The minimum acceptable signal for an active site survey depends on the type of applications and the data rates that the users require. For 802.11ac, which operates in the 5 GHz band, Aruba recommends a signal of -65 dBm or better for high-performance applications such as voice and video, and a signal of -72 dBm or better for basic applications such as Web and email1. These values are based on the receiver sensitivity of typical 802.11ac clients and the expected signal-to-noise ratio (SNR) for different modulation and coding schemes (MCS). A higher SNR means a higher data rate and a better user experience.

Therefore, the architect should look for a signal of -65 dBm in the 5 GHz band to determine the test AP range for 802.11ac, assuming that the users run high-performance applications. A signal of -75 dBm in the 5 GHz band might be too weak to support the desired data rates and quality of service. A signal of -65 dBm or -75 dBm in the 2.4 GHz band is irrelevant for 802.11ac, as it does not operate in that band.

References:

Aruba Validated Reference Design: 802.11ac Networks

Best Practices for Monitoring and Troubleshooting 802.11ac Networks