ROHC Sliding Window Adaptation During Cellular Handovers
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Solution Overview
Problem
During handover procedures in cellular communication networks, conventional Robust Header Compression (ROHC) schemes experience decompression failures and packet losses due to consecutive packet losses, leading to inefficient compression and the need for partial re-initialization using large headers, which degrades performance.
Innovation Solution
The method involves adapting the sliding compression window by not removing any reference values during handover or mobility procedures, and only removing older values once the process is complete, allowing for more compact formats and maintaining compression efficiency without discarding received packets or requiring modifications to the ROHC specification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ROHC schemes are used during handover procedures, then compression is maintained, but decompression failures and packet losses occur due to consecutive packet losses
Solution Approach 1:
The patent dynamically adapts the compression window size based on handover detection. During handover procedures, the window size is increased to accommodate consecutive packet losses, while in normal operation the standard window size is used. This dynamic adjustment resolves the contradiction by maintaining reliability during handovers without permanently sacrificing compression efficiency.
Solution Approach 2:
The patent changes the parameter of compression window size from a fixed value to a variable that adapts to handover conditions. By detecting handover events and adjusting the window size parameter accordingly, the system maintains decompression success during handovers while preserving normal compression efficiency when handovers are not occurring.
2Reliability
If partial re-initialization is performed using large headers during handover, then decompression reliability is improved, but compression efficiency degrades due to large header size
Solution Approach 1:
The patent dynamically adjusts the compression window size during handover to prevent the need for re-initialization with large headers. By adapting the window size to accommodate handover conditions, the system maintains reliability without resorting to resource-intensive large header formats.
Solution Approach 2:
Instead of fully re-initializing compression context with large IR-DYN headers during handover, the patent applies partial action by temporarily adjusting only the window size parameter. This partial adaptation provides sufficient robustness during handover without the overhead of complete re-initialization, thereby conserving radio resources.
3Reliability
If the compression window size is increased during handover to accommodate packet losses, then decompression reliability improves, but compression efficiency temporarily decreases
Solution Approach 1:
The patent implements dynamic window size adjustment that is temporary and handover-specific. The increased window size is applied only during detected handover procedures and automatically reverted afterward. This resolves the contradiction by accepting temporary compression overhead only when necessary for reliability during handovers.
Solution Approach 2:
The patent applies periodic action by temporarily modifying compression parameters during handover events and then returning to normal operation. The handover detection and parameter adjustment occurs periodically only when handover conditions are met, minimizing the impact on overall compression efficiency while ensuring reliability during critical handover periods.
Data Source
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AI summary
The present invention concerns a method for optimizing ROHC RTP (Robust Header Compression Real Time Protocol) compression applied to IP header of data packets stream so as to use more compact formats enable to remain in a steady state, to never discard received packet, and to serve radio resources without requiring to modify ROHC specification. In the method, when handover or mobility procedure is started, new reference values are normally added to a sliding compression window, but no reference value is removed from the window as long as the handover or mobility procedure is on going. After the handover or mobility procedure is complete, when the number of values transmitted on the new radio link are appropriate to cope against the error properties on the new link, all older values can be removed at once from the compression window, thereby reverting to normal window operation.