Sidelink Scheduling With Multiple Time-Frequency Occasions
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Solution Overview
Problem
In wireless communication systems, particularly in unlicensed or shared sidelink frequency bands, the unpredictability of channel access procedures like LBT leads to non-deterministic transmission opportunities for sidelink communications, resulting in latency and reliability issues due to potential transmission delays and dropped packets.
Innovation Solution
Implementing inter-UE coordination (IUC) that utilizes multiple time-frequency occasions for sidelink communications, selected based on parameters such as QoS, LBT success rate, and channel busy ratio, to provide multiple transmission opportunities and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single time-frequency occasion is used for sidelink transmission in unlicensed bands, then device complexity is reduced, but reliability deteriorates due to non-deterministic channel access
Solution Approach 1:
The transmitting UE performs channel access procedures in advance for multiple future time-frequency occasions and shares the results with the receiving UE through IUC communications. This preliminary action allows both UEs to know in advance which occasions are suitable for transmission, eliminating the need for the receiving UE to perform independent channel access procedures and reducing overall system complexity while improving reliability.
Solution Approach 2:
The transmitting UE acts as an intermediary by performing channel access procedures and sharing the results with the receiving UE through IUC communications. This intermediary approach allows the receiving UE to benefit from the transmitting UE's channel access information without independently performing channel access, thereby reducing device complexity while maintaining high reliability.
2Reliability
If LBT procedure is performed before each transmission in shared frequency band, then channel access reliability is improved, but transmission latency increases due to unpredictable channel availability
Solution Approach 1:
The transmitting UE performs channel access procedures in advance for multiple future time-frequency occasions and shares the results with the receiving UE. This allows both UEs to identify suitable transmission occasions beforehand, eliminating the need for last-minute channel access attempts and reducing transmission latency while maintaining channel access reliability.
Solution Approach 2:
The system dynamically selects transmission occasions based on pre-performed channel access results. The transmitting UE shares information about which future occasions are clear for transmission, allowing the receiving UE to dynamically schedule transmissions at optimal times without performing independent LBT procedures, thereby reducing latency while maintaining reliability.
3Reliability
If multiple time-frequency occasions are provided for sidelink transmission, then transmission reliability is improved through multiple attempts, but device complexity increases due to coordination requirements
Solution Approach 1:
The transmitting UE serves as an intermediary by performing channel access procedures and sharing results with the receiving UE through standardized IUC communications. This approach enables multiple transmission occasions to be coordinated efficiently, as the receiving UE can use the shared channel access information to determine suitable transmission times without independent LBT procedures, thereby improving reliability while managing coordination complexity.
Solution Approach 2:
The transmission process is segmented into multiple independent time-frequency occasions, each with its own channel access result. The transmitting UE performs channel access for each occasion separately and shares the results with the receiving UE. This segmentation allows the system to improve reliability through multiple attempts while managing complexity by treating each occasion as an independent unit with standardized coordination procedures.
4Adaptability or versatility
If channel access procedure is performed dynamically before each transmission, then adaptability to channel conditions is improved, but deterministic transmission scheduling becomes difficult
Solution Approach 1:
The transmitting UE performs channel access procedures in advance for multiple future time-frequency occasions and shares the results with the receiving UE. This preliminary action provides deterministic scheduling information about future transmission opportunities, allowing the receiving UE to plan transmissions in advance while still adapting to actual channel conditions based on the pre-performed LBT results.
Solution Approach 2:
The system combines dynamic channel access procedures with deterministic scheduling by having the transmitting UE perform LBT in advance for multiple occasions and share results with the receiving UE. This allows the receiving UE to deterministically schedule transmissions at known good times while the system remains adaptable to changing channel conditions through the periodic refresh of channel access information.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first user equipment (UE) may receive, from a second UE, an inter-UE coordination (IUC) communication indicating multiple time-frequency occasions for at least one of a sidelink data communication or a sidelink feedback communication, the multiple time-frequency occasions being based at least in part on one or more parameters. The first UE may transmit, to the second UE or another UE, the sidelink data communication or the sidelink feedback communication using at least one time-frequency occasion of the multiple time-frequency occasions. Numerous other aspects are provided.