Wireless Device Synchronization via UDP Timestamp Exchange
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Solution Overview
Problem
High-level communication protocols like TCP introduce uncertainty in message delivery latency, making synchronization of wireless devices challenging due to unpredictable latency and increased complexity, which hampers the adoption of wireless sensing systems in aircraft.
Innovation Solution
Switching to a simpler protocol like UDP for synchronization purposes, while using TCP for reliable data transfer, and employing methods to account for message losses by adjusting the number of reference broadcasts and using relative synchronization techniques to calculate clock offsets accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-level protocols like TCP are used for wireless communication, then communication reliability is improved, but message delivery latency becomes unpredictable and synchronization accuracy deteriorates
Solution Approach 1:
The patent segments the communication protocol into two distinct layers: a high-level TCP protocol for reliable data transfer and a low-level UDP protocol for synchronization. This segmentation allows each protocol to perform its specialized function optimally - TCP ensures delivery reliability while UDP provides predictable timing characteristics for synchronization purposes.
Solution Approach 2:
The patent introduces an intermediary synchronization mechanism that operates independently from the main data communication channel. By using UDP as an intermediary for timestamp exchange and synchronization, the system bypasses the latency variability inherent in TCP while maintaining the reliability benefits of TCP for actual data transfer.
2Measurement precision
If simpler protocols like UDP are used for synchronization, then latency predictability is improved, but message loss increases and requires additional complexity to handle
Solution Approach 1:
The patent employs partial action by sending multiple reference timestamp messages (excessive action) to ensure that at least some messages are successfully received despite UDP's unreliable delivery. By transmitting more messages than strictly necessary, the system compensates for potential message losses while maintaining synchronization accuracy.
Solution Approach 2:
The synchronization mechanism incorporates feedback through timestamp echo messages, where receiving nodes send back their received timestamps to the transmitting node. This feedback loop allows both nodes to calculate clock offsets and detect message losses, enabling the system to compensate for UDP's unreliable delivery characteristics.
3Device complexity
If wireless sensing systems are implemented in aircraft, then weight and complexity are reduced, but synchronization challenges increase due to protocol limitations
Solution Approach 1:
The patent segments the wireless sensing system into distinct functional layers: a simple UDP-based synchronization layer for time coordination and a TCP-based data transfer layer for reliable communication. This segmentation reduces overall system complexity by allowing each layer to use optimized, straightforward protocols rather than requiring a single complex protocol to handle all functions.
Solution Approach 2:
The patent creates a universal synchronization mechanism that can be applied across different wireless sensing nodes and sensor types in aircraft systems. By establishing a common timestamp exchange protocol using UDP, the system provides a universal time reference that works across diverse sensors and communication scenarios, simplifying integration while maintaining precision.
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AI summary
An apparatus for synchronizing devices includes a central access point node configured to utilize a low latency protocol to transmit a series of synchronization messages to the devices, transmit and receive data acquisition commands and responses from the devices using a high reliability protocol different from the low latency protocol, and calculate and apply relative clock offsets for each device based on the series of synchronization messages. The apparatus may also account for failure in delivery of a portion of the series of synchronization messages by recording timestamp data at the devices to send to the central access point prior to the central access point calculating the relative clock offsets.