5G NR UE Receive Beam Determination via Aperiodic CSI-RS
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Solution Overview
Problem
In 5G New Radio (NR) systems, determining the spatial quasi co-location (QCL) assumption for aperiodically triggered channel state information reference signals (CSI-RS) within transmission configuration indicator (TCI) states is challenging, especially when scheduling offsets are significant, affecting beam alignment and data transmission efficiency.
Innovation Solution
A method and apparatus for user equipment (UE) to determine the receive beam for PDSCH and PDCCH transmissions based on aperiodic CSI-RS resources, utilizing either the beam pattern of the latest or most recent aperiodic CSI-RS transmission, or an existing spatial QCL assumption, depending on scheduling thresholds and signal quality, to ensure accurate beam alignment and data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aperiodic CSI-RS resources are used for beam alignment, then data transmission efficiency is improved, but determining spatial QCL assumption becomes challenging with significant scheduling offsets
Solution Approach 1:
The patent applies preliminary action by determining the spatial QCL assumption in advance based on the scheduling offset value. The UE calculates whether the scheduling offset exceeds a threshold and pre-determines which TCI state to use for the PDSCH reception, eliminating the need for real-time determination during data transmission and resolving the challenge of significant scheduling offsets.
2Reliability
If beam alignment is maintained with significant scheduling offsets, then system performance is improved, but the complexity of beam management increases
Solution Approach 1:
The patent applies parameter changes by using the scheduling offset value as a decision parameter to select between different TCI state determination methods. When the scheduling offset exceeds a threshold, the UE uses a different approach (based on aperiodic CSI-RS) compared to when it is below the threshold, thereby maintaining beam alignment accuracy while managing complexity through parameter-based decision making.
3Measurement precision
If the latest aperiodic CSI-RS transmission is used for receive beam determination, then beam alignment is improved, but latency increases when scheduling offsets are significant
Solution Approach 1:
The patent resolves the latency issue by performing preliminary determination of the spatial QCL assumption based on the scheduling offset. The UE calculates the appropriate TCI state in advance using the known scheduling offset value, rather than waiting for the latest aperiodic CSI-RS transmission, thereby reducing beam determination latency while maintaining alignment accuracy.
Data Source
AI summary
An apparatus configured to be employed in a user equipment (UE) associated with a new radio (NR) communication system is disclosed. The apparatus comprises one or more processors configured to process a physical downlink shared channel (PDSCH) scheduling signal, received from a gNodeB associated therewith, wherein the PDSCH scheduling signal is configured to schedule a transmission of PDSCH. In some embodiments, the PDSCH scheduling signal comprises a transmission configuration indicator (TCI) state indicative of a channel state information reference signal (CSI-RS) resource that is triggered aperiodically. In some embodiments, the apparatus is further configured to determine a receive (Rx) beam to be utilized for the reception of the scheduled PDSCH transmission, that forms a PDSCH Rx beam, based on the indicated CSI-RS resource.