Underwater Sensor Node Positioning with Joint Path Loss Estimation
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Solution Overview
Problem
Existing marine environmental monitoring wireless sensor networks (MEM-WSNs) face challenges in accurately positioning underwater nodes due to dynamic marine environments, unknown path loss factors, and underwater signal attenuation, leading to low positioning accuracy and robustness.
Innovation Solution
A high-precision and high-robustness positioning method for MEM-WSNs that establishes a received signal strength model, jointly estimates path loss factors and target positions using an interior point method and block coordinate update, transforming the problem into a generalized trust region sub-problem to optimize node positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing positioning methods are used in MEM-WSNs, then the positioning process is simple, but the positioning accuracy is low due to unknown path loss factors, underwater absorption effects, and dynamic node movements
Solution Approach 1:
The patent transforms the positioning problem by changing parameters: it converts the original positioning equations into a polynomial form with new variables (e.g., u = x² + y², v = x, w = y), and introduces auxiliary parameters like path loss factor β and absorption coefficient αf as estimation targets. This parameter transformation enables the use of polynomial solving methods and improves positioning accuracy while managing complexity through mathematical reformulation
Solution Approach 2:
The patent introduces intermediary mathematical constructs to bridge the gap between RSSI measurements and position coordinates. Specifically, it uses polynomial equations as intermediaries to relate the unknown positions to measurable RSSI values, and introduces auxiliary variables (u, v, w) as intermediate steps in the calculation process. This intermediary approach enables accurate positioning without directly solving the complex original equations
2Adaptability or versatility
If all nodes move in real-time in the ocean, then the network adapts to dynamic marine environment, but the topological structure becomes highly dynamic making accurate localization difficult
Solution Approach 1:
The patent explicitly addresses dynamic node movements by formulating positioning equations that do not assume stationary nodes. The method estimates positions based on RSSI measurements taken at different time instances, accommodating the fact that both anchor and unknown nodes move in the dynamic ocean environment. The polynomial-based approach remains valid regardless of node motion states, enabling continuous accurate positioning in highly dynamic topologies
3Ease of operation
If underwater acoustic communication is used for node communication, then wireless communication is achieved in underwater environment, but signal attenuation and absorption loss reduce communication effectiveness and positioning accuracy
Solution Approach 1:
The patent converts the harmful effects of underwater signal attenuation and absorption into beneficial information for positioning. By explicitly modeling the path loss factor β and absorption coefficient αf, and treating them as estimation targets alongside position coordinates, the method transforms the degradation of RSSI signals into additional constraints that help determine both positions and environmental parameters. The harmful attenuation effects become useful for characterizing the underwater propagation medium
Solution Approach 2:
The patent introduces new parameters to account for underwater propagation effects: path loss factor β and absorption coefficient αf. These parameters are incorporated into the polynomial positioning equations, allowing the system to estimate both positions and propagation characteristics simultaneously. This parameter expansion enables the method to handle underwater signal degradation while maintaining positioning accuracy
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
The method achieves precise and robust positioning of underwater nodes, considering real-time movement and underwater absorption effects, enhancing accuracy and reliability in marine environmental monitoring.
Implementation Method 1
establishing a received signal strength model according to a signal propagation loss and an underwater sound propagation absorption effect
Implementation Method 2
establishing a received signal strength model according to a signal propagation loss and an underwater sound propagation absorption effect
Data Source
AI summary
A node positioning method for marine environmental monitoring wireless sensor networks is provided, which jointly estimates node positions and path loss factors by considering the node real-time movement and the path loss and absorption effect of underwater communication; transforms an original non-convex problem into a non-negative constrained least squares framework, and finds the optimal solution of marine node positions by two stages of interior point method and block coordinate update. In the first stage, the problem is re-expressed by using the penalty function according to the interior point method to obtain the approximate solution; and in the second stage, the original problem is transformed into a generalized trust region sub-problem, and the approximate solution obtained by the interior point method is used as the initial estimation, the accurate estimation values of the marine node position and path loss factor are obtained by iterative solutions combined with the block coordinate update.