Living Body Localization Using Combined Partial CSI Signals
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Solution Overview
Problem
Existing radio systems that output only a part of channel state information (CSI), such as M×1 or 1×N, face difficulties in accurately estimating the direction or location of a living body due to the need for full CSI (M×N elements) to perform such estimations.
Innovation Solution
A method involving a first radio with M antenna elements and a second radio with N antenna elements, where M and N are natural numbers greater than or equal to two, transmits signals multiple times to observe reflection signals, calculates combined complex transfer functions, and reduces errors caused by clock frequency and transmission power to estimate the direction or location of a living body using biological information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a radio outputs only a part of CSI (M×1 or 1×N), then the device complexity is reduced, but the measurement precision for estimating direction or location deteriorates
Solution Approach 1:
The patent combines outgoing CSI (M×1) and incoming CSI (1×N) to construct a complete M×N channel state information matrix. By merging these two partial CSI sets through complex transfer function calculations, the system achieves full MIMO channel characterization without requiring simultaneous transmission from all M antennas and reception at all N antennas at the same time, thus reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent performs preliminary measurements by transmitting signals from each antenna element individually and recording the complex transfer functions. These preliminary CSI measurements are then combined and processed to construct the complete channel state information, enabling accurate direction and location estimation without requiring full CSI to be captured simultaneously.
2Measurement precision
If full CSI (M×N elements) is acquired to estimate direction or location, then measurement precision is improved, but the use of energy and time increase
Solution Approach 1:
The patent segments the CSI acquisition process into two independent parts: outgoing CSI measurement (M×1) and incoming CSI measurement (1×N). Instead of requiring simultaneous full MIMO transmission and reception which would consume M×N times more energy, the system performs these measurements separately and combines them, reducing energy consumption while maintaining the ability to estimate direction and location with full precision.
Solution Approach 2:
The patent uses partial CSI measurements (M×1 and 1×N) that are sufficient when combined to achieve the same estimation capability as full CSI (M×N). This partial action approach reduces the total energy consumption and measurement time while maintaining measurement precision for direction and location estimation.
3Reliability
If clock frequency error and transmission power error are present, then the reliability of the radio system is reduced, but correcting these errors requires additional processing complexity
Solution Approach 1:
The patent uses the incoming CSI measurements as feedback to correct errors in the outgoing CSI measurements. By comparing and combining the complex transfer functions from both directions, the system can identify and compensate for clock frequency errors and transmission power errors, improving reliability without requiring overly complex correction mechanisms.
Solution Approach 2:
The patent introduces complex transfer function calculations as an intermediary process that mediates between the outgoing and incoming CSI measurements. This intermediary calculation layer enables the system to correct for clock frequency and power errors by processing the relationship between transmitted and received signals in both directions, improving reliability through a manageable level of processing 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
Accurately estimates the direction or location of a living body by combining outgoing and incoming CSI, effectively reducing errors from clock frequency and transmission power, even with radios that output only a part of CSI.
Implementation Method 1
transmitting, using one first antenna element among the M first antenna elements, a first transmission signal multiple times to a measurement target region
Implementation Method 2
observing a plurality of first reception signals that are received by the N second antenna elements and that include reflection signals reflected from a living body
Implementation Method 3
PTL 5 discloses a method of distinguishing between a Doppler shift caused by a person and a clock frequency error between a transmitter and a receiver
Data Source
AI summary
An estimation method includes: transmitting first transmission signal from one of M first antenna elements of first radio; observing, by N second antenna elements of second radio, first reception signal including reflection signal of first transmission signal from living body; transmitting second transmission signal from one of N second antenna elements; observing second reception signal including reflection signal of second transmission signal from living body; calculating first combined complex transfer function representing propagation characteristics between M first antenna elements and N second antenna elements; calculating second combined complex transfer function by calculation on first combined complex transfer function to reduce effects of clock frequency error and power error between first radio and second radio; extracting biological information of predetermined frequency range corresponding to component related to living body in second combined complex transfer functions; and estimating direction or location of living body using biological information.