Vehicular Device Roadside Unit State Transition
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Solution Overview
Problem
Vehicular ad hoc networks (VANETs) face challenges in expanding communication range and efficiently disseminating safety messages to all vehicles, especially those outside the initial reachability area, without relying on fixed infrastructure.
Innovation Solution
Vehicular devices temporarily act as roadside units by positioning themselves on the boundary of the reachability area and moving towards the event source, broadcasting notification messages to uninformed vehicles within their range, and transitioning states based on predefined periods and vehicle density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vehicular devices rely on fixed infrastructure (RSUs) for message dissemination, then message delivery reliability is improved, but device complexity and infrastructure cost increase
Solution Approach 1:
Vehicular devices autonomously determine their own role as temporary RSUs based on their position relative to the event source and reachability area boundaries. The system self-organizes without external infrastructure by having vehicles independently assess their suitability for message broadcasting based on geometric relationships with the event source and other vehicles.
Solution Approach 2:
Vehicular devices perform multiple functions: they act as both mobile nodes in V2V networks and as stationary-like RSUs for message broadcasting when positioned appropriately. The same vehicle hardware serves dual purposes depending on its location and movement state, eliminating the need for dedicated infrastructure.
2Loss of information
If vehicular devices broadcast messages continuously, then message dissemination coverage is improved, but energy consumption increases
Solution Approach 1:
The broadcasting behavior of vehicular devices is dynamic rather than static. Vehicles transition between mobile and temporary RSU states based on their real-time position relative to the event source and reachability area boundaries. This dynamic state change allows the system to optimize energy usage by activating broadcasting only when geometric conditions are satisfied.
Solution Approach 2:
The system changes the operational parameter of message broadcasting from continuous to conditional based on geometric parameters (position relative to event source, distance to reachability area boundary). Vehicles modify their broadcasting behavior according to these parameter changes, transmitting only when positioned optimally for maximum dissemination efficiency.
3Loss of information
If vehicular devices act as temporary RSUs for extended periods, then message dissemination effectiveness is improved, but movement flexibility deteriorates
Solution Approach 1:
Vehicular devices engage in periodic broadcasting while in temporary RSU state, rather than continuous transmission. The vehicle broadcasts messages at intervals during its stationary period, achieving effective dissemination without requiring prolonged immobility. This periodic action reduces the impact on movement flexibility.
Solution Approach 2:
Vehicles determine their suitability for temporary RSU role in advance based on their current position and movement trajectory. By assessing geometric conditions before committing to the RSU state, the system ensures that vehicles only become stationary when the dissemination benefit justifies the movement interruption, optimizing the trade-off between effectiveness and flexibility.
Data Source
AI summary
A method performed by one or more processors, comprising: receiving a notification message indicative of an occurrence of an event; determining that a position of a vehicular device that is associated with the one or more processors is located on a boundary of a reachability area surrounding a source of the event; determining that a direction of movement of the vehicular device is towards the source; responsive to determining that the position is on the boundary of the reachability area and that the direction of movement of the vehicular device is towards the source, entering a roadside unit state; detecting one or more vehicular devices that are uninformed of the occurrence of the event and that are located outside of the reachability area; and broadcasting the notification message to the one or more uninformed vehicular devices.