Wireless Sensor Node Group Synchronization via Local Clock Compensation
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Solution Overview
Problem
In wireless sensor systems, communication latency variations among nodes due to differences in signal strength, distance, noise, and protocol methods lead to poor synchronization during simultaneous data acquisition, making it challenging to accurately anticipate and correct for latency.
Innovation Solution
Each wireless sensor node includes a local clock that is resynchronized and receives a scheduled start time message with a group identifier, allowing it to trigger data acquisition synchronously with other nodes in the group, enabling synchronized data acquisition across multiple wireless sensor nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If broadcast messages are used to initiate data acquisition at multiple wireless sensor nodes simultaneously, then data acquisition can be triggered across the network, but communication latency variations cause poor synchronization among nodes
Solution Approach 1:
The system performs preliminary actions by having each sensor node determine its own compensated start time before data acquisition begins. The server calculates latency compensation values in advance based on node characteristics, and nodes apply these compensations to their local clocks to establish synchronized start times without requiring simultaneous message reception.
2Measurement precision
If communication latency is corrected to improve synchronization, then synchronization accuracy improves, but the complexity of anticipating and correcting latency increases
Solution Approach 1:
Each wireless sensor node independently determines its own latency-compensated start time using pre-configured compensation values and its local clock. The server provides the compensation parameters, but each node autonomously calculates and applies the compensation, eliminating the need for complex centralized coordination or inter-node communication for synchronization.
Data Source
AI summary
A wireless sensor system includes wireless sensor nodes, each including a sensor interface that interfaces with sensing circuitry, a wireless interface to communicate with a wireless access point, at least one processor, and memory. The memory has instructions stored thereon that, when executed by the at least one processor, cause the wireless sensor node to compare a group identifier received in a message at the wireless interface with a group identifier of the wireless sensor node. Based on determining that the group identifier received matches the wireless sensor node, a start time to trigger is set in the wireless sensor node according to a start time defined in the message. A local clock of the wireless sensor node is monitored. Based on determining that the local clock has reached the start time to trigger, sensor data are acquired through the sensor interface and transmitted on the wireless interface.