Which metric best indicates client experience in a WLAN design?

SNR is calculated as the difference between the received signal level (RSSI) and the ambient noise floor, expressed in dB. A client with strong RSSI but an equally high noise floor will have low SNR and suffer poor throughput and high retransmissions, whereas a client with moderate RSSI and a very low noise floor will perform excellently. SNR directly predicts the modulation and coding scheme (MCS) a client can sustain, making it the single best indicator of actual radio link quality.

RSSI measures only received signal power in absolute terms and ignores the noise floor, so a high RSSI in a noisy RF environment can still result in a poor client experience.

Observed data rate is a result metric that reflects current channel conditions after the fact - it does not proactively indicate link quality or predict whether the experience will degrade.

Round-trip latency primarily reflects network infrastructure, queuing, and application server performance rather than the quality of the wireless RF link between client and AP.