Distance Estimation Device Using Signal-Power Calibration
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Solution Overview
Problem
Current distance estimation in OFDM systems using RSSI is prone to errors due to environmental influences, and when CSI is combined with RSSI, accuracy decreases due to AGC effects.
Innovation Solution
A distance estimation device and method that calculates a signal-power calibration value by dividing signal-path power by noise-path power, using CSI, and then uses this value along with RSSI to obtain a path-loss exponent for accurate distance estimation, while filtering noise with low-pass filters and selecting appropriate Lfactor_C-to-γ curves based on RSSI thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RSSI is used for distance estimation, then the estimation can be performed, but the accuracy is affected by environmental influences resulting in greater distance estimation error
Solution Approach 1:
The patent introduces CSI as an intermediary parameter to bridge the gap between RSSI and actual distance. By using CSI to calculate signal-path power and noise-path power, the system creates a more reliable measurement chain that is less susceptible to environmental variations, thereby improving distance estimation accuracy
Solution Approach 2:
The patent changes the measurement parameters from relying solely on RSSI to using CSI-derived signal-path power and noise-path power. This parameter transformation allows the system to capture channel characteristics more accurately, reducing the impact of environmental factors on distance estimation
2Measurement precision
If CSI is used with RSSI for distance estimation, then more accurate results can be obtained, but the accuracy decreases due to AGC gain effects on the CSI
Solution Approach 1:
The patent extracts the harmful AGC gain component from the CSI by separately calculating signal-path power and noise-path power. By isolating and eliminating the AGC-influenced portion through the calibration process, the system recovers the true channel characteristics needed for accurate distance estimation
Solution Approach 2:
The patent implements a feedback mechanism where the calculated signal-power calibration value is used to adjust and correct the distance estimation process. This feedback loop continuously compensates for AGC gain effects, maintaining measurement accuracy despite varying AGC conditions
3Measurement precision
If signal-path power and noise-path power are calculated from CSI and divided to obtain signal-power calibration value, then AGC effects are mitigated, but the device complexity increases due to additional calibration circuit and processing steps
Solution Approach 1:
The calibration circuit is designed to perform multiple functions: it processes CSI to extract signal-path and noise-path power, calculates the signal-power calibration value, and applies corrections to distance estimation. This multi-functionality reduces the need for separate dedicated circuits for each task, thereby limiting the increase in overall device complexity
Data Source
AI summary
An estimation device is provided. The distance estimation device includes a calibration circuit and a distance estimation circuit. The calibration circuit may receive channel state information (CSI), and obtain signal-path power and noise-path power according to the CSI, and perform calculation to divide the signal-path power by the noise-path power to obtain a signal-power calibration value. The distance estimation circuit is coupled to the calibration circuit. The distance estimation circuit receives a received signal strength indication (RSSI) and the signal-power calibration value, and obtains a path-loss exponent according to the RSSI and the signal-power calibration value, and obtains a distance-estimation value according to the signal-power calibration value and the path-loss exponent.