Real-Time Text Continuity via RTP Sequence Estimation
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Solution Overview
Problem
Conventional mobile devices with unsynchronized dual real-time transport protocol (RTP) stacks experience significant RTT session discontinuities or drops during handovers between different radio access networks, primarily due to large sequence number (SN) jumps.
Innovation Solution
A method for maintaining RTT session continuity involves estimating the sequence number associated with the target radio access network after a handover, using an equation that incorporates the latest sequence number received before handover and a delay estimate, allowing the session to continue seamlessly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional handover methods are used between radio access networks, then network switching is achieved, but RTT session continuity is lost due to large sequence number jumps
Solution Approach 1:
The patent applies preliminary action by estimating the sequence number before the actual handover occurs. The system calculates the expected sequence number for the target radio access network based on the current sequence number and a delay estimate, allowing the RTP stack to be pre-configured with the correct sequence number before handover executes, thus preventing sequence number mismatches and maintaining RTT session continuity.
2Adaptability or versatility
If dual RTP stacks are used for different radio access networks, then network versatility is improved, but RTT discontinuities occur during handover without standard synchronization interface
Solution Approach 1:
The patent applies self-service by enabling the RTP stack to automatically estimate and adjust sequence numbers during handover without requiring external synchronization from a standard interface. The system uses internal resources (current sequence number, delay estimate) to compute the next sequence number, making the dual RTP stack self-sufficient in maintaining continuity across different radio access networks (WiFi, LTE, 5G) without dependent synchronization mechanisms.
3Reliability
If sequence number estimation is performed, then RTT session continuity is maintained, but computational processing is required during handover
Solution Approach 1:
The patent applies parameter changes by using a simple mathematical formula to estimate the sequence number: Next Sequence Number = Current Sequence Number + (Delay Estimate / RTP Packet Interval). This transforms the complex problem of sequence number synchronization into a straightforward parameter calculation, reducing handover processing complexity while maintaining RTT session continuity across radio access network transitions.
Data Source
AI summary
A mobile device is configured to perform a method for continuing a Real-time Text (RTT) session during a handover from a first radio access network to a second radio access network. The method includes, after detecting a handover from the first radio access network to the second radio access network during the RTT session between the mobile device and another device, estimating a sequence number associated with the second radio access network after the handover and continuing the RTT session on the second radio access network based on the estimated sequence number.