Traditional car keys are based on PKE/RKE technology, which is vulnerable to relay attacks. The positioning accuracy of mobile phone Bluetooth is not good enough. This article will introduce a car digital key solution based on NXP UWB technology, which has higher positioning accuracy, supports keyless entry and one-button start via mobile phone, and makes mobile phone unlocking possible.
The NXP NCJ29D5 is the first in a new generation of ultra-wideband (UWB) ICs designed to meet the connectivity and functional safety needs of the global automotive industry. UWB ICs enable cars to know the exact location of the user, with positioning accuracy down to the centimeter level. For the first time, smartphone-based car access offers the same convenience as a best-in-class remote key. Users can open and start their car with their phone in their pocket or bag, and enjoy secure remote parking services via their smartphone. In addition, the new UWB ICs minimize the risk of car theft via relay attacks.
UWB chip NCJ29D5 has the following features:
- Compliant with IEEE 802.15.4 HRP UWB PHY standard
- Supports center frequencies from 6.5 GHz to 8.0 GHz (AES-128 and AES-256)
- Low power consumption, Hard Power Down State can reach nA level
- Built-in configurable current limiter for coin cell battery powered applications
- Supports narrowband interference cancellation (NBIC) and has excellent co-channel interference suppression capabilities
- ARM®Cortex-M33 32-bit processor 55.2 MHz
- ARM® AHB-Lite bus matrix and dual-master NS-DMA for fast data transfer
- Integrated temperature sensor for crystal temperature drift compensation
- Supports high-precision external temperature sensors for precise crystal temperature drift compensation
Introduction to WPI Group's UWB automotive solution:
- The solution is mainly divided into 5 parts: key end, body anchor point, in-car anchor point, base station Bluetooth and BCM. The composition of each part is as follows:
- Key side: BLE KW38 + UWB NCJ29D5
- 4 x Body anchor points: 4 x (MCU S32K144 + UWB NCJ29D5)
- In-car anchor point: 1 x (MCU S32K144 + UWB NCJ29D5)
- Base station Bluetooth: KW38
- BCM：S32K144
Working principle of UWB solution:
- BCM as the overall dispatch ECU
- Motion sensor wakes up BLE broadcast
- BLE is used for early connection configuration of UWB and low power consumption management
- The UWB on the Keyfob starts measuring distance with each UWB anchor point
- BCM calculates the positioning result based on the measurement results of each anchor point
- BCM calculates the position of the Keyfob and takes corresponding actions
Figure 1 Schematic diagram of the working principle of the UWB solution
UWB solution test arrangement:
Keyfob can be a mobile phone or a car key, including BLE and UWB functions. There are 5 anchor points on the base station side of the vehicle. The in-vehicle positioning anchor point A1 is located near the center console, and the outside positioning anchor points A2~A5 are located at the four corners of the vehicle. The base station BLE is located on the center console, and the BCM communicates with the base station BLE and UWB anchor points through CAN.
Figure 2 Schematic diagram of UWB solution test layout
Finally, with the help of the host computer software, the precise positioning of the key can be visually seen. The GUI marks the welcome area, unlocking area, and in-car starting area, and can also display the location of the key outside the car body (front, back, left, and right).
Figure 3 UWB solution host computer software effect diagram
►Scenario application diagram
►Display board photos
►Solution Block Diagram
►Core technology advantages
UWB is a carrier-free signal that uses nanosecond narrow pulses to transmit data with a bandwidth of 500MHz Accurate positioning, can achieve centimeter-level positioning Low system complexity, low power spectrum density of transmitted signals Frequency range: 3.1GHz~10.6GHz, can coexist with Wi-Fi/Bluetooth and other signals Insensitive to channel fading, strong multipath resolution
►Solution Specifications
Compliant with IEEE 802.15.4Z HRP UWB PHY standard Supports center frequencies from 6.5 GHz to 8.0 GHz (AES-128 and AES-256) Vehicle body multi-anchor positioning solution (BLE+UWB) Can prevent relay attacks and encrypt positioning data
