WNIC Clock Synchronization for Wireless Networks
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Solution Overview
Problem
Current clock synchronization methods in wireless networks, such as IEEE 802.11's Time Synchronization Function (TSF) and Precision Time Protocol (PTP), face challenges in achieving high accuracy due to frequency skew and hardware inefficiencies, particularly in ad-hoc or mesh-based industrial networks where variable bandwidth and RF signal uncertainties affect synchronization precision.
Innovation Solution
A device and method that utilize a Wireless Network Interface Controller (WNIC) clock to receive offset and skew correction information from higher protocol layers, allowing for periodic adjustments to the counter of the WNIC clock to correct for frequency skew, thereby achieving high precision synchronization without the need for additional dedicated hardware clocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PTP protocol is used for high precision synchronization, then synchronization accuracy is improved, but hardware complexity increases due to need for dedicated hardware clocks
Solution Approach 1:
The existing WNIC clock is made multi-functional by enabling it to perform both its original wireless communication timing function and the additional function of PTP synchronization. The clock is adapted to generate both standard communication timestamps and PTP timestamps, eliminating the need for a separate dedicated PTP hardware clock while maintaining high synchronization accuracy.
Solution Approach 2:
The patent merges the PTP synchronization function with the existing WNIC clock infrastructure. By combining the timestamping capabilities and correction mechanisms into the single WNIC clock system, the patent achieves high-precision synchronization without requiring additional dedicated hardware clocks, thus reducing overall hardware complexity.
2Measurement precision
If additional dedicated hardware clocks are added for PTP, then synchronization accuracy is improved, but hardware overhead increases
Solution Approach 1:
The WNIC clock is enhanced to serve dual purposes: maintaining wireless communication timing and providing PTP synchronization. By making the existing clock multi-functional rather than adding a separate dedicated clock, the patent achieves high synchronization accuracy while minimizing hardware overhead.
Solution Approach 2:
The existing WNIC clock infrastructure is utilized to provide PTP synchronization services without requiring additional dedicated hardware resources. The clock serves itself by generating both communication and PTP timestamps, and the correction units use the same hardware resources already present in the WNIC.
3Productivity
If software timestamping is used, then hardware efficiency is improved, but synchronization accuracy deteriorates due to network stack uncertainties
Solution Approach 1:
The patent replaces software-based timestamping with hardware-based timestamping by enhancing the WNIC clock to generate timestamps in hardware at the moment of packet transmission and reception. This substitution eliminates the uncertainties introduced by software network stack processing while maintaining hardware efficiency.
Solution Approach 2:
The WNIC clock generates timestamps preliminarily at the exact moment of packet transmission and reception in hardware, before the packets enter the software network stack. This preliminary hardware timestamping captures the precise timing information without being affected by subsequent software processing delays or uncertainties.
Data Source
AI summary
A device for wireless communication according to a standard communication protocol adapted to operate at the Physical layer and/or Medium Access Control layer of the protocol, and includes a Wireless Network Interface Controller, abbreviated WNIC, the WNIC having: a transmitter and receiver; a WNIC clock, implementing a local timer according to the standard communication protocol. The device further includes: an interface adapted to receive offset correction information and skew correction information from one or more higher protocol layers; an offset correction unit adapted to correct the reference time of the WNIC clock based on the offset correction information; a skew correction unit adapted to correct the frequency of the WNIC clock based on the skew correction information.