Wireless Clock Synchronization via Intermediary Timing Reference
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Solution Overview
Problem
Current wireless communications networks in Industrial Automation applications fail to achieve precise time synchronization between network devices, as the frame structure, processing, and buffering introduce uncontrolled asymmetries in synchronization message transmission times, making it impossible to assume equal transmission times for synchronization messages in both directions, which is required by protocols like PTP and PTCP.
Innovation Solution
A method where User Equipment receives reference signals from a wireless communications network node, calculates a time offset based on propagation delay, and sets a master clock to a common network time, allowing slave clocks to synchronize with this master clock, enabling accurate synchronization across network devices even in wireless networks without modifying existing devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireless communications networks are used for Industrial Automation, then network flexibility and ease of deployment are improved, but time synchronization precision deteriorates due to uncontrolled asymmetries in message transmission times
Solution Approach 1:
The patent introduces a wireless base station as an intermediary that generates and transmits timing reference signals to multiple user equipment. This intermediary provides a common time reference that slave devices can use to synchronize their clocks, overcoming the asymmetry problem in wireless communications without requiring modifications to existing network devices.
Solution Approach 2:
The patent replaces the mechanical assumption of equal transmission times in wired networks with a wireless timing reference system. Instead of relying on symmetric message exchange that assumes equal propagation times, the system uses downlink timing reference signals from the base station to establish absolute time references at each user equipment, substituting the mechanical symmetry assumption with a wireless timing distribution mechanism.
2Ease of operation
If PTP or PTCP protocols are used for time synchronization in wireless networks, then time synchronization functionality is provided, but synchronization accuracy deteriorates due to frame structure and processing asymmetries
Solution Approach 1:
The wireless base station acts as a timing intermediary that distributes synchronized time references to all user equipment in the network. This mediator provides a common time reference that eliminates the need for peer-to-peer synchronization protocols like PTP or PTCP, which fail in asymmetric wireless environments. The base station's downlink signals serve as the authoritative time source for all slave devices.
Solution Approach 2:
The patent creates a timing equipotential environment by having all user equipment derive their time references from the same downlink signals from the base station. This ensures that all devices operate from a common time potential, eliminating the timing asymmetries that plague wireless PTP/PTCP implementations where devices at different locations experience different transmission delays.
3Adaptability or versatility
If wired networks are upgraded to wireless, then network deployment flexibility is improved, but device compatibility deteriorates as modifications to network devices would be required
Solution Approach 1:
The wireless base station serves as a timing intermediary that provides synchronization references without requiring modifications to existing slave devices. The base station transmits timing information in existing wireless downlink signals, and slave devices can extract and use this timing information with their existing hardware, maintaining backward compatibility while enabling wireless deployment.
Solution Approach 2:
The patent makes the timing reference system universal by embedding synchronization information in standard wireless downlink signals that all user equipment already receives for normal operation. This multi-functional approach allows the same wireless infrastructure to serve both data communication and time synchronization functions, eliminating the need for separate synchronization hardware or protocol modifications.
Data Source
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AI summary
A User Equipment comprises a master clock, for example a Precision Time Protocol, PTP, or Precision Time Control Protocol, PTCP, network clock. The User Equipment further comprises circuitry configured to set the master clock based on signals from a wireless communications network node and a time offset, wherein the time offset is based on the propagation delay between the wireless network node and the User Equipment. The circuitry is further configured to send timing information to a network device in a communications network having a slave clock, whereby the network device can synchronize its slave clock with respect to the master clock comprised within the User Equipment.