Wireless Time Synchronization via Coarse and Fine Calibration
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving accurate event and time synchronization across multiple devices, particularly in managing latencies and synchronizing clocks across System-on-Chips, which affects applications like synchronized audio experiences in media products.
Innovation Solution
A two-step approach for time synchronization involving coarse and fine synchronization processes, where the coarse synchronization aligns devices on a millisecond scale, followed by fine synchronization to reduce misalignments to microseconds, using Wi-Fi Time Synchronization Function (TSF) clocks and manipulating latencies through hardware or software mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single synchronization approach is used, then the system is simpler to implement, but it cannot achieve both coarse and fine synchronization accuracy
Solution Approach 1:
The synchronization process is divided into two distinct segments: coarse synchronization that aligns devices on a millisecond scale, and fine synchronization that reduces misalignments to microseconds. This segmentation allows each process to be optimized independently, achieving high overall accuracy without excessive complexity.
Solution Approach 2:
Coarse synchronization is performed as a preliminary action before fine synchronization. By first establishing millisecond-level alignment, the system creates a foundation that enables the subsequent fine synchronization to achieve microsecond accuracy more efficiently.
2Ease of operation
If wireless synchronization is implemented, then cable connections are removed and flexibility is enhanced, but latency management becomes more challenging
Solution Approach 1:
The Wi-Fi Time Synchronization Function (TSF) clock serves as an intermediary time reference that all devices synchronize to. This mediator enables wireless devices to achieve precise synchronization without direct cable connections, managing latency through a centralized time reference.
Solution Approach 2:
The patent replaces mechanical cable connections with wireless communication systems. By substituting the physical connection mechanism with wireless TSF-based synchronization, the system achieves flexibility while managing latency through software and protocol-level mechanisms.
3Measurement precision
If hierarchical synchronization with multiple time scales is used, then synchronization accuracy is improved, but the time management complexity increases
Solution Approach 1:
The system introduces a hierarchical time scale dimension with multiple levels: coarse time scale for millisecond alignment and fine time scale for microsecond precision. This dimensional approach allows the system to manage different accuracy requirements at different hierarchical levels, improving overall precision while organizing complexity systematically.
Data Source
AI summary
A method includes calibrating, at a wireless device, a wireless fidelity (Wi-Fi) chipset-level timer based on a time synchronization function (TSF) frame received from a Wi-Fi access point. The method also includes performing, at the wireless device, a coarse synchronization of a microcontroller-level or CPU-level timer based on the calibrated Wi-Fi chipset-level timer. The method further includes performing, at the wireless device, a fine synchronization of the microcontroller-level or CPU-level timer after the coarse synchronization. The fine synchronization is performed according to a first time scale measured in first time units and the coarse synchronization is performed according to a second time scale measured in second time units that are a multiple of the first time units.