Multi-Channel TDOA Synchronization Using Transmit Clock Signal
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Solution Overview
Problem
Current TDOA location systems in wireless networks face challenges in accurately calculating Time Difference Of Arrival (TDOA) between location receivers operating on different channels due to unsynchronized message transmission, leading to timing uncertainties that exceed a few nanoseconds, which is not achievable with current transmitter units while maintaining compliance with network transmission requirements.
Innovation Solution
A method and system for synchronously transmitting messages across multiple channels using a transmit clock signal, where messages are started at intervals consisting of one or multiple periods of the transmit clock signal, allowing location units to determine the time of arrival and a master unit to calculate TDOA, thereby minimizing timing errors and ensuring accurate location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If messages are transmitted on multiple channels without synchronization, then location receivers can operate on different channels, but timing uncertainty increases beyond a few nanoseconds
Solution Approach 1:
The patent implements periodic synchronized message transmissions using a transmit clock signal that operates at regular intervals. Each message is transmitted at a precise time determined by the clock signal, creating a periodic transmission pattern that enables accurate TDOA measurement across multiple channels while maintaining timing synchronization
Solution Approach 2:
The transmit clock signal serves as an intermediary that coordinates message transmission across multiple channels. This clock signal acts as a reference that synchronizes the transmission timing, allowing location receivers on different channels to accurately determine time of arrival and calculate TDOA with nanosecond precision
2Reliability
If transmission timing is determined by processor initiation and CCA, then network compliance is maintained, but accurate TDOA measurement cannot be achieved
Solution Approach 1:
The patent segments the transmission timing function into two independent parts: a precise transmit clock signal that generates accurate transmission timestamps, and the network protocol layer that handles CCA and compliance requirements. This segmentation allows the clock signal to provide nanosecond-precise timing while the protocol layer maintains network compliance, resolving the contradiction between accuracy and compliance
Data Source
AI summary
A wireless network has at least one wireless unit which transmits messages in multiple channels. The messages are synchronously transmitted using a transmit clock signal. The at least one wireless unit starting transmission of the messages at intervals consisting of at least one of one or multiple periods of the transmit clock signal. A plurality of location receivers are used for receiving the messages at different channels transmitted by the wireless units within the wireless network and determining a time of arrival for the received messages. At least one master unit is used for receiving the time of arrival from each of the location units. The location of the wireless unit is to be determined on the Time Difference Of Arrival (TDOA) of the transmitted messages at the location units.