As a device starts to shift to lower PHY rates, what factors usually influence a...

Comprehensive and Detailed Explanation:

Devices dynamically adjust their PHY rates based on link conditions to maintain connectivity. Factors that influence a downward shift in data rates include:

A. Signal degradation: Weaker signals (e.g., due to distance or obstruction) cause devices to drop to more robust, lower PHY rates.

B. Packet loss: High packet error rates trigger rate adjustments to improve reliability.

C. Interference: Competing RF signals can lead to retransmissions and lower effective throughput.

D. Retransmissions: Repeated retransmissions indicate poor link quality, prompting lower data rates to improve reliability.

“A device may reduce PHY rates due to poor SNR, high packet error rates, interference, or excessive retransmissions. Lower data rates offer greater robustness in degraded RF conditions.”

— CWDP-305 Study Guide, Chapter: ProtocolandSpectrum Analysis