5G • 5G-Advanced (Rel-18)
SBFD Slot Formats
Simultaneous DL/UL Sub-Band Slot Structure
Flexible slot format definitions in 3GPP Rel-18 where specific sub-carrier blocks inside an OFDM symbol are designated for DL while others are designated for UL.
Technical Explanation
Legacy 5G slot formats configure every symbol across the entire carrier as DL, UL, or Flexible. Rel-18 SBFD enhances Slot Format Indicator (SFI) tables in DCI Format 2_0 to support two-dimensional time-frequency resource grids, signaling which PRB ranges carry PDSCH and which carry PUSCH within the identical 14-symbol slot boundary.
Key Functions
- Extends DCI Format 2_0 to signal two-dimensional frequency-partitioned slot formats
- Configures sub-band-specific PDCCH monitoring and PUSCH transmission opportunities
- Allows legacy UEs to interpret SBFD slots as conventional pure DL or pure UL slots
- Provides ultra-fast sub-millisecond dynamic switching between full-carrier DL and SBFD modes
Specifications
3GPP TR 38.858, TS 38.213 (Rel-18)
Interfaces
Uu (DCI Format 2_0)
Related 5G Concepts
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