Vehicular Ethernet Window Resetting for DUP ACK Packet Loss
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Solution Overview
Problem
Packet loss and retransmission during mass data transmission in vehicular Ethernet communication lead to time loss due to hardware limitations and speed mismatches in receiver hardware queues.
Innovation Solution
An Ethernet controller for vehicles adjusts the window size based on duplicate acknowledgement (DUP ACK) to prevent packet loss and retransmission, resetting the window size to a reduced value corresponding to the amount of data transmitted up to the DUP ACK and considering the maximum transmission unit (MTU) size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the TCP/IP module continuously transmits a series of data packets with a large collective window size regardless of receiving ACK, then data transmission speed is improved, but packet loss occurs due to receiver hardware queue limits
Solution Approach 1:
The window size is dynamically adjusted based on receiver feedback. The TCP/IP module continuously transmits data packets using a currently set window size, and when a duplicate ACK is received, the window size resetting unit resets the window size to a reduced value. This dynamic adjustment allows the system to maintain high transmission speed when conditions are good while preventing packet loss when the receiver queue becomes full.
Solution Approach 2:
The system uses duplicate ACK packets as feedback signals from the receiver to detect when packet loss is occurring. When the receiver's hardware queue becomes full, it sends duplicate ACKs, which the transmitter detects and uses to trigger window size resetting. This feedback mechanism enables the system to adapt transmission parameters based on actual receiver capacity.
2Reliability
If packet loss occurs during mass data transmission, then data integrity is compromised, but retransmission causes time loss
Solution Approach 1:
The system performs preliminary action by resetting the window size before packet loss occurs. When a duplicate ACK is detected, the window size is immediately reset to a reduced value, preventing further packets from being sent that would exceed the receiver's queue capacity. This proactive measure avoids the need for retransmission and the associated time loss.
3Productivity
If the window size is continuously increased for mass data transmission, then transmission efficiency is improved, but receiver hardware queue overflow occurs
Solution Approach 1:
The system applies preliminary anti-action by implementing a mechanism to prevent queue overflow before it occurs. The duplicate ACK detection and window size resetting unit continuously monitors receiver status and resets the window size when signs of queue saturation appear (duplicate ACKs), thereby preventing the harmful effect of queue overflow and associated packet loss.
Data Source
AI summary
An Ethernet controller for a vehicle includes a Transmission Control Protocol/Internet Protocol (TCP/IP) module configured to continuously transmit a series of data packets having a collective size as large as a set window size or less regardless of receiving acknowledgement (ACK) from a receiver, where the window size is initially set to a window size value acquired from the receiver. The Ethernet controller also includes a window size resetting unit configured to reset the window size to a reduced value when a duplicate acknowledgement (DUP ACK) is received from the receiver.