5G • RAN
Flexible Symbol
Flexible OFDM Symbol (F-Symbol)
TDD symbol whose direction can be dynamically overridden by scheduling DCI, PRACH, or SRS.
Technical Explanation
In 5G TDD frame structures, symbols designated as 'Flexible' (F) are neither permanently Downlink nor Uplink. A flexible symbol can be scheduled as downlink reception via DCI Format 1_0/1_1, as uplink transmission via DCI Format 0_0/0_1, or used as a guard period during DL-to-UL switching to accommodate round-trip propagation delay.
Key Functions
- Can be dynamically commanded to DL reception or UL transmission
- Functions as variable guard period for RF switching between DL and UL
- Provides granular control over TDD duty cycle and interference coordination
Specifications
3GPP TS 38.211, TS 38.213
Interfaces
Uu
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