ROHC Compressor State Retention During VoLTE Video Call Switching
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in Robust Header Compression (ROHC) when switching between Voice over Long Term Evolution (VoLTE) calls and video calls, as the ROHC compressor state is reset, leading to a degradation in compression efficiency due to the need to revert to the Initial and Refresh state, resulting in increased bandwidth usage.
Innovation Solution
A method is introduced to retain the ROHC compressor state by sharing Real-time Transport Protocol (RTP) header information between the Application Processor (AP) and Communication Processor (CP) during call switches, allowing the ROHC compressor to reuse its context by sending recent RTP header information from the CP to the AP during VoLTE to video call transitions and from the AP to the CP during video to VoLTE transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the audio path is switched between Application Processor (AP) and Communication Processor (CP) during call transitions, then the system can handle different call types (VoLTE and video calls) on appropriate processors, but the ROHC compressor state is reset and must revert to Initial and Refresh state, degrading compression efficiency
Solution Approach 1:
The patent applies preliminary action by sharing RTP header information from the current processor (AP or CP) to the target processor before the audio path switch occurs. This allows the ROHC compressor on the target processor to pre-configure its context with the necessary header information, so when the switch happens, the compressor can immediately continue in its current state (FC or SC) rather than resetting to IR state, thus maintaining compression efficiency during call transitions
2Reliability
If the ROHC compressor moves back to Initial and Refresh (IR) state to update header fields during call switches, then the RTP header fields can be updated to reflect new call parameters, but the ROHC compression rate degrades due to increased overhead
Solution Approach 1:
The patent applies copying by transmitting the RTP header information from the source processor to the target processor before the audio path switch. The target processor copies this header information into its ROHC compressor context, allowing it to reconstruct the necessary header fields without needing to reset to IR state. This copying mechanism ensures header field accuracy is maintained while avoiding the bandwidth overhead associated with transitioning to and from IR state
Data Source
AI summary
A method for retaining a Robust Header Compression (ROHC) state in a User Equipment (UE) during switching from a Voice over Long Term Evolution (VoLTE) call to a video call or vice versa is provided. When the VoLTE call is in progress and if a user switches the VoLTE call to the video call, then the RTP header information is sent to an Application Processor (AP) from a Communication Processor (CP). The ROHC compressor continues the compression of the RTP packets using the existing built context for the video call. Further, when the video call is in progress and if the user switches the video call to the VoLTE call, then the RTP header information is sent to the CP from the AP. The ROHC context is reused by exchanging the RTP header information between the AP and the CP.