PEPS Key Fob Wakeup Control for Low-Power BLE-UWB Authentication

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Solution Overview

Problem

Conventional Passive Entry Passive Start (PEPS) key systems consume significant power in the key fob due to the need for continuous RF connection with the vehicle, leading to battery drain.

Innovation Solution

A low-power PEPS key system that uses a portable device with transceiver units in a shutdown state by default, activating only upon receiving a periodic wakeup signal from the vehicle, and utilizing communication protocols like Bluetooth Low Energy (BLE) and Ultra-Wideband (UWB) for authentication and connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the key fob continuously maintains RF connection with the vehicle for authentication, then the authentication reliability is improved, but the power consumption of the key fob increases significantly

Engineering Contradiction:

Improveauthentication reliabilityVSAvoidpower consumption of key fob

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The vehicle periodically transmits wakeup signals to the key fob instead of maintaining continuous RF connection. The key fob activates its transceiver only when receiving these periodic wakeup signals, performing authentication at discrete intervals rather than continuously, thereby significantly reducing power consumption while maintaining authentication reliability when needed.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The key fob enters a low-power state and allows the vehicle to initiate communication by transmitting wakeup signals. This shifts the active role to the vehicle side, which has power supply, while the key fob conserves energy by remaining passive and only activating when stimulated by external wakeup signals.

Inventive Principle:

Principle #25Self-service

2Use of energy by moving object

If the transceiver units are kept in shutdown state to reduce power consumption, then the power consumption is reduced, but the response time for authentication may increase

Engineering Contradiction:

Improvepower consumption of key fobVSAvoidauthentication response time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The vehicle periodically transmits wakeup signals in advance before authentication is needed, prompting the key fob to activate its transceiver units beforehand. This preliminary activation ensures the key fob is ready for authentication when the vehicle initiates the process, minimizing actual response time while maintaining low power consumption between wakeups.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12342281B2Low power key systems and methods

Publication Date: 2025.06.24 FORD GLOBAL TECH LLC

AI summary

A Passive Entry Passive Start (PEPS) method is described. The method includes obtaining, via a BLE receiver of a key fob, a first BLE wakeup signal from a vehicle. In response to obtaining the first wakeup signal, the method includes activating a BLE transceiver of the key fob. Upon activation of the BLE transceiver, the method includes activating a UWB transceiver of the key fob via the BLE transceiver. When the UWB transceiver is activated, the method includes receiving a challenge signal from the vehicle via the UWB transceiver. Upon receiving the challenge signal, the method includes transmitting a response to the challenge signal via the UWB transceiver. Based on the response to the challenge signal, the method includes receiving a success signal from the vehicle. Upon receiving the success signal, the method includes deactivating BLE transceiver and the UWB transceiver.