Dynamic Receiver Window for Indoor Positioning Accuracy
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Solution Overview
Problem
Existing indoor locationing systems face inaccuracies due to multi-path reflections and signal interference, leading to suboptimal signal-to-noise ratios and erroneous position detection of mobile devices in indoor environments.
Innovation Solution
A real-time locationing system dynamically adjusts the receiver window duration based on the consistency rate of ranging signals, decreasing the window when the consistency rate exceeds a threshold and increasing it when it falls below, to optimize the signal-to-noise ratio and enhance position detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver subsystem remains continuously enabled to receive all ranging signals, then no ranging signals are missed, but the signal-to-noise ratio deteriorates due to inclusion of inconsistent reflected signals
Solution Approach 1:
The receiver subsystem transitions from a static continuous reception mode to a dynamic selective reception mode. The receiver window is dynamically adjusted in duration and positioning based on predicted arrival times of direct signals, enabling the system to adaptively optimize between completeness and precision of signal reception.
Solution Approach 2:
The system performs preliminary calculations of expected arrival times for direct ranging signals based on known transmitter and receiver positions. This preliminary action allows the receiver window to be pre-positioned and pre-duration-adjusted before actual signal reception, ensuring that only consistent direct signals within the predicted time window are captured.
2Reliability
If the receiver window duration is increased to capture more ranging signals, then signal completeness improves, but the signal-to-noise ratio worsens due to inclusion of reflected signals
Solution Approach 1:
The duration of the receiver window is changed as a variable parameter rather than being fixed. Based on calculated arrival times and signal consistency criteria, the window duration is adjusted to optimally capture direct signals while excluding reflected signals that arrive at different times, thereby improving the signal-to-noise ratio.
Solution Approach 2:
The system replaces a mechanical approach of continuously monitoring all possible signal arrivals with a calculated, predictive approach. By substituting continuous reception with a timed window based on theoretical arrival time calculations, the system efficiently distinguishes between direct and reflected signals without requiring continuous high-power reception.
3Measurement precision
If the receiver window duration is decreased to filter out inconsistent signals, then the signal-to-noise ratio improves, but the risk of missing valid ranging signals increases
Solution Approach 1:
The system incorporates feedback mechanisms where the actual received signal times are compared against predicted arrival times. This feedback loop allows the system to verify whether direct signals were successfully captured within the receiver window and to adjust subsequent window parameters accordingly, ensuring that valid signals are not missed while maintaining high signal-to-noise ratio.
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 improves the accuracy of position detection and tracking of mobile devices by filtering out inconsistent signals and optimizing the signal-to-noise ratio, leading to more precise location determination in indoor environments.
Implementation Method 1
Each ultrasonic transmitter transmits a plurality of ultrasonic ranging signals, preferably as ultrasonic pulses in the 20-22 kHz frequency range
Implementation Method 2
The flight time difference between the transmit time that each ranging signal is transmitted and the receive time that each ranging signal is received along each direct path, together with the known speed of each ranging signal, are used, among other factors, to determine the distance
Implementation Method 3
RF, optical and acoustic locationing systems are all subject to multi-path reflections and scattering of their respective ranging signals off various reflecting and/or absorbing surfaces, such as walls, ceilings, floors, curtains, windows, shelves, equipment
Implementation Method 4
The ultrasonic pulses are received by an ultrasonic receiver, e.g., a microphone, on the mobile device
Data Source
AI summary
A transmitter subsystem periodically transmits ranging signals at transmit times, and a receiver subsystem receives the ranging signals at receive times within a receiver window having an adjustable time duration. A real-time position of a mobile device supporting one of the subsystems is determined based on differences between the receive and transmit times. An expected arrival time for the transmitted ranging signals is determined based on the real-time position of the mobile device. Each receive time is compared with the expected arrival time to obtain a consistency rate of the ranging signals that are received by the receiver subsystem directly from the transmitter subsystem. The time duration of the receiver window is dynamically adjusted based on the consistency rate.