Beam Failure Management for Out-of-Sync User Equipment
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Solution Overview
Problem
Conventional beam failure detection (BFD) and beam failure recovery (BFR) procedures are inefficient when a user equipment (UE) is in an uplink out-of-synchronization (OOS) state, as the limited uplink capabilities prevent successful completion of these procedures, leading to unnecessary power drain and inefficient resource allocation.
Innovation Solution
The method involves receiving a timing advance command (TAC) from a camped cell, initiating a time advance timer (TAT), and when the TAT expires, entering an OOS state. In this state, the UE suspends BFD and BFR procedures, thereby conserving power and optimizing resource allocation until the UE re-enters the in-sync state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs beam failure detection and recovery procedures while in the uplink OOS state, then the UE can attempt to recover from beam failure, but the procedures fail to complete successfully due to limited uplink capabilities
Solution Approach 1:
The patent applies dynamics by making the BFD and BFR procedures conditional based on the TAT state. The UE dynamically adjusts its behavior - performing beam failure procedures when TAT is running (in-sync state) and suspending them when TAT is not running (OOS state). This dynamic adaptation ensures procedures are only executed when uplink capabilities are sufficient to support them.
2Reliability
If the UE continuously performs BFD and BFR procedures regardless of synchronization state, then beam failure can be detected and recovered, but power is wasted on unnecessary operations when uplink capabilities are limited
Solution Approach 1:
The patent implements partial action by conditionally executing BFD and BFR procedures only when necessary - specifically when the TAT is running and the UE has adequate uplink capabilities. When the TAT is not running, the UE performs only partial monitoring (stopping BFD/BFR) rather than complete suspension, allowing quick resumption when synchronization is restored. This avoids wasting power on procedures that cannot succeed.
Solution Approach 2:
The TAT serves as a feedback mechanism that informs the UE about its synchronization state with the network. Based on this feedback (TAT running or not running), the UE adjusts its beam failure management behavior accordingly, creating a closed-loop system that optimizes power consumption while maintaining reliability.
3Adaptability or versatility
If the UE attempts BFR procedure while OOS in uplink, then beam failure recovery may be initiated, but the procedure cannot be completed due to inability to perform appropriate uplink signaling
Solution Approach 1:
The patent applies preliminary action by checking the TAT state before initiating BFD and BFR procedures. The UE proactively determines whether it is in a suitable state (TAT running) to perform beam failure procedures, preventing futile attempts before they can consume resources or cause errors. This preliminary check ensures that only when uplink synchronization is established does the UE attempt beam failure recovery.
Data Source
AI summary
Devices, systems and methods for implementing beam failure management techniques at a user equipment (UE). The UE receives a timing advance command (TAC) from a currently camped cell and initiates a time advance timer (TAT). When the TAT is running the UE is in a first operating state. The first operating state indicates that the UE is in time alignment with the cell. The UE identifies that the TAT has expired. When the TAT is not running the UE is in a second operating state. The second operating state indicates that the UE is not in time alignment with the cell. The UE implements one or more beam failure management techniques based on the UE operating in the second operating state.