The Guide to Wi-Fi Network Design: Strategies for Success

Recall the days when our homes or offices were cluttered with tangled wires, restricting our movements and tying us to fixed locations. Wireless technology has revolutionized our lives, evolving from a novelty to an indispensable necessity. Gone are the days of bulky, desk-bound laptops; we now embrace sleek gadgets that seamlessly connect us to the world, wherever we roam.

Now, this move towards wireless is changing how our networks work also. Traditional wired networks with cables are starting to show their limitations. You can see it everywhere: more wireless gadgets, that need the internet, and the importance of being flexible anywhere.

This shift indicates a future where wireless takes centre stage, with Wi-Fi serving as the backbone of our interconnected lives. To fully leverage this wireless landscape, Network Engineers must understand how to design and implement Wi-Fi networks. This knowledge ensures that our networks are both fast and reliable, covering all our needs in this wireless world

Understand Your Deployment Scenario

The deployment scenario for which an engineer sets up the Wi-Fi network plays a major role in design decisions. Here are some key factors to consider as you begin planning your design

Location

Consider the deployment scenario when setting up a Wi-Fi network—it significantly influences design decisions. Different locations have varying needs regarding coverage area and potential interference sources. For instance:

Homes typically require fewer access points (APs) due to their smaller size.
In contrast, sprawling office buildings or factories with thick walls and metal structures may need more APs to ensure coverage.

While Wi-Fi design tools are available and valuable, a successful network design relies on a blend of software insights and design principles. These tools can’t always account for every real-world variable, and sometimes they might not be readily available. In these situations, understanding core design principles becomes even more critical

Number Of Users: How many devices will connect to the network simultaneously? Streaming 4K videos on multiple devices requires a different approach than basic internet browsing for a small family.

Bandwidth Requirement : Consider the typical bandwidth requirements of each user in the network. Activities such as online gaming and video conferencing demand considerably more bandwidth than simple email checking. Furthermore, take into account your total outbound (WAN) bandwidth — the internet speed supplied by your ISP to your network.

This information can be collected by a survey of the location or by your clients supplying the necessary details.

WiFi Designer Tools Are Your Friend

Sample Image of Ubiquiti Design Center’s Tool
Floor Plan source: RoomSkecher

Wi-Fi design tools offer a powerful advantage for planning and optimizing your wireless network before any physical installation. You can upload existing floor plans or create them virtually within the software. This allows you to visualize the estimated signal coverage from strategically placed access points (APs). This visualization helps you identify potential dead zones before installing equipment, allowing you to adjust the AP placement for optimal coverage.

These tools go beyond simple visualization. They factor in wall materials, signal attenuation, and interference sources to predict the signal strength at different locations. This prediction ensures consistent and reliable Wi-Fi performance across your entire network.

Some tools take it further by recommending configuration settings for your APs based on the specific network design you create. This simplifies the configuration process and helps optimize performance for your unique needs. Additionally, the software can generate heatmaps after you’ve virtually placed the APs. These heatmaps visually represent the predicted signal strength throughout the area, clearly showing strong and weak signal zones. With that data, you can fine-tune the AP layout for an even more optimized network.

Start With The Lowest Performing Client Device.

Rather than simply installing powerful access points (APs) and hoping for success, designers should focus on the capabilities of the least sophisticated client device. Why? Because these devices often influence roaming decisions and minimum data rates, directly affecting overall network performance.

If the weakest client maintains a strong signal, ideally between -60dBm and -65dBm, it translates to smooth operation for all devices. This involves strategically placing APs closer to client locations to optimize signal strength from the client’s perspective.

Installing APs as close to client devices as possible reduces interference and increases the signal-to-noise ratio (SNR) value.

5GHz And 2.4GHz Bands

As a WiFi network designer, you’ll primarily work with two major wireless radio bands: the 2.4GHz and 5GHz bands. While newer technologies like the 6GHz band exist, we would focus on the widely used 2.4GHz and 5GHz bands. By gaining a deep understanding of these bands, you’ll be well-prepared to design WiFi networks efficiently, adapting to evolving technology

A breakdown of these two bands

2.4 GHz: This band offers greater range and better penetration through walls. However, it comes with the drawback of slower speeds for a limited number of usable channels. This limitation can lead to interference issues in congested environments.

5 GHz: This band boasts higher bandwidth, translating to significantly faster speeds. The downside? It has a shorter range and weaker ability to penetrate walls compared to 2.4 GHz. However, 5 GHz offers more usable channels, which helps minimize interference.

Selecting the ideal band for your network depends on factors, such as device compatibility, coverage area, channel interference, and bandwidth requirements. Prioritize compatibility with the least capable device, as newer devices typically support both bands. Assess coverage needs and signal path obstacles; opt for 2.4 GHz in congested spaces and 5 GHz in open areas for better performance.

