Area Optimized Wi-Fi and how to do it
In the previous edition we described in detail how we optimize the Wi-Fi connection in a single home context, typically in larger rural houses where coverage and reach is the dominating problem.
In urban apartment buildings the problems are very different. Apartments are typically not that large and one floor, so coverage is no longer the dominant problem. Instead we get interference, as your signal is typically strong enough to be visible to all neighbouring apartments.
What is interesting is that if we apply the rural fix to the urban problem, we only make things worse. In the single home context, the solution is often to make the signal louder through extenders. In the urban apartment context this will only increase the interference. So we need a completely different, collective approach.
In urban settings, the dominant problem is the scarcity of frequency. We only have a limited selection of frequency channels, and it is critical to make use of them as effectively as possible. If a neighbour has a strong signal into your apartment, it will make one channel less available to you. If there are many of these neighbouring networks visible in an apartment, we say that the network is congested.
There are three main approaches to fix congestion
- Reduce the interference by Smart Channel Planning and Signal Power Optimization
- Reduce Protocol Overhead, i.e. reduce air time spent sending beacon frames
- Active Band Steering, i.e. typically move to 5GHz if possible when 2.4GHz channels are full
Smart Channel Planning
When controlling the majority of routers in an apartment complex, one can carefully plan which routers use which channel depending on the channels the neighbours are utilizing. You can read the full story here https://medium.com/domos-creating-the-home-it-assistant/darwin-the-sysadmin-3c89cabb21e6
Signal Power Optimization
Intuition says increasing the signal strength improves the Wi-Fi performance. In apartment buildings, the opposite is true. When appropriate, we reduce the broadcasted signal strength to eliminate interference and create more free channels. This might have side effect of shorter reach, but this will in most cases not reduce the transfer rates. So the effect is simply non-congested Wi-Fi as the neighbouring networks are no longer interfering.
Every Wi-Fi network is transmitting something known as Beacon frames that informs devices that the network exists. This is carried out 5 to 10 times per second, and typically at the lowest transfer rate possible to secure robust connection. Typically, beacon frames consume several percentage points of the available network. So if there are many networks visible on the radio, it might clog the network, even before any actual data is transmitted.
In these cases we can reduce the beacon frame frequency, and also increase the transfer rate. Typically this can reduce the airtime consumption by 90%.
Active Band Steering
As a last resort, if we are unable to successfully isolate the networks and reduce overhead, we will look at forcing dual band devices to a band that is less congested. This typically means forcing some devices to 5GHz band. If the access points deployed don’t support dual band radio already, we will calculate which networks are the heaviest consumers in the most congested areas. Basically looking at removing a node in the network by moving all the traffic to 5GHz, and optimizing the resulting performance in the overall network.