Wireless Backhaul Synchronization for Blind Sensor Stations
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Solution Overview
Problem
In wireless geolocation networks, sensor stations that are blocked or blind, unable to determine their location or synchronize with a common time base, pose challenges for accurate transmitter location and time synchronization, especially in environments where GPS signals are obstructed.
Innovation Solution
A network of reference sensor stations, synchronized via GPS or terrestrial signals, broadcasts a wireless communications waveform to blind or deficient sensor stations, enabling them to determine their location and synchronize with the geolocation network through a backhaul communications network, even without direct connections to three or more reference stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor stations use GPS or terrestrial signals to determine location and synchronize time, then location accuracy and time synchronization are improved, but the solution fails in impaired environments where GPS signals are obstructed
Solution Approach 1:
The patent introduces reference sensor stations as intermediary nodes that have determined their locations through GPS or terrestrial signals. These reference stations broadcast their location and timing information to blind sensor stations via wireless communications, enabling the blind stations to determine their locations and synchronize time without direct GPS access. This intermediary approach resolves the contradiction by providing a fallback mechanism that works in impaired environments while maintaining accuracy.
Solution Approach 2:
The patent segments the sensor network into two functional groups: reference sensor stations that can access GPS/terrestrial signals and blind sensor stations that cannot. The reference stations perform the location determination and time synchronization functions, while blind stations receive this information through wireless communications. This segmentation allows each group to operate according to its capabilities, resolving the environmental adaptability issue.
2Device complexity
If blind sensor stations attempt to determine location without reference stations, then device complexity is reduced, but location determination and time synchronization cannot be achieved
Solution Approach 1:
Reference sensor stations serve as intermediaries that provide location and timing information to blind sensor stations through wireless communications. This allows blind stations to achieve reliable location determination without having the complexity of GPS receivers or terrestrial signal receivers, while maintaining high reliability through the reference station network.
Solution Approach 2:
The wireless communication network serves multiple functions: it provides the primary communication channel for sensor data transmission and simultaneously acts as a positioning and time synchronization system for blind stations. This multi-functionality allows the system to maintain reliability without increasing device complexity at the blind stations.
3Device complexity
If the wireless backhaul network is used for both communication and synchronization, then device complexity and infrastructure requirements are reduced, but measurement precision for location determination may be affected
Solution Approach 1:
The system performs preliminary time synchronization by having reference sensor stations broadcast their timing information to blind stations before location measurements are taken. This preliminary synchronization action ensures that all stations are on a common time base before the actual measurement process, maintaining measurement precision while using the same wireless infrastructure for both communication and synchronization.
Solution Approach 2:
The patent implements feedback mechanisms where reference sensor stations continuously broadcast their location and timing information, and blind stations adjust their local clocks and position calculations based on this feedback. This feedback loop maintains time synchronization precision while using the wireless backhaul network for both communication and synchronization purposes.
Data Source
AI summary
Transmitters are located with a network of sensors by measuring signal characteristics at multiple known locations and processing these measurements at a central node. The sensors communicate their location to the central node along with measured characteristics of the transmitter's signal, and may be required to synchronize with other sensors. Often, GNSS receivers are utilized to locate and synchronize the sensors. However, the GNSS signals may be attenuated by obstructions. In this case, the sensors determine their location by making ranging measurements with sensors that can receive the GNSS signals. The waveform for the wireless backhaul permits this ranging. Additionally, many sensors can determine their location and time synchronize with the geolocation network through reception of signals from other sensors even if they do not have a direct connection to sensors that know their location and are time synchronized.