Wireless Reliability


The IEEE 802.11 specification has proven to be a very reliable way to do networking. Wireless LANs (Local Area Networks) are capable of achieving Gigabits of speed with little to no effort. This makes wireless a competitor with Ethernet and many other networking technologies. But is it as reliable and will it continue to be so?



WLANs are founded on an environment of unreliability. Wireless LANs are forced to share the spectra they operate on with other technologies, as well as many other WLANs. This makes WLANs prone to error because of increased collisions between signals within the spectra. For example, 802.11b/g exclusively operates in the 2.4 GHz band. This small piece of spectra is stretched thin, with only 11 channels in the US. Only 3 of those are non-overlapping channels so interference from other WLANs is high. It also can get interference from even something as simple as a microwave. The whole band a relatively low signal-to-noise ratio (SNR) as it is and has a lot of EVM (Error Vector Magnitude) - a measurement of how far a transmission is from its ideal constellation. This means many packets are received scrambled because a subcarrier was unable to achieve the correct phase and amplitude due to the noise.


In contrast we have the 5 GHz band, which has 24 non-overlapping channels, making it far less likely for WLANs to interfere with one another. The 5GHz also doesn’t have to compete for space with other technologies so it has relatively high SNR making it much less likely to incur interference. 802.11ac, the newest IEEE substandard, exclusively operates in the 5GHz band because it needs spectra large enough to accommodate its 80MHz bounded channel.


We also have the 802.11ad standard that operates within the completely open 60GHz band. Since it is a relatively unallocated spectrum, it has extremely high SNR. Many technologies are employed to make 802.11 fast and more reliable and there are a few we’ll outline for you today.

Jackson Corson, Wireless Technician