5G • RAN
Xn-U Interface
Xn User Plane Interface
User plane interface connecting neighboring gNodeBs for packet forwarding during handovers and split bearers.
Technical Explanation
The Xn-U interface utilizes GTP-U over UDP/IP. During handovers, source gNodeBs forward unacknowledged downlink packets across Xn-U to the target gNodeB, preventing packet loss. In Dual Connectivity (NR-DC), Xn-U transports user data split between master and secondary nodes.
Key Functions
- Forwards unacknowledged downlink data packets during handover to prevent loss
- Transports split bearer user plane data in Dual Connectivity
- Employs GTP-U encapsulation over standard UDP/IP transport
Specifications
3GPP TS 38.420, TS 38.425
Interfaces
XnXn-U
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