Vehicle-to-Vehicle Broadcast Packet Density Control
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Solution Overview
Problem
Conventional ad-hoc networks in the automotive field, such as WLAN, IEEE 802.11, IEEE 802.15, and DSRC, fail to provide the necessary communication range, bandwidth, and time delay for reliable vehicle-to-vehicle multi-hop broadcast communication, especially in safety applications, where fast and efficient information dissemination is critical, particularly in congested road conditions.
Innovation Solution
A wireless vehicle-to-vehicle communication system that reduces the number of packets transmitted by implementing congestion detection and efficient flooding algorithms, using position data to determine vehicle density and adjust packet transmission frequency, and employing a method where only necessary vehicles retransmit packets, with the last vehicle sending to avoid collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ad-hoc networks (WLAN, IEEE 802.11, DSRC) are used for vehicle-to-vehicle communication, then the system is simple to implement, but the communication range is insufficient and time delay is too long for safety applications
Solution Approach 1:
The patent segments the broadcast communication into multiple unicast transmissions. Each vehicle receives position data from other vehicles and retransmits it as unicast packets to specific target vehicles, dividing the complex broadcast function into simpler, manageable unicast segments that can be handled by existing communication infrastructure
Solution Approach 2:
The patent introduces intermediate vehicles as mediators in the communication process. These vehicles receive position data from source vehicles and forward it to destination vehicles, acting as relays that extend communication range and reduce direct transmission requirements, thereby improving reliability without requiring direct line-of-sight between all vehicles
2Loss of information
If all vehicles transmit position data packets frequently to ensure safety information is available, then information freshness is improved, but bandwidth is exceeded and communication efficiency deteriorates
Solution Approach 1:
The patent applies local quality by making transmission frequency and packet generation location-dependent. Vehicles adjust their transmission behavior based on local conditions such as presence of vulnerable road users, traffic density, and relative positions. Only vehicles in specific locations or situations generate and transmit packets, rather than all vehicles transmitting uniformly
Solution Approach 2:
The patent uses partial action by having only necessary vehicles transmit position data packets. Instead of all vehicles transmitting continuously, the system determines which vehicles need to transmit based on local conditions, reducing overall traffic while ensuring sufficient information availability for safety applications
3Loss of time
If packet transmission frequency is increased to reduce time delay, then information availability is improved, but the number of packets exceeds bandwidth capacity
Solution Approach 1:
The patent applies preliminary action by having vehicles continuously track and store position data of other vehicles in advance. When a transmission opportunity arises or a safety event occurs, the pre-collected data can be immediately transmitted without waiting for new measurements, reducing time delay while avoiding continuous high-frequency transmissions
Solution Approach 2:
The patent merges multiple position data updates into single transmission events. Instead of transmitting every position update separately, the system combines multiple data points and transmits them together, reducing the total number of packets while maintaining information availability. This is particularly evident in how intermediate vehicles aggregate and forward data
Data Source
AI summary
The present invention relates to a method and apparatus for reducing the number of packets in a vehicle-to-vehicle multi-hop broadcast communication. The method determines a position data comprising a position, a velocity and a direction of a receiving vehicle (1, 2, 3, 4), receives a position data comprising position, velocity and direction from sending vehicles (1, 2, 3, 4), and calculates a relative position between the receiving vehicle (1, 2, 3, 4) and the sending vehicle (1, 2, 3, 4). Next, a density of vehicles is calculated from the calculated relative positions. The position data of the receiving vehicle (1, 2, 3, 4) is periodically sent, and the time for periodically sending the position data of the receiving vehicle (1, 2, 3, 4) is set in accordance with the calculated density of vehicles.