LTE Physical Signals

#LTE Physical Signals 

-- Downlink Physical Signals
1-DL Demodulation Reference Signals (RS).
2-Synchronization Signals.

-- Uplink Physical Signals
1- UL Demodulation Reference Signals.
2- Sounding Reference Signals.

In addition to data and control information, LTE defines other physical signals, including Reference Signals and Synchronization Signals.

The eNodeB and UE use Demodulation Reference Signals (DRS) to estimate RF channel quality (measure SNR).

The eNodeB transmits periodic Synchronization Signals (SS) to synchronize each UE with the recurring physical slots and frames.

The eNodeB uses Sounding Reference Signals (SRS) to control frequency-dependant scheduling for a UE. As needed, the eNodeB orders the UE to transmit special (sounding) Reference Signals over some or all of the occupied subcarriers during 1 or 2 symbols times. The eNodeB uses the sounding results to schedule specific frequency ranges for that UE.