Context-Based Packet Retransmission With Adaptive ACK Timeout
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Solution Overview
Problem
Existing communication protocols lack the ability to dynamically change packet semantics for individual fragments in flight based on application needs, leading to unnecessary retransmissions and inefficient handling of lost packets.
Innovation Solution
A method and system that dynamically determine whether to retransmit lost packets based on a NRTx header field value and adapt the timeout period according to instantaneous channel conditions, allowing for context-based retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP transmits all data packets in reliable mode with ACK awaiting, then packet delivery reliability is improved, but unnecessary retransmissions occur when ACK loss is due to channel delay rather than packet loss
Solution Approach 1:
The patent applies dynamics by making the retransmission decision adaptive rather than static. The transmitter dynamically adjusts its behavior based on real-time channel conditions and ACK reception status. When ACK loss is detected, the system determines whether to retransmit based on current channel state, switching between reliable and best-effort modes as needed, thereby avoiding unnecessary retransmissions while maintaining reliability when required.
Solution Approach 2:
The patent changes the parameter of packet transmission mode from fixed (always reliable) to variable (dynamic selection between reliable and best-effort). By modifying the transmission mode parameter based on channel conditions and ACK status, the system optimizes the balance between reliability and retransmission overhead, allowing selective retransmission only when beneficial.
2Speed
If RTP uses UDP best effort mode, then transmission speed is improved, but no retransmission occurs for lost packets
Solution Approach 1:
The patent makes the transmission mode dynamic by allowing the system to switch between best-effort (RTP/UDP) and reliable (TCP-like with ACK) modes based on channel conditions. When channel conditions are good and packet loss is low, best-effort mode maintains high transmission speed. When packet loss is detected and channel conditions deteriorate, the system transitions to reliable mode to ensure delivery, thus adapting speed and reliability trade-off in real-time.
3Stability of the object's composition
If SCTP transmits packets via reliable-ordered stream, then in-sequence delivery is improved, but all lost packets are retransmitted without option to change semantics
Solution Approach 1:
The patent applies dynamics by enabling the transmitter to change packet transmission semantics dynamically during the data transfer phase. Instead of being fixed to reliable-ordered or unreliable-unordered modes, the system can adaptively switch between reliable and best-effort modes for individual packets or streams based on application needs and channel conditions, providing versatility while maintaining in-sequence delivery when required.
Solution Approach 2:
The patent changes the transmission mode parameter from fixed (reliable-ordered or unreliable-unordered) to dynamic. By allowing parameter modification during data transfer, the system can adjust packet semantics to match changing channel conditions and application requirements, achieving both stability in delivery and adaptability in transmission behavior.
4Reliability
If ACK timeout period is extended to accommodate channel delay, then ACK loss is reduced, but retransmission time is increased
Solution Approach 1:
The patent applies dynamics by making the timeout period adaptive rather than fixed. The timeout value is dynamically adjusted based on real-time channel conditions, allowing extension when channel delay is high to prevent false retransmissions, while maintaining shorter timeout values when channel conditions are good to minimize retransmission delay. This dynamic adjustment resolves the contradiction between reliability and time loss.
Data Source
AI summary
State of the art data transmission approaches require all the lost data packets to be retransmitted, which may not be required in a variety of scenarios. Existing protocols lack the option to change packet semantics on the fly for individual fragments on the fly for the same stream. Also, parameters including maximum number of retransmissions permitted are set beforehand, one for entire stream. Method and system in embodiments disclosed herein provide an approach for context-based retransmission of lost packets. Method and system disclosed in the embodiments herein identifies one or more packets as lost packets based on reception status of acknowledgement (ACK) within a dynamically adaptive timeout period, and then based on value of a NRTx header field associated with the lost packet, determines whether or not to retransmit the lost packet. Value of the dynamically adaptive timeout period is recalculated dynamically, based on a determined instantaneous channel condition.