Wi-Fi Design Fundamentals for Modern Networks

Designing wireless networks has become both an art and a critical skill for wireless engineers in today’s fast-paced world of evolving technology and the constant demand for greater speed and reliability.

Below is a list of the most fundamental factors to consider that can help you make better decisions when designing Wi-Fi for any environment.

Design Fundamentals for Wi-Fi

Understand the Requirements

Understand what you need your Wi-Fi to do for your users and devices. Not all Wi-Fi is created equal—nor should it be.

Several factors, such as wall types, ceiling heights, and the number of users, will influence the type and number of access points (APs) required, as well as their placement. The more information you gather, the more accurate and effective your design will be.

Key Questions to Ask When Designing Wi-Fi for Capacity

1. Define the desired coverage area and identify any exclusion zones. Its important to have a visual representation of the excluded areas so we don't end up with APs in storage rooms or vacated spaces where Wi-Fi coverage is not required.

2. Determine the number of users in specific areas.(e.g., How many users per classroom or office space?)

3. Estimate the number of devices each user will connect.(Phones, laptops, tablets, IoT devices, etc.)

4. Is Voice over Wi-Fi (VoWi-Fi) required? Consider latency, jitter, and roaming requirements.

5. Are there aesthetic or mounting constraints?(For example: APs must be hidden, ceiling-mounted, or not visible in public areas.)

6. Are legacy devices in use that require specific frequency bands or compatibility considerations?

7. Is there a preferred vendor for access points and antennas?Choose the AP that meets your technical needs—avoid overpaying for unnecessary features.

8. Identify critical applications and their bandwidth requirements.(Video conferencing, cloud apps,specialized software, etc.)

   
   

The latest wireless design software allows you to define coverage areas and user profiles, specifying the number of clients and application types in order to calculate airtime utilization and determine the number of access points required based on demand.

Designing the WLAN

To deliver optimal performance, always design your WLAN based on network requirements and fundamental Wi-Fi principles.

1. Design for the LCMI (Least Capable, Most Important Device) Ensure the LCMI can connect and perform well. If the LCMI functions optimally, other devices will likely follow suit.

2. Channel Width Selection: Avoid using the AP manufacturer defaults of 80 MHz width channels on the 5 GHz band. Narrower channels (20 or 40 MHz) are often more appropriate, especially in environments with significant channel overlap and high density of APs and clients.

3. Dealing with Co-Channel Interference: Choose 20 MHz channels over 40 MHz. It's better to have two APs using separate 20 MHz channels than two APs using overlapping 40 MHz channels.

4. Device Connectivity Strategy: Use wired connections for stationary devices (e.g., printers, smart TVs). Reserve wireless connections for mobile or portable devices (e.g., laptops, tablets). This helps preserve RF spectrum for devices that truly need it.

5. Match AP Transmit Power to LCMI Capabilities: Avoid overpowering the network by configuring APs to match the maximum transmit power of the LCMI. Learn the LCMI capabilities and try to match the power level on the AP. This will prevent an unbalance of transmit power between the AP and the client.

6. DFS Channels: Use DFS channels to reduce interference by expanding the number of available channels in your channel plan. However, avoid them if you experience frequent radar interference—such as unexpected channel changes or DFS events in logs. DFS channels are often shared with weather Doppler radar, military radar systems, and airport surveillance radar.

7. Band Planning : Prioritize the 5 GHz and 6 GHz bands for WLAN design. Use 2.4 GHz only when necessary due to its congestion and limited non-overlapping channels.

8. SSID Strategy:

   - If needed, create a unique SSID for 2.4 GHz to prevent clients from band-steering unpredictably.

   - Stick to a maximum of 3-4 SSIDs to reduce management frames overhead, increase airtime availability and improve roaming.

9. 5GHz Channel Interference Mitigation: First, reduce the transmit power. If interference remains, consider turning off select 5 GHz radios to reduce contention.

10. Channel Plan for 2.4 GHz: Use only non-overlapping channels 1, 3 and 6.

Installing the APs

If you have an existing wireless infrastructure, review the following checklist and make corrections as needed:

1. Perform a full inventory of all wireless equipment, including AP model, name, and MAC address, before mounting any access points.

2. Install APs with internal omnidirectional antennas on the ceiling, no higher than 25 feet, and always facing downward. Never mount APs inside ceiling tiles.

3. Ensure APs and antennas are installed below any obstructions.Use conduit and an electrical box to suspend the AP below the obstruction to provide optimal coverage to the intended area. You may paint the conduit to match the building's aesthetics if needed.

4. Never mount APs with internal omnidirectional antennas on a wall like a clock.This alters the signal pattern and weakens performance for client devices.

5. Avoid placing APs in hallways.This creates signal “tails” and negatively impacts roaming performance.

6. Use directional or specialized antennas for APs mounted above 25 feet or where signal needs to be focused in a specific direction.

7. Label each AP with its name or the last four digits of its MAC address for easier identification and troubleshooting.

8. Secure APs in protective enclosures in public spaces or arenas to prevent accidental damage or tampering.

Proper physical installation of access points is essential for ensuring optimal wireless coverage, performance, and client experience. Pay close attention to mounting height, orientation, obstructions, and environmental constraints. Avoid common mistakes like placing APs in hallways or inside ceiling tiles, and always use the right antenna type for the scenario. A well-documented, thoughtfully installed network will lead to better reliability, easier troubleshooting, and longer-lasting infrastructure.

We hope this has been helpful in highlighting the importance of following the fundamental principles of designing and installing wireless networks for any environment. A well-planned WLAN ensures reliable performance, efficient use of spectrum, and long-term scalability.