Sidelink Resource Overbooking for Persistent Unlicensed Access
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in accessing unlicensed radio frequency spectrum for sidelink communications due to channel access failures caused by other devices operating on different radio access technologies, leading to degraded performance.
Innovation Solution
A framework for overbooking resources in the unlicensed spectrum, allowing user equipment (UE) to perform multiple listen-before-talk procedures and reserve additional resources for sidelink communications, even after initial access failures, and release unused resources for others to use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE performs a single LBT procedure to access unlicensed spectrum resources for sidelink communications, then the access process is simple and quick, but the reliability of access is degraded due to potential LBT failures caused by other devices operating on different radio access technologies
Solution Approach 1:
The UE performs multiple LBT procedures in advance (first LBT, second LBT, and potentially third LBT) before actually transmitting sidelink communications. By conducting these preliminary channel access attempts and reserving resources accordingly, the system ensures that the UE has reliable access rights to the unlicensed spectrum resources even if some LBT procedures fail, thus resolving the contradiction between access reliability and procedure complexity
Solution Approach 2:
The channel access procedure is made dynamic by allowing the UE to adaptively perform different numbers of LBT procedures based on outcomes. If the first LBT succeeds, the UE may proceed with transmission or perform additional LBTs to secure persistent access. The system dynamically adjusts the access strategy between single LBT and multiple LBTs based on channel conditions and previous outcomes, balancing reliability requirements with procedural complexity
2Reliability
If a UE reserves additional resources through overbooking to ensure persistent access after LBT failures, then the reliability of sidelink communications is improved, but the resource utilization efficiency deteriorates due to reserved resources potentially remaining unused
Solution Approach 1:
The system changes the parameter of resource reservation by introducing overbooking, where the UE reserves more resources than initially needed (e.g., reserving resources for both first and second LBT outcomes). This parameter change allows the UE to secure persistent access rights while the actual resource consumption is adjusted dynamically based on which LBT procedures succeed, thus improving reliability without permanently wasting resources
Solution Approach 2:
When the UE successfully accesses the channel through the first LBT procedure, it discards the previously reserved additional resources (from the second LBT procedure) and makes them available for other UEs to use. This discarding and recovering mechanism ensures that overbooking does not lead to permanent resource waste, as unused reserved resources are released back to the pool for system-wide utilization, balancing reliability improvement with resource efficiency
3Reliability
If a UE performs multiple LBT procedures using consecutive slots to maintain persistent reservation, then the access reliability is improved, but the time required for channel access increases
Solution Approach 1:
The UE performs multiple LBT procedures as preliminary actions within consecutive slots before actual sidelink transmission begins. By completing these LBT procedures in advance and securing resource reservations upfront, the system ensures that once transmission starts, it can proceed reliably without repeated access attempts, thus improving access reliability while minimizing the time loss during the actual communication phase
Solution Approach 2:
The system maintains continuous useful action by having the UE perform LBT procedures in consecutive slots without interruption, ensuring persistent reservation of resources. This continuous approach allows the UE to methodically work through multiple LBT attempts while keeping the channel access process flowing, reducing idle time and ensuring that once access is secured, the transmission can proceed without further interruptions, thus balancing reliability improvement with time efficiency
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit a first sidelink signal indicating a set of resources that are reserved at the UE for sidelink communications. The UE may perform multiple listen-before-talk (LBT) procedures using respective consecutive slots of the set of resources. The UE may transmit another sidelink signal using a portion of the set of resources following the multiple LBT procedures. The UE may release a remaining portion of the set of resources after transmitting the second sidelink signal. Another UE may receive the first sidelink signal including the indication of the set of resources. The other UE may detect the remaining portion of the set of resources that may be available for the other UE to use for first sidelink communications based on overbooking at the UE.