5G NR SUL Planner & Uplink Coverage Validator
Validate NR supplementary-uplink band combinations (TS 38.101-1 Rel-17/18/19), calculate NUL vs SUL uplink link-budget coverage benefits, and model UE switchedUL/dualUL timing constraints.
3GPP release & deployment architecture
Normal uplink (NUL) carrier
Supplementary uplink (SUL) carrier
UE capability & operating mode
RF link budget & coverage assumptions
Rel-19 | n78 (100 MHz) + n83 (20 MHz SUL)
SUL pair compatibility inspector
Specification & Configuration Rules Engine
The combination n78 + n83 is standardized in Rel-19 (TS 38.101-1 Table 5.2E.1-1).
UE configured operating mode is switchedUL with 1Tx on NUL and 1Tx on SUL. Switching period: 140 µs.
3GPP TS 38.101-1 Band Combination Reference Data
Understanding 5G NR Supplementary Uplink (SUL) Architecture
In high-frequency 5G NR deployments (such as 3.5 GHz C-band n78 or 3.7 GHz n77), downlink range typically exceeds uplink range due to lower UE transmit power (+23 dBm vs gNB +46 dBm EIRP) and higher atmospheric attenuation. Supplementary Uplink (SUL) pair a high-frequency downlink carrier with a separate, lower-frequency uplink-only carrier (e.g. 700 MHz n83 or 1.8 GHz n80) to significantly extend cell-edge uplink coverage.
SUL vs Carrier Aggregation (CA)
Unlike Uplink Carrier Aggregation (UL CA) where two uplink carriers transmit simultaneously to double data throughput, SUL is primarily an uplink coverage extension mechanism. The cell schedules the UE on either the Normal Uplink (NUL) or Supplementary Uplink (SUL) depending on path loss.
switchedUL vs dualUL Modes
Under switchedUL, the UE dynamically switches between NUL and SUL using a single Tx chain (requiring an RF switching gap). Under dualUL, the UE utilizes separate Tx chains to transmit on both carriers simultaneously without switching delays.
3GPP SUL Technical Glossary & Definitions
The primary uplink carrier paired with the NR downlink serving carrier in the same operating band.
An additional uplink-only carrier operating in a lower frequency band configured to supplement NUL coverage.
UE operating capability to transmit on either NUL or SUL in time-domain multiplexed slots via a single Tx chain.
UE capability allowing simultaneous transmission on NUL and SUL using dual transmit RF chains.
Power Class 2 (+26 dBm) or Power Class 1 (+31 dBm) terminal capability to boost cell-edge uplink link margin.
3GPP Release 18 spectrum-sharing arrangement for dynamic scheduling of supplementary uplink resources across SA and NSA.
Frequently Asked Questions (FAQ)
Why is SUL still relevant in 3GPP Release 18 and Release 19?
SUL is actively expanding in current 3GPP specifications. Rel-18 (CR 580551) introduced overlapping SUL band combinations (such as n28–n83 and n1–n84) and clarified inter-band non-zero switching gaps (CR 573143). Rel-19 (v19.6.0, CR 599268) standardized High Power UE (HPUE) combinations with SUL.
How does SUL impact RACH initial access and cell selection?
During cell selection, if the gNB broadcasts SUL parameters in SIB1 (ServingCellConfigCommonSIB), the UE evaluates the measured RSRP against the SUL threshold (rsrp-ThresholdSSB-SUL). If RSRP is below threshold, the UE initiates PRACH on the SUL carrier.
What is the difference between free-space path loss and urban macro estimates in SUL planning?
Free-space path loss assumes a propagation exponent of γ = 2.0 (ideal line-of-sight). The 3GPP Urban Macro model uses γ = 3.5, which accounts for diffraction, building penetration, and shadow fading, yielding a more realistic coverage radius estimate in cellular network planning.