Does SI request RACH happens using contention free or contention based in NR?

Question

Handover RACH will be initiated as Contention free, RNTI will be included in Mobility info. But while doing RACH What will be the RNTI value included in RAR? Will this be same as Mobility RNTI?

Answer 1

As I know, In the contention-free mode, the eNB can uniquely identify the UE by a received preamble sequence, due to the fact
that the preamble to be used has been communicated to the UE in advance. Such a scenario is possible in certain cases,
e.g., during a handover between two eNBs.
In on demand SI request RACH, RACH-ConfigDedicated mode used & it is used for handover to the cell. So I think in this case contention-free RA procedure will use.
Waiting for other expert comment !!

Answer 2

►The Random Access Procedure is used for four cases:
• Initial access from disconnected state (RRC_IDLE)
• Handover requiring random access procedure
• DL or UL data arrival during RRC_CONNECTED after UL PHY has
lost synchronization (possibly due to power save operation)
• UL data arrival when are no dedicated scheduling request channels
available
►There are two forms of the Random Access Procedure
• Contention based (applicable to all four events)
• Non-contention based (applicable to only handover and DL data
arrival)