Does Dual 5Ghz band make a difference?

Let’s talk about single 5Ghz vs dual 5Ghz radios in Access Points.

Single vs Dual 5Ghz radios?

Most vendors ship wifi systems with dual band radios (meaning 2.4Ghz and 5Ghz). However, some vendors have released dual 5GHz radio wifi systems (in addition to the 3rd radio on 2.4Ghz band), making these systems tri-band.

Why Dual 5Ghz radios?

In theory, dual 5Ghz band radios double the performance and capacity, over single 5Ghz band radio.

Theory is great, but did anyone test this claim in the real world?

Real world test

Aruba (on 2016-07-14) did a series of test to determine whether this dual 5Ghz make a difference, as compared to a single 5Ghz radio.

The conclusion was as follows:

  • Two 5GHz radios on the same AP would adversely impact the max performance and add no additional capacity benefits.
  • Unless further enhancements in RF filtering and isolation between radios are added to the dual 5GHz mode, and more spectrum is opened in 160MHz, customers should take additional care in designing an environment with dual 5GHz radios.
  • This test was performed on 2016-07-14. Since then, the vendor might have released software updates that solve these performance issues.

My thoughts

  • Let’s start by saying that dual 5Ghz band radios is not a feature of the IEEE’s 802.11ac or 802.11ax specification, meaning it’s up to the vendors to correctly implement this in their hardware and software.
  • Both enterprise vendors, Cisco and Aruba, advertise their top-performing access points as dual 5Ghz capable.
  • I’m sure that both Cisco and Aruba, with their technical expertise and funding, figured out the best approach to make dual 5Ghz radios work.
  • If “Vendor X” advertises dual 5Ghz band, you have to ask yourself whether you trust this vendor to do this feature correctly.

My recommendations

For dual 5Ghz band capable wifi systems:

  1. Keep one 5Ghz band radio on.
  2. Perform wireless network tests.
  3. Turn on the second 5Ghz band radio.
  4. Perform wireless network tests.
  5. Compare the difference and decide for yourself whether it improved or not.