Dual-band routers are all but standard nowadays (Tri-band routers even exist now), but many people don’t stop to think “why is a dual-band router is worth having?”
The FCC (and most communications authorities worldwide) have set aside certain frequencies for local area high speed wireless transmissions, aka Wi-Fi. These frequencies are 2.4GHz and 5GHz.
The original Wi-Fi standards released in 1999 – 802.11b and 802.11a (now also known as Wi-Fi version 1 and Wi-Fi version 2) only operated on single bands. 802.11b operated at 2.4GHz and 802.11a operated at 5GHz
As technology matured and Wi-Fi become more prevalent, it become obvious that using additional frequency bands was an effective way to provide additional bandwidth, support additional devices, and reduce interference.
Starting with the 802.11n (Wi-Fi version 4) standard released in 2009, both 2.4GHz and 5GHz bands were included in the standard, paving the way for the first dual-band routers to be produced.
Benefits of dual-bands
Prior to the ratification of 802.11n, we had two standards (802.11b and 802.11g) using the 2.4GHz spectrum, and one standard (802.11a) using the 5GHz spectrum.
802.11b/g ended up being much more popular and widespread, likely due to the fact that it was cheaper. As a result, the 2.4GHz spectrum was much more crowded.
Compounding the issue, the following non-WiFi devices also operate (or create interference) in the 2.4GHz spectrum:
This resulted in the 2.4GHz band being really crowded. Having the ability to use the 5GHz band with the newer 802.11n and 802.11ac standards really alleviates this congestion issue.
Differences between 2.4GHz and 5GHz
Aside from the obvious difference (Look, different numbers!), there are some technical differences between the two spectrums.
The first difference, is range. Lower frequencies can penetrate objects better than higher frequencies, so the 2.4GHz spectrum generally results in better range than 5GHz. The difference, although noticeable, is not huge.
5GHz can generally transmit data faster (better modulation schemes) than 2.4GHz.
Number of channels, channel width
2.4GHz only has 11 channels in North America, only 3 of which are non-overlapping. Non-overlapping basically means they are channels don’t have as much interference from nearby networks, assuming everyone is playing by the same rules.
5GHz has 23 channels in North America, and all of them are non-overlapping. This makes it much easier to avoid interference in dense environments. Less interference = better speed and reliability.
Bringing it all together
So what exactly is a dual-band router?
A dual-band router is a device that is equipped with two radios operating simultaneously – one that operates at 2.4GHz, and another that operates at 5GHz.
Devices connecting to the router will then have the choice of which band to use. Some devices only have a 2.4GHz radio equipped and thus will have to connect via 2.4GHz, while others can use either band and will generally choose the 5GHz band due to the fact that it is less crowded and has more clear channels.
The main point is this: offloading some devices onto the 2.4GHz spectrum and others onto the 5GHz spectrum increases the performance for everyone.
Make sure your next router or access point is dual-band!
Andrew Namder is an experienced Network Engineer with 20+ years of experience in IT. He loves technology in general, but is truly passionate about computer networking and sharing his knowledge with others. He is a Cisco Certified Network Professional (CCNP) and is working towards achieving the coveted CCIE certification. He can be reached at firstname.lastname@example.org.