IoT Time Synchronization Using Delay Compensation Feedback
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Solution Overview
Problem
Existing LPWA technologies for IoT devices experience varying transmission delays and time synchronization errors of several hundred milliseconds due to network delays and retransmissions, which are critical for time-point authentication and synchronization with servers.
Innovation Solution
A system for time synchronization between a server and IoT devices using network time protocol (NTP) and real-time clock (RTC) modules to calculate and exchange absolute time points, averaging transmission times to achieve sub-millisecond precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LPWA technologies are used for IoT communication, then low-power wide-area network coverage is achieved, but transmission delay varies and time synchronization error reaches several hundred milliseconds
Solution Approach 1:
The system implements a feedback mechanism where the server sends time synchronization signals to IoT devices, and devices report their local time and received time back to the server. The server calculates time differences and sends correction instructions, creating a closed-loop feedback system that continuously adjusts and improves time synchronization accuracy despite network delay variations.
Solution Approach 2:
The server acts as an intermediary that mediates time synchronization between multiple IoT devices and a reference time source. It receives time data from devices, calculates synchronization errors, and distributes correction information, serving as a central coordinating entity that resolves timing conflicts and ensures consistent time across the network.
2Productivity
If multiple IoT devices share low-rate data transmission band, then network resource utilization is improved, but transmission delay increases and becomes unpredictable
Solution Approach 1:
The system performs preliminary time synchronization by having the server send time synchronization signals to IoT devices before actual data transmission occurs. This advance timing setup allows devices to adjust their local clocks and establish accurate time references, ensuring that subsequent data transmissions can be properly timed and synchronized even under shared network conditions.
3Measurement precision
If time synchronization is performed using server time, then centralized time management is achieved, but network delay causes synchronization error of several hundred milliseconds
Solution Approach 1:
The system segments the time synchronization process into multiple measurement components: the server records when it sends the time signal, the device records when it receives the signal and when it sends the response back, and the server records when it receives the response. By dividing the synchronization process into these segments, the system can calculate and compensate for network delays in each direction, achieving much higher precision than simple server-time broadcasting.
Data Source
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AI summary
Provided is a system for time synchronization between a server and an Internet-of-Things (IoT) device. The system may include a server configured to broadcast a time-point synchronization signal including absolute time point information; and an IoT device configured to receive the broadcast time-point synchronization signal and calculate absolute time point information by using the absolute time point information included in the time-point synchronization signal, computation time information according to an internal computation operation, and transmission time information required to receive the time-point synchronization signal.