Multicarrier Direction Estimation for Moving Body Detection
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Solution Overview
Problem
Conventional methods face challenges in accurately estimating the distance and direction to a moving object, particularly living bodies, due to the need for dedicated hardware and high-cost equipment, and difficulties in synchronizing transmission and reception sides, limiting the applicability to household devices like wireless LAN.
Innovation Solution
An estimating device using a multicarrier signal, such as an OFDM signal, with transmission and reception antennas, calculates complex transfer functions and correlation matrices to extract moving object information, allowing accurate direction estimation by analyzing subcarrier phase offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods use dedicated hardware and high-cost equipment for position estimation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables wireless communication devices to perform both communication and position estimation functions using existing hardware components. The position estimation function is implemented by utilizing the communication device's transmission and reception capabilities along with signal processing algorithms, eliminating the need for dedicated position estimation hardware.
Solution Approach 2:
The patent uses copies of existing communication signals (reference signals, pilot signals) for position estimation purposes. By analyzing these copied signals that are already being transmitted for communication, the system can derive position information without requiring separate dedicated signals or hardware.
2Measurement precision
If conventional methods use dedicated hardware for position estimation, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent makes position estimation technology accessible to household wireless communication devices by implementing it as a software-based function that utilizes existing communication hardware. This eliminates the barrier of requiring specialized expensive equipment, allowing widespread deployment in consumer devices.
3Measurement precision
If conventional methods synchronize transmission and reception sides, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service synchronization mechanism where the receiving device autonomously estimates position based on received signals without requiring complex coordination or synchronization protocols with the transmitting device. The system independently processes signals to extract position information, eliminating the need for intricate inter-device synchronization.
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 enables precise estimation of direction and distance to a moving object using existing communication devices, reducing costs and enhancing accuracy by filtering out unnecessary components and focusing on frequency-specific variations.
Implementation Method 1
a reception signal which is received by the N reception antenna elements and includes a reflected signal which is the multicarrier signal transmitted from the M transmission antenna elements that has been reflected or scattered by the moving object
Implementation Method 2
a reception signal which is received by the N reception antenna elements and includes a reflected signal which is the multicarrier signal transmitted from the M transmission antenna elements that has been reflected or scattered by the moving object
Implementation Method 3
a plurality of complex transfer functions each indicating a propagation characteristic between the M transmission antenna elements and the N reception antenna elements
Data Source
AI summary
An estimating device: generates a multicarrier signal; causes a transmission antenna including M transmission antenna elements to transmit the multicarrier signal; measures, for a first period equivalent to a cycle derived from an activity of a moving body, a reception signal which is received by N reception antenna elements included in L reception antennas and includes a reflected signal of the multicarrier signal transmitted from the M transmission antenna elements and reflected or scattered by the moving object; calculates, for each of subcarriers, complex transfer functions each indicating a propagation characteristic between the M transmission antenna elements and the N reception antenna elements, using the reception signal measured in the first period; calculates a correlation matrix based on the complex transfer functions; calculates subcarrier phase offsets from an imaginary component of the moving object information; and estimates a direction from the estimating device to the moving object.