Roadside Radio Unit Signal Retransmission for V2X Reliability
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Solution Overview
Problem
Existing communication systems between roadside radio units and vehicles face reliability issues due to short range and latency problems in wireless direct communication, and longer transmission times in mobile radio connections, which can disrupt traffic flow and reduce communication availability.
Innovation Solution
A method where a roadside radio unit broadcasts a sequence of radio signals with temporal assignments, and upon receiving a response signal indicating faulty or missing signals, it broadcasts a repeated signal with increased power or different frequency to ensure reliable communication, using either wireless direct or mobile radio connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If wireless direct communication (WLAN/DSRC) is used for V2X communication, then latency is reduced and communication speed is improved, but communication range is limited to only a few hundred meters and reliability deteriorates in poor reception conditions
Solution Approach 1:
The system implements periodic broadcasting of radio signals at defined clocking intervals (1-10 Hz) with sequential numbering. When a signal is missed or faulty, the system periodically retransmits the same signal until successful reception is confirmed, transforming a single unreliable transmission into a periodic series of transmission attempts.
Solution Approach 2:
The system employs feedback mechanisms where receiving entities (vehicles or monitoring units) send response signals back to the roadside radio unit to confirm successful reception. The roadside unit monitors these responses and determines whether retransmission is necessary based on the feedback, creating a closed-loop communication system that adapts to reception conditions.
2Length of stationary object
If mobile radio connection is used for V2X communication, then communication range is extended beyond short range, but transmission time increases to generally longer than WLAN connection
Solution Approach 1:
The system merges two communication modes: wireless direct communication (WLAN/DSRC) for low-latency local communication and mobile radio for extended range. The roadside radio unit uses WLAN for primary broadcasting to nearby vehicles, while maintaining mobile radio connection for broader coverage and fallback communication, combining the advantages of both systems.
Solution Approach 2:
The system performs preliminary broadcasting of radio signals using high-speed WLAN communication to vehicles in the immediate vicinity. Only when signals are not received or range is exceeded does the system resort to mobile radio transmission, performing the faster action first and falling back to the slower action only when necessary.
3Measurement precision
If radio signals are broadcast in a specified time sequence with fixed intervals, then temporal assignment and synchronization are improved, but communication availability deteriorates when signals are lost or faulty
Solution Approach 1:
The system prepares for potential signal loss by implementing a buffer mechanism. When a radio signal is not received or is determined faulty within the expected time window, the system cushions against the disruption by retransmitting the missed signal, ensuring that the temporal sequence is maintained and no information is permanently lost.
Solution Approach 2:
The system ensures continuous useful action by maintaining the broadcast sequence even when individual signals are lost. Through retransmission of missed or faulty signals, the system continues to deliver the complete set of temporal assignments to all receiving entities, maintaining the continuity of the communication sequence despite individual transmission failures.
4Reliability
If repeated signals are broadcast upon receiving response signals indicating faulty or missing signals, then communication reliability is improved, but device complexity and energy consumption increase
Solution Approach 1:
The system implements self-service through automatic retransmission logic. When the roadside radio unit receives a response signal indicating a faulty or missing broadcast, it automatically determines the need for retransmission and executes the repeated broadcast without human intervention, managing the complexity through automated decision-making rather than manual control.
Data Source
AI summary
A method for securing communication between a roadside radio unit and vehicles in the surroundings of the roadside radio unit. The method includes: broadcasting a sequence of radio signals to the surroundings by means of the roadside radio unit, wherein the radio signals each have a temporal assignment; receiving a response signal from a vehicle or a stationary monitoring unit, wherein the response signal represents at least the temporal assignment of a radio signal that was faulty or not received by the vehicle or by the monitoring unit; and broadcasting a repeated signal by means of the roadside radio unit as a function of the received response signal, wherein the repeated signal represents the faulty or not-received radio signal and is in particular characterized as a repeated signal.