Self-Synchronized Streaming Architecture for Seamless Handovers
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Solution Overview
Problem
Current data streaming systems in mobile telephony and video conferencing face challenges in maintaining continuous audio streams during handovers, leading to interruptions due to factors like varying transmission protocols, clock drifts, and inter-radio access technology handoffs, which require muting to compensate for data stream disruptions.
Innovation Solution
A method for synchronizing streaming data by estimating buffer overflow or underflow and smoothly adjusting the data stream to prevent these issues, implemented in a software-based architecture within a cell phone's digital baseband unit, allowing for seamless handoffs without muting the audio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hard handoff is used in GSM networks, then frequency change and base station switching can be performed, but audio stream interruption occurs requiring muting
Solution Approach 1:
The system performs preliminary actions by pre-synchronizing the mobile device's clock with the target base station's clock before handoff occurs. This advance clock synchronization ensures that when the handoff takes place, the mobile device is already time-aligned with the target cell, preventing audio stream interruptions and eliminating the need for muting during the transition.
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring clock drift between the mobile device and network, and dynamically adjusting the synchronization status. This feedback loop allows the system to detect potential synchronization issues before they cause audio interruptions and to maintain continuous audio streaming during handoffs by real-time clock adjustment.
2Device complexity
If clock drift is not compensated, then system complexity is reduced, but audio stream synchronization deteriorates
Solution Approach 1:
The system changes the clock parameter dynamically by adjusting the mobile device's clock frequency and phase based on detected drift from the network clock. This parameter adjustment mechanism compensates for clock drift without requiring complex hardware modifications, maintaining synchronization accuracy through software-based clock tuning while keeping the overall system relatively simple.
3Reliability
If muting is applied during handoff, then audio stream continuity is maintained, but user experience deteriorates
Solution Approach 1:
By performing preliminary clock synchronization with the target base station before handoff, the system eliminates the need for muting during transitions. This advance preparation ensures that the audio stream continues uninterrupted during handoff, maintaining both technical reliability and high user experience quality without audible gaps or silence.
4Adaptability or versatility
If inter-radio access technology handoff is supported, then network versatility is improved, but handoff complexity increases
Solution Approach 1:
The system implements a universal clock synchronization mechanism that works across different radio access technologies (GSM, WCDMA, and future technologies). This multi-functional synchronization approach allows the mobile device to handle handoffs between different network types using the same fundamental clock alignment principles, reducing the need for technology-specific complex handoff management while maintaining broad network compatibility.
Data Source
AI summary
Synchronization of downlink streaming data is performed by estimating the likelihood of an underflow or an overflow in an output buffer upon receipt of each encoded data frame to determine if synchronization will be needed. After each encoded data frame is decoded it is then synchronized if the estimate indicated synchronization would be needed. Synchronization of uplink steaming data is performed by estimating the likelihood of an underflow or an overflow in an input buffer upon sending of each encoded data frame to an output modem for transmission to determine if synchronization will be needed. If needed, synchronization will be performed later on a portion of data samples taken from the input buffer that are used to form a frame of un-encoded data samples.