The 2020 Practical Guide to Bluetooth
On January 7th, 20202 the Bluetooth SIG announced the latest version of Bluetooth technology, version 5.2. With each new version, new features and improvements are added to extend what the technology can do. The major changes introduced in the latest version are the ISOC (Isochronous Channels), which lays the foundation for the implementation of LE (Low Energy) Audio, LEPC (LE Power Control), and EATT (Enhanced Attribute Protocol).
Before we continue discussing the latest Bluetooth and its features, we should get to know the Bluetooth technology. We will explain to you not only what the Bluetooth protocol is but why it’s the best technology for what it does.
What Is Bluetooth?
Bluetooth is a communication technology that allows devices (e.g., smartphones, laptops, peripherals, PDAs, etc.) to transmit voice or data over short distances without cables or wires. If you’ve ever connected your smartphone to your car, you’ve used Bluetooth.
The name Bluetooth was taken from Harald Bluetooth, a 10th-century Danish king who was said to unite warring regional tribes of Denmark into a single kingdom. That analogy was used because Bluetooth technology is designed to unite a broad range of different devices across a unifying communication standard.
Wireless Personal Area Network (WPAN) is a type of network that uses wireless communication technologies, such as Bluetooth, to isolate the communications of devices in such a way that only devices on that network can communicate to each other. This improves reliability and security.
Television sets, radio receivers, and Wi-Fi all pick up programs beamed using radio waves to send and receive data. Bluetooth radio-wave technology is similar to these technologies, but what sets it apart is the fact it was designed for extremely reliable communications of up to five devices at a time. Bluetooth wireless gadgets connect via this technology using built-in radio antennas that support transmission via the version of the protocol the device is using (BD/EDR only, BLE only, or BD/EDR and BLE).
Bluetooth applications boast low power consumption compared to Wi-Fi and costs less to implement. Bluetooth v4.0 which was adopted in 2010 includes low energy consumption via Bluetooth Low Energy or BLE which was an improvement on the first version of Bluetooth now called Bluetooth Classic. Bluetooth v4.0 features enhanced range, multi-vendor interoperability, and low cost. Due to lower power requirements, Bluetooth products that use Bluetooth 4.0 won’t drain their batteries as fast as Classic, even when they’re connected to other Bluetooth devices (such as Bluetooth speakers or headsets) all the time.
How Bluetooth Works
Bluetooth transmitters send/receive radio bands in a band of 79 different channels or frequencies centered on 2.45 GHz. That frequency is set apart from mobile phones, radio, and television, and reserved for use by scientific, medical, and industrial gadgets. Because the low power of Bluetooth transmitters cannot take a signal that far, Bluetooth products will not interfere with any other devices in your vicinity. One of Bluetooth’s upsides is that these short-range transmitters don’t travel far and use virtually no power. Theoretically, they are more secure than Wi-Fi networks that operate over longer ranges. In practice, there are a few security concerns, and we discuss those in our guide to Bluetooth security.
When Bluetooth is turned on, devices automatically detect and connect to one another. Up to 8 different devices can communicate at once – one being the master device, while the rest connect as slave devices. Since each pair of devices uses one of the 79 available frequencies, they don’t interfere with each other. When connecting, two devices pick a frequency or channel randomly, and if a frequency is already taken, they will randomly switch to another frequency. This technique is commonly known as FHSS – frequency hopping spread-spectrum. A pair of devices can constantly switch the frequency they’re using up to 1,000 times per second to reduce the risk of eavesdropping on the connection and minimize the risk of interference from other devices.
Piconet is an ad-hoc network that is formed when a group of several Bluetooth devices are sharing information. In a piconet, the master device is the one that controls the network, while the slave devices follow its instructions. Other devices can leave or join an existing piconet at any moment. When two or more separate piconets join and share information, they form a network called scatternet.
Difference between Classic Bluetooth and Bluetooth Low Energy
Bluetooth Low Energy technology has appeared with Bluetooth version 4.0. It is a low power version of the original Bluetooth standard. As we mentioned previously, the original Bluetooth standard is now referred to as Bluetooth Classic. Classic and BLE are incompatible because they use different FHSS schemes, even though they operate in the same 2.4 GHz band. The Bluetooth Low Energy technology is constantly in sleep mode, except when it’s making a connection. The connection time for classic Bluetooth is approximately 100 ms, while Bluetooth LE takes only several milliseconds.
Today’s smartphones have built-in Bluetooth radios. Pairing is the process of connecting two Bluetooth devices. It works like this: two devices broadcast their presence to one another, and the devices are connected by selecting the device ID or name of one device from another device. It is important to know which device you are connecting, as there may be a code or PIN you need to enter that helps ensure you are connecting with the right device. Introduced into Bluetooth v2.1, Secure Simple Pairing (SSP) aims to simplify the pairing process of Bluetooth devices by eliminating the need for a number and encrypting all of the data transferred. Some devices that use Bluetooth to communicate do not pair. These devices are known as Beacons. Beacons are used primarily to enhance shopping experiences by being location aware and serving content depending on where in a store that user is walking or standing. Beacon technologies are discussed later on in this guide. The available technologies include Beacons, iBeacons (Apple), Eddystones (Google), and RuuviTags.
