RSS AoA 3D Localization Using Spherical WLS
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Solution Overview
Problem
Existing 3-D localization methods in wireless sensor networks face challenges with high computational complexity and noise sensitivity, particularly in large-scale networks and 3-D scenarios, with many methods designed for 2-D scenarios or low noise conditions, and they often require sophisticated mathematical tools or iterative processes.
Innovation Solution
A Weighted Least Squares (WLS) method that combines Received Signal Strength (RSS) and Angle of Arrival (AoA) measurements, shifting to spherical coordinates to establish new relationships, providing a closed-form solution with low computational complexity and high accuracy, independent of anchor density and noise conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sophisticated mathematical tools (SDP, second order cone relaxation) are used to improve localization accuracy, then measurement precision is improved, but computational complexity increases rapidly with network size
Solution Approach 1:
The patent transforms the localization problem by changing the coordinate system from Cartesian to spherical coordinates, and changes the measurement representation from raw RSS values to path loss values. This parameter transformation enables the derivation of a closed-form WLS solution that avoids the computational burden of SDP and second order cone relaxation methods while maintaining localization accuracy
Solution Approach 2:
The patent extracts and eliminates the iterative optimization step from the localization process by deriving a closed-form solution. By taking out the need for complex mathematical tools like SDP and focusing on a direct algebraic solution, the method achieves comparable accuracy with significantly reduced computational complexity
2Measurement precision
If iterative methods (bisection procedure, SDP) are used to solve localization problems, then measurement precision is improved, but productivity decreases due to increased computational load and error propagation
Solution Approach 1:
The patent skips the iterative optimization process entirely by deriving a closed-form solution. The WLS estimator with closed-form expression allows the system to rush through the computation in a single step, avoiding multiple iterations of bisection or SDP procedures, thereby eliminating error propagation and significantly improving computational efficiency
Solution Approach 2:
The patent extracts and eliminates the iterative computation step from the localization pipeline. By formulating a closed-form solution, the method removes the need for repeated calculations and convergence checks, achieving both high precision and high productivity
3Device complexity
If 2-D localization methods are applied to 3-D scenarios, then device complexity is reduced, but measurement precision deteriorates due to inadequate modeling of 3-D spatial relationships
Solution Approach 1:
The patent explicitly transitions from 2-D to 3-D by introducing the elevation angle as an additional dimension. The spherical coordinate system naturally accommodates 3-D spatial relationships with three components (azimuth, elevation, and range), enabling accurate 3-D localization while maintaining algorithmic simplicity through the closed-form WLS solution
4Measurement precision
If GPS receivers are installed in all sensors to improve location accuracy, then measurement precision is improved, but loss of substance increases due to augmented network costs
Solution Approach 1:
The patent enables target sensors to determine their own locations autonomously using only RSS and AoA measurements from anchor nodes. This self-service localization eliminates the need for expensive GPS receivers in target sensors, significantly reducing network costs while maintaining acceptable location accuracy through the proposed WLS method
Data Source
AI summary
An apparatus and a method for RSS/AoA target 3-D localization in wireless networks and wireless sensor networks (WSNs), utilizing combined measurements of received signal strength (RSS) and angle of arrival (AoA) are disclosed herein. By using the spherical coordinate conversion and available AoA observations to establish new relationships between the measurements and the unknown target location, a simple closed-form solution is developed. The method disclosed herein has a straightforward adaptation to the case where the target's transmit power is also not known. A representative set of simulations and experiments verify the potential performance improvement realized with embodiments of the method for RSS/AoA target 3-D localization in wireless networks.