Due to its greater number of usable channels, 5 GHz is preferable in congested environments and for high-speed requirements.

Interference And SNR (Signal To Noise Ratio)

Wireless networks rely on clear signal transmission for peak performance. Yet, unwanted signals from other devices or nearby access points (APs) can disrupt communication, impacting network speed and reliability. This interference occurs when multiple APs on the same channel attempt simultaneous data transmission.

Signal-to-Noise Ratio (SNR) measures the strength of the desired signal against background noise (interference). Higher SNR values (in dB) indicate stronger signals and better connection quality, while lower SNR values suggest potential issues.

Obstructions, poor AP placement, and interference from other APs on the same channel can all contribute to lower SNR. For instance, if a user’s AP broadcasts at -68 dBm and a neighbour’s Wi-Fi network broadcasts at -81 dBm on the same channel, the resulting SNR is 13 dB, significantly affecting performance.

A stable wireless connection typically requires an SNR above 20 dB, with 25 dB being the recommended minimum. The values below indicate potential issues, while higher values are preferred.

While formulas exist for SNR calculation, online resources can simplify the process if you know the desired and unwanted signal values.

Channels And Channel Width

Think of WiFi channels as lanes on a highway, each with a limited capacity for data. A single WiFi channel is similar to a single lane, allowing a moderate data flow.

However, you can expand this capacity by grouping lanes, creating a wider “highway” through channel bonding. This increases data flow, by adding more lanes to a highway, resulting in faster WiFi speeds.

Two key types of channel-based interference affect WiFi network performance: co-channel and adjacent channel interference.

Co-channel interference is the most disruptive, it occurs when different APs use the same channel. It’s like two people shouting on the same walkie-talkie channel, drowning out each other’s voices, even with different SSIDs.

Adjacent Channel Interference is less disruptive but still affects performance. It happens when WiFi networks use channels close together, causing some signal bleed-over. Picture two people shouting on neighbouring channels – you can still hear some of the other person’s message, making it harder to understand your own. This interference can occur even with different SSIDs.

Thus, prioritizing non-overlapping channels is vital for minimizing interference

Recommended Channels for 2.4 GHz

The 2.4 GHz Wi-Fi band offers 11 channels, each 20 MHz wide with a 5 MHz separation. While channel bonding combines channels for wider bandwidth (up to 40 MHz), it’s best to stick to individual 20 MHz channels.

Here’s why:

Reduced Interference: Wider channels are more susceptible to interference from nearby networks. In congested areas, like apartments or neighbourhoods with many Wi-Fi networks, using 20 MHz channels minimizes interference.
Compatibility: Many older Wi-Fi devices don’t support wider channels. By using 20 MHz channels, you ensure compatibility with all devices on your network, regardless of their age or capabilities

Choosing the Right 2.4Ghz Channel(s) for Optimal Signal Stability

Within the available 20 MHz channels, 1, 6, and 11 are recommended because they don’t overlap. This non-overlapping nature translates to better signal stability and reduced errors in your Wi-Fi network.

Manually configuring channels on your access points (APs) is recommended over leaving them in auto mode, especially in environments with multiple APs. This approach offers finer control, improves stability, and reduces transmission errors.

Sample Layout of 3 APs with proper channel separation

Recommended Channels for 5 GHz

The 5 GHz Wi-Fi band holds a notable edge over 2.4 GHz in channel availability. Unlike the constrained options in the 2.4 GHz band, 5 GHz offers a broader range with numerous non-overlapping channels, typically around 48 (varies by region).

While channel bonding enables merging these channels for expanded bandwidth (up to 160 MHz in certain cases), the ideal channel width hinges on your specific requirements:

und 48 (varies by region).

While channel bonding enables merging these channels for expanded bandwidth (up to 160 MHz in certain cases), the ideal channel width hinges on your specific requirements:

For Enterprise Environments: For complex enterprise Wi-Fi deployments with many devices, using 20 MHz channels is often preferred. This strategy provides several benefits:

More Channels to Use: With 20 MHz channels, you have access to a larger pool of non-overlapping channels, allowing you to distribute network traffic more efficiently across multiple access points (APs) and reduce congestion.
Reduced Interference Potential: Narrower channels are less susceptible to interference from other networks operating on nearby frequencies, leading to a more stable and reliable connection for all devices.

However, using 20 MHz channels comes at the cost of sacrificing some potential speed compared to wider channels.

For Home Networks and Low-Interference Environments: If you prioritize speed for your home network or operate in a location with minimal Wi-Fi congestion, using wider channels like 40 MHz or even 80 MHz (the maximum supported by most devices) can be a good option. This approach offers significant speed improvements compared to 20 MHz channels, allowing faster data transfers and smoother streaming experiences.

