for channel access.

In this scenario, each user will attempt to transmit data without first obtaining permission from a central controller. This is known as grant-free communication, and it can be used to improve the efficiency of communication networks by reducing the amount of time spent waiting for permission from a central controller. The users will compete with each other for access to the channel by sending out packets of data at regular intervals. The user that transmits its packet first is granted access to the channel and can then send its data. If two or more users send their packets simultaneously, then a collision occurs and none of them are able to send their data until all packets have been cleared from the channel. To avoid collisions, users must carefully adjust their transmission timing so that they do not interfere with each other's transmissions.