Wireless Receiver Distance Estimation via Rician K Factor
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Solution Overview
Problem
In multipath environments, existing methods for estimating the distance of a wireless tag using RSSI are unreliable due to significant variations caused by fading, leading to inaccurate distance calculations.
Innovation Solution
A wireless receiver system that estimates the Rician K factor from the variation in received signal power, uses this factor to separate line-of-sight and non-line-of-sight components, and calculates distance based on the line-of-sight component power, thereby improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RSSI-based distance estimation is used in multipath environments, then distance can be estimated using a single receiver, but the estimation accuracy deteriorates significantly due to fading variations
Solution Approach 1:
The patent changes the parameter used for distance estimation from total received power (RSSI) to line-of-sight component power. By extracting the LOS component through statistical analysis of power variations, the system maintains single receiver operation while achieving accurate distance estimation despite multipath fading effects.
2Device complexity
If total received power is used for distance estimation, then calculation is simple, but accuracy deteriorates due to multipath fading variations
Solution Approach 1:
The patent segments the total received power into distinct components: line-of-sight power and multipath power. By separating these components through statistical analysis of power variations, the system can use only the LOS component for distance estimation, improving accuracy while maintaining relatively simple calculation procedures.
Solution Approach 2:
The patent extracts the line-of-sight component from the total received power by analyzing power variations. This extraction process isolates the useful signal component from the harmful multipath components, enabling accurate distance estimation without being affected by fading variations.
3Measurement precision
If line-of-sight component separation is implemented, then distance estimation accuracy improves, but system complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the system uses its own received signal variations to automatically separate the line-of-sight component. By monitoring power variations and applying statistical analysis, the system performs self-adjustment to extract the LOS component without requiring external assistance or complex additional hardware.
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 proposed solution significantly reduces the Root Mean Squared Error (RMSE) in distance estimation, providing a more accurate and reliable method compared to traditional RSSI-based approaches, with a narrower distribution of estimated values around the actual distance.
Implementation Method 1
The single receiver receives radio waves from a tag, and estimates the distance using the fact that the attenuation through the channel is a function of the distance on the basis of their intensity
Data Source
AI summary
According to one embodiment, a wireless receiver includes reception circuitry and processor circuitry. The reception circuitry receives a radio wave from a radio wave emitter. The processor circuitry estimates a parameter of a ratio of a first received power of a line-of-sight component in the radio wave to a second received power of the radio wave, estimate the first received power based on the parameter and a value of the second received power; and calculate a distance to the radio wave emitter, based on the first received power.