URLLC
Ultra-Reliable Low-Latency Communication
The 5G service category engineered for mission-critical applications requiring sub-millisecond radio latency and 99.999% (five-nines) reliability.
Technical Explanation
URLLC is tailored for delay-sensitive and mission-critical communications where packet loss or latency spikes could lead to catastrophic failure. It provides user-plane radio latencies as low as 0.5–1 ms with 99.999% to 99.9999% reliability. Key enablers include flexible subcarrier spacing (mini-slots), grant-free (configured grant) uplink transmissions, aggressive packet duplication via Dual Connectivity, pre-emption of eMBB traffic, and short TTI (Transmission Time Interval). Typical use cases include autonomous vehicles (V2X), industrial robotics, smart grid automation, and remote telesurgery.
Key Functions
- Mini-slot scheduling (2, 4, or 7 OFDM symbols) for rapid turnaround
- Configured Grant (grant-free) uplink transmissions eliminating scheduling request delays
- Packet duplication across multiple independent radio carriers (PDCP duplication)
- Pre-emption indication allowing urgent URLLC traffic to puncture ongoing eMBB transmissions