Before you can start troubleshooting problems with slow Wi-Fi network speeds, you need to verify if there really is a problem. The easiest way to confirm this is to measure your network’s actual upload and download speeds. Still, how do you do that? Can you do that by just looking at the PHY data rates being used? Could you use your network’s expected bandwidth? Or do you need to actually measure throughput?
Here is the difference between the different options:
• PHY Data Rate is defined as the speed at which packets are transferred over a communications channel inclusive of headers, control, and management frames. This is not the same as the actual amount of data frames being transferred. It does not take into consideration data encoding, modulation, encryption, or noise and interference levels that could impact airtime utilization.
• Bandwidth is defined as being the maximum amount of data that can be delivered over a communication channel, not the actual amount of data. Same as with PHY data rates, bandwidth doesn’t take into consideration headers, control and management frames, data encoding, modulation, encryption, noise levels, interference, etc.
• Throughput is defined as the actual amount of data packets that travel over a communication channel, or the actual data upload and download speeds. Throughput is usually measured in bits per second (bps) or megabits per second (Mbps). Only the DATA frames are taken into consideration when measuring throughput, with the net impact of data encoding, modulation, etc., factored in.
In conclusion, if you want to validate Wi-Fi network performance you should always measure your network’s throughput. The best way to do so is by using a test tool that will allow you to measure your throughput against an endpoint on your network. An example of a commonly used endpoint is iPerf, which is a software application that can be used to measure incoming traffic and generate outgoing traffic from any device on the network.
Lastly, something else to keep in mind is that the actual amount of data being transferred (throughput) is always lower than the supported PHY data rates. Normally, the actual throughput is 60-70 percent of the supported data rates, since it takes into consideration the effects that data encoding, modulation, encryption, airtime utilization, noise levels, interference, etc. have on the actual amount of data that can be transmitted.