What is the RSSI Function of the Wireless RF Module?

When purchasing wireless modules, we will see in the specifications that some RF modules have RSSI functions, but some do not. So, what does RSSI mean and what functions does it have?

RSSI: full name is "Received Signal Strength Indication", the normal range of RSSI can be: -93dBm ~ -113dBm; it can be regarded as RSSI abnormal, if the value beyond this range. The dBm value corresponding to RSSI has no physical meaning, but just an indicator value of signal strength.

RSSI is an optional part of the wireless transmission layer, used to judge the link quality, and whether to increase the broadcast transmission strength. To explain in plain words, the RSSI function is used to judge the strength of the wireless signal.

The biggest advantage of the wireless module with RSSI function is that: it can read the wireless signal strength in the environment and judge whether the channel is occupied. If it is occupied, select another channel, if not, enter the channel. However, it is not recommend to use the RSSI function by the chip manufacturers, because the RSSI value determines that the channel is idle, and the result may be inaccurate under the LORA modulation technology. For this reason, the channel idle detection under the LORA modulation can be replaced by CAD.