What is Bluetooth's indoor range & mobile coverage area?

One of the key considerations when deciding on the infrastructure your location - be it a retail shop, a healthcare facility, a smart workplace or something else - required when looking to enable an indoor positioning system, indoor navigation and/or indoor mapping is what technology you should use. Bluetooth beacons, WiFi access points, camera-based solutions - they all have positives and drawbacks. (Incidentally, if you want further information on how to select the right infrastructure for your business, we have put together a useful post about that which you can read here).

One of the key questions we get asked by businesses looking to make this decision is the indoor range of these technologies, specifically Bluetooth. Most everyday uses of Bluetooth - headphones, computing peripherals such as keyboards and mice, certain types of remote controls - are similar in that they are rarely involve the two devices being far apart. When they are, the Bluetooth connection can be highly variable. If you connect a pair of Bluetooth headphones to a smartphone, the range you can achieve from the phone before the signal starts to break up depends on the devices involved and any objects or major obstructions between them.

Nowadays, we’re all familiar with the strength of WiFi signals indoors; how they’re strongest next to an access point, how they gradually become weaker the further you are from the access point, and how moving into another room can weaken the signal strength further. Bluetooth’s signal range, meanwhile, is something we’re less naturally in tune with.

What is Bluetooth’s range?

Bluetooth's range differs based on the device's power, its Bluetooth class, and the context in which its used- however, for the majority of users, the ranges below apply:

Theoretically, Bluetooth has no hard limit on range; with enough power, a device would be able to connect to another via Bluetooth over a kilometer away. However, the vast majority of devices (including smartphones, laptops, and computers) that leverage Bluetooth limit its power to 2.5 milliwatts, resulting in a typical range of around 10 meters. This range can be less if the signal has to travel through objects and walls.

However, Bluetooth low energy (BLE) beacons, the type typically used in indoor positioning and indoor navigation (IPIN) systems, do have a higher range - generally, the range on these devices stands at around 80 meters. 

In indoor environments in particular, however, calculating the range of a Bluetooth device with any degree of accuracy is much more difficult due to the number of potential obstructions present. We cover these in our next section.

What influences Bluetooth’s indoor range/ mobile coverage area?

Several key factors play a role in how much range Bluetooth has within an indoor environment. The three major factors are:

• Power - the majority of common Bluetooth devices that we use everyday only allocate a limited amount of power to Bluetooth to help save battery power. Bluetooth beacons, meanwhile, allocate more power and thus have a higher range.
• Obstructions - the range of a given Bluetooth device used in an empty, open building such as a warehouse will be greater than if used in a typical home, with multiple walls and other blocking objects.
• Interference - Bluetooth, like other radio signal-based technology, can be susceptible to ‘noise’ and interference from other devices. If there are hundreds of Bluetooth devices attempting to connect to a single source, it can limit the communication range.
  
  

Is the range impacted by phone signal?

There is no direct correlation between phone signal and Bluetooth; just because you have a phone signal ‘black spot’ in a particular indoor area, there’s no specific reason why this would be the case for Bluetooth signal. Equally, Bluetooth signal is completely independent of general phone signal strength; it can work without it.

The one caveat would be, for example, a room within your indoor location/ business with particularly thick walls and ceilings, which would impact both phone and Bluetooth signal (if trying to reach devices beyond that room). However, if using Bluetooth for indoor positioning and navigation, you would be able to circumvent this by simply placing a Bluetooth beacon within the affected area. It would be much harder to engineer a solution for phone signal.

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Can Bluetooth's range be extended?

Bluetooth's range can be extended, most commonly by special repeater devices which allow the Bluetooth signal to 'bounce' further. Certain Bluetooth devices can be used to create what's known as a mesh network, where the Bluetooth devices themselves can also act as repeaters for other signals, boosting the general power and range of the entire network of Bluetooth devices.

In a practical sense, when it comes to enabling an indoor environment for blue dot or indoor mapping purposes, Bluetooth beacons themselves are cheap enough that the additional cost and technical complicated of buying repeaters instead isn't worth bearing.

How important is Bluetooth signal strength when implementing indoor positioning and indoor navigation (IPIN)?

While it is important to consider the range of whatever device type you’re using for your indoor positioning and navigation system, each use case varies enormously. Any IPIN system will require multiple signal points to work effectively - the bigger the area that is being mapped, the more signal points will be needed in order to deliver an accurate positioning service. 

With this in mind, it’s perhaps more important to look at the overall cost of the solution. For example, with the standard 80 meter range of most Bluetooth low-energy (BLE) beacons, you may find you need 10 to accurately map your business location, whereas you may only need 7 high powered WiFi access points to achieve the same coverage. However, when factoring in the cost of the WiFi access points, plus the need to power them via mains electricity (compared to the battery power of the Bluetooth beacons), the range of the two solutions is less important to the decision than the ultimate cost. In many scenarios, Bluetooth beacons remain the clear choice for IPIN systems, thanks to the combination of range, low cost, battery power and accuracy that they provide.