Wireless Positioning Using Signal Strength and Vector Products
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Solution Overview
Problem
Existing methods for estimating the position of a wireless client in wireless communication, such as three-point positioning, require accurate pre-setting of access point positions and are prone to errors due to obstacles, increasing installation burden and shadowing influences.
Innovation Solution
An information processing system using a cooperative position estimation method based on signal strength between access points and wireless clients, which estimates relative positions and determines inside/outside relationships with respect to polygonal target areas formed by access points, reducing the need for precise access point placement and minimizing shadowing effects by dividing areas and using vector products for accurate determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-point positioning method is used to estimate wireless client position, then position coordinates can be calculated, but accurate pre-setting of access point positions is required which increases installation burden
Solution Approach 1:
The patent replaces the mechanical coordinate-based positioning system with a signal-strength-based relative position estimation system. Instead of calculating absolute position coordinates using three-point positioning, the system estimates relative positions between access points and wireless clients based on signal strength measurements, eliminating the need for precise access point position setting while maintaining positioning functionality
Solution Approach 2:
The patent changes the fundamental parameter used for positioning from absolute coordinate values to relative position relationships based on signal strength. By using signal strength as the primary parameter and estimating relative positions rather than absolute coordinates, the system removes the requirement for accurate access point position pre-setting during installation
2Measurement precision
If three-point positioning method is used to calculate position coordinates, then wireless client position can be specified, but access point cannot be moved which reduces system flexibility
Solution Approach 1:
The patent implements a dynamic positioning system where access points can be moved without requiring recalculation of absolute position coordinates. The system continuously estimates relative positions based on current signal strength measurements, allowing access points to be repositioned flexibly while maintaining accurate position specification through real-time relative position estimation
3Measurement precision
If straight line distance is calculated using signal strength, then position coordinates can be obtained, but obstacles cause shadowing which introduces errors in distance calculation
Solution Approach 1:
The patent replaces the direct straight line distance calculation method with a relative position estimation approach that uses signal strength to determine positional relationships without explicitly calculating Euclidean distances. This substitution avoids the shadowing problem that affects direct distance calculations through obstacles
Solution Approach 2:
The patent introduces signal strength as an intermediary parameter between the physical distance and position calculation. Instead of directly converting signal strength to straight line distance (which is affected by shadowing), the system uses signal strength to estimate relative position relationships, making the shadowing effect a secondary concern rather than a primary error source
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 reduces the installation burden of access points and improves position estimation accuracy by eliminating the need for precise access point placement and minimizing shadowing influences, allowing for more accurate determination of wireless client positions within target areas.
Implementation Method 1
a straight line distance between the wireless client and each access point is calculated on the basis of the signal strength of radio waves in the wireless communication between each access point and the wireless client
Data Source
AI summary
There is provided an information processing system including a relative-position estimation processing unit configured to estimate a relative position between an access point and a wireless client by using a cooperative position estimation method using distance information based on a signal strength between the access point and the wireless client; and an inside/outside determination processing unit configured to determine an inside/outside positional relationship between a polygonal target area formed by access points and the wireless client, in which the inside/outside determination processing unit determines whether the wireless client is present inside or outside the target area by determining a direction of vector product of the access points forming a side of the target area and a direction of vector product of the wireless client and the access point as a vertex of the polygonal area.