How an established radio link works
The 5G New Radio interface

On an established link, the terminal must be able to identify, on the downstream channel, the resources to be listened to in order to decode the packets intended for it, and, on the upstream channel, the resources it can use to transmit its data. This is the resource allocation mechanism. In addition, it needs reference signals to analyze the channel and demodulate the signal correctly, especially in the case of multi-antenna transmission.