Vehicle Smart Key Position Detection Using Time-Division Antenna Signaling
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Solution Overview
Problem
Existing smart entry systems for vehicles face challenges in accurately detecting the position of a smart key due to crosstalk between antennas, which can lead to unintended engine starting when the key is outside the vehicle.
Innovation Solution
A short-distance radio communication system that uses multiple antennas both inside and outside the vehicle to transmit call signals and RSSI bursts, allowing the smart key to measure signal strength indicators and compare them with thresholds to determine its position accurately, thereby preventing engine starting when the key is outside.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple antennas are provided inside and outside the vehicle for smart key detection, then the coverage of signal detection is improved, but crosstalk between antennas occurs causing inaccurate position determination
Solution Approach 1:
The patent applies periodic action by transmitting call signals and RSSI bursts in sequential time slots to different antennas. The in-vehicle unit transmits a first call signal with first RSSI burst through the first antenna, then transmits a second call signal with second RSSI burst through the second antenna. This time-division multiplexing approach allows multiple antennas to operate without mutual interference, eliminating crosstalk while maintaining comprehensive detection coverage. The smart key measures RSSI values during specific time periods corresponding to each antenna's transmission, enabling accurate position determination.
2Reliability
If a high-power signal is transmitted to one antenna to detect smart key, then the detection capability is improved, but other antennas receive interfering signals causing false detection
Solution Approach 1:
The patent applies segmentation by dividing the detection process into separate time slots for each antenna. Instead of all antennas transmitting simultaneously, the system segments the transmission so that the first antenna transmits during a first time period and the second antenna transmits during a second time period. This temporal segmentation allows each antenna to transmit high-power signals for reliable detection without causing crosstalk to other antennas, as they operate in isolation during their respective time slots.
3Device complexity
If antennas are placed close to each other inside the vehicle for compact design, then the device complexity is reduced, but signal coverage overlap causes detection errors
Solution Approach 1:
The patent applies dimensionality change by introducing the time dimension to resolve the spatial overlap problem. Since antennas are placed close together in space (reducing device complexity), the system differentiates their signals by assigning them to different time dimensions. The first antenna transmits during a first time period and the second antenna transmits during a second time period, allowing the smart key to distinguish between overlapping spatial coverages through temporal separation. This enables compact antenna placement without sacrificing detection precision.
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 system effectively detects the position of the smart key even in cases of crosstalk, preventing accidental engine starting and ensuring secure vehicle operation.
Implementation Method 1
The in-vehicle unit transmits a first burst together with a call signal for calling the portable unit through the first antenna, and then transmits a second burst subsequent to the first burst through the second antenna
Implementation Method 2
the portable unit receives the signals transmitted from the in-vehicle unit; measures respective received signal strength indicators from the first and second bursts contained in the received signals
Data Source
AI summary
This short-distance radio communication system for a vehicle includes an in-vehicle unit having more than one antenna and a portable unit performing radio communications with the in-vehicle unit. The in-vehicle unit transmits a first burst together with a call signal for calling the portable unit through a first antenna, and transmits a second burst subsequent to the first burst through a second antenna. The portable unit receives the signals transmitted from the in-vehicle unit, measures respective received signal strength indicators from the first burst and the second burst contained in the received signals, and responds to the in-vehicle unit according to results of comparing the respective indicators with given thresholds.