Bluetooth, developed in the late 1990s, is a technology designed to enable short-range wireless communication between electronic devices, such as between a laptop and a smartphone or between a computer and a television. Bluetooth radio technology was developed by L. M. Ericsson in 1994. The standard is named after the King of Denmark, Harald Blaatand (“Bluetooth”).
Major mobile phone manufacturers and technology providers comprising IBM, Nokia, Intel, Ericsson, and Toshiba created the BluetoothSpecial Interest Group (SIG). The aim of the group was to invent an open speciﬁcation for wireless technologies of short range. Bluetooth SIG continues to oversee Bluetooth technology today. 3COM, Microsoft, Lucent, and Motorola also promote the SIG group currently. The SIG now has more than 1900 companies since it was created.
Bluetooth works by using radio frequencies, rather than the infrared spectrum used by traditional remote controls. As a result, Bluetooth eliminates the need not only for a wire connection but also for maintaining a clear line of sight to communicate between devices.
Bluetooth allows for short-range data transfer between devices. Bluetooth technology is useful when transferring information between two or more devices that are near each other when speed is not an issue, such as telephones, printers, modems and headsets. It is best suited to low-bandwidth applications like transferring sound data with telephones (i.e. with a Bluetooth headset) or byte data with hand-held computers (transferring files) or keyboard and mice. As an example, it is commonly employed in headsets for mobile phones, enabling hands-free phone use.
Bluetooth Low Energy
Bluetooth Low Energy generally referred to as “Bluetooth Smart” was speciﬁcally created for scenarios, which have a low duty cycle and was marketed to the public in October 2010. For instance, a belt that records the heart rate can be hooked on for many hours, say during a workout session, but will only need to send a limited number of bytes of data per second. Therefore, in an enhanced and optimized protocol, Bluetooth radios will be kept “on” for just a few milliseconds. In comparison, a headset or a wireless speaker would transmit much more data (typically many kilobytes in just one second and the radio is turned on for a reasonably long time.
Bluetooth Low Energy (BLE) was devised speciﬁcally for use cases that Bluetooth classic was not suited for. Currently, Bluetooth Smart has been broadly adopted in many types of health and ﬁtnessapplications including some sports-related use cases. The BLE technology also has potential for use in medical devices and for newer applications such as beacons and proximity tags. Recently there is also an increase in many types of “connected” devices for home networking and smart grids, as well as an array of smartwatches, motion monitoring devices, and other smart tools and gadgets.
Bluetooth Smart serves as a driver of the Internet of Things (IoT). Instead of acquiring a direct internet connection, gadgets that are Bluetooth Smart may acquire Internet connectivity via other devices that are Bluetooth Smart Ready. This approach provides a cheaper and lower power-consuming solution. It is predicted that by 2023, more than 1.6 billion Bluetooth Low Energy devices will be shipped each year, and 90% of all Bluetooth devices will include Bluetooth Low Energy technology.
The Bluetooth system operates in the 2.4 GHz Industrial, Science, and Medical (ISM) band. The frequency band is in the 2400.0–2483.5 MHz range, with Radio Frequency (RF) channels being spaced at 1 MHz. Two data transmission modes are deﬁned: Basic Rate (BR) which uses a shaped, binary frequency Modulation (FM) to minimize transceiver complexity, and Enhanced Data Rate (EDR) which uses Phase Shift Keying (PSK) modulation and has two further variants:π/4-Diﬀerential QuadraturePhase Shift Keying (DQPSK) and Diﬀerential Phase Shift Keying (DPSK). Basic Rate (BR) mode is a mandatory part of the Bluetooth speciﬁcation. The modulation that BR uses is Gaussian FrequencyShift Keying (GFSK). In Enhanced Data Rate (EDR) mode, the scheme used for modulation is altered inside the packet. The packet header and the access code are sent using the Basic Rate of 1 Mbit/s GFSKmodulation scheme, while subsequent synchronization sequence, payload, and trailer sequence are transmitted with the EDR PSK modulation scheme.
