Sync Type (LTE)

Default: P-SS Primary Synchronization Signal for downlink
PUSCH Physical Uplink Shared Channel DM-RS DeModulation Reference Signal (LTE) for uplink

Range: P-SS or C-RS Cell-specific RS for downlink
PUSCH DM directed mesh: The realizations of a physical mesh using substantially directional antennas. See also: mesh-RS, PUCCH Physical Uplink Control Channel DM-RS, S-RS, or PRACH Physical Random Access Channel for uplink

Sync Type sets the channel or signal to be used for synchronization. The current selection of Sync Type is shown to the right of the SyncCorr data result in the Error Summary trace.

Downlink

The LTE Long Term Evolution demodulator can be set to use either the Primary Sync Signal (P-SS) or the cell-specific reference signal (C-RS) to synchronize the downlink signal.

This synchronization is performed at the frame level. For smaller scale adjustments (such as at the symbol or slot level), see the EVM Minimization parameter.

P-SS is normally used for downlink synchronization. However, when P-SS is impaired in some way (for example, P-SS has a different Cell ID than C-RS), C-RS can be used for synchronization so that the signal can be demodulated.

S-SS must be present in the time capture (Raw Main Time) for demodulation to occur, since finding S-SS Secondary Synchronization Signal is the only way to distinguish between the beginning and the middle of a frame.

When Sync Type is set to C-RS:

The Error Summary data result SyncCorr shows which C-RS antenna port's reference signal was used for synchronization to the right of the correlation value.
Autodetection of Cell ID and Custom RS-PRS are not supported.
The reference C-RS port must be specified, since the demodulator does not automatically search the reference measurement channel for all C-RS antenna ports when Sync Type is set to C-RS.

Uplink

The demodulator can use PUSCH DM-RS, PUCCH DM-RS, S-RS, or PRACH for synchronization. Only the channels or signals that are defined for the current user (by selecting the Present in Signal check box for that signal in the LTE Allocation Editor) will be available as synchronization options.

PUSCH, PUCCH, PUSCH DM-RS, PUCCH DM-RS, and SRS Signaling Reference Signal powers in the LTE Allocation Editor are specified relative to the 0 dB level determined by the power of the channel chosen for synchronization.

For example, when:

Sync Type is set to PUCCH DM-RS
PUCCH DMRS Power (dB) = 3 dB
PUSCH Power (dB) = 1.2 dB

In this case, the demodulator would set the 0 dB level to be 3 dB below the average power of PUCCH DMRS and would expect PUSCH average power to be 1.2 dB above the 0 dB level, which is equivalent to 1.8 dB below the average PUCCH DMRS power.

Sync Type also determines which channel's Sync Slot parameter is used for frame boundary calculation. See the LTE Allocation Editor topic for more information about defining a sync slot or click one of the following links for instructions on configuring the sync slot for a particular channel.