5G NR Beam Update Robustness with DCI-Triggered SRS Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In 5G NR frequency range 2 (FR2), the dynamic re-selection of spatial and path-loss reference signals for uplink channels is crucial due to beam dependency, but existing DCI-based beam update mechanisms can fail, leading to beam mismatch and degraded uplink performance during UE mobility and low signal-to-noise ratio scenarios.
Innovation Solution
The DCI triggering AP CSI-RS for beam updates is enhanced by including a trigger for an aperiodic SRS, which the UE transmits back to the base station upon decoding, confirming successful reception and enabling synchronized beam updates at both the UE and gNB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DCI-based beam update mechanism is used for dynamic re-selection of spatial reference signals, then beam adaptability during UE mobility is improved, but system reliability deteriorates due to potential DCI decoding failures and beam mismatch
Solution Approach 1:
The patent implements a feedback mechanism where the UE transmits an aperiodic SRS in response to DCI triggering, providing confirmation to the gNB that the DCI was successfully decoded. This feedback loop allows the gNB to verify beam update reception and retransmit or adjust the beam update if the SRS is not received, thereby resolving the reliability issue while maintaining beam adaptability
Solution Approach 2:
The patent triggers an aperiodic SRS transmission as a preliminary confirmation action before finalizing the beam update. By requiring the UE to send this confirmation signal first, the system ensures that the beam update was properly received and processed, preventing premature beam switching that could lead to mismatch and improving overall update reliability
2Speed
If DCI triggering mechanism is used for beam updates, then beam update speed is improved, but robustness deteriorates in low SNR scenarios due to increased failure probability
Solution Approach 1:
The aperiodic SRS serves as a feedback signal confirming successful DCI decoding. In low SNR scenarios, if the gNB does not receive the expected SRS from the UE, it indicates potential DCI decoding failure, allowing the gNB to retransmit the DCI or adjust transmission parameters, thereby maintaining robustness while preserving the fast beam update capability
Solution Approach 2:
The patent prepares for potential DCI decoding failures by implementing a confirmation mechanism through aperiodic SRS. This cushioning approach ensures that if the initial DCI transmission fails in low SNR conditions, the system has a verification step in place to detect and correct the failure, preventing beam mismatch without sacrificing update speed
Data Source
Figure 1
Figure 2
Figure 3
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.