5G • RAN
Uplink Preemption
Uplink Cancellation Indication (CI)
Mechanism where gNodeB instructs an eMBB UE to cancel pending uplink transmission to free resources for URLLC.
Technical Explanation
Introduced in 3GPP Rel-16, Uplink Cancellation Indication (CI) uses DCI Format 2_4 scrambled with CI-RNTI to instruct a scheduled eMBB UE to immediately cancel or suppress its planned PUSCH or SRS transmission, guaranteeing clean, interference-free spectrum for an urgent incoming URLLC uplink burst.
Key Functions
- Cancels scheduled eMBB PUSCH/SRS transmission in real-time via DCI Format 2_4
- Guarantees zero uplink interference for critical URLLC transmissions
- Operates with sub-millisecond reaction time using CI-RNTI
Specifications
3GPP TS 38.213
Interfaces
Uu
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