Time Sensitive Networking Over Wi-Fi Mesh
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Solution Overview
Problem
Current IEEE 802.11 time synchronization mechanisms are deficient for wireless mesh networks, lacking a reference architecture for designing and integrating Precision Time Protocol (PTP) hardware clock and RX/TX timestamping units, and are not fully defined for exchanged frames, leading to suboptimal time synchronization and radio resource utilization.
Innovation Solution
Implementing a global time synchronization mechanism across multiple access points in a wireless mesh network, using IEEE 802.1AS to synchronize a common clock signal, enabling simultaneous time-triggered operations and restricted Target Wake Time (rTWT) execution, and enhancing Multi-AP and distributed MIMO performance by synchronizing RF local oscillator phase-locked loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current IEEE 802.11 time synchronization mechanisms are used, then basic wireless networking is achieved, but time synchronization accuracy is insufficient for advanced features like Multi-AP joint transmission and distributed MIMO
Solution Approach 1:
The patent segments the time synchronization system into distinct functional components: a reference clock source, timestamping units at each access point, and synchronization message exchange mechanisms. This segmentation allows each component to be optimized independently while working together to achieve high-precision time synchronization without requiring complete system redesign.
Solution Approach 2:
The patent introduces synchronization messages as intermediaries that carry timestamp information between access points and the reference clock. These messages act as carriers that transfer timing information without requiring direct physical connection to the reference clock source, enabling distributed time synchronization while maintaining accuracy.
2Productivity
If time-triggered operations are implemented across multiple access points, then radio resource utilization is optimized, but coordination complexity increases
Solution Approach 1:
The patent implements preliminary time synchronization before actual data transmission occurs. By establishing synchronized clocks and timestamping mechanisms in advance, access points are prepared to execute time-triggered operations without needing complex real-time coordination during data transmission, thus optimizing radio resource utilization while managing coordination complexity.
Solution Approach 2:
The patent employs feedback mechanisms where access points exchange synchronization status and timing information. This feedback loop allows the system to adjust and coordinate time-triggered operations dynamically, ensuring efficient radio resource utilization while maintaining manageable coordination complexity through continuous monitoring and adjustment.
3Reliability
If RF local oscillator phase-locked loops are synchronized, then Multi-AP and distributed MIMO performance is enhanced, but implementation difficulty increases
Solution Approach 1:
The patent replaces complex mechanical/electronic synchronization of RF local oscillators with a software-based timestamping and message exchange mechanism. Instead of directly synchronizing hardware oscillators across multiple access points, the system uses software timestamping units and synchronization messages to achieve coordinated timing, thereby enhancing reliability while reducing implementation complexity.
Data Source
AI summary
This disclosure describes a system for applying precise timing to a mesh wireless Wi-Fi network. The precise timing allows for multiple access points (APs) to serve a single station (STA) when the STA is located in a wireless footprint of more than one access point without the need for a wireless trigger frame. Various examples are described including the use of orthogonal frequency division multiple access (OFDMA), time division multiple access (TDMA) and multi-access point joint transmission.