Radio Node Time Synchronization Using Envelope Markers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current packet-based time synchronization protocols like NTP and PTP require heavy network infrastructure and suffer from inaccuracies due to unequal uplink and downlink delays, as well as high processing delays from the high protocol layer.
Innovation Solution
The method employs equal delays introduced by a radio path in the physical layer for time measurements, using modulation envelope signals as time markers to synchronize clocks in radio nodes, thereby improving synchronization accuracy to the nanosecond level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If packet-based time synchronization protocols (NTP/PTP) are used, then time synchronization can be achieved, but the accuracy deteriorates due to unequal uplink and downlink delays and high processing delays
Solution Approach 1:
The patent replaces the packet-based mechanical synchronization system (NTP/PTP) with a physical layer electromagnetic wave-based system. By using the physical layer radio path properties where the speed of light is constant and known, the system eliminates the inaccuracies caused by packet processing delays and unequal network delays, achieving nanosecond-level synchronization accuracy.
Solution Approach 2:
The patent changes the fundamental parameter used for synchronization from packet transmission time (which varies due to processing delays) to the speed of light (which is constant and known). By using the relationship between distance and speed of light, the system achieves deterministic and accurate time synchronization without the variability inherent in packet-based approaches.
2Measurement precision
If packet-based time synchronization protocols are used, then time synchronization can be achieved, but the device complexity increases due to heavy network infrastructure requirements
Solution Approach 1:
The patent extracts the essential synchronization function from the complex packet-based infrastructure and implements it directly at the physical layer. By removing the need for clocks, servers, and clients that characterize NTP/PTP, the system achieves time synchronization with minimal infrastructure, using only radio nodes that can measure the physical layer signal properties.
Solution Approach 2:
The patent enables radio nodes to perform time synchronization autonomously by utilizing the inherent physical layer properties of the radio path. Each node can independently measure the time of flight and calculate synchronization without requiring external synchronization servers or complex network infrastructure, making the system self-sufficient and infrastructure-light.
3Ease of operation
If high protocol layer processing is used for time synchronization, then synchronization protocol functionality is achieved, but processing delays increase
Solution Approach 1:
The patent substitutes the high protocol layer processing mechanism with a physical layer measurement approach. Instead of using NTP/PTP protocols that require multiple processing steps at higher layers, the system directly measures physical layer signal properties (time of flight, signal characteristics) to achieve synchronization, dramatically reducing processing delays.
Solution Approach 2:
The patent skips the intermediate protocol processing layers (application layer, transport layer) and goes directly to the physical layer for synchronization. By rushing through the protocol stack to the physical layer where measurements can be performed with minimal processing, the system eliminates the time-consuming processing delays inherent in packet-based protocols.
Data Source
AI summary
An apparatus comprises a sampling circuit configured to sample transmit and receive signals of a first radio node to be transmitted to or received from a second radio node. Transmit-side and receive-side envelope detectors are configured to produce transmit-side and receive-side envelope signals based on sampled transmit and receive signals. A transmit-side time measurement unit is configured to generate, based on the transmit-side envelope signal, a transmit-side marker signal based on a pre-defined transmit-side threshold, measure at least one first time delay between at least one time start pulse and at least one marker of the transmit-side marker signal and store to a memory and/or output said at least one first time delay. A receive-side time measurement unit is configured to implement the corresponding functionalities as described for the transmit-side time measurement unit in the receive-side.