In the process of WiFi network design, you need to consider many factors to plan it out thoroughly. In this blog article, I won’t cover the typical step-by-step of ‘how to design a WLAN’, instead, I will highlight key elements that you should take into consideration to successfully design a WLAN.
WiFi Network Design. Key considerations
1) Plan for capacity not for coverage
Not that long ago, designing a WiFi network was pretty much focused around physical site surveys to determine the number of access points needed to provide enough coverage. Afterward, you would evaluate the results and compare the amount of APs against an acceptable minimum of signal strength, and the whole WLAN design would be deemed a success.
Going down this road is suitable for WLANs that are planned for coverage but certainly is not the right approach to meet capacity requirements. For instance, when you plan for RF coverage, you leave out key elements like the number of concurrent users, applications’ bandwidth needs, and capabilities that you would cover if you design for capacity instead.
Wireless engineers and IT consultants need to fully understand the network design requirements to ensure a successful design. This step is crucial, so don’t skip it! This will help you reduce the need for further site surveys after you deploy the WiFi infrastructure and deploy additional access points in the long run.
Grab all the details:
- What types of applications will be expected in the network, e.g., web browsing, VoIP calls, software, or video streaming? Calculate the bandwidth per user.
- What technologies should WiFi infrastructure support (802.11 a/b/g/n/ac)?
- How many client devices will connect to the WiFi network simultaneously? It will help you to determine the number of spatial streams, technology, and access point type.
- What are the key areas you need to cover and provide WiFi?
- Estimate the number of concurrent devices per area
- Check if there are any limitations for cabling or any aesthetic requirements, e.g., mesh solution.
- Also, consider power constraints. It’s way more useful to have an infrastructure equipped with PoE+ that allows you to support high performing access points.
Once you gather all this information, you can adequately plan for capacity!
2) Channel utilization
The WiFi network management platform you choose should have a tool to manage radiofrequency. So, it can dynamically assign access points channels, adjust the access point transmit power, and provide coverage lapse mitigation for the WiFi infrastructure.
For instance, for the 802.11ac wireless standard, radio frequency management should be executed at 20, 40, and 80MHz channel widths. Different client devices will support different channel widths for the 802.11 protocols. Client devices that support the wider channel widths will support higher bandwidth within the particular protocol.
Estimate how many client devices you can allocate per band. With newer technologies, more client devices now support dual-band operation, and hence using proprietary implementation devices can be steered to 5 GHz. A typical design approach is to do a 30/70 split between 2.4 GHz and 5 GHz.
Take into consideration when designing WLANs, especially for high-density environments, that roaming will happen very often. Having access points that support fast roaming or a WiFi management software that can give this capability to access points is crucial—fast roaming aids in reducing application latency while the client device roams from one access point to another.
Furthermore, the placement of access points plays a significant role in roaming. Even after deploying the access points in the right locations, roaming may not perform as you would expect. This is merely due to the variety of client devices connected in the network with diverse Network Interface Cards (NICs) and roaming algorithms.
Keep in mind that in high-density environments, it is acceptable if a client device doesn’t roam to every access point in the roaming path and only roams to every other access point, as far as roaming is seamless before the client device’s Received Signal Strength Indicator (RSSI) falls between 75 dBm to 80 dBm.
Although the client device usually takes the roaming decision, access points such as the Ubiquiti Unifi AC Long Range allows you to enable the fast roaming feature on the access point. Lastly, to maximize speed and facilitate roaming, you should disable lower data rates in support of legacy wireless protocols.
4) Think Mobile
A good WLAN design needs to be built up, also, for mobile – its a must, not a luxury! The wireless design for deployment should be optimized for every device, from smartphones and IoT to computers and tablets. Having the right wireless design comes first, especially when ensuring elevated device performance and overall mobility for a better end-user experience. This also means considering features such as 802.11r/w/v.
To maximize performance in the wireless space and simplify deployment, try to minimize the number of SSIDs being broadcasted into the environment. The drawback of enabling more SSIDs is that it generates extra channel utilization due to overhead. A target of three SSIDs per access point provides for a flexible yet straightforward deployment model.
For example, you can have one SSID using a captive portal for guest access and 802.1x client provisioning. A second SSID for 802.1x authenticated users and devices. And a third SSID for particular use cases or specialized wireless devices, e.g., Wi-Fi-enabled VoIP phones, non-802.1x capable devices, or specialized network devices.
For other use cases, different SSIDs may be required depending on your specific needs, but strive for no more than 3 SSIDs per access point.
Users want to connect their personal devices to public and private WiFi networks. It’s the standard. Just make sure that users are routed through a web content filter to provide a secure browsing experience to all users.
Lastly, have a limit per-user bandwidth consumption in the network to manage its performance. Don’t forget to take into account that the BYOD trend has a direct consequence on the bandwidth and throughput requirement.
7) Bandwidth limitation
Our last recommendation for a better WiFi network design is to put in place a per-client device bandwidth limit on all the WiFi network traffic. Consider that if you prioritize applications such as video and voice, it will significantly impact the network’s bandwidth, limiting the performance of other applications. For instance, 5 Mbps is a good recommendation for a per-client bandwidth limit in a high-density environment. Of course, you can neglect this limit for specific devices and applications and adjust it to your particular needs.
With the ever-increasing use of IoT devices, as well as the exponential use of cloud-based applications, critical to businesses everywhere, it forces IT specialists and consultants to be one step ahead of the game and be prepared. This means having the right wireless network design to meet the client’s needs.