5G • RAN
Downlink Preemption
URLLC Downlink Resource Preemption
Mechanism allowing urgent URLLC data to immediately preempt ongoing eMBB downlink transmissions.
Technical Explanation
To meet strict 1 ms latency targets, urgent URLLC data cannot wait for current eMBB slots to finish. The gNodeB preempts (punctures) ongoing eMBB PDSCH resource elements to transmit URLLC data immediately, and subsequently alerts affected eMBB UEs via DCI Format 2_1 (INT-RNTI) so they can salvage remaining code blocks.
Key Functions
- Instantly punctures active eMBB PDSCH allocations for urgent URLLC data
- Broadcasts preemption indication to affected UEs via DCI Format 2_1
- Prevents corrupted eMBB code blocks from poisoning receiver LLR buffers
Specifications
3GPP TS 38.213, TS 38.214
Interfaces
Uu
Related 5G Concepts
Want to memorize 5G concepts like this one?
Study it with SuperMemo SM-2 spaced repetition flashcards.