It has become an undeniable reality that Wi-Fi access is a requisite part of everyday life. In order to satisfy our ever-increasing appetite for connectivity, wireless networks will continue to grow. Extending a Wi-Fi network for greater coverage can be as simple as adding another access point (AP). However, you may find that this has an adverse impact on network performance with client devices that do not roam well from one AP to the next.
With any discussion of roaming, it’s important to understand that the decision to roam is determined by the client device. Wi-Fi was originally conceived with the idea that there would be very few APs, so client devices were designed to hang on to an AP as long as possible. This means that even if a client can talk to an AP with better signal quality, it may stay attached to another AP.
Roaming in a Wi-Fi network occurs when the client device decides to detach from one AP and reattach to a different AP. You might think that if a client ‘sees’ an AP with a stronger signal or better signal quality, it would initiate a roam and try to attach to the AP with the best network link. Unfortunately, this isn’t how roaming works.
Although a few standards have been proposed and even adopted to help roaming, most of these standards are not widely implemented in APs or client devices. Most device manufacturers try to tailor their drivers to get the best user experience from a device and tend to keep their roaming algorithms proprietary.
Large space with three Access Points (APs) for adequate coverage.
Standard Wi-Fi Roaming
Let’s look at how a typical device roams. When a device attempts to connect to a Wi-Fi network, it will first search for APs. When it finds an AP to which it can authenticate, it will connect and participate on the network. As the client device moves around and away from the connected AP, the signal level and quality will degrade. The client may move closer to another AP with a better signal level and quality, but it won’t connect to this AP because it’s really only aware of the AP to which it’s already connected. It won’t search for new APs until the signal from the attached AP deteriorates to a point where there is little, if any, capability to exchange data. Once the client reaches this level, the user is probably already unable to stream video, talk over VoIP or control their Wi-Fi-enabled thermostat. Eventually, most clients will scan for a new AP. Unfortunately, this all-too-common scenario results in unhappy Wi-Fi users and dissatisfied customers.
To minimize frustrated Wi-Fi users, it’s up to the installer to deploy solutions that optimize the overall roaming experience for their customers. Fortunately, there are products and methods that make this relatively easy.
Wi-Fi client device in a standard multi-AP wireless network. The client is “stuck” to an AP with lower signal strength and little to no connectivity, even though a nearby AP with better signal strength is available.
The Rise of the Wi-Fi Controller
The best way to improve the customer roaming experience is to add a Wi-Fi controller to the network. A true controller can prompt client devices to move seamlessly from AP to AP, always trying to maintain the best signal quality. The wireless controller has an advantage in that it communicates with all of the APs and monitors connected clients, giving it a ‘big picture’ view of the network. The controller tracks each client and how the APs see them, allowing the controller to determine which AP will provide the best signal quality for each client.
(a) The controller determines that the client could be connected to a nearby AP with better signal and sends a disconnect command to the client. (b) The client disconnects, then connects to the AP with the better signal.
Sometimes a Controller Isn’t a Controller
It is important to note that not all wireless controllers will make roaming better. Some wireless controllers simply make deployment and management easier. While faster deployment is a worthy cause, this class of product would be more appropriately called a “wireless configurator”. True wireless controllers like Luxul’s XWC-1000 Wireless Controller do more than configuration and management—they help client devices roam and improve the user experience.
Luxul XWC-1000 Wireless Controller
As an integrator, you should also understand that some clients simply don’t roam as well as others. As stated previously, manufacturers modify their client drivers to maximize performance in a given environment. Sometimes this leads to a situation where even a wireless controller can’t make roaming perfect for a particular device. To learn more about Wi-Fi, roaming limitations, and design considerations, visit luxul.com/wifi-art-and-science.
Advanced Controller Capabilities
Some wireless controllers offer advanced tracking and reporting on client network usage, device location, domain controller integration and rogue access point detection. While these features can be crucial in enterprise applications, they may not be so useful in most residential or light commercial application. So, be sure to evaluate your customer’s budget and needs so as not to unnecessarily incur additional costs for your business and your customers. It simply doesn’t make sense to pay for expensive capabilities you and your customers won’t ever use.
Consider also that wireless controllers and APs work together as a system. There are many different choices for Wi-Fi controllers, but don’t expect a controller from one vendor to work with APs from another vendor.
Your customers need stable, secure and useable Wi-Fi, and they need it in increasingly larger spaces and under more challenging conditions. Determining the best wireless solutions will require a little homework on top of considering customer requirements and budgets. Some controllers are only meant for network configuration and can’t help with roaming at all. Some controllers are designed for the enterprise market and have prices and features to match. Finally, some controllers are designed just for the home and small office and the integrators who serve those markets. As an integrator, what you really care about is simple installation, high-quality and cost-effective hardware, good support when you need it, and happy customers that won’t need expensive follow-up service calls. The right wireless controller can help you meet those needs.