Bluetooth 6

Bluetooth is a wireless technology for short distances. It connects devices that are close to each other without cables: headphones with a phone, a keyboard with a laptop, a smartwatch with a phone. The standard is maintained by an industry consortium and regularly revised so that all manufacturers adhere to the same rules. Bluetooth 6 is the edition of these rules that was released in September 2024. Its most important innovation is called Channel Sounding: two devices can use it to measure how far apart they are — accurate to within a few centimeters. Previously, they could only roughly estimate the distance from signal strength, which was often quite off.

Why centimeters matter more than a hand’s width

The old distance estimation was simply too imprecise for security purposes. Bluetooth measured how strongly a radio signal arrived and inferred the distance from that. But a wall, a pants pocket, or a body dampens the signal just as much as additional meters would. For a digital car key system, this is a real problem.

Criminals exploited this with so-called relay attacks. In these attacks, two perpetrators intercept the key’s radio signal inside the house and relay it all the way to the car in the driveway. The car believes the key is right next to it and unlocks. A genuine time-of-flight measurement isn’t fooled by this, because the relay measurably costs time.

There’s a second point as well: precise positioning was previously reserved for specialized devices with their own radio technology, such as the ultra-wideband chips in expensive smartphones. Bluetooth, on the other hand, is built into virtually every battery-powered device. When this capability moves into a chip that’s already installed anyway, it suddenly becomes cheap and widespread.

What happens during Channel Sounding

Channel Sounding combines two measurement methods. In the first, both devices send a signal back and forth to each other and time how long it takes. Radio waves travel at the speed of light, i.e. about 30 centimeters per nanosecond. The distance can be calculated directly from the measured time.

The second method uses the phase of the radio wave. You can picture a radio wave as a wave oscillating evenly. The devices transmit on multiple frequencies and compare at which point in the oscillation the signal arrives each time. This shift reveals the distance very precisely, but is only unambiguous as long as the distance isn’t too great. That’s why time-of-flight measurement provides the rough framework and phase measurement provides the fine detail.

Besides Channel Sounding, Bluetooth 6 also brings less conspicuous improvements. Devices can establish connections faster, send data packets in more flexible sizes, and filter out advertising packets more efficiently. This saves power, which directly extends battery life for earbuds or sensors running on a coin cell.

When the technology will reach you

One point is often misunderstood: Bluetooth 6 cannot be added via a software update. Channel Sounding requires new radio chips, because the time measurement has to happen in the hardware. So your current phone won’t get this feature, no matter how many more updates it receives. Chip manufacturers like Nordic and Qualcomm have been shipping suitable components since 2025, and they’re gradually appearing in end devices.

The first applications are likely to be car keys in smartphones, door locks, and access cards. Key finder tags will also benefit: instead of just “somewhere nearby,” the app could guide you to within half a meter of the couch. In warehouses and hospitals, the technology is being used to locate tools or equipment.

In the news, you’ll usually encounter the term in product announcements and at trade shows like CES. Pay attention to one distinction there: the version number alone says little about which features a device actually supports. Many of the standard’s new features are optional, so manufacturers are allowed to leave them out. “Bluetooth 6” on the packaging therefore doesn’t automatically mean that Channel Sounding is included.