In-Vehicle Device Location Identification Using RSSI Differences
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional keyless entry systems face accuracy issues in identifying the location of a portable device due to variations in received signal strength measurements across different types of portable devices.
Innovation Solution
An in-vehicle device with multiple transmitting antennas transmits measurement signals and calculates distances to preset areas based on differences in signal strengths, using methods like Mahalanobis or Euclidean distances, to accurately identify the location of a portable device, independent of the device type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional RSSI-based location identification is used, then the system can identify portable device location, but the accuracy decreases due to variations in received signal strength measurements across different portable device types
Solution Approach 1:
The patent transforms the location identification approach by changing from using absolute RSSI values to using difference values between RSSI measurements from multiple antennas. This parameter transformation eliminates device-type variations because the difference between signals received at different antennas remains consistent across different portable devices, while absolute RSSI values vary by device type. The controller calculates difference values (e.g., RSSI1 - RSSI2) to determine location, making the measurement independent of portable device characteristics.
2Measurement precision
If multiple transmitting antennas are used to improve location accuracy, then the system can calculate distances to preset areas, but the device complexity increases
Solution Approach 1:
The patent divides the vehicle's detection space into multiple preset areas (e.g., driver side, passenger side, rear areas) and assigns transmitting antennas to different segments. Each antenna is positioned to optimally detect portable devices in specific zones. The controller segments the location identification task by determining which preset area contains the portable device based on RSSI difference patterns, thereby simplifying the overall detection problem into manageable spatial segments.
Solution Approach 2:
The patent introduces difference values as an intermediary parameter between the raw RSSI measurements and the final location identification. Instead of directly using absolute RSSI values to determine location, the system first calculates difference values between signals from different antennas, then uses these difference values to identify the preset area. This intermediary transformation eliminates the influence of portable device characteristics and provides a more reliable basis for location determination.
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 enhances the accuracy of identifying the portable device's location by accounting for signal strength variations, ensuring reliable operation across different portable device types.
Implementation Method 1
an in-vehicle device transmitter configured to transmit measurement signals via the plurality of respective transmitting antennas
Implementation Method 2
the portable device measures received signal strength indicator (RSSI) of each of the measurement signals
Data Source
AI summary
An in-vehicle device includes a plurality of transmitting antennas, an in-vehicle device transmitter configured to transmit measurement signals via the plurality of respective transmitting antennas, an in-vehicle device receiver configured to receive, from a portable device, a measurement result signal that includes measurement data of received signal strengths of the respective measurement signals that have been transmitted from the plurality of respective transmitting antennas; and an in-vehicle device controller configured to calculate first distances from the portable device to a plurality of preset areas, based on differences between the received signal strengths of the respective measurement signals included in the measurement result signal, and to identify an area to which the portable device belongs from the plurality of preset areas based on the first distances.