Which Devices Use Bluetooth Applications?
Originally, Bluetooth was developed with a specific use in mind, but the technology has been maturing and developing ever since. Today, it’s used in many different devices for sending information across short distances. For example, Bluetooth products like your wireless headphones and wireless speakers, communicate with your home hub, smartphone, or tablet using Bluetooth. Also, if your car was manufactured in the last few years, its sound system most likely offers Bluetooth connectivity (adding it to older cars is also easy).
Bluetooth allows users to listen to (or stream) music while at the same time talking through a wireless microphone and headset. Bluetooth also allows people to access the smart device’s contact information, use wireless mice and keyboards and even use joysticks. RuuviTags allow people to get wireless weather information including temperature, humidity, and even sense movement.
Most laptops come with built-in Bluetooth to make it easier to connect with peripherals like mice, keyboards, scanners, and printers. Some desktop PCs also have it, but we often see Bluetooth added to them via USB dongle. As for consoles, only PlayStation 4 supports third-party Bluetooth devices natively, while other game consoles use it in some manner for wireless communication. IoT devices have recently begun to support Bluetooth technology because it can be a low-power solution for keeping smart IoT devices connected to a central hub.
Limitations of Bluetooth
Bluetooth does have its downsides, but these issues are less significant as the protocol developers have continued to improve usability and security of the technology. First, classic Bluetooth can be a real battery drainer. However, newer devices come with Bluetooth versions 4.0, 4.1, 4.2, 5.0, and 5.1, which are the Low Energy versions. Also, the Bluetooth range is limited to about 100m, which is further reduced by obstacles such as walls, metal objects, water, and human bodies. Also, the pairing process may be difficult or easy depending on the manufacturers, devices involved, and other factors that can hinder connection attempts.
New Features in Bluetooth v5.0 and v5.1
The improvements in newer versions of Bluetooth can be felt only when used with compatible peripherals. In other words, if you purchase a new phone with Bluetooth v5.0, you won’t see any benefits if all your peripherals were designed for Bluetooth 4.2 or any earlier version. However, users can continue to use their existing Bluetooth 4.2 and older accessories because Bluetooth is backward compatible. If you buy new headphones or speakers with Bluetooth v5.0, they will work better thanks to your Bluetooth 5.0 smartphone.
- Dual audio. Bluetooth v5.0 allows you to play audio on two connected devices at the same time. That means you could have two pairs of wireless headphones or speakers connected to your smartphone, with audio streaming to both of them at once. Also, you could stream two different Bluetooth audio sources to two different wireless devices at the same time, meaning that two people can listen to two different songs streaming from the same phone.
- Low energy. All the improvements being made to Bluetooth technology are focused on the BLE specification, which is a low-power version of this technology. BLE has lower energy requirements to reduce the energy usage of Bluetooth devices. Meaning that it drains a smart device’s battery slower than Classic. It was originally used for beacons, wearables, and other devices with low power consumption, but it had some major restrictions.
- More distance, speed, and throughput. The primary benefits of Bluetooth v5.0 are greater range, speed, and data rates. Compared to older versions, 5.0 core specifications have two times the speed, four times the Bluetooth range, and eight times the broadcasting message capacity – with all the improvements of BLE. Bluetooth specification v5.0 devices can achieve data transfer speeds of up to 2 Mbps (Bluetooth v4.2 supports 1 Mbps). Devices can communicate over distances of up to 240 m (800 feet).
- Direction-finding. In Bluetooth core specification version 5.1, Bluetooth added a direction-finding capability. Thanks to this feature, Bluetooth devices can determine the direction of a signal that’s being transmitted from another device. This feature can significantly enhance location services solutions. With direction-finding, devices can use information about the direction of another device and use triangulation to improve location accuracy. The benefits of this new feature are great for key proximity and positioning use cases. The solutions that could benefit from enhanced direction-finding include item finding solutions, proximity marketing, PoI information solutions, Real-Time Locating (RTLS) solutions, and indoor positioning (IPS) solutions.
Many of these direction finding capabilities are being targeted for use in Beacon devices. As we previously mentioned, Beacons are used to provide targeted messages and even offers (sale!) depending on where the user is located. While very technical, direction finding uses techniques including Angle of Arrival (AoA) and Angle of Departure (AoD) to detect the direction of a Bluetooth signal to less than a 1-meter accuracy. Using AoA, assets broadcast locations to an AoA locator such as a wireless access point, connected light or smart luminaire. These locators measure the signal’s arrival angle. When using AoD to locate beacons, Beacons transmit AoD information, including the beacon’s coordinates using multiple antennas. Mobile devices, including smartphones receive the beacon’s location information and calculate a position.