了解蓝牙通道探测: 它是如何运作的, 好处, 及应用

Minew 扬. 20. 2025
目录

    介绍

    Bluetooth technology is a prominent part of the wireless communication world. It enables indoor positioning and seamless connection between 蓝牙低功耗 (低功耗蓝牙) 设备. 在蓝牙中引入 6.0, 蓝牙频道的声音技术吸引了许多行业的关注. It’s known for the secure, precise-ranging capabilities of Bluetooth devices. But what exactly is it, and how can it be a game-changer in Bluetooth positioning? Follow the blog, and we’ll dive into more details about Bluetooth Channel Sounding.

    understanding bluetooth channel sounding

    The History of Channel Sounding

    Bluetooth positioning technology has been developed as industries keep requiring more accurate and secure tracking solutions. In the beginning, BLE used 信标 to achieve simple proximity detection. These beacons sent out signals that nearby devices could pick up, estimating distance based on signal strength (接收信号强度指数). This made it possible for basic applications like simple asset tracking and proximity marketing.

    在蓝牙中 5.1, Bluetooth technology made a great leap forward in positioning with Bluetooth Direction Finding. 蓝牙 5.1 introduced new methods like 到达角 (迎角) 和出发角 (AOD) to make devices capable of sensing the direction of signals. Beyond that, it took accuracy to the next sub-meter level. These changes have transformed indoor navigation and location-based solutions.

    What is Channel Sounding?

    Bluetooth Channel Sounding is introduced in the Bluetooth 6.0 core specification for secure, fine-ranging between Bluetooth devices. It uses Phase-based Ranging (策略性BR) and Round-trip Time (实时传输时间) to measure the distance, providing centimeter-level accuracy compared to the Received Signal Strength Indicator (接收信号强度指数). The combined use of these two methods makes Bluetooth Channel Sounding a considerable choice in applications requiring high security, such as digital keys and identity authentication.

    How does Channel Sounding Work?

    The secure, fine-ranging capability is achieved by two methods: Phase-based Ranging (策略性BR) and Round-trip Time (实时传输时间).

    Phase-based Ranging (策略性BR):

    By measuring the phase difference of wireless signals, PBR technology can accurately determine the distance between two devices. There are two devices — the Initiator and the Reflector — involved in PBR. Here’s how it works:

    信号传输: The Initiator sends out a radio signal with a known frequency and phase.

    Signal Reception: The Reflector measures the phase of the received signal and sends a response back to the Initiator.

    Phase Difference Measurement: The Initiator calculates the phase difference between the sent and received signals, which provides information on the signal’s travel time.

    Distance Calculation: Using the known travel time and the speed of light or electromagnetic waves, the distance between the two devices is calculated.

    Compared to solutions like RSSI, PBR offers more accurate measurements and is harder to manipulate.

    phase-based ranging

    Round-trip Time (实时传输时间):

    Round-trip Time (实时传输时间) stands for the time it takes for a signal to travel from an Initiator to a Reflector and then back again to the Initiator. In a typical measurement system, the Initiator sends a signal to the Reflector. The Reflector then sends a response back to the Initiator. RTT is the total time taken for the signal to travel from the sender to the receiver and back. In Bluetooth Channel Sounding, RTT is used as a supplementary method to verify PBR measurements and prevent relay attacks from man-in-the-middle (MITM) attacks.

    round-trip time

    The Benefits of Channel Sounding

    High-accuracy Distance Measurement: It provides precise distance measurements with centimeter-level accuracy, improving location tracking precision.

    安全: The complexity of phase-based measurements makes it harder to spoof, enhancing security.

    Enormous Bluetooth Device Ecosystem: Based on the standard Bluetooth protocol, the devices can leverage the large Bluetooth ecosystem and work seamlessly with other BLE devices and systems.

    低功耗: BLE-enabled devices typically have long service lives. Some BLE-enabled sensors remain reliable for up to 5 年.

    多功能性: In addition to Bluetooth Channel Sounding, 蓝牙 6.0 defines more new features to increase technical flexibility.

    The Use Cases of Channel Sounding

    室内导航

    Bluetooth Channel Sounding performs well in areas where GPS signals are unreliable, like shopping malls, 机场, 和医院. It provides real-time indoor guidance that can enhance visitor experiences. 同时, it ensures privacy protection in sensitive areas like hospitals.

    Find My Solution

    By accurately measuring the distance between devices, Channel Sounding can improve查找我的” 应用. This can be used for locating lost items or tracking devices, offering reliable results even in crowded or signal-blocked areas.

    资产追踪

    Channel Sounding plays a key role in asset tracking solutions, ensuring the precise location of equipment or inventory in real-time. Its accuracy helps businesses track assets in warehouses, 工厂, logistics hubs, or other locations where high precision is required.

    近距离营销

    With Channel Sounding, proximity-based marketing systems can target customers more effectively. By accurately determining customer locations, businesses can send personalized offers or advertisements when a customer is near a specific product or location.

    The Comparsion of Channel Sounding and other Positioning Solutions

    In comparing AoA vs channel sounding for positioning solutions, channel sounding provides a more detailed assessment of the wireless channel’s characteristics, including multipath effects, while AOA focuses on direction estimation. Here is the completely table of the comparison among channel sounding, AoA and RSSI:

    特征 蓝牙信道探测 接收信号强度指数 到达角 (迎角)
    Localization Metric Calculates distance based on time of flight and phase-based ranging Estimates distance using signal strength from the transmitter Determines relative angle between two points
    准确性 Centimeter-level accuracy Meter-level accuracy Sub-meter accuracy
    安全 安全性高, hard to spoof Lower security, easy to spoof Moderate security, less prone to spoofing than RSSI
    Environmental Interference Less affected by environmental factors Highly affected by environmental factors Less affected by environmental interference, but still sensitive to obstacles
    Advantages 高精度, 安全的, ideal for complex environments where need fine-ranging capability and high security Simple and cost-saving, good for basic proximity detection Scalable, low-power real-time tracking solution

    The Future of Channel Sounding

    The future of Bluetooth Channel Sounding looks promising. According to Bluetooth SIG, Bluetooth Channel Sounding provides huge technical flexibility to developers. It is set to address the location ambiguity issues in high-density environments, where traditional positioning methods may not work as well. A secure, fine-ranging positioning technology can help developers, especially in the IoT industry, unlock possibilities in more applications, such as high-value asset tracking, FindMy solutions, and digital solutions for end customers.

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