WIA-PA Clock Synchronization Frequency Offset Estimation
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Solution Overview
Problem
The existing time synchronization mechanism in WIA-PA networks fails to accurately estimate and compensate for frequency offsets, leading to rapid time errors and reduced synchronization precision, and is burdened by high computation complexity, especially due to the neglect of delays in message transmission.
Innovation Solution
A clock synchronization frequency offset estimation method that involves a child node receiving beacon frames to calculate time adjustments and estimate the relative frequency offset using specific timestamp formulas, allowing for local time adjustments and separate frequency offset estimation after multiple synchronization periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the current beacon frame synchronization mechanism is used to simply estimate clock offset without frequency offset compensation, then the estimation process is simple, but time errors rapidly accumulate and synchronization precision deteriorates
Solution Approach 1:
The patent segments the synchronization process into two distinct phases: (1) clock offset estimation using beacon frame timestamps, and (2) frequency offset estimation using timestamp differences across multiple beacon frames. This segmentation allows each estimation type to be performed with appropriate precision without requiring complex joint estimation, thereby maintaining simplicity while improving overall synchronization accuracy.
Solution Approach 2:
The patent performs preliminary frequency offset estimation by calculating timestamp differences between consecutive beacon frames before applying time synchronization adjustments. This preliminary action of estimating frequency offset first allows the system to compensate for drift before final time alignment, preventing error accumulation and maintaining synchronization precision without requiring continuous high-frequency beacon broadcasts.
2Measurement precision
If the broadcast frequency of beacon frames is increased to maintain time synchronization precision, then time synchronization precision is improved, but communication overhead and energy consumption increase
Solution Approach 1:
The patent implements feedback by continuously estimating frequency offset using timestamp differences from received beacon frames and applying compensation to the local clock. This feedback mechanism allows the system to maintain synchronization precision over extended periods without increasing beacon frame frequency, as the frequency offset compensation actively corrects drift in real-time, reducing the need for frequent synchronization beacons and thereby lowering energy consumption.
Solution Approach 2:
The patent changes the parameter of beacon frame frequency from high to low by utilizing frequency offset estimation and compensation. Instead of relying on frequent beacon frames to maintain precision, the system estimates frequency offset using timestamp differences and adjusts the local clock accordingly, allowing synchronization to be maintained with lower beacon frequency, thus reducing communication overhead and energy consumption.
3Measurement precision
If general clock offset and frequency offset joint estimation method is used, then comprehensive synchronization is achieved, but computation burden and complexity increase
Solution Approach 1:
The patent segments the joint estimation problem into two separate estimation processes: clock offset estimation based on beacon frame timestamps and frequency offset estimation based on timestamp differences. By separating these estimations, the patent avoids the computational complexity of joint estimation while achieving comprehensive synchronization through sequential application of both corrections.
Solution Approach 2:
The patent performs partial estimation by separately estimating clock offset and frequency offset in two distinct steps rather than performing full joint estimation simultaneously. This partial action approach reduces computational burden by breaking down the complex joint estimation problem into simpler, sequential estimations that can be performed with lower computational resources while still achieving accurate synchronization.
4Use of energy by moving object
If the time synchronization period is prolonged to reduce communication overhead, then energy consumption is reduced, but time error accumulation increases
Solution Approach 1:
The patent implements feedback through continuous frequency offset estimation and compensation, which actively corrects time drift that would otherwise accumulate over extended synchronization periods. This feedback mechanism enables the system to prolong the time between beacon frame broadcasts while maintaining synchronization precision, as the frequency offset compensation continuously corrects drift rather than allowing it to accumulate.
Solution Approach 2:
The patent changes the synchronization approach by introducing frequency offset compensation based on timestamp difference analysis. This parameter change allows the system to extend synchronization periods without proportionally increasing time error accumulation, as the frequency offset estimation and compensation actively counteracts drift over the extended period, thereby reducing energy consumption while maintaining precision.
Data Source
AI summary
The present invention claims a clock synchronization frequency offset estimation method adapted to a WIA-PA network, and belongs to the technical field of industrial wireless sensor networks. The method comprises the following steps: A. receiving a beacon frame, broadcast by a time source device, by a child node in the WIA-PA network in each time synchronization period to obtain a sending timestamp and a receiving timestamp, then adjusting a local time by taking a difference value between the two timestamps as a time adjustment quantity, repeating the process above, and after a plurality of synchronization periods, separately estimating a frequency offset with a statistical signal estimation method; and B. when anode is required to report its own time, compensating a node time with the estimated relative frequency offset. With the method, the time synchronization precision is effectively increased, a synchronization error is restrained from freely increasing in the time synchronization period, the synchronization period is prolonged, and both the communication overhead of the network and the energy consumption of the node are reduced.