DFS Channels and Geolocation:

The 5 GHz band includes DFS (Dynamic Frequency Selection) channels, shared with critical applications like weather radars. Although these channels offer additional bandwidth potential, their availability can be unpredictable. Routers may switch channels if radar activity is detected. Geolocation affects DFS channel usage due to regulatory restrictions, with some regions having stricter limitations. Installation location matters; DFS channels are better suited for indoor use, as outdoor installations, especially with direct line of sight to weather radars, may experience disruptions due to radar activity.

5GHz Channels
Image Source: Fortinet

Penetration vs. Congestion:

While 5 GHz offers more channels and potentially higher speeds, it has a significant drawback compared to 2.4 GHz: weaker signal penetration. Solid objects like walls and furniture easily absorb 5 GHz signals. This can limit the range of your Wi-Fi network in buildings with thick walls or multiple floors. However, the abundance of channels in the 5 GHz band helps overcome the congestion issues that plague the limited channels in the 2.4 GHz band, leading to a more reliable and efficient Wi-Fi experience overall.

Proper Data Rate Implementation Improves Network Performance

Picture this: devices with lower data rates hogging more airtime on a shared Wi-Fi channel, like slow cars clogging up a busy highway. This ‘airtime’ is the time each device spends occupying the channel for communication.

In bustling enterprise environments with many devices, having a lot of slow devices can drag down the entire network. Slow devices consume more airtime, leaving less for others, leading to frustratingly slow speeds and longer waits for data transmission.

This airtime hogging by some devices also sparks more intense competition among devices, like rush hour traffic jams, causing data collisions and packet corruption. We need solutions to streamline airtime usage to unclog these bottlenecks caused by sluggish devices.

Enter: setting minimum data rates for client devices on access points (APs). This feature ensures only devices meeting a certain speed threshold can connect, preventing the network from slowing to a crawl.

We recommend a minimum data rate of 24 Mbps for both 5GHz and 2.4 GHz bands for enterprise environments. This helps trim down airtime usage by slower devices, giving the network a much-needed speed boost.

Consider a 12 Mbps minimum rate on the 2.4 GHz band for broader device compatibility. While more inclusive, keep in mind that performance might take a hit compared to the 24 Mbps option.

Of course, there’s a trade-off: setting a minimum data rate could leave older or weaker devices out in the cold. It’s all about striking the right balance between improved performance and potential connectivity losses.

Placement Of AP Fresnel Zone Problem

To illustrate the importance of access point (AP) placement, let’s consider a common scenario in hotels and hostels for example. Using an online sample floor plan like this one by Apnaghar, we would see a major cause of poor Wi-Fi signal strength: improper AP placement.

Sample Image Of APs Placed in The Walkway

To minimize disruption within guest rooms, some hotel or hostel owners mistakenly install APs in hallways, walkways, or balconies. While this approach might seem convenient from a maintenance perspective, it leads to significant signal degradation for guests in their rooms.

The WIFI Fresnel zone is a critical area that surrounds the line of sight between your Wi-Fi transmitter (access point) and your device (receiver). It’s not a perfect sphere, but a non-uniform, ellipsoid-shaped region. The first 60% of this zone is important for maintaining a strong and reliable connection.

The first 60% of the Fresnel zone is considered the most critical area. Minimizing obstructions within this area is essential for maintaining a strong and reliable Wi-Fi connection.

Depection of the signal path using a single AP

Infrastructure Requirements

The access point requires both a network connection, typically through a switch or other networking medium, as well as power. Wireless APs may support varying network interface speeds, such as 100Mbps (Fast Ethernet), 1000Mbps (Gigabit), or even up to 2.5Gbps. The choice of interface depends on the number of users per AP and the expected bandwidth.

Many modern APs support Power over Ethernet (PoE), especially wall, pole, and ceiling mount variants, simplifying installation. However, PoE standards and wattage requirements may vary. Designers or engineers must assess AP power and bandwidth requirements based on user count and bandwidth needs.

With this information, they can determine the appropriate switch type, PoE standard, total switch power, and switch port bandwidth. Using the wrong configuration may result in power or bandwidth issues.

Additionally, consider using Cat6 cables for most installations.

Every other Thing

While there are numerous other valuable aspects to consider, covering every configuration and context in one article may be overwhelming. However, we’ve addressed some key considerations. These include managing interference through band and channel selection, optimizing AP placement for signal strength and reception, effective bandwidth management, and leveraging WiFi design tools for installation assistance and infrastructure planning.

By implementing these strategies, you’re likely to achieve a stable WiFi installation suitable for most homes and small business setups.

In future discussions, we can look into additional factors such as wireless security, antenna selection, radius configurations, setting up multiple SSIDs on different VLANs, and more.