Dears.
In NR CA, is it necessary to perform a RACH procedure when adding Scell?
No, it is not.
The RACH procedure involves the UE transmitting a random access preamble on the RACH, which is then detected by the network. Based on the preamble, the network assigns a temporary radio resource to the UE and sends a random access response (RAR) message, which contains the assigned radio resource and other information. The UE then uses the assigned radio resource to transmit its data.
When adding a secondary cell (Scell) to an NR CA configuration, it is generally not necessary to perform a RACH procedure. In NR CA, the Scell is typically configured with a default scheduling grant that allows the UE to transmit data on the Scell without the need for a RACH procedure. However, in some cases, the network may require the UE to perform a RACH procedure on the Scell in order to allocate additional resources or to perform other tasks.
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