's availability, the process for gaining access, and where to go for support. This training will increase the probability of a successful deployment and productive use of the WLAN.
Challenges in support
After deploying the network and turning it up, wireless has unique support challenges that tend to require specialized staff and tools. Many organizations have dedicated wireless engineers and architects on their staff, which is recommended. This staff may be involved in monitoring IPS/IDS system and wireless utilization trends. They also should perform thorough testing and certification of each application, device, or system on the wireless network. During and after deployment, in the fine-tuning stage, this staff is also invaluable for troubleshooting RF and network issues.
It is critical that staff assigned to support the WLAN have the necessary tools and training to successfully manage the network. Some key tool sets that a wireless administrators use are a spectrum/laptop analyzer, LAN planner, and site planner.
Postinstallation modifications and improvements can be made to a wireless healthcare network, but their results will be limited; support and maintenance plans must be well thought out. “Making it up as you go along” can lead to a logistical headache on par with (going back to our highway analogy) Los Angeles rush hour traffic coursing through a bobsled course. It is critical to make all attempts to design for not only current requirements, but in anticipation of future needs. The key to a successful and adaptable WLAN lies in its design foundation and support strategy based on this outlook. HD
Ali Youssef is IT Architect and Bob Zemke is Solutions Architect for Managed Services, Siemens Communications, Inc.