UE Beam Selection for Secondary Cell Failure Recovery
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Solution Overview
Problem
Conventional beam failure recovery operations in wireless communication networks experience high latency and reduced reliability, particularly in URLLC modes, due to the ambiguity in handling transmissions between Step 1 and network confirmation in the two-step process.
Innovation Solution
The proposed solution involves user equipment (UE) selecting and using a new beam for transmission or reception prior to receiving confirmation from the network, allowing for immediate beam switching and reducing ambiguity in beam usage during recovery operations, which can be facilitated through MAC CEs without requiring a traditional Step 2 communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional two-step beam failure recovery process is used, then network control and coordination are maintained, but latency increases and reliability decreases
Solution Approach 1:
The UE performs beam selection and switches to the new beam before receiving network confirmation. The UE proactively selects a candidate beam from available reference signals and switches to it during the ongoing RACH procedure, rather than waiting for network instruction. This preliminary action reduces recovery latency while maintaining reliability through subsequent network validation.
Solution Approach 2:
The patent skips the traditional sequential execution where the UE must complete Step 1 (beam failure indication) and receive Step 2 (beam indication from network) before switching beams. Instead, the UE rushes through by performing beam selection and switching in parallel with or before receiving the network response, thereby reducing the overall recovery time.
2Productivity
If UE selects and uses new beam prior to network confirmation, then latency is reduced and throughput is improved, but ambiguity in beam usage during recovery operations increases
Solution Approach 1:
The network provides feedback by sending a beam failure recovery response that confirms or corrects the UE's selected beam. The UE monitors for this feedback and adjusts its beam selection accordingly. This feedback mechanism resolves the ambiguity by allowing the UE to act independently initially while ensuring final coordination with the network through the response message.
Solution Approach 2:
The UE performs self-service by autonomously selecting the candidate beam and switching to it without waiting for network instruction. The UE uses its own measurements of reference signals to determine the best beam, thereby reducing latency. The network's role is reduced to validating and confirming the UE's self-selected beam through the recovery response.
3Reliability
If traditional Step 2 communication is required for beam indication, then network control is maintained, but additional communication overhead and latency are introduced
Solution Approach 1:
The patent extracts the essential beam selection function from the traditional two-step protocol and implements it as a UE autonomous function. The UE takes out the beam selection task from the network-controlled process and performs it independently using local measurements of reference signals, thereby simplifying the communication protocol while maintaining reliability through subsequent network confirmation.
Solution Approach 2:
Reference signals serve as an intermediary that enables the UE to perform beam selection without direct network instruction. The UE measures the reference signals transmitted by the gNB and uses these measurements to autonomously select the best beam, thereby reducing the need for explicit Step 2 communication while maintaining network control through the recovery response.
Data Source
AI summary
User equipment (UE) based beam selection for beam failure recovery operations are disclosed. A method of wireless communication includes: identifying a beam failure event associated with a first beam and a secondary cell and transmitting a beam failure recovery request for the secondary cell. The method further includes selecting a second beam for secondary cell communications prior to receiving a response to the beam failure event, and transmitting or receiving a communication to or from the secondary cell using the selected second beam.