Why Adding More Access Points Can Actually Make WiFi Worse
Your WiFi isn't performing well.
Some areas are slow. Users complain about dropped connections. Devices sometimes struggle to roam.
The obvious solution seems simple:
Add more access points.
Sometimes that's exactly what the network needs.
But surprisingly, adding more WiFi access points can also make an existing wireless network perform worse.
WiFi performance depends on much more than signal strength. Access points share radio spectrum, compete for airtime and interact with neighboring wireless cells.
A properly designed network therefore isn't about installing as many access points as possible.
It's about installing the right number of access points, in the right locations, operating at the right power levels and on the right channels.
More WiFi Signal Doesn't Always Mean Better WiFi
One of the biggest misconceptions about wireless networking is that stronger signal automatically means better performance.
It doesn't.
A device can have excellent signal strength and still experience:
Slow speeds
High latency
Packet loss
Unstable applications
Poor roaming
High channel utilization
Wireless interference
Signal strength is only one component of wireless performance.
WiFi uses shared radio spectrum. Devices and access points operating on the same channel must compete for opportunities to transmit.
Adding another AP therefore doesn't simply add more signal.
It adds another radio transmitter to the RF environment.
WiFi Is a Shared Medium
Ethernet and WiFi behave very differently.
With a switched Ethernet network, individual devices can have dedicated wired connections to the network.
WiFi operates over shared radio channels.
When multiple devices use the same channel within hearing range of each other, they generally need to share available airtime.
Imagine several people trying to have conversations in the same room.
With two people, communication is easy.
Add 20 people speaking simultaneously and communication becomes much more difficult.
Wireless networks have a similar challenge.
The objective of professional WiFi design is therefore not simply to provide coverage.
We also need to manage how the available RF spectrum is being used.
The Problem With Co-Channel Interference
One of the major problems created by excessive access point density is Co-Channel Interference, commonly called CCI.
Imagine three nearby access points all operating on the same WiFi channel.
AP 1 — Channel 36
AP 2 — Channel 36
AP 3 — Channel 36
These access points don't operate as three completely independent networks.
If they can hear each other, they share the same RF airtime.
When one device is transmitting, other devices using that channel may need to wait before transmitting.
As the number of devices and APs competing for the same channel increases, available airtime becomes increasingly valuable.
This is why simply installing additional APs without considering channel reuse can reduce network efficiency.
More Access Points Can Mean More Interference
Consider an office where 10 access points provide good coverage.
Someone notices a few connectivity problems and decides to install another 10 APs.
There is now excellent signal almost everywhere.
But there may also be:
More overlapping wireless cells
More APs operating on reused channels
Higher channel utilization
More contention for airtime
More neighboring networks visible to client devices
The signal became stronger.
The network did not necessarily become better.
This is an important principle:
Coverage and performance are not the same thing.
Excessive Transmit Power Can Make the Problem Worse
Another common mistake is operating every access point at maximum transmit power.
It sounds logical:
More power = more coverage = better WiFi.
But wireless communication is two-way.
An access point may transmit strongly enough for a smartphone or scanner to hear it from a considerable distance.
That doesn't necessarily mean the smaller client device can transmit back equally well.
Excessive AP power can also create oversized wireless cells.
Those larger cells may:
Overlap unnecessarily
Increase co-channel contention
Encourage clients to remain connected to distant APs
Reduce channel reuse efficiency
Make roaming less predictable
Professional WiFi design therefore involves controlling RF power, not simply maximizing it.
Sometimes turning an AP's transmit power down can improve the network.
Too Much Cell Overlap Can Affect Roaming
Some overlap between neighboring access points is normally desirable.
A mobile device needs an opportunity to discover another suitable AP as it moves through the building.
But excessive overlap can create its own problems.
Imagine a warehouse scanner standing in one location and hearing:
AP01 at -55 dBm
AP02 at -58 dBm
AP03 at -60 dBm
AP04 at -62 dBm
AP05 at -65 dBm
The scanner has many strong access points available simultaneously.
That might sound excellent.
But depending on the client device and network design, such excessive cell overlap can contribute to inefficient channel reuse and less predictable roaming behavior.
The objective is not to make every AP visible everywhere.
The objective is to create controlled wireless cells that provide sufficient coverage and appropriate overlap.
The Client Device Makes the Roaming Decision
Another important WiFi concept is that roaming is generally client-driven.
The access points can provide information and features that assist roaming, but the client device ultimately decides when it wants to leave one AP and connect to another.
Different devices behave differently.
A modern smartphone may roam very effectively.
An older barcode scanner or industrial device may hold onto an access point much longer.
This behavior is sometimes called a sticky client.
Imagine a worker walking through a warehouse.
The scanner connects to AP01.
As the worker moves away, AP02 becomes closer and stronger.
But the scanner may continue using AP01 until its internal roaming threshold is reached.
If wireless cells are excessively large because AP transmit power is too high, this behavior can become more noticeable.
Good roaming therefore depends on the relationship between:
AP placement + RF power + cell size + overlap + client behavior.
