Wi-Fi Network Design Tips
The main aspects you want to address during the planning stage are throughput, roaming, and capacity requirements, RF interference, optimum access point (AP) locations and channels, and AP powering method.
If you’re planning to use the Wi-Fi for just light traffic like email and web browsing throughput and roaming then this isn’t a huge concern, but they are if you plan to use heavy and sensitive applications like voice (VoWLAN) or video streaming. If using sensitive applications like that, look into the requirements specified by the vendor of the applications (such as minimum signal, latency, and roaming hand-off times) and plan accordingly.
Capacity issues usually only become a concern when you think you’ll have more than 15 to 20 devices simultaneously connected to a single AP. In a typical office environment with wide-spread Wi-Fi coverage and users spread fairly evenly this isn’t usually an issue, but can very likely be if you offer public wireless access for large groups.
To check for RF interference and find optimum access point (AP) locations and channels you should do what is called an RF site survey. You can go around with free Wi-Fi stumblers to check for neighboring wireless networks, but the best option is to perform a full site survey with professional tools. Survey tools, like from AirMagnet, Ekahau, and TamoSoft, allow you to generate heatmaps of signal coverage and other related stats. They also allow you to generate fully simulated Wi-Fi environments to predict coverage and performance from equipment you haven’t deployed yet.
If you suspect there are issues with inference from non-Wi-Fi devices, like other wireless or electronic devices using the same or close wireless band to that of Wi-Fi, you should use a RF spectrum analyzer to help identify it so you can remedy or stop the interference. Some Wi-Fi surveying and analyzer tools support spectrum analyzer integration, but require an additional piece of hardware to scan the airwaves.
For every Wi-Fi deployment, you need to choose a method of powering the APs you mount throughout the building. If you plan on using PoE capable APs and already have a PoE capable switch you should ensure they’re compatible PoE versions. If the switch doesn’t support PoE but the APs do, consider using PoE injectors for each AP.
Wi-Fi Configuration
Configuring the wireless network isn’t usually difficult but time should be spent in choosing the correct settings, such as for the security, network names (SSIDs), and wireless channels.
When choosing a security method for your private SSID(s), remember WEP security is not secure. Use at least the pre-shared key (PSK) mode of WPA2 security with 13+ mixed character passphrases with no words from the dictionary. Most APs allow you to support both WPA (TKIP) and WPA2 (AES-CCMP); however for better security you should select only WPA2 (AES-CCMP).
For businesses or organizations, the enterprise mode of WPA2 should really be used. Though much more complicated to setup than the PSK mode, the enterprise mode uses 802.1X authentication to give each user their own login credentials. Everyone having the same Wi-Fi password is a problem when someone leaves the organization or they lose a device that its saved in; you’d have to change the password when these situations arise. But with the enterprise mode you’d just have to revoke or change the password for just the affected user.
Using the enterprise mode requires you to have a RADIUS server in order to perform the 802.1X authentication. There are many RADIUS server options out there, including open source solutions that are free and hosted services if you don’t want to setup your own.
You usually want to set the same network names (SSIDs) across all the APs to allow for better roaming. But there’s no real right or wrong answer when differentiating between bands (2.4 and 5GHz) in the SSIDs. Setting the same SSIDs for both bands allows the client devices to choose the band, some of which choose smartly, like the one providing the best signal or performance while others just connect to the first one it sees. Specifying the band in the SSIDs allows the end user to choose, but most users won’t understand the difference.
If utilizing multiple SSIDs (more than one SSID per band) than ensure the SSIDs are assigned with the proper settings for the wireless security and VLANs.
When using APs with two or more spatial streams for MIMO, you’ll have the option of using channel-widths greater than the original 20MHz to increase the throughput. However using these larger channel-widths may cause channel overlap and interference issues, especially in the smaller 2.4GHz band. Some APs come by default set to automatically allow all channel-widths, thus you may want to verify it’s set only to 20MHz until you ensure the larger ones won’t cause problems.
