Randomized Receive Time-Stamp Clocks for Packet Synchronization
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Solution Overview
Problem
Network packet communications face challenges in achieving precise time and frequency alignment due to systematic time-stamp granularity errors, which are difficult to filter out, especially in packet-switched networks where the slave clock's time-stamp errors are synchronized with the master clock's rate, leading to constant or low-frequency errors that affect synchronization accuracy.
Innovation Solution
Implementing randomized slave time-stamp clock rates that are different from the master time-stamp clock rates, either by setting them to a rational multiple or using time-varying frequencies, and applying spread spectrum techniques or delta-sigma modulation to randomize the slave clock, thereby reducing systematic time-stamp granularity errors and making them easier to filter out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the slave clock uses the same time-stamp clock rate as the master clock, then time alignment is simplified, but systematic time-stamp granularity errors occur that are difficult to filter out
Solution Approach 1:
The slave clock intentionally uses a different time-stamp clock rate than the master clock, creating an asymmetric relationship between the two clocks. This asymmetry causes the time-stamp granularity errors to vary from packet to packet rather than remaining systematic, making the errors filterable through standard filtering techniques.
Solution Approach 2:
The invention introduces dynamic variation in the time-stamp sampling process by using different clock rates. This dynamic approach transforms the static, systematic granularity errors into dynamic, random-like errors that can be effectively filtered out using standard filtering methods.
2Measurement precision
If the slave clock rate is made different from the master clock rate to reduce systematic errors, then time-stamp granularity accuracy improves, but device complexity increases
Solution Approach 1:
The invention changes the clock rate parameter of the slave time-stamp clock to be different from the master clock rate. This parameter change is the core mechanism that transforms systematic errors into filterable errors, achieving improved measurement precision with relatively simple implementation.
3Reliability
If randomized clock rates are used to reduce systematic errors, then synchronization accuracy improves, but the complexity of time-stamp processing increases
Solution Approach 1:
The invention converts the harmful effect of different clock rates (which creates variable time-stamp granularity) into a beneficial effect. By making the granularity errors random rather than systematic, the errors become filterable, and standard filtering techniques can remove them, ultimately improving synchronization accuracy.
Data Source
AI summary
Systems and methods are disclosed for utilizing slave (receive) time-stamp clock rates that are different from master (sender) time-stamp clock rates to randomize and thereby reduce systematic time-stamp granularity errors in the communication of network packets. The slave (receive) time-stamp clock rate for some embodiments is set to be a fixed value that has a relationship with the master (sender) time-stamp clock rate such that the ratio of the slave (receive) clock rate to the master (sender) clock rate is a rational number. Other embodiments use a time-varying frequency for the slave (receive) time-stamp clock rate to randomize the slave (receive) time-stamp clock with respect to the master (sender) time-stamp clock. Additional time-stamps can also be generated using a slave (receive) time-stamp clock having a rate set to equal the rate of the master (sender) time-stamp clock signal. Further spread spectrum and/or delta-sigma modulation techniques can be applied to effectively randomize the slave (receive) time-stamp clock.