Header Compression Logic for Out-of-Order Packet Delivery
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Solution Overview
Problem
Existing header compression algorithms in packet-switched networks are not robust against packet misordering, which can lead to decompression failures and reduced compression efficiency, especially in channels that do not guarantee in-order delivery of packets.
Innovation Solution
The use of external information regarding the degree of packet misordering allows the compressor and decompressor to optimize their logic and parameters, such as the window based least significant bits encoding parameter p, and state transition configurations, to improve robustness against misordering while maintaining packet loss robustness, thereby enhancing compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If header compression algorithms assume in-order packet delivery, then compression efficiency is improved, but robustness against packet misordering deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-configuring the decompressor with a reordering buffer and sequence number tracking mechanisms before packets arrive. This allows the system to anticipate and handle out-of-order packets without decompression failures, maintaining robustness while preserving compression efficiency.
Solution Approach 2:
The patent introduces an intermediary reordering buffer between the compressed packet stream and the decompressor. This buffer acts as a mediator that temporarily stores out-of-order packets, resequences them according to their sequence numbers, and then delivers them in the correct order to the decompressor, resolving the contradiction between compression efficiency and misordering robustness.
2Volume of moving object
If window based least significant bits encoding is used for compression, then header size is reduced, but sensitivity to packet misordering increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing sequence number tracking and reordering buffer mechanisms before packets with window based least significant bits encoding arrive. This allows the system to handle misordered packets correctly even though the compressed header format is highly sensitive to ordering, maintaining both small header size and robustness.
Solution Approach 2:
The patent introduces an intermediary reordering buffer that sits between the compressed packet stream using window based encoding and the decompressor. This intermediary maintains sequence number information and reorders packets before decompression, protecting the sensitive compressed format from misordering issues while preserving the small header size benefits.
3Reliability
If decompressor discards packets during resynchronization, then decompression failure is prevented, but packet loss increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the decompressor with reordering buffer and sequence number tracking capabilities before misordered packets arrive. This allows the decompressor to handle out-of-order packets correctly using the buffered information, preventing decompression failures without needing to discard packets, thus avoiding unnecessary packet loss.
Solution Approach 2:
The patent introduces an intermediary reordering buffer that prevents decompression failures by resequening packets before they reach the decompressor. This intermediary eliminates the need for the decompressor to discard packets during resynchronization, as the buffer has already arranged packets in the correct order, thereby preventing both decompression failures and unnecessary packet loss.
Data Source
AI summary
For use in packet-switched networks, a method is provided for using external information regarding the degree of misordering of packets, to make header compression more robust against such misordering.