Summary
We discussed the main aspects to consider when designing your Wi-Fi network. However since Wi-Fi utilizes the airwaves, the security and performance should be monitored closely after deployment as well. At least periodic RF site surveys should be performed to ensure wireless coverage and performance is still acceptable, neighboring networks aren’t interfering, and rogue access points or wireless routers haven’t been setup. In conjunction with site surveys consider deploying a wireless intrusion detection or RF analyst solution that can monitor the airwaves for these types of issues.
WiFi Network Design: a practical guide for planning and implementation
Once upon a time, WiFi network design planning involved grabbing a floor plan and plotting locations for access points with a protractor. This was a tedious and time-consuming activity. Access points no longer require manual power and channel settings. Wireless planning has also become much more simple, thanks to great software options. However, the downside is that wireless devices and the world of WiFi continue to get more complex than ever.
Initially, WiFi network design involved a large emphasis on coverage, as only a select group of people used and relied on wireless on a regular basis. With more and more companies opting for BYOD, it is hard to find a regular user who does not rely on wireless every day and often on multiple devices. Needless to say, wireless network design has changed significantly.
This article provides engineering insight and practical techniques for designing, planning, and implementing a wireless network that is robust, compliant, and without borders.
Key elements of a robust and reliable WiFi network design strategy should include the following considerations.
Plan for capacity, not just 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 number 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.
In this method, key elements like the number of concurrent users, and applications’ bandwidth needs are left out. Wireless engineers and IT consultants need to fully understand the WiFi network design requirements to ensure a successful design. This will help reduce the need for further site surveys after the deployment of the WiFi infrastructure in the long run.
Key points to consider:
- Types of applications expected in the network, e.g., web browsing, VoIP calls, software, or video streaming.
- Technologies that the WiFi infrastructure supports (802.11 a/b/g/n/ac).
- Number of client devices that connect to the WiFi network simultaneously (helps to determine the number of spatial streams, technology, and access point types).
- Key geographical areas you need to cover and provide WiFi in and the number of concurrent devices per area.
- Power constraints. It’s way more useful to have an infrastructure equipped with PoE+ that allows you to support high-performing access points.
Channel utilisation
The WiFi network management platform should have incorporated 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 wider channel widths will support higher bandwidth within the particular protocol.
Estimate how many client devices can be allocated 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.
Think mobile – Again, think mobile
A good WiFi network design needs to be built up, also, for mobile – it is very crucial to the success of any WiFi network deployment in recent times. 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.
SSIDs
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 open SSID for all unmanaged devices (daily guests, consultants, BYOD, customers..) with captive portal authentication. 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.
BYOD
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. Also since there are multiple devices involved, the BYOD solution should be compliant with local and global data privacy regulations. To understand how data privacy has changed digital businesses in the past few years, check out our latest report.
Lastly, a per-user bandwidth consumption limit is essential in the network to manage its performance. It is important to take into account that the BYOD trend has a direct consequence on the bandwidth and throughput requirement.
IOT
The advent of the Internet of Things (IoT) has brought additional complexity to WiFi network design. With the proliferation of interconnected devices, ranging from sensors and smart appliances to industrial equipment, a robust WiFi network must be capable of handling the increased traffic and unique requirements of IoT devices. The design strategy should incorporate considerations such as device density, data throughput, and latency to ensure seamless connectivity and optimal performance for IoT applications. Additionally, security measures must be implemented to safeguard sensitive data transmitted between IoT devices and the network. By integrating IoT elements into the WiFi network design, organizations can harness the full potential of this transformative technology and unlock new possibilities for automation, monitoring, and efficiency.
Bandwidth limitation
The final recommendation for a better WiFi network design is to put in place a per-client device bandwidth limit on all the WiFi network traffic. Priority must be given to applications such as video and voice. For instance, 5 Mbps is a good recommendation for a per-client bandwidth limit in a high-density environment.
With multiple connection modes and device types becoming a common norm at offices, hotels, guest houses, etc. it won’t be wrong to say that a poorly planned and implemented WiFi network design can negatively impact the IT productivity of your entire organization. It might even be detrimental in some situations and could hamper critical business processes. Hence IT infrastructure teams must keep all these parameters in mind in order to think for the long run and design a WiFi network that is robust, compliant, and hassle-free.