Methods And Apparatuses Of Determining Quasi Co-Location (Qcl) Assumptions For Beam Operations

What is this patent about?

’896 is related to the field of wireless communication systems, specifically addressing beamforming techniques in 5G New Radio (NR) networks. Beamforming allows a User Equipment (UE) to focus its signal transmission or reception in a particular direction, improving signal strength and reducing interference. This is achieved by applying spatial domain filters based on Quasi Co-Location (QCL) assumptions. However, when a UE is configured with multiple Control Resource Sets (CORESETs), ambiguities arise in determining the appropriate QCL assumption for beam operations, potentially leading to unfavorable beam switching.

The underlying idea behind ’896 is to resolve ambiguities in QCL assumptions when a UE monitors multiple CORESETs. The key inventive insight is to prioritize the CORESET with the lowest CORESET Identity (ID) for determining the QCL assumption, especially when receiving aperiodic Channel Status Information-Reference Signal (CSI-RS) or when a scheduling offset between a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH) is below a certain threshold. This ensures a more consistent and predictable beamforming behavior, avoiding unnecessary beam switches.

The claims of ’896 focus on a UE configured to monitor multiple CORESETs within an active Bandwidth Part (BWP) of a serving cell. Specifically, the UE applies the QCL assumption associated with the CORESET having the lowest ID to receive an aperiodic CSI-RS. Furthermore, when a PDSCH is scheduled by a PDCCH with a short scheduling offset, the UE applies the QCL assumption used for receiving the PDCCH to also receive the PDSCH, again prioritizing the CORESET with the lowest ID.

In practice, the invention ensures that the UE consistently uses the beam associated with the lowest CORESET ID when receiving aperiodic CSI-RS or PDSCH scheduled with a short offset. This is particularly relevant when multiple CORESETs overlap in time, potentially having different QCL assumptions. By consistently using the lowest CORESET ID, the UE avoids rapid beam switching, which can degrade performance. The invention also addresses scenarios where some CORESETs are not actively monitored, providing rules for how the UE should handle QCL assumptions in such cases.

This approach differs from prior solutions by providing a clear and unambiguous rule for selecting the QCL assumption when multiple CORESETs are configured. Previous systems might have left the UE to determine the QCL assumption based on less deterministic factors, leading to inconsistent behavior and potential performance degradation. By prioritizing the CORESET with the lowest ID, the invention provides a simple and effective mechanism for ensuring consistent beamforming, especially in scenarios with overlapping CORESETs and short scheduling offsets, thereby improving the overall reliability and efficiency of the wireless communication system.