Sensor Node Positioning Using Signal of Opportunity Transit Time
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Solution Overview
Problem
Existing methods for determining the position of sensor nodes in a sensor network face challenges such as high manual effort, limited accuracy, and additional hardware costs, especially in indoor environments where GPS-based methods are ineffective.
Innovation Solution
A method that measures the transit time difference and angle of incidence of 'Signals of Opportunity' between sensor nodes, allowing for accurate position determination without requiring knowledge of the transmitter's location, using OFDM-modulated signals for precise reference frequency determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GPS-based positioning methods are used, then position determination is possible outdoors, but the method fails indoors without line of sight to satellites
Solution Approach 1:
The patent uses OFDM-modulated transmission signals from existing broadcast transmitters (DVB-T, DAB) as an intermediary carrier for positioning. These signals serve as a mediator that can penetrate building structures, enabling indoor positioning without requiring direct satellite line of sight. The transmitter locations are determined through signal parameter analysis rather than requiring explicit knowledge of transmitter positions.
2Ease of manufacture
If manual position determination on maps is used, then no additional hardware is needed, but the method requires high manual effort and has limited accuracy
Solution Approach 1:
The system enables sensor nodes to autonomously determine their own positions using signals received from broadcast transmitters. The nodes automatically measure signal parameters (arrival time, angle of incidence) and calculate their positions without requiring manual map marking or external assistance. This self-service approach eliminates manual effort while maintaining hardware simplicity.
3Measurement precision
If D-GPS method is used to achieve position accuracy of less than 5 meters, then high positioning accuracy is achieved, but additional effort is required with a reference receiver
Solution Approach 1:
The patent extracts the positioning function from the complex D-GPS system by using the existing OFDM broadcast signals as the positioning carrier. Instead of requiring a reference receiver and complex differential processing, the system uses signal parameters (arrival time and angle of incidence) from standard broadcast transmissions to achieve meter-level accuracy without additional reference infrastructure.
4Measurement precision
If transmitter location knowledge is required for position determination, then positioning can be performed, but the method requires special receiving stations at known locations
Solution Approach 1:
Instead of requiring knowledge of transmitter locations to determine receiver position, the patent inverts the approach by having the receiver measure signal parameters (arrival time and angle of incidence) from the transmitter and use these measurements to calculate its own position. This inversion eliminates the need for pre-established receiving stations with known locations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves higher accuracy in position determination with minimized atmospheric influence and reduced hardware costs, enabling effective indoor positioning with improved ease of implementation.
Implementation Method 1
Position determination using Signals of Opportunity is based on determining the signal propagation times of the transmission signals from several transmitters with known locations and the receiver at an unknown location.
Implementation Method 2
determination of the angle of incidence of the signal of opportunity at the sensor node
Implementation Method 3
The transmitters are designed to emit an OFDM-modulated transmission signal. The sensor nodes are designed to receive an OFDM modulated signal.
Data Source
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AI summary
The invention relates to a method for determining the position of a first sensor node relative to a second sensor node, wherein the first and the second sensor nodes are communicatively connected to each other and are a constituent part of a sensor network, comprising the method steps: reception of signal sections of transmitted signals from at least two transmitters by the first and the second sensor node, beginning at a time t1 for a time period tRX; determining the angle of incidence of the transmitted signals to at least one of the sensor nodes; determining the distance between the sensor nodes from the propagation time differences of the transmitted signals from the at least two transmitters received at the first and second sensor nodes; determining the position of the first sensor node relative to the second sensor node from the distance between the sensor nodes and the angle of incidence of the transmitted signals, wherein the sensor nodes determine the time t1 and the time period tRX in relation to a reference frequency which is derived from the received transmitted signal from at least one of the transmitters.