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Digital Car Keys Step into Era of UWB Dec 19, 2023

The BLE Legend

BLE-enabled digital car key systems that realize features of passive keyless entry (PKE) or even passive entry and passive start (PEPS) have reaped wide popularity among car makers, as that single ECU gives their new models an intelligent face lift.

However, existing BLE systems are inherently vulnerable to relay attacks, making PKE/PEPS exposed to thefts and hijacks. A TikTok short video showing how two thieves stole a Bentley with some simple relay attack tool in thirty seconds went viral recently.

UWB Came to Rescue

Such incidents aroused worries among motorists and car buyers, and also prompted carmakers to rethink the baseline technology of the existing digital car key system. The Ultra-Wide-Band (UWB) technology came into their scope of view. Due to its features of much higher locating precision and ultra-high frequency pulse radio that is immune to relay attacks, it has become a major part of the global standard for digital car keys issued by the Car Connectivity Consortium – CCC3.0. Other two-car connectivity standard bodies – ICCE and ICCOA also recognized it by including it as a major enabling technology.

Digital Car Keys Step into Era of UWB

From 2022 on, car makers such as BMW, BYD, Geely and NIO began to ship UWB-enabled car models for premium car owners. Such quick adoption is not only built upon the technology's supremacy but also over a belief that the economy of scale will be realized soon. The source in the technical circle said Qualcomm will release a UWB-embedded smartphone SoC in early 2024. That will prompt major phone makers to produce UWB smartphones to join the league of Apple iPhone, making the UWB installation base terminal wise dramatically increase. And people believe in the near future, the UWB will become a ubiquitous wireless communication technology in daily life. The foreseeable huge terminal user base boosted undoubtedly car makers’ confidence in the technology.

Why UWB for Digital Keys?

Now, let us look at some major technical properties of UWB to get a deeper understanding of why we need UWB for next-generation digital keys of future vehicles.

Precise Location

The UWB communication involves the information exchange between the UWB keyfob (also known as Tag) and the UWB Anchor installed in the car. The Time-of-Flight (ToF) measurement uses specific fields in the UWB messages as timestamps to calculate precise distance. UWB technology utilizes very short pulses (lasting only nanoseconds) of low-power signals with a wide bandwidth (> 500 MHz). UWB’s wide bandwidth and short pulses bring little interference and few multi-path effects compared to narrowband signals. In some ways, UWB can effectively measure range with an accuracy of up to 10cm.

UWB Ranging Process

Enhanced Security

Today's technologies relying on signal strength to evaluate distance are vulnerable to relay attacks. Car thieves intercept and amplify the signal strength of a valid key and deceive the receiver into believing that the digital key is nearby. Then, these attacks cause the locked car to unlock easily.

However, UWB technology is not susceptible to such attacks because it measures distance based on time. In a relay attack, the message transmission will experience additional latency, making it appear that the key is farther away from the receiver. Moreover, the IEEE 802.15.4z standard extends a security level called Scrambled Timestamp Sequence (STS) at the PHY layer. This feature adds a cryptographic timestamp to protect against decoding or manipulation by third parties.

High Data Rate

The pulse radio requires a lot more spectrum to ensure reliability. That is why it is called "Ultra-wideband." In UWB, a single band typically covers a width of 500MHz, whereas 4G LTE with 5 to 20MHz band or 20MHz to 80MHz for WiFi. Thanks to the broad spectrum, pulsed data can be transmitted rapidly without compromising accuracy. It is proven that UWB can achieve data transmission rates of hundreds of Mbit/s to several Gbit/s in the range of about 10 meters.

These special features of UWB significantly contribute to developing new-generation digital keys for the Intelligent Connected Vehicle (ICV) industry.

UWB for More Automotive Applications

With its unprecedented development and innovation, UWB technology also will shoot up in more automotive scenes, including but not limited to digitally sharing car keys with others, personal settings configuration, automated valet parking(AVP), Radar-based kick sensor, Radar detection for child and pet in-vehicle safety, etc. It is believed that UWB will be involved in more wireless connectivity in the Vehicle to Everything (V2X) industry in the coming days.

Now let’s explore RF-star’s digital car keys embedded with UWB and BLE technology.

RF-star Released UWB+BLE Digital Car Key Solution

RF-star recently released a digital car key solution that integrated UWB, BLE and NFC technologies. The three played their respective roles in concert to ensure the car access feature both user-friendly and highly secure.

Block diagram of UWB+BLE digital keys from RF-star

Wake-up Service with BLE

The BLE node in the car detects a smartphone approaching from as far as more than 30 meters. When the node verifies the BLE public key of the phone, the car initiates the first data exchange and verifies the authenticity of the digital car key. This initial interaction establishes a connection between the car and the authorized smartphone of the car owner, ensuring the car's low power consumption.

Nevertheless, BLE technology lacks enough precision to accurately locate the car key within a few centimeters. In the next moment, UWB comes into play.

Centimeter-Level Localization Accuracy with UWB

When the car owner with a digital key is close to 10 meters away from the vehicle, the first BLE connection will trigger UWB components to locate the holder of the key fob or smartphone. This is realized using in-car transmitting/receiving units known as UWB anchor nodes. In general, one UWB anchor installed in the car center console and four of them placed in the "corners" of the vehicle, can perfectly achieve precise positioning of the mobile terminal under almost all conditions.

UWB Protect Against Relay Attacks

As the UWB security part states, individual UWB anchors in smartphones or cars calculate the distance based on the time measurement. Hackers are scarcely able to intercept and relay the signal from a key to the vehicle.

What’s more, all communications are secured through the Digital Key standard protocol with public and private keys to encrypt and decrypt messages.

NFC as Alternative in Case of Emergency

The digital key with NFC technology is a backup solution for car access when the smartphone battery runs out.

CCC, ICCE and ICCOA Compliant

Since 2023, RF-star has been a member of the Car Connectivity Consortium(CCC), the Intelligent Car Connectivity Industry Ecosystem Alliance (ICCE) and the Intelligent Car Connectivity Open Alliance (ICCOA). Its UWB+BLE digital car keys comply with the CCC Digital Key Release 3 and other important standards, to help build an open and collaborative ecosystem for smart vehicles.

Cost-Effective Automotive-Grade Solution

RF-star offers digital keys integrated 1+3 and 1+4 UWB anchors based on easy-use automotive-grade chips from China, which can achieve centimeter-level positioning accuracy and higher safety.

Besides, the customization of digital car keys, with an expandable configuration of 1+N anchor nodes is also ready for you.

For more information about UWB +BLE digital keys and automotive applications, visit or reach us by email address

About RF-star

Shenzhen RF-star Technology Co., Ltd (RF-star) is a leading global provider of wireless communication modules and solutions, specializing in low-power modules for IoT, industrial, automotive, and consumer applications. With over a decade of engagement in Bluetooth and IoT communication technology and extensive expertise, we are capable of bringing reliable, convenient, secure and intelligent connectivity service to every industry, enriching smart life with a perfect wireless experience.

RF-star's product portfolio ranges from BLE modules, ZigBee modules, WiFi modules, Sub-1Ghz modules, Matter modules, Thread Modules, UWB modules Wi-SUN modules and customized service. As the official third-party IDH of TI and a trusted partner for customers worldwide, RF-star is committed to delivering cutting-edge wireless solutions.

Related Resources: Bluetooth BLE PEPS And UWB Digital Car Key

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