Vehicle Access System Mitigating Multipath Errors in UHF Low Energy Signals

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional passive entry/passive start systems face challenges in accurately determining the location of portable access devices due to multipath propagation errors in ultra-high frequency low energy signals, which can lead to incorrect angle of arrival estimations and subsequent location determination errors.

Innovation Solution

The system employs multiple antennas at a vehicle to receive and transmit radio frequency signals, estimating angles of arrival and departure to determine a resultant angle of arrival, which is used to accurately locate portable access devices, thereby mitigating multipath errors and improving location determination accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If ultra-high frequency low energy signals are used for passive entry systems, then communication range and energy efficiency are improved, but multipath propagation errors cause inaccurate location determination

Engineering Contradiction:

Improveenergy efficiencyVSAvoidlocation determination accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The system implements two-way communication where the portable access device sends a first signal to the vehicle and receives a second signal in response. The device measures both the angle of departure of the transmitted signal and the angle of arrival of the received signal, using feedback from the vehicle's transmission to correct for multipath propagation errors in the initial location determination

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from one-way signal transmission to two-way communication, adding a temporal and directional dimension to the measurement process. By measuring angles in both transmission and reception directions, the system creates additional measurement dimensions that enable error correction through comparison and calculation of the resultant angle of arrival

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If one-way low-frequency wake-up function is used, then device activation is simplified, but location accuracy deteriorates due to inability to correct multipath errors

Engineering Contradiction:

Improvedevice activation simplicityVSAvoidlocation determination accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system maintains the simple one-way wake-up activation but adds a two-way communication phase for location determination. The portable device transmits a wake-up signal, receives a response signal from the vehicle, and uses the measured angles from both directions to calculate corrected location information, thus preserving operational simplicity while improving measurement precision

Inventive Principle:

Principle #23Feedback

3Reliability

If two-way radio frequency authentication is implemented, then security is enhanced, but system complexity increases

Engineering Contradiction:

Improveauthentication securityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The two-way communication infrastructure serves multiple functions simultaneously: it provides authentication security through encrypted password exchange, enables location determination through angle measurements, and corrects multipath errors through comparative analysis of transmission and reception angles, thus reducing overall system complexity by consolidating multiple functions into a single communication framework

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 location determination for portable access devices, reducing errors associated with multipath propagation and enabling reliable access control and vehicle operation.

Implementation Method 1

Methodology Applied

Scientific EffectMultipath propagation: Reflection

Data Source

PatentUS11270533B2Ultra-high frequency low energy based phone as a key access to a vehicle using two-way communication for multipath mitigation

Publication Date: 2022.03.08 DENSO CORP

AI summary

A system includes a transceiver and an access module. The transceiver is implemented at a vehicle: receives a first RF signal from a portable access device via multiple antennas; transmits a second RF signal from the vehicle to the portable access device; and receives a third RF signal from the portable access device. The third RF signal indicates an AOD of the first RF signal or a second AOA of the second RF signal as received at the portable access device. The access module: estimates a first AOA of the first RF signal; determines a resultant AOA based on the first AOA and the AOD or the second AOA; determines a location of the portable access device relative to the vehicle based on the resultant AOA; and permits access to the vehicle or control of a portion of the vehicle based on the location of the portable access device.