For “SQI” (Speech Quality Index), a document found on ericsson.com states that “SQI assesses the speech quality as perceived by the mobile station user. (…) The SQI values are based on bit error and frame erasure rates and their respective distributions”. So, SQI will be more relevant in terms of customer perception (perceived quality is strongly related to frame erasure rate) for the voice only. For the benchmarking of data services, SQI should not be used.
For RxQual, it_can_NOT_be_in_dBm. It is either in percentage (but in this case, it’s more appropriate to call it “BER”) or in a scale of discrete integer values, often taken from 0 to 7, which reflects different ranges of the BER.
Additional note: In both cases, BER or RxQual have no “unit”. Percentage is a format for numbers.
If you see anything in “dBm”, it is a measure of power. So I guess you mistook RxQual and RxLev.