V2X Sidelink Packet Preemption for High-Priority Traffic
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Solution Overview
Problem
In sidelink systems like V2X, existing semi-persistent scheduling (SPS) limits data packet size and periodicity, leading to inefficient transmissions, high interference, and latency issues, especially when high-priority packets are not received due to simultaneous lower priority transmissions.
Innovation Solution
Wireless devices dynamically identify and preempt lower priority reservations to ensure high-priority packet transmissions by determining relative priorities and communicating accordingly during the same transmission time interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If semi-persistent scheduling (SPS) is used for resource allocation, then resource allocation is simplified and centralized control is achieved, but transmission efficiency decreases and latency increases due to limited packet size and periodicity
Solution Approach 1:
The patent implements dynamic resource selection where UEs can adaptively choose transmission resources based on real-time channel conditions and packet priorities, transitioning from static SPS to dynamic scheduling. This allows the system to maintain simplified resource allocation while improving transmission efficiency through flexible resource adaptation.
Solution Approach 2:
The patent segments the resource allocation process into two parts: centralized configuration of resource pools and decentralized dynamic selection within those pools. This segmentation allows the complexity of dynamic scheduling to be managed while maintaining centralized control benefits, resolving the contradiction between scheduling simplicity and transmission efficiency.
2Adaptability or versatility
If multiple UEs transmit packets simultaneously without SPS, then transmission flexibility increases, but interference increases and packet reception reliability decreases
Solution Approach 1:
The patent implements feedback mechanisms where UEs monitor channel conditions and adjust their transmission decisions based on detected interference levels and successful reception of priority indicators from other UEs. This feedback loop maintains transmission flexibility while improving packet reception reliability through adaptive interference management.
3Device complexity
If UEs cannot transmit and receive packets at the same time, then half-duplex operation simplifies device design, but latency increases when high-priority packets must wait for lower-priority transmissions to complete
Solution Approach 1:
The patent implements preliminary transmission of priority indicators before actual data packet transmission. When a UE detects a high-priority packet, it transmits a priority indicator immediately, allowing receiving UEs to prepare for potential preemption. This preliminary action reduces latency by enabling faster response to high-priority traffic while maintaining half-duplex operation.
4Productivity
If one UE schedules a lower priority packet transmission, then resource allocation is made, but resources become unavailable for higher priority packet transmissions, causing latency
Solution Approach 1:
The patent changes the priority parameter dynamically during the transmission process. When a high-priority packet needs to preempt a lower-priority transmission, the system adjusts the effective priority parameter of the packets involved, allowing the high-priority packet to access resources immediately while the lower-priority packet is rescheduled. This parameter change resolves the contradiction by enabling flexible resource reallocation based on updated priority conditions.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some systems (e.g., sidelink systems, such as vehicle-to-everything (V2X) systems), wireless devices may perform dynamic resource reservations to schedule packet transmissions (e.g., data packet transmissions). Different packets may correspond to different priority levels. To support flexible resource reservation for high priority packets, wireless devices may implement techniques for preempting lower priority reservations. For example, a wireless device may identify reservations for transmitting different packets during a same transmission time interval (TTI). The device may determine whether a first or second packet has a higher relative priority and may communicate in the V2X system during the TTI according to the relative priorities. For example, a device that reserved the TTI for the lower priority packet may refrain from transmitting the packet during the TTI, while a device that reserved the TTI for the higher priority packet may transmit the packet.