V2X Collision Detection via SCI-ACK Feedback Mechanism
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Solution Overview
Problem
Vehicle-to-Everything (V2X) communication systems face data collisions due to multiple devices selecting the same channel index for control channel transmission, leading to message loss and interference, especially in scenarios with high numbers of V2X terminals in close proximity or outside each other's transmission range, where legacy technologies like IEEE 802.11 and LTE-D2D/PC5 struggle with deterministic and low-latency message transmission.
Innovation Solution
A method for V2X communication that involves selecting a control channel from a resource pool, transmitting sidelink control information, monitoring for acknowledgement indicators, and postponing data transmission if no acknowledgement is received, allowing for collision detection and handling within a communication period structured with dedicated resource pools for control and data channels, enabling distributed resource allocation and mobility handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple V2X terminals transmit control information on the same channel index, then channel utilization increases, but data collision and message loss occur
Solution Approach 1:
The patent implements an acknowledgment mechanism where receiving terminals send ACK/NACK feedback for received control information. Transmitting terminals monitor this feedback to detect collisions (indicated by NACK or absence of ACK) and adjust their transmission behavior accordingly, resolving the contradiction between high channel utilization and reliable message delivery
Solution Approach 2:
The patent introduces dynamic channel selection where terminals randomly select different channel indexes for retransmission based on collision detection. This dynamic adaptation allows the system to maintain high channel utilization while avoiding repeated collisions, thereby improving message delivery reliability
2Loss of time
If V2X terminals transmit data immediately without collision detection, then transmission latency is reduced, but interference and message loss increase
Solution Approach 1:
The patent performs preliminary collision detection by monitoring ACK/NACK feedback before transmitting data. This preliminary action allows terminals to identify potential collisions early and adjust their transmission timing, reducing both latency and interference by avoiding unnecessary retransmissions
Solution Approach 2:
The patent applies preliminary anti-action by having terminals postpone data transmission when collision is detected through NACK feedback. This prevents the harmful interference that would result from simultaneous transmissions, while minimizing latency through targeted rather than blanket retransmission delays
3Adaptability or versatility
If distributed resource allocation is used for V2X communication, then network coverage and adaptability improve, but collision detection capability deteriorates
Solution Approach 1:
The patent introduces an intermediary acknowledgment mechanism that facilitates collision detection in distributed networks. Even when terminals are outside each other's transmission range and cannot directly detect collisions, the receiving terminal acts as an intermediary by sending NACK feedback, enabling the transmitting terminal to detect collisions indirectly and maintain reliable communication across extended network coverage
Data Source
AI summary
A vehicle-to-everything (V2X) communication system, and method of communication in the V2X communication system is provided. The method includes: selecting, at a first V2X device, a control channel of a control channel resource pool; transmitting, on the selected control channel, sidelink control information (SCI) to a second V2X device; monitoring, at the first V2X device, an SCI acknowledgement (SCI-ACK) resource pool for an SCI-ACK indicator (SCI-ACK-IND) corresponding to the transmitted SCI; and in response to receiving a positive SCI-ACK-IND corresponding to the transmitted SCI, transmitting data to the second V2X device in a data resource pool according to the SCI.