ULPI Features (5G NR/5G-Advanced)
(Uplink only) enables or disables ULPI (uplink performance improvement), an O-RAN Radio Access Network feature under development that is intended to improve uplink massive MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. (mMIMO) performance.
- enables the editabilty of the Valid DMRS Sequence parameter and adds Not Provided as a Sync Source parameter choice to allow demodulation of PUSCH without DMRS. This enables ULPI support for DMRS-beamforming with equalization (DMRS-BF-EQ) in the O-RU.
(default) - the Valid DMRS Sequence parameter remains grayed out and checked and the Sync Source Not Provided choice is grayed out and not available, meaning that a PUSCH DMRS is required for channel estimation and equalization.
About ORAN ULPI
For ORAN ULPI, the O-RU (DUT Device under Test: An acronym used to describe some type of electrical apparatus connected to test instrumentation. The apparatus can range from a single component to a complex subsystem such as a mobile phone, base station or MSC.) can operate DMRS beamforming in two possible modes: DMRS-based beamforming with equalization (DMRS-BF-EQ) or DMRS-based beamforming without equalization (DMRS-BF-NEQ). In both approaches, the O-RU uses DMRS channel estimation to derive beamforming weights, but they differ in whether or not equalization is performed in the O-RU.
DMRS-BF-EQ
In DMRS-BF-EQ mode, the O-RU (DUT) performs DMRS channel estimation and equalization; therefore, DMRS transfer from O-RU to O-DU/analyzer can be removed or muted to reduce fronthaul bandwidth and the IQ data can be demodulated by the O-DU or VSA without further equalization. You can do this on the VSA by disabling (unchecking) the PUSCH Valid DMRS Sequence parameter, which also automatically changes the channel Sync Source parameter to Not Provided. In this configuration, because there is no DMRS present in the IQ data, the VSA does not perform equalization of the PUSCH, regardless of the Equalizer Training > Signal Source setting.
DMRS-BF-NEQ
In DMRS-BF-NEQ mode, the O-RU (DUT) performs channel estimation for Beamforming operation, and O-DU or VSA performs the Equalization operation. Both data and DMRS are transmitted from O-RU in this mode. The VSA does the equalization and demodulation/decoding.
See Also
