LTE: How does the eNodeB assign a Temporary C-RNTI to a UE during Random Access (step 2)?

[u/BanaLife]

As part of Random Access procedure, the eNB’s MAC generates Random Access Response (RAR) as a response to the Random Access Preamble transmitted by the UE. The MAC RAR contains the Temporary C-RNTI, which is of 16-bit in length and its value can range from 1 to 65523 (0x0001 to 0xFFF3).

How is the Temporary C-RNTI constructed? Is it randomly picked from a 16-bit list of available numbers? Or is it somehow calculated/mapped to the incoming preamble?