RRC Resume Procedure

Technical Explanation

In RRC_INACTIVE, the UE retains security keys and bearer contexts. When data arrives, the UE transmits RRCResumeRequest using its I-RNTI. The network authenticates the request and returns RRCResume, reactivating all radio bearers without round trips to the 5G Core network, slashing connection setup latency by 75%.

Key Functions

• Restores connection from RRC_INACTIVE in under 10 ms
• Authenticates UE using I-RNTI and ShortMAC-I without core interaction
• Reactivates suspended user plane bearers instantly