yes i know those bands.
it’s just the average rxlev of the signal received in UL by the BTS while there is no MS on it. It means it’s the level of “I” (interference) on the frequency of the TRX.
A HW problem (in ANC or in TRX) might lead to a leaking of signal into the Rx path, so the TRX believes there is a lot of noise, while actually the TRX is self-generating noise.
Man, that does sound a lot like my wife :))
Usually though, a bad value in the bands mean there is interference. Not a HW problem (but that’s possible too)