5G NR DCI-Triggered Beam Updates With Aperiodic SRS Feedback
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Solution Overview
Problem
In 5G NR frequency range 2 (FR2), the dynamic re-selection of spatial and path-loss reference signals for beam updates is prone to failures due to undetected Downlink Control Information (DCI), leading to beam mismatches between User Equipment (UE) and the gNB, which degrades uplink performance.
Innovation Solution
The DCI triggering aperiodic CSI-RS for beam updates is enhanced by including a trigger for aperiodic SRS, allowing the UE to confirm successful decoding through AP SRS transmission, ensuring synchronized beam updates at both UE and gNB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DCI triggering aperiodic CSI-RS is used for beam updates, then beam update capability is enabled, but robustness deteriorates due to undetected DCI causing beam mismatches
Solution Approach 1:
The patent implements a feedback mechanism where the UE transmits an aperiodic SRS in response to the DCI trigger, and the gNB detects this SRS to confirm successful DCI decoding. This feedback loop ensures that beam updates are synchronized between gNB and UE, resolving the reliability issue while maintaining beam update capability.
Solution Approach 2:
The patent requires the gNB to transmit the DCI trigger and the UE to prepare and transmit the aperiodic SRS before the actual beam update is executed. This preliminary action ensures that both sides are synchronized and ready for the beam update, preventing mismatches caused by undetected DCI.
2Reliability
If DCI decoding confirmation is added through aperiodic SRS transmission, then beam update synchronization is improved, but uplink signal transmission requirements increase
Solution Approach 1:
The patent leverages the aperiodic SRS, which is already configured for other purposes in the system, to serve the additional function of DCI decoding confirmation. This multi-functional use of the SRS avoids introducing completely new signaling mechanisms and reduces the incremental energy burden.
Solution Approach 2:
The UE uses its own uplink transmission (the aperiodic SRS) to convey confirmation of DCI decoding status. Rather than requiring a separate dedicated confirmation channel or additional signaling, the system repurposes an existing uplink resource to serve the confirmation function, minimizing additional energy requirements.
Data Source
AI summary
Systems and methods for improving the robustness of a DCI triggered beam update in 5G NR are disclosed herein. A g Node B (gNB) may associate a reference signal to a beam pattern (or beam configuration) and prepare Downlink Control Information (DCI) of a Physical Downlink Control Channel (PDCCH) that includes aperiodic Channel-State Information Reference Signal (AP CSI-RS) information indicating the beam pattern. A user equipment (UE) may decode the DCI, extract the AP CSI-RS information, update the beam pattern of a reference signal based on the AP CSI-RS information, and generate an uplink (UL) feedback message indicating that the PDCCH was successfully decoded by the UE. The gNB may then decode the uplink (UL) feedback message and, in response, update a receive (RX) beam of the gNB to correspond to the beam pattern associated to the reference signal.