A combination of devices connected via Bluetooth in an ad-hoc mode is called a piconet. In a piconet, one Bluetooth device acts as a master and the other devices act as slaves. The device that starts communication is the master node and the other devices are slaves. A piconet consists of a minimum of two connected devices and can extend up to eight connected devices (one master and seven slaves). Every Bluetooth device can act as a master or a slave device. When there is a single slave device, a piconet is a simple point-to-point link. A point-to-multipoint arrangement can have a maximum of seven active slaves under the control of a single master. Slaves always exchange data through the master node. Communication across piconets creates a scatternet. Scatternets exist when a Bluetooth device is a slave in one piconet and simultaneously a master or a slave in another piconet.
All devices share the Bluetooth master’s clock. The basic clock has a clock cycle time of 312.5 microseconds (µs). The time base of packet exchange is the basic clock. A slot of 625 microseconds consists of two clock cycles; a slot pair of 1250µs consists of two slots. The master sends in even slots and receives in odd slots; for the case of slaves, transmission occurs in odd slots and reception occurs in even slots. Upon powering up, a Bluetooth device can operate in slave mode when the master device is already operating. The slave waits for inquiries from the masters and provides replies. The master and slave devices can change roles, which would be necessary when a Bluetooth device participates in more than one piconet.
Bluetooth operation utilizes seven diﬀerent protocols: radio protocol, baseband protocol, RadioFrequency Communication (RFCOMM), the Service Discovery Protocol (SDP), Link management protocol (LMP), the Logical Link Control and Adaptation Layer Protocol (L2CAP), and the HostController Interface (HCI) protocol.
Bluetooth-enabled devices can establish Synchronous Connection-Oriented (SCO) and Asynchronous Connectionless links (ACL). Data packets use ACL primarily while voice packets use SCO. ACL links are primarily deﬁned for data transmission. They support asymmetrical, symmetrical and packet-switched connections.
Annual shipments of Bluetooth-enabled devices are set to top seven billion by 2026, according to the technology’s industry body, driven by new categories of devices. Bluetooth technology powers everything from smartphones and wearables to smart home devices and headphones. It extends its reach into other areas, like virtual reality (VR), asset tracking, and low-energy audio devices. The Bluetooth Special Interest Group (SIG) said shipments slumped during the pandemic as Covid-19-related lockdowns hampered consumer demand and disrupted supply chains.
Bluetooth Low Energy (LE) Audio is one of the biggest growth areas, promising higher quality sound and lower power consumption for products like speakers, headsets and earbuds. By 2026, shipments of Bluetooth-enabled earbuds will reach 619 million – two thirds of all wireless headsets. In Meanwhile, the characteristics of LE Audio will enable entirely new products like smart hearing aids.
Bluetooth LE Audio is set to change the way we listen, but what drives the technology itself? Bluetooth LE Audio works through compressing the necessary data using an algorithm known as a Low Complexity Communication Codec (LC3) to reduce the throughput. Once received, another algorithm decompresses the data, allowing users to stream the same audio quality at reduced bitrates. This design also makes the creation of untethered earphones easier, as both can receive the stream with synchronized playback (through isochronous channels) instead of the old point-to-point stream.
Bluetooth wearables gaining strong momentum
The Internet of Things (IoT) has seen incredible growth in a very short period. Smart wearables are one of the most popular consumer IoT segments, a trend that will continue to grow in 2022. Most common are smartwatches and fitness trackers, but connected wearables are becoming more diverse. Examples include smart rings, smart glasses, and connected fabrics such as apparel, which will grow rapidly this year.
From smart home appliances to health sensors and medical innovations, Bluetooth technology connects billions of everyday devices and enables countless device inventions and use cases. New forecasts from the 2022 Bluetooth Market Update show approximately 5.1 billion annual Bluetooth device shipments in 2022 alone. Greater awareness of personal health, wellness and fitness monitoring, coupled with an increase in telehealth requirements during the pandemic, is driving the growth in wearables shipments.
