5G • 5G-Advanced (Rel-18)
Side-Control Information (SCI)
Over-The-Air Repeater Control Protocol over Uu
Control signaling transmitted from the gNodeB to the NCR over the Uu interface, configuring the repeater's beamforming matrices and on-off timing.
Technical Explanation
To control an NCR, the gNodeB transmits Side-Control Information (SCI) formatted as specialized DCI or MAC CE messages over a lightweight control link (NCR-MT). The SCI instructs the repeater exactly when to switch between transmit and receive, which spatial beam direction to point toward moving UEs, and what amplification gain to apply per slot.
Key Functions
- Transmits beamforming and timing configuration commands from gNodeB to repeater
- Formats control signaling using lightweight DCI and MAC Control Elements over Uu
- Synchronizes repeater TDD switching boundaries with the serving macro base station
- Updates spatial beam steering angles dynamically as user equipment moves
Specifications
3GPP TR 38.867, TS 38.212 (Rel-18)
Interfaces
Uu (SCI / DCI)
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