上行:
Two types of uplink reference signals are supported:
- Demodulation reference signal, associated with transmission of PUSCH or PUCCH
- Sounding reference signal, not associated with transmission of PUSCH or PUCCH
The same set of base sequences is used for demodulation and sounding reference signals.
下行:
Five types of downlink reference signals are defined:
- Cell-specific reference signals (CRS)
- MBSFN reference signals
- UE-specific reference signals (DM-RS)
- Positioning reference signals (PRS)
- CSI reference signals (CSI-RS)
There is one reference signal transmitted per downlink antenna port.