Written by: Chuck Feild, Senior Manager of Development & Engineering
I recently had the privilege of attending a Certified Network Wireless Administrators (CNWA) course, provided by Certified Network Wireless Professionals and hosted by Tech Data Canada. At the very start of the course, the instructor informed us that by the time the course was finished, we would be “amazed that WiFi ever works at all”. He wasn’t wrong.
I have been working for SolutionInc for 19+ years writing networking software, building and managing networks, and participating in many other custom software development projects. After so long in the industry, I thought I had a really solid understanding of WiFi technology, and how to build a proper WiFi network; I was wrong. The CWNA course showed me just how little I knew about building and configuring a proper (and successful) WiFi network.
WiFi technology is very complex, and very susceptible to outside interference (just like all radio communication). The original 2.4 GHz band (still widely used today) is an open frequency range that is shared with numerous other technologies. The simplest of outside influences can have a major impact on your network. The CWNA course taught me how to identify and mitigate these problems. Something so common as a microwave oven will interfere with WiFi on the 2.4GHz band. If you are not careful, your whole network could become unusable when someone is reheating last night’s pasta for today’s lunch. Picture the impact that has on a 10 floor+ office building with thousands of employees. The sources of possible interference are very surprising, and include Bluetooth and usb3 devices. Technology which is present in every modern device.
The different WiFi frequency bands (2.4 GHz and 5 GHz) have different characteristics in signal propagation, which affects the speed and airtime availability the access points (APs) can provide. The speed of a WiFi connection is impacted by many factors, a lot of which are out of our control. We are able to control the number of devices on a private network, but not the number of devices on a public network. Every device on the network is fighting for air time, so every additional device slows the network down. We control the channels we use on our own network, but we can’t stop other WiFi networks that are in range from having access points on the same channels, or worse, conflicting channels. Through proper network design, we ensure that there are enough access points for the number of devices expected on the network, providing ample air time for each device. And through proper network configuration, we ensure the channel selection minimizes channel conflicts.
The difference in signal propagation between WiFi frequency bands also has a direct impact on access point placement and antenna choice for maximum coverage. The quality of the WiFi coverage is very susceptible to the placement of the access point and the orientation of the access point antenna(s). I know, that sounds very obvious, but judging from some “professionally” installed access points I have seen, it isn’t as obvious as it should be. A lot of people think that radio waves can travel really far, and penetrate everything. We all think that because an FM radio works in your basement. But FM radio uses a frequency that can penetrate into your basement, it was designed to do that. The 2.4 GHz frequency used by older WiFi equipment is prone to absorption, so every single thing between your device and your access point is slowing you down, including the air. And the newer 5 GHz WiFi equipment has even less range, because it is even more susceptible to absorption. Therefore, the less “stuff” between your device and your access point, the better the signal strength, and therefore, the faster the connection.
I know, it seems obvious, but don’t put the access point under the counter because it is convenient. Take the time to mount it to the wall or ceiling. It will have a measurable impact on your network performance. And when you are considering how to mount your access point, take the antenna orientation into account. The most common access point antenna is omnidirectional, and the signal will spread out from the access point in all directions. Sounds great, but in reality, the signal will probably spread out like a doughnut. It will be designed to reach far and wide in one “plane”, but not very far in another. It most cases, you will want your access point signal to spread out horizontally, to cover the most floor space. If you have a multi-story building, install an access point on each floor. If you get the antenna orientation wrong, you will not get the coverage or speed you are expecting, and could be causing unnecessary interference with your (or someone else’s) access points in other locations of the building. Access points can come with a variety of antenna types, and the CWNA course taught me that I
knew very little of about the subject and was excited to learn more.
You must also remember that, like most things, a WiFi network requires periodic maintenance. New sources of interference, outside of your control, can be introduced. Reviewing your channel mapping and performing a spectral analysis on a routine basis will ensure your network is performing at its best.
In short, if you want a “professional grade” WiFi network, you need to hire a certified professional to design and install it. Someone walking around your site with a simple app on their phone telling you where to place access points may work in some circumstances, but not most.
Oh and you can visit our website to find out more about our site services and how we will provide you with a professional grade WiFi network site survey.