Access Control Apparatus for Vehicle-to-Vehicle Slot Collision Detection
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Solution Overview
Problem
In vehicle-to-vehicle communication systems, increased vehicle density at intersections leads to a higher probability of packet signal collisions due to shared wireless channels, which can result in failed data transmission and hinder the objective of preventing collision accidents.
Innovation Solution
An access control apparatus that detects and broadcasts information on empty and collision slots within a frame, allowing terminal apparatuses to select and use slots with minimal interference, thereby reducing packet signal collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vehicle density increases at intersections to improve communication coverage, then more terminal apparatuses can participate in vehicle-to-vehicle communication, but the probability of packet signal collisions increases due to shared wireless channels
Solution Approach 1:
The wireless communication channel is segmented into multiple time slots within each frame structure. Terminal apparatuses are assigned to specific time slots for transmission, dividing the shared channel into discrete segments that reduce interference and collision probability among multiple vehicles at the intersection
Solution Approach 2:
The access control apparatus performs preliminary detection of slot usage conditions before allowing transmissions. By detecting which slots are already occupied or colliding in advance, the system can guide terminal apparatuses to select appropriate slots, preventing collisions before they occur
2Ease of operation
If CSMA/CA access control is used in wireless LANs to manage shared channels, then terminal apparatuses can communicate without centralized control, but carrier sense fails when terminal apparatuses are far apart or obstacles attenuate radio waves
Solution Approach 1:
The access control apparatus acts as an intermediary that receives transmission requests from terminal apparatuses, detects slot usage conditions, and provides guidance information back to the terminals. This mediator approach maintains decentralized operation while overcoming the limitations of carrier sense in obstructed or distant communication scenarios
Solution Approach 2:
The system implements feedback mechanisms where the access control apparatus monitors slot usage and provides guidance information to terminal apparatuses about which slots are available or experiencing collisions. This feedback loop enables terminal apparatuses to adjust their transmission timing based on real-time channel conditions
3Productivity
If broadcast transmission is used to send information to a large number of terminal apparatuses, then communication efficiency improves, but the number of collisions increases with more vehicles at intersections
Solution Approach 1:
The broadcast communication is segmented into multiple time slots within frames, allowing multiple terminal apparatuses to transmit simultaneously in different slots without colliding. This maintains high communication efficiency by utilizing the full channel capacity while preventing collisions through temporal separation
Solution Approach 2:
The frame structure with repeating time slots provides periodic transmission opportunities for terminal apparatuses. This periodic action allows efficient broadcast communication while the repeating pattern enables the access control apparatus to detect and manage collisions systematically across multiple frames
Data Source
AI summary
It is specified that a frame containing at least the plurality of slots is repeated. A detecting unit detects a slot usable in the communications between terminal apparatuses, from among a plurality of slots. A modem unit and an RF unit broadcast the information on the detected slot. A power measuring unit in the detecting unit measures the respective received powers of the plurality of slots, and an empty slot identifying unit identifies a slot whose received power is less than a threshold value.