5G • RAN
SRS
Sounding Reference Signal
Uplink reference signal transmitted by the UE to allow the gNodeB to estimate uplink channel quality and reciprocity.
Technical Explanation
SRS is transmitted across the uplink channel to provide the gNodeB with frequency-selective channel state information. In TDD systems, channel reciprocity allows the gNodeB to deduce downlink channel state from uplink SRS, enabling precise massive MIMO downlink beamforming and precoding without UE CSI feedback overhead.
Key Functions
- Enables uplink channel sounding and frequency-selective scheduling
- Supports channel reciprocity for downlink Massive MIMO beamforming in TDD
- Facilitates beam management, antenna switching, and codebook selection
Specifications
3GPP TS 38.211, TS 38.214
Interfaces
Uu
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