Technical Tip: Most Important, Least Capable device principle on wireless network design, tunning and operations
Description
This article describes a Wi-Fi design principle known as the 'Most Important, Least Capable' device to find a baseline for Wi-Fi design and tuning.
Scope
FortiGate as a wireless controller, FortiAP.
Solution
One of the most important challenges of operating and designing a wireless network in the enterprise, education, hospitality, retail, and industrial vertical markets is accommodating all sorts of Wi-Fi devices. It is necessary to ensure with a certain amount of confidence that most devices, if not all, will support all intended applications in the coverage area.
These kinds of devices can be as diverse as the market can offer, while applications are as diverse as the places where those services are offered and supported over a Wi-Fi network.
In enterprise spaces, using collaborative tools like Microsoft Teams, Zoom, and Hangouts is the minimum requirement expected at desks and in conference or meeting rooms with an authorized Wi-Fi device. Those spaces are often equipped with smartboards and videoconferencing devices connected to the Wi-Fi network to enhance content sharing with remote assistants.
In educational places such as Pre-K, K-12, and middle schools, Wi-Fi networks are often used with school-provided, low-end devices and applications offered over a centralized educational portal operated by government agencies or other third parties.
High schools and universities typically allow students and teachers to bring their own devices (BYOD approach) to access educational platforms and school services. The use of advanced technology in classrooms, such as smartboards, collaboration tools, and even VR applications, is expected today or in the near future. Those users are more likely to use high-end devices, the latest Android or iOS devices, and gaming laptops, often at the same time.
Retail networks can vary to accommodate convenience services for users, such as complementary Wi-Fi access and self-checkout services utilizing their own smartphones. They also support staff devices like mobile point-of-sale systems and barcode scanners to control sales inventory in real time. Hospitality networks often share most of the characteristics mentioned above.
In warehouses and factories, in addition to barcode scanners, environmental sensors, industrial equipment, machinery, and autonomous devices (robots) managed over a cloud or central application are frequently encountered. These are expected to be consistently supported to maintain real-time visibility of production chains.
The examples mentioned in the paragraphs above demonstrate that it is very difficult and almost impossible to accommodate all device and application requirements over Wi-Fi networks.
The best approach is to try to standardize the device types to be used in the coverage area and define core applications to be supported over the network to meet the business and institutional goals of the organization. This is often not possible for several reasons:
Users' lack of knowledge regarding the business operations.
Budget constraints or considerations for technology renewal.
Long upgrade cycles for end-user devices.
Inability to control what devices will be used in coverage areas.
Those are the main reasons Wi-Fi networks end up supporting a myriad of devices of all kinds, both older and newer.
This is why Wi-Fi network designers, administrators, and support staff need to determine which device is most important to support and how it is used over the network.
As Wi-Fi devices use the same channel to communicate with each other and a FortiAP one at a time, the overall network performance over a cell served by a FortiAP radio is set by the lowest capable device connected to it.
The most basic configurations on a FortiGate wireless controller, such as transmit channel, basic association rates, TX power output, and roaming support technologies, are dependent on the Wi-Fi capability of the lowest-spec device (the least capable one) allowed by the regulatory domain configuration. Design constraints, such as determining the number of FortiAP radios needed to support a specific quantity of devices over a coverage area and the ideal FortiAP installation locations, are also heavily dependent on this least capable device.
Before attempting to troubleshoot a Wi-Fi network, consider the following points:
Check if this is an issue for all Wi-Fi-connected devices or just a certain type of device.
Verify if the issue always occurs when a certain number of devices are used in the area.
Determine if all applications fail or if a specific application must work properly at all times for users.
This is when the 'most important, least capable' device concept is useful. If a Wi-Fi network is designed and tuned to properly support this kind of device, other more sophisticated devices will likely behave properly as well.
It is also useful to determine if those issues are due to improper FortiAP or FortiGate configuration and behavior, or if it is a network design failure. This helps find out if there is a possible workaround or compromise that solves it.
Organizations should enforce device standardization whenever feasible.