Does My Organisation Need a Wireless Site Survey?
Cloud Architect
Andrew Milne
- October 25th, 2017
- 8 min read
When talking to organisations about their network and issues, one of the most common topics that comes up is wireless.
Cloud Architect
Andrew Milne
When talking to organisations about their network and issues, one of the most common topics that comes up is wireless.
Complaints vary from "the wireless is slow" to "the wireless is so unreliable that our team has given up on it." Typically, the more you talk to end-users, the more apparent these frustrations become. As organisations become more mobile, open-plan, and collaborative, getting the wireless right is more important than ever. A wireless site survey is a key step in getting it right.
There have been a number of misconceptions and fallacies over the years that have resulted in poor wireless performance. I remember hearing of schools that were told:
"These Access Points are so powerful you will only need one every 3 or 4 classrooms."
Or businesses that got told:
"These Access Points are so smart that you just need to plug them in; they’ll optimise themselves."
While modern access points have powerful self-optimisation features, they aren't a silver bullet. These automated systems can't account for unique building materials, high-density areas, or external interference without a proper plan. Relying on them alone often leads to wireless that is temperamental at best, or completely unusable for most. Eventually, people resign themselves to the fact that this is what wireless is like, and give up on it altogether.
There are many factors to consider when deciding to install wireless. ‘Where do I want access?’ is an easy first decision to make. ‘How do I achieve useable access in these locations?’ is a slightly harder question that is often not properly considered. A wireless site survey can help provide an answer to the latter.
A wireless site survey uses specialised tools to create a visual map of the radio frequency (RF) environment in a given area. It helps to highlight areas where there will be coverage issues or interference.
The fact that wireless signals are invisible makes it a difficult technology to understand. The average person might see a full-strength connection icon on their device and assume they should have great performance. But even if you see a high speed, it doesn’t necessarily mean that you’ll receive a decent connection.
Thankfully, there are tools that create a visual representation of what is going on. Using these visualisations, often called "heat maps," you can then make informed changes that result in real-world performance improvements.
To perform a survey, an engineer walks through the entire building with a laptop running specialist software and connected to high-gain antennas. By loading a scaled map of the building and marking their position as they walk, the software collects valuable data about the RF environment at each point, allowing for the creation of the heat maps that let you see exactly what's going on.
Wireless connections can be affected by a number of things. Walls of different consistencies can weaken (or "attenuate") the wireless signal to varying degrees. In older buildings with thick concrete or steel, walls can kill the signal altogether. Other devices such as cordless phones, video senders, or even old microwave ovens can also cause interference.
Even the number of people in a room can affect connections, partly because they bring additional devices, but also because the human body works surprisingly well to absorb RF signals. However, one of the most common issues we see is the wireless network interfering with itself.
A key concept in wireless is ‘airtime’. In its most simple form, a wireless access point sends and receives signals to everyone connected to it, but it is only ever talking to one client at any single point in time. It achieves this by rapidly switching between different clients and sharing its airtime. However, airtime is also shared between different access points talking on the same channel.
If you were to introduce a new access point nearby on the same channel, rather than doubling your capacity, you’ve actually created a problem. Each access point now has to stop and wait for the other to finish talking. You can end up with two access points running at 50% capacity, or even less given the overhead of making this work. More often than not, this results in significant performance degradation caused by ‘Co-Channel Interference’.
Another common cause of poor wireless performance is when people connect to access points from too far away, or through walls and objects that reduce the signal strength. As the signal strength decreases, so does the speed at which the client can communicate.
Thinking about airtime again, this slow client now takes longer to send the same amount of data. This means it uses up more of the access point's total airtime, leaving less for everyone else. This results in a situation where your device shows a high-speed connection, but the real-world performance is painfully slow for everyone connected to that AP.
Without analysing your wireless network and knowing what is going on, interference often goes undiagnosed. In most cases, people simply lose faith in the technology and go back to their desks to plug in a cable.
Alongside a careful review of configurations, the heat maps that a wireless site survey creates allow for networks to be fine-tuned through the strategic movement of access points and changes to power and channel settings. I have even helped organisations improve their overall wireless performance by turning some of their access points off, or in a few cases, removing them altogether.
No matter how advanced access points become, manufacturers still actively promote the use of wireless site surveys to establish and maintain high-performing wireless networks.
A predictive site survey can be performed without an engineer even entering the building. It is done by using a scale map and loading it with walls, materials, and other available information. The map allows you to move the virtual access points around the map to make a prediction of the expected performance of the configurations. This is a great idea if you have not purchased your system yet. It acts as a good starting point to identify what you might need.
Commonly the predictive survey takes place before a building is finished. This is so the network can be incorporated and designed, just like the cabled network or power.
A passive site survey is a wireless site survey on pre-existing wireless systems. This survey listens to wireless traffic to detect active access points. It measures signal strength and noise levels. Having predictive and passive heat maps is especially useful while installing and fine-tuning new systems.
A proper wireless site survey provides the blueprint for a network that is both reliable and high-performing. It moves you from guesswork to a data-driven design that accounts for your unique physical environment and user density.
At Dynamo6, we move beyond theory to deliver robust, real-world networking solutions. A perfect example of this is our work with the MADE of Hamilton precinct, where we designed and implemented a multi-tenant Wi-Fi network capable of handling high-density usage across multiple businesses and public spaces. This wasn't achieved by just plugging in access points; it was the result of a meticulous design and survey process.
Whether you're planning a new deployment or struggling with an existing network, our approach ensures you get the performance and reliability you need. When you're ready to get your connectivity sorted for good, reach out to our team to explore our networking and Managed IT Services.