Sidelink HARQ Feedback Suppression for Continuous Unlicensed Transmission
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Solution Overview
Problem
In sidelink communication using an unlicensed spectrum, the terminal device fails to utilize subsequent retransmission resources within channel occupancy time, leading to reduced communication efficiency and quality due to the need for repeated listen before talk processes.
Innovation Solution
The terminal device selects a target logical channel that is HARQ feedback disabled and sends indication information to indicate that the transport block is also HARQ feedback disabled, allowing subsequent transmissions within the channel occupancy time without requiring additional LBT, thereby ensuring continuous communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the terminal device does not use subsequent retransmission resources of a TB in COT, then the terminal device can simplify transmission control, but the terminal device needs to perform LBT again before using transmission resources of another TB, reducing communication efficiency
Solution Approach 1:
The terminal device performs preliminary action by selecting a target logical channel with HARQ feedback disabled before transmission, and setting the HARQ feedback disabled flag in advance. This preliminary configuration allows the terminal to avoid repeated LBT processes when using subsequent transmission resources within COT, as the HARQ feedback mechanism is pre-established to suppress feedback requests during continuous transmission.
Solution Approach 2:
The invention ensures continuity of useful action by maintaining the HARQ feedback disabled state throughout the COT period. Once the terminal device sets the HARQ feedback disabled flag for a target logical channel, this state persists for all subsequent transmissions within the same COT, eliminating interruptions for LBT re-negotiation and enabling continuous transmission of multiple TBs without resume pauses.
2Productivity
If the terminal device uses COT for transmission of multiple TBs, then the terminal device can improve channel utilization, but the terminal device cannot directly use transmission resources of another TB subsequently without repeated LBT, reducing communication quality
Solution Approach 1:
The invention applies local quality by differentiating the HARQ feedback attribute at the logical channel level. The terminal device selects a target logical channel with HARQ feedback disabled and applies this specific attribute to transmissions within COT. This localized attribute assignment allows different logical channels to have different HARQ feedback behaviors, enabling continuous transmission for selected channels while maintaining proper feedback mechanisms for others.
Solution Approach 2:
The invention changes the HARQ feedback parameter from enabled to disabled state for the target logical channel. By modifying this critical parameter before transmission begins, the terminal device transforms the transmission behavior to allow continuous operation within COT without repeated LBT. This parameter change is reflected in the SCI indication information and maintains consistency throughout the COT period.
3Reliability
If the terminal device performs LBT before each transmission, then the terminal device can ensure fair channel access, but the terminal device cannot continuously transmit data in COT, reducing transmission throughput
Solution Approach 1:
The invention segments the COT period into different transmission phases with different LBT requirements. The terminal device performs LBT initially to acquire COT, then segments subsequent transmissions into continuous blocks where the HARQ feedback disabled flag suppresses intermediate LBT requirements. This segmentation allows the terminal to maintain fair initial access while enabling high-throughput continuous transmission during COT.
Solution Approach 2:
The HARQ feedback disabled flag acts as an intermediary mechanism that mediates between channel access fairness and transmission throughput. This intermediary suppresses the need for repeated LBT during COT while maintaining the fairness principle through initial LBT and COT allocation. The intermediary flag allows the system to balance fairness and throughput by controlling feedback behavior rather than eliminating LBT entirely.
Data Source
AI summary
This application provides a communication method, apparatus, and system, and is applied to the field of communication technologies. The communication method provided in this application includes: obtaining first channel occupancy time; determining that first transmission succeeds on a first transmission resource within the first channel occupancy time, where the first transmission is used to send a first transport block to a receiving terminal device; determining that a second transmission resource of the first transport block exists within the first channel occupancy time; and performing second transmission by using the second transmission resource. Based on the communication method provided in embodiments of this application, the sending terminal device can continue to use a subsequent transmission resource of the first transport block to perform transmission.