V2X 1-Shot Messaging via Random Timer and SPS
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Solution Overview
Problem
In dense vehicle environments, the C-V2X system experiences persistent collisions and consecutive packet losses due to multiple vehicles selecting the same radio resources, leading to increased probability of missed packets and impaired vehicle tracking for V2X applications.
Innovation Solution
A duration-based 1-shot messaging system that uses a transceiver and controller to transmit a sequence of connected messages using Semi-Persistent Scheduling (SPS) with a random 1-shot duration timer, allocating independent resources for a 1-shot transmission upon timer expiration, thereby avoiding persistent collisions and packet losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Semi-Persistent Scheduling (SPS) is used for V2X message transmission, then transmission reliability is improved through periodic resource allocation, but persistent collisions occur in dense vehicle environments leading to consecutive packet losses
Solution Approach 1:
The patent implements a dual periodic mechanism: SPS provides periodic resource allocation for regular transmissions, while a separate 1-shot duration timer triggers periodic 1-shot transmissions at random intervals. This layered periodic action ensures that even when SPS resources collide, vehicles can transmit via 1-shot resources, preventing consecutive packet losses and maintaining transmission reliability in dense environments.
2Productivity
If multiple vehicles select the same radio resources in dense environments, then resource utilization efficiency is improved, but persistent collisions increase leading to missed packets
Solution Approach 1:
The patent dynamically changes the transmission resource parameter by introducing a random 1-shot duration timer that selects between SPS and 1-shot resources. This parameter change allows vehicles to switch resource types based on timer expiration, reducing persistent collisions while maintaining resource utilization efficiency through the randomness introduced in resource selection timing.
3Reliability
If 1-shot resources are allocated independently of SPS resources, then collision avoidance is improved, but resource allocation complexity increases
Solution Approach 1:
The system implements self-service through autonomous resource selection: the 1-shot duration timer automatically triggers 1-shot resource allocation when expired, and the vehicle independently switches between SPS and 1-shot resources based on timer status. This self-service mechanism reduces collision avoidance complexity by eliminating the need for complex centralized coordination, as each vehicle autonomously manages its resource selection based on local timer state.
Data Source
AI summary
A sequence of connected messages is transmitted using Semi-Persistent Scheduling (SPS) of a predefined period. A random value for a 1-shot duration timer is set, the random value being chosen as being between a minimum and a maximum multiple of the predefined period. Responsive to expiration of the 1-shot duration timer, 1-shot resources are allocated for a 1-shot transmission, independent of SPS-allocated resources of the SPS, and a next packet of the sequence of connected messages is transmitted as a 1-shot message using the 1-shot resources instead of using the SPS-allocated resources of the SPS.