Default Aperiodic CSI-RS Beam Determination for 5G NR
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Solution Overview
Problem
Current 5G NR wireless communication systems face challenges in efficiently managing aperiodic channel state information reference signals (CSI-RS) due to differences in numerology between downlink control information (DCI) and CSI-RS, leading to beam-switching timing issues and potential delays in signal processing.
Innovation Solution
The system determines a default CSI-RS beam based on the lowest identifier of the CORESET in the latest monitored slot or quasi-co-located assumptions, and adjusts the scheduling offset between DCI and CSI-RS to be smaller than the reported beam-switch-timing threshold, ensuring timely and accurate beam alignment for CSI-RS reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scheduling offset between DCI and CSI-RS is reduced to improve timing efficiency, then beam switching timing issues are exacerbated due to numerology differences
Solution Approach 1:
The patent applies preliminary action by pre-determining the default beam for CSI-RS reception based on CORESET beam information before the actual CSI-RS transmission. The UE stores the beam information associated with the lowest-ID CORESET in the latest monitored slot, so when aperiodic CSI-RS is triggered, the beam is already prepared and can be applied immediately without waiting for additional beam determination time.
Solution Approach 2:
The patent uses the CORESET beam information as an intermediary to indirectly determine the CSI-RS beam. Instead of directly configuring the CSI-RS beam, the system uses the CORESET beam (which is already established and monitored) as a proxy or mediator to infer the appropriate beam for CSI-RS reception, thereby resolving the timing and reliability conflict.
2Loss of time
If aperiodic CSI-RS is triggered with same numerology to reduce processing delay, then beam switching timing becomes critical and more difficult to manage
Solution Approach 1:
The patent applies self-service by enabling the UE to autonomously determine the default beam for CSI-RS reception using its own stored CORESET beam information. The UE monitors and stores beam information locally, and when aperiodic CSI-RS is triggered, it automatically retrieves and applies the appropriate beam without requiring network intervention or complex external coordination, thereby reducing processing delay while managing complexity internally.
Solution Approach 2:
The patent changes the parameter approach by shifting from dynamic beam configuration to a predefined default beam based on CORESET information. Instead of continuously adjusting beam parameters, the system establishes a default beam parameter based on the lowest-ID CORESET in the latest monitored slot, simplifying the timing management complexity while maintaining efficiency.
3Ease of operation
If default beam determination is based on CORESET with lowest identifier to simplify beam selection, then beam accuracy may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-establishing the default beam based on CORESET information before the actual beam selection is needed. The UE monitors and stores beam information associated with CORESETs in advance, so when beam selection is required, the system already has the necessary information ready, ensuring both simplicity and accuracy without requiring complex real-time decisions.
Solution Approach 2:
The patent uses CORESET beam information as an intermediary that bridges the gap between simple beam selection and accurate beam determination. The lowest-ID CORESET serves as a reliable intermediary reference that is both easy to identify (simplicity) and provides sufficient beam information for accurate CSI-RS reception (precision), resolving the contradiction between ease of operation and measurement precision.
Data Source
AI summary
A UE receives DCI in a PDCCH, the DCI triggers reception of AP CSI-RS, and the PDCCH has a first numerology and the AP CSI-RS has a second numerology. The UE determines, when a CORESET is configured on an active BWP of a serving cell for receiving the AP CSI-RS and when the first numerology is the same as the second numerology, a default AP CSI-RS beam for receiving the AP CSI-RS based on a beam used for receiving the CORESET with a lowest ID in a latest monitored slot of the active BWP of the serving cell. The UE determines, otherwise when the first numerology is the same as the second numerology, the default AP CSI-RS beam for receiving the AP CSI-RS based on a QCL assumption of a PDSCH TCI state with a lowest ID on the active BWP of the serving cell for receiving the AP CSI-RS.