On the relationship between received signal strength and received signal strength index of IEEE 802.11 compatible radio transceivers

Every WiFi, ZigBee or Bluetooth compatible radio chip provides a byte of information related to the received signal strength (RSS), the so called received signal strength index (RSSI). In a given point in space, on a specific radio channel, the RSS has a unique value at a given moment in time. Still, radio chips produced by different manufacturers will report different RSSI numbers. So RSSI is only related to, but not identical to RSS. In this paper, a formula that relates RSS and RSSI is derived. The validity of this theoretical assumption is tested on various vendors’ data. For Microchip’s MRF24WB radio chip the testing is done experimentally. Keywords—received signal strength; received signal strength index; dBm; netvork interface card; WiFi; RF;