This read-write INTEGER (7..16), defaulting to 11 dBmV per the description, sets the average noise level at which a frequency hop should occur on this RPM I-Port, though the data-error thresholds take precedence when the data rate exceeds hcxRpmMinErrRatioCells. An admin uses it as a secondary, noise-based trigger for hopping when cell-error rates alone haven't yet flagged trouble on this specific input. For example, an admin tightens hcxRpmCnrThres on an I-Port with a history of marginal carrier-to-noise readings so it hops proactively before errors accumulate.