On-Vehicle Relay Bandwidth Management for Packet Loss Prevention
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Solution Overview
Problem
In on-vehicle network systems, when multiple low-priority data connections are established, high-priority and large-sized data transmissions can lead to packet loss and increased transmission delays due to bandwidth limitations, especially when the receiving buffer capacity is restricted by RAM constraints.
Innovation Solution
An on-vehicle relay device that monitors and manages bandwidth usage across the network, permitting transmissions only when the cumulative usage rate remains below a predetermined threshold, prioritizing messages based on urgency and size, and adjusting waiting times for notification of transmission completion to prevent excessive delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple low-priority data connections are established in the receiver-side node, then the network can handle more data traffic, but high-priority and large-sized data transmissions may cause packet loss and increased transmission delays due to bandwidth limitations and restricted RAM capacity
Solution Approach 1:
The relay device performs preliminary actions by calculating the sum of bandwidth usage rates before permitting transmission. It determines whether adding the first message's bandwidth usage to existing messages exceeds the threshold, and only permits transmission if the sum remains within the threshold. This preventive approach avoids packet loss and transmission delays before they occur.
Solution Approach 2:
The system dynamically manages bandwidth allocation by evaluating each transmission request in real-time. The relay device calculates the cumulative bandwidth usage rate dynamically, comparing it against the threshold for each permission request. This dynamic adjustment ensures optimal network resource utilization while maintaining transmission reliability.
2Reliability
If the receiving buffer size is increased to accommodate more data, then packet loss is reduced, but the RAM capacity constraint is violated
Solution Approach 1:
Instead of increasing buffer size, the system performs preliminary bandwidth usage calculation before permitting transmission. By proactively determining whether the sum of bandwidth usage rates exceeds the threshold, the system prevents buffer overflow conditions that would require larger RAM capacity.
Solution Approach 2:
The relay device implements feedback control by continuously monitoring bandwidth usage rates and adjusting transmission permissions accordingly. When the cumulative usage approaches the threshold, the system restricts new transmissions, thereby maintaining reliable data reception within the fixed RAM capacity constraints.
3Reliability
If bandwidth usage threshold is set low to prevent overload, then transmission reliability is improved, but network productivity decreases
Solution Approach 1:
The system dynamically adjusts transmission permissions based on real-time bandwidth usage conditions. Rather than using a fixed low threshold that would always limit throughput, the relay device evaluates each request dynamically, permitting transmissions when the sum of usage rates remains below the threshold while preventing overload when it approaches the limit.
Solution Approach 2:
The threshold parameter is optimized to balance reliability and productivity. By setting the threshold at an appropriate level and dynamically evaluating the sum of bandwidth usage rates against it, the system achieves both transmission reliability and acceptable network throughput, avoiding both packet loss and unnecessary transmission restrictions.
Data Source
AI summary
An on-vehicle relay device that is connected to a first on-vehicle device and a second on-vehicle device via an on-vehicle network, and relays a message transmitted from the first on-vehicle device to the second on-vehicle device, includes a processor configured to receive a permission request for transmission of a first message from the first on-vehicle device, determine whether the total of the usage rate of the bandwidth of the on-vehicle network used by at least one message already permitted to be transmitted via the on-vehicle network, and the usage rate of the bandwidth of the on-vehicle network used by the first message is equal to or smaller than a predetermined threshold value, and send a reply that permits transmission of the first message, to the first on-vehicle device, when the sum is equal to or smaller than the predetermined threshold value.