ROHC IPv4 Header Compression for Fragmented Packets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The standard Robust Header Compression (ROHC) protocol RFC 3095 assumes no fragmentation of IPv4 packets, leading to limitations in header compression when packet sizes exceed the Maximum Transmission Unit (MTU), resulting in inefficient data transmission in satellite communication systems.
Innovation Solution
Introduce a 'more_frag_and_frag_offset_indicator' flag in the dynamic portion of the ROHC header to indicate IPv4 packet fragmentation, allowing the 'More fragment flag' and 'fragment offset' fields to be appended, enabling effective compression of fragmented IPv4 headers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the standard ROHC protocol is used to compress IPv4 headers, then header overhead is reduced and bandwidth efficiency is improved, but fragmented IPv4 packets cannot be compressed leading to loss of compression capability
Solution Approach 1:
The patent dynamically adjusts the ROHC header format by conditionally including fragmentation indicator fields (MF bit and fragment offset) only when fragmentation is detected. This allows the protocol to adapt its structure based on the actual packet characteristics, maintaining compression efficiency for non-fragmented packets while enabling support for fragmented packets when needed.
Solution Approach 2:
The patent modifies the ROHC protocol parameters by introducing new fields (fragmentation indicator, MF bit, fragment offset) and changing the behavior of existing fields based on packet fragmentation status. This parameter adaptation allows the protocol to handle both fragmented and non-fragmented packets effectively, resolving the contradiction between compression efficiency and fragmentation support.
2Adaptability or versatility
If fragmentation support is added to ROHC headers, then compression capability for all packet types is improved, but header complexity increases
Solution Approach 1:
The patent segments the header modification into distinct components: a fragmentation indicator field, a More Fragment (MF) bit, and a fragment offset field. These segmented elements are added only when needed, allowing the system to manage complexity through modular addition rather than requiring a completely complex header structure for all cases.
Solution Approach 2:
The patent applies partial action by adding fragmentation support fields only when fragmentation is detected in the packet, rather than including all possible fields in every header. This selective approach reduces the average header complexity while maintaining the capability to handle fragmented packets when required.
Data Source
AI summary
A communication system and method for receiving a datagram with an uncompressed IPv4 header at a ROHC compressor in the communication system and compressing the uncompressed IPv4 header using the ROHC compressor to form the datagram with the ROHC header. The compressing by the ROHC compressor includes setting a flag in a dynamic part of an initialization and refresh (IR) packet of the ROHC header indicating that a ‘more fragment flag’ (MF) bit and a non-zero ‘fragment offset’ field are present in the ROHC header, as well as appending the MF bit and the non-zero ‘fragment offset’ field at an end of the IR packet.