More APs Also Means More Channel Planning
WiFi operates within a limited amount of available spectrum.
As AP density increases, channel planning becomes increasingly important.
Ideally, nearby access points should be configured to minimize unnecessary channel reuse.
But eventually channels must be reused.
The challenge is making sure APs using the same channel are sufficiently separated wherever possible.
This is particularly important in:
Large offices
Warehouses
Hotels
Schools
Healthcare facilities
Conference environments
High-density venues
Installing additional access points without considering the existing channel plan can therefore create new RF problems.
Channel Width Matters Too
Channel width is another important consideration.
Using wider channels can provide higher potential data rates, but wider channels also consume more available spectrum.
For example, a network using 80 MHz channels has fewer non-overlapping channel opportunities than one using 40 MHz or 20 MHz channels.
In a dense wireless environment, this can significantly affect channel reuse.
Sometimes a properly designed network using narrower channels can deliver better overall capacity and consistency than a network using very wide channels everywhere.
Again, bigger isn't automatically better.
The correct configuration depends on the environment and application requirements.
Adding APs Can Absolutely Be the Right Solution
None of this means adding access points is bad.
Many wireless networks genuinely don't have enough APs.
Additional access points may be required because of:
Coverage gaps
High client density
Building expansion
New warehouse racking
Increased capacity requirements
New applications
Poor original AP placement
Changes to building construction
Outdoor coverage requirements
The important question isn't:
“Should we add more access points?”
The better question is:
“Why is the network performing poorly?”
Once that question has been answered, engineers can determine whether the solution involves adding APs, moving APs, removing APs or simply changing the RF configuration.
Sometimes Removing an Access Point Can Improve WiFi
This can seem counterintuitive.
But in an overly dense wireless deployment, removing or disabling an unnecessary access point can sometimes improve the RF environment.
Another option may be reducing transmit power.
Or changing channels.
Or changing channel widths.
Or relocating an AP.
The physical number of access points is only one variable.
A wireless network is a complete RF system, and all of those variables interact.
How Do You Know If You Have Too Many Access Points?
You can't reliably determine this simply by counting APs.
Ten APs could be excessive in one building and completely inadequate in another.
It depends on factors such as:
Building size
Construction materials
Floor layout
Number of users
Device types
Applications
Required capacity
AP placement
Antenna type
Channel configuration
Transmit power
RF interference
This is where a professional WiFi site survey becomes valuable.
Instead of guessing, engineers can measure the actual wireless environment.
A WiFi Site Survey Shows What's Really Happening
A professional WiFi site survey can help identify whether poor performance is caused by insufficient coverage or something entirely different.
Depending on the environment, engineers can analyze:
Signal Strength
Are devices receiving sufficient signal?
Signal-to-Noise Ratio
Is the desired signal sufficiently above the surrounding RF noise?
Channel Utilization
How heavily are wireless channels being used?
Access Point Coverage
How many APs can devices hear in different areas?
Cell Overlap
Are wireless cells overlapping appropriately?
Interference
Are neighboring networks or other RF sources affecting performance?
Roaming
How does connectivity behave as devices move throughout the facility?
These measurements allow engineering decisions to be based on actual data.
Example: A Warehouse With Poor Scanner Performance
Imagine a distribution center experiencing dropped scanner connections.
The warehouse already has 25 access points.
The immediate proposal is to add another five.
But a professional RF survey discovers something different.
Coverage is already strong.
The actual problems are:
AP transmit power is too high
Too many neighboring APs can hear each other
Several APs reuse the same channels nearby
Cell sizes are excessive
Scanners remain associated with distant APs
Adding five more APs would not solve those problems.
It could make them worse.
Instead, the solution may involve:
Reducing transmit power
Adjusting channel assignments
Optimizing channel width
Repositioning selected APs
Adjusting antenna orientation
Optimizing the RF cell design
No additional access points may be required.
That's the difference between adding equipment and engineering the network.
Design for Coverage AND Capacity
A professional WiFi network needs to achieve several objectives simultaneously.
It needs:
Coverage
Devices must receive sufficient RF signal.
Capacity
The network must support the required number of users and applications.
Quality
Signal-to-noise ratio and RF conditions must support reliable communication.
Mobility
Mobile devices should be able to move through the environment effectively.
Efficiency
Available spectrum should be used intelligently.
The correct number of access points is the number required to achieve those objectives — not simply the largest number the budget allows.
Better WiFi Starts With Better RF Design
When WiFi isn't performing properly, buying more hardware should not automatically be the first step.
First determine what's actually wrong.
The solution might be:
More access points
Fewer access points
Different AP locations
Different antennas
Lower transmit power
Better channel planning
Different channel widths
Improved network configuration
Every environment is different.
That's why professional wireless engineering starts with measurement and design rather than assumptions.
Don't Add APs Until You Understand the Problem
WiFiMax USA provides professional WiFi site surveys, RF analysis, wireless design, network optimization and post-installation validation for commercial and industrial environments.
If your WiFi network has strong signal but still performs poorly, adding more access points may not be the answer.
We can measure the existing RF environment, identify the cause and develop a practical remediation plan.