Uplink LBT Failure Reporting Across Cells Without BWP Switching
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Solution Overview
Problem
In wireless communication systems using unlicensed spectrum, the issue of how to send an LBT failure MAC CE when consistent uplink LBT failure occurs in a serving cell is unresolved, leading to potential misinterpretation by the network side device.
Innovation Solution
A terminal side device cancels the consistent uplink LBT failure status in a cell by sending an LBT failure MAC CE in another BWP or using a CG/DG grant of a second cell without immediate BWP switching, and initiates a random access procedure only after receiving DCI for BWP switching, ensuring accurate communication with the network side device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal side device sends an LBT failure MAC CE in the serving cell where consistent uplink LBT failure occurs, then the network side device can be notified of the LBT failure status, but the network side device may incorrectly understand the cell status
Solution Approach 1:
The patent introduces a BWP switching mechanism as an intermediary step between LBT failure detection and MAC CE transmission. When the terminal detects consistent uplink LBT failure in a first BWP, it switches to a second BWP before sending the LBT failure MAC CE. This intermediary action prevents the network side device from misinterpreting the cell status while ensuring reliable notification of the LBT failure condition.
2Ease of operation
If the terminal side device switches BWP immediately upon detecting LBT failure, then it can send the LBT failure MAC CE successfully, but unnecessary BWP switching occurs increasing system complexity
Solution Approach 1:
The patent applies preliminary action by checking whether the terminal is currently in a BWP switching process before executing BWP switching. If the terminal is already undergoing BWP switching when LBT failure is detected, the patent waits for the switching to complete before sending the LBT failure MAC CE, thereby avoiding unnecessary additional BWP switching operations and reducing system complexity.
3Stability of the object's composition
If the terminal side device waits for BWP switching completion before sending LBT failure MAC CE, then BWP switching conflicts are avoided, but transmission delay increases
Solution Approach 1:
The patent implements a dynamic decision-making mechanism that adapts BWP switching behavior based on real-time system state. The terminal checks whether it is currently in a BWP switching process and adjusts its LBT failure MAC CE transmission timing accordingly. This dynamic approach ensures BWP switching consistency while minimizing unnecessary delays by only waiting when actually needed.
Data Source
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AI summary
Embodiments of this application provide a communication method and apparatus. The method includes: When determining that consistent uplink LBT failure occurs in a first BWP of a first cell, a terminal side device may indicate, to a network side device by using an uplink resource in a second cell, that the consistent uplink LBT failure occurs in the first cell. According to the foregoing method, the terminal side device indicates, by using the second cell in which no consistent uplink LBT failure occurs, that the consistent uplink LBT failure occurs in the first cell, so that the network side device can more quickly determine that the consistent uplink LBT failure occurs in the first cell. Therefore, the LBT failure can be recovered as soon as possible.