Sidelink Resource Handling Under Consistent LBT Failure
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Solution Overview
Problem
The existing New Radio (NR) operation in unlicensed bands faces challenges with consistent listen-before-talk (LBT) failures in sidelink transmissions, leading to unreliable communication due to inconsistent channel access, particularly affecting HARQ feedback processes.
Innovation Solution
Implementing a solution to detect consistent LBT failures and transmit information about these failures among terminal devices and network devices, enabling adaptive resource management and retransmission strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedure is performed before each SL transmission to co-exist with other wireless systems on unlicensed bands, then channel access reliability is improved, but communication consistency deteriorates due to frequent LBT failures
Solution Approach 1:
The transmitting UE performs LBT procedure in advance before SL transmission and proactively reports the LBT result to the receiving UE. This preliminary action allows the receiving UE to know beforehand whether transmission will occur, enabling it to prepare appropriate reception actions and avoid communication inconsistencies caused by unexpected transmission drops.
Solution Approach 2:
The transmitting UE feeds back LBT failure information to the receiving UE through uplink signaling or sidelink signaling. This feedback mechanism enables the receiving UE to adjust its reception strategy based on actual transmission status, maintaining communication consistency even when LBT failures occur frequently.
2Object-affected harmful factors
If SL UE drops SL transmission when LBT fails, then channel access conflict is reduced, but communication reliability deteriorates due to consistent LBT failures
Solution Approach 1:
The transmitting UE reports LBT failure information to the receiving UE, enabling the receiving UE to understand that transmission drops are due to LBT failures rather than other issues. This feedback maintains communication reliability by allowing the receiving UE to appropriately handle expected transmission failures.
Solution Approach 2:
The system dynamically adjusts communication behavior based on LBT failure status. When LBT failures are detected, the transmitting UE informs the receiving UE, and the receiving UE dynamically adjusts its reception strategy accordingly, maintaining reliable communication despite frequent transmission drops.
3Adaptability or versatility
If LBT procedure is performed before each transmission, then co-existence with other wireless systems is improved, but communication efficiency deteriorates due to transmission drops
Solution Approach 1:
By implementing feedback of LBT failure information from transmitting UE to receiving UE, the system maintains communication efficiency despite LBT-induced transmission drops. The receiving UE can optimize resource usage and avoid redundant operations based on the feedback information.
Solution Approach 2:
The LBT failure information acts as an intermediary signal between transmitting and receiving UEs, coordinating their behaviors to maintain efficient communication while respecting unlicensed band access requirements. This intermediary information enables both UEs to synchronize their actions despite transmission interruptions.
Data Source
AI summary
Example embodiments of the present disclosure relate to coping with consistent listen-before-talk (LBT) failure. A first terminal device may determine that a consistent listen-before-talk, LBT, failure on a set of sidelink resources is detected; and transmit, to at least one of a second terminal device or a network device, information related to the consistent LBT failure. In this way, reliability of sidelink communication may be improved even in consistent LBT failure situations.