5G • 5G-Advanced (Rel-18)
XR Discard Timer Optimization
Application-Aware PDCP/RLC Packet Discard Mechanism
Flushes expired video packets from base station buffers immediately when their display deadline has passed, saving bandwidth for upcoming frames.
Technical Explanation
In interactive video streaming, delivering a packet after its display refresh deadline is worse than useless: it wastes radio spectrum and consumes decoding time. Rel-18 updates the PDCP discard timer to track video frame lifetimes: if radio congestion delays a packet past its frame presentation timestamp, the gNodeB purges it immediately, freeing the channel for the next frame.
Key Functions
- Purges expired video packets from transmission queues before they waste radio spectrum
- Synchronizes PDCP layer discard timers with application-layer presentation deadlines
- Prevents cascade buffer bloat where obsolete video frames delay subsequent live frames
- Frees up base station queue space and radio resource blocks during temporary fading dips
Specifications
3GPP TR 38.835, TS 38.323 (Rel-18)
Interfaces
Uu (PDCP/RLC)
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