This article provides an overview
Legong Technology and Qiuyuan Electronics have developed a new Bluetooth digital key solution for automobiles based on the Bluetooth 6.0 certified KW47 chip, which implements single-point Channel Sounding (CS) and multi-node listening. This solution offers high-precision Channel Sounding ranging capabilities, assisting automotive manufacturers in distance measurement and area positioning, injecting strong momentum into the current Bluetooth positioning market.
Solution Introduction
The KW47 BLE single-point CS + multi-node listening digital key positioning solution utilizes Bluetooth listening and Channel Sounding (CS) techniques. The positioning anchor points obtain the Bluetooth signal RSSI values of the key using NXP Handover technology, and the central node acquires the CS ranging values to locate the key. This solution is developed based on the KW47 chip and employs a dual onboard PCB antenna design. The prototype hardware is shown in Figure 1. It only requires a Bluetooth connection between the key and the central node, using Bluetooth technology’s CS and secure encryption mechanisms to enhance positioning accuracy and security, enabling users to unlock their vehicles seamlessly. The system consists of one central node and three listening nodes, as illustrated in the block diagram in Figure 2.
Figure 1 Prototype Hardware
Figure 2 System Block Diagram
The table below compares the performance of BLE Channel Sounding and RSSI positioning technologies. It is evident that traditional Bluetooth systems use Received Signal Strength Indicator (RSSI) for positioning, which has limited accuracy. In contrast, Bluetooth Channel Sounding technology combines Phase-Based Ranging (PBR) and Round-Trip Time (RTT) measurements to achieve high precision and end-to-end security, allowing devices supporting Bluetooth Channel Sounding to continuously measure distances with greater accuracy and security. Therefore, the introduction of Channel Sounding technology will enhance environmental perception capabilities and significantly improve positioning accuracy and stability.
Table 1 Performance Comparison of BLE Channel Sounding and RSSI Technologies
Solution Deployment and Positioning Effect
The central node of this solution is located in the center console/armrest box, while the three listening nodes are positioned on the right front fender, trunk, and left front fender of the vehicle, as shown in Figure 3. The system identifies the area where the key is located by obtaining the RSSI values and CS ranging values of the connected key, including: invalid area, welcome area, driver unlock area, passenger unlock area, trunk unlock area, and interior area, as shown in Figure 4.
Figure 3 Node Layout in the Vehicle
Figure 4 Positioning Area Results
Demo Video
The demo video of the solution is as follows:
Solution Advantages
➢ Utilizes the KW47 Bluetooth chip certified by Bluetooth 6.0;➢ Integrates RSSI listening with CS ranging, allowing for controllable positioning area range;➢ Fully implemented based on BLE technology, with a complete ecosystem and low cost;➢ CS process frequency hopping supports 72 channels, enabling multi-antenna ranging with strong anti-interference capabilities;➢ Simple architecture, requiring only a Bluetooth connection with the key;➢ Obtains RSSI for each connection event, with millisecond-level filtering algorithms.
With the advent of electrification and intelligence, the new energy vehicle industry is rapidly developing both domestically and internationally. The digital key, which continuously integrates new technologies, is attracting a large number of automotive users. A simple, easy-to-use, and stable digital key solution is key to enhancing the user experience of digital keys.
Previous Recommendations
Supporting Bluetooth Channel Sounding: NXP’s two new wireless MCUs lead you into a new era of high-precision secure spatial awareness!
Cooperation Consultation
