What is Bluetooth Low Energy?
Bluetooth Low Energy is a wireless, low-power personal area network that operates in the 2.4 GHz ISM band. Its goal is to connect devices over a relatively short range. BLE was created with IoT applications in mind, which has particular implications for its design. For example, IoT devices tend to be constrained and require extended battery use, so BLE favors low power consumption over continuous data transfer. In other words: when not in use, it goes into sleep mode to conserve energy.
What is essential to understand when talking about BLE-equipped devices is the architecture behind the technology, particularly its asymmetry. A device may function either in a central or peripheral role. Imagine your smartphone and your smart band: the more “advanced” and complex smartphone is the central device; the smart band, which has limited functionality – is the peripheral. Neither two central nor two peripheral devices can talk to each other. Communication is only possible between a central and a peripheral device. To overcome that limitation, a device may have both a central and a peripheral mode configured, as many smartphones do.
The device mode should not be confused with its Generic Attribute Profile (GATT), where a device can either act as a server or a client. Once two devices establish a connection, the one that sends out the data is the server, and the one that receives it is the client. So if a smart band sends, let’s say, heart rate monitor readings to the smartphone, then it acts as a server. But if the smartphone sends a software update to the smart band, then the smartphone is the server.
Is BLE the same as Bluetooth?
One more important question that we need to answer when talking about Bluetooth Low Energy is how it differs from Bluetooth Classic – the technology we all know for its famous icon that we click on when we want to pair our devices. Does it differ at all?
The answer is yes. BLE is an independent standard that is incompatible with the “classic” Bluetooth. The latter was first introduced commercially over 20 years ago and is now essentially no longer being developed by the Bluetooth Special Interests Group (SIG). However, “not being developed” doesn’t mean “not being used.” You will frequently find it in devices that require continuous connection, predominantly audio devices, such as wireless speakers or headphones.
Meanwhile, SIG introduced Bluetooth Low Energy in its 2010 Bluetooth 4.0 specification (with later, 2016 Bluetooth 5 specification, being devoted exclusively to BLE). Its main focus was on the growing market of health- and fitness-related devices and smart home and indoor location.
You may be largely unaware which standard your devices use, as most laptops, tablets, and smartphones come equipped with both Bluetooth Classic and BLE for a seamless user experience, regardless of what peripheral they have. Having said that, there are some critical differences between the two:
- Bluetooth Classic is designed for continuous, two-way communication, whereas BLE transfers smaller packets of data over short periods of time;
- as the name suggests, Bluetooth Low Energy has much smaller energy consumption (as much as 100 times smaller than Bluetooth Classic!);
- on the other hand, because Bluetooth Classic is not so limited, it has a longer range and higher data throughput.
Where can you find BLE?
Bluetooth Low Energy is used virtually anywhere, which is one of its core strengths compared to other low-power networks. It is a commonly recognized and applied standard that essentially doesn’t require specialized compatible hardware to be deployed. So if BLE is so popular, how is it being used?
Fitness trackers and smart appliances
This is one of the primary use cases for Bluetooth Low Energy that arguably made it so ubiquitous. Because Bluetooth technologies (both classic and BLE) are so commonly available in smartphones, tablets, and laptops, it stands to reason that personal devices that we frequently pair with them – such as fitness trackers and various smart appliances – would use these, too.
While you can think of even more constrained devices, smart appliances and trackers usually have pretty heavy limitations as well. The bulk of their energy goes into basic functioning. Consider your smart band: it probably measures your steps or monitors your heartbeat continuously, using up a lot of battery life. If it were constantly relaying that information to your phone, too, it would drain the battery life a lot faster. This is why manufacturers look for ways to save energy here and there, and BLE is a perfect solution.
Indoor location tracking
One of the major BLE benefits is that it can be used for accurate positioning where GPS can’t – indoors. You can use BLE-equipped devices as beacons, i.e., to broadcast data to all devices in the vicinity, rather than to have one-to-one exchange. Based on that, devices capable of processing that data (such as phones) or simply capturing and relaying it further (such as access points) can determine the beacon’s position.
This is why BLE is frequently used in indoor navigation systems, for example, in shopping malls that want to provide customers with GPS-like indoor mapping that will help them navigate to their favorite shop. But retail software for indoor positioning has more applications. Among other things, stores can use platforms such as Linkyfi to identify potential customers nearby and advertise their best deals (for example, via push notifications) for more targeted marketing that attracts more attention.
