Real-Time Location System RSSI Channel Model Calibration
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Solution Overview
Problem
Conventional real-time location systems (RTLS) based on RSSI values for Wireless Sensor Networks (WSNs) face accuracy and stability issues due to timing variability in indoor environments, as they rely on fixed channel model parameters that do not account for dynamic changes in signal propagation.
Innovation Solution
A method that periodically and automatically determines the characteristic parameters of the transmission channel, such as the attenuation coefficient and power received at a reference distance, to improve the accuracy of location estimations by dynamically updating the channel model based on measured RSSI values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed channel model parameters are used for location estimation, then the system complexity is reduced and ease of operation is improved, but the measurement precision and reliability of location estimation deteriorate due to timing variability in dynamic indoor environments
Solution Approach 1:
The patent applies the dynamics principle by transitioning from fixed channel model parameters to dynamically updated parameters. The system periodically recalibrates the channel model parameters (such as attenuation coefficients and reference power values) based on current RSSI measurements from anchor nodes, allowing the location estimation system to adapt to changing environmental conditions in indoor spaces, thereby maintaining measurement precision without excessive complexity
Solution Approach 2:
The patent implements parameter changes by modifying the channel model parameters periodically rather than using fixed values. The system changes parameters such as the attenuation coefficient (α) and reference power (P0) based on measured RSSI values over time, enabling the location estimation to account for environmental variations while maintaining a balance between accuracy and system complexity
2Reliability
If channel model parameters are updated periodically and automatically, then the reliability and measurement precision of location estimation are improved, but the device complexity and use of energy increase
Solution Approach 1:
The patent applies periodic action by updating channel model parameters at scheduled intervals rather than continuously. The system performs calibration operations periodically using RSSI measurements from anchor nodes, which maintains reliability and measurement precision while avoiding the excessive energy consumption and complexity associated with continuous parameter updates
Solution Approach 2:
The system implements self-service through automatic calibration procedures that use existing RSSI measurements from anchor nodes to update channel model parameters without requiring manual intervention or additional specialized hardware. The blind nodes themselves participate in the calibration process by measuring and reporting RSSI values, reducing overall system complexity
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 approach enhances the accuracy and stability of location estimations in WSNs by adapting to changing environmental conditions, reducing errors associated with timing variability and improving the precision of blind-node position determination.
Implementation Method 1
measuring the RSSI value relative to the transmitted signal between said mobile wireless device and each of the fixed wireless devices
Implementation Method 2
a model that describes the trend of the RSSI values relative to the transmitted signal between said mobile wireless device and each of the fixed wireless devices of said pair of fixed wireless devices, as a function of the distance
Data Source
AI summary
An embodiment concerns the field of real-time location systems (RTLS) based on RSSI (Received Signal Strength Indication) measurements. An embodiment is based on determining the distances between wireless device of a network based on a model that describes the relation of the RSSI value relative to the packet exchanged between nodes as a function of the distance, wherein said model depends on at least one characteristic parameter of the transmission channel and wherein at least said characteristic parameter of the transmission channel is determined periodically and automatically, exploiting the known distances among fixed nodes. In this way, the errors relative to possible time-variability of the transmission channel are reduced and the accuracy and stability of the location measurements are increased.