5G • Spectrum
SUL
Supplementary Uplink
Paired low-frequency uplink carrier dedicated to enhancing uplink coverage for mid-band and mmWave cells.
Technical Explanation
High-frequency TDD carriers (e.g. 3.5 GHz C-Band or 28 GHz mmWave) suffer from severe uplink coverage limitations due to UE transmit power limits (23 dBm) and higher path loss. Supplementary Uplink (SUL) pairs the high-frequency downlink with a dedicated low-frequency uplink (e.g. 700 MHz or 800 MHz), switching uplink transmission seamlessly between carriers.
Key Functions
- Overcomes uplink cell-edge coverage bottlenecks in C-band and mmWave
- Pairs high-frequency downlink with sub-1 GHz supplementary uplink
- Improves cell-edge throughput by up to 10 dB
Specifications
3GPP TS 38.101-1, TS 38.300
Interfaces
Uu
Related 5G Concepts
Want to memorize 5G concepts like this one?
Study it with SuperMemo SM-2 spaced repetition flashcards.