There is no standardized relationship of any particular physical parameter to the RSSI reading. The 802.11 standard does not define any relationship between RSSI value and power level in milliwatts or decibels referenced to one milliwatt (dBm). Vendors and chipset makers provide their own accuracy, granularity, and range for the actual power (measured as milliwatts or decibels) and their range of RSSI values (from 0 to RSSI maximum). One subtlety of the 802.11 RSSI metric comes from how it is sampledRSSI is acquired during only the preamble stage of receiving an 802.11 frame, not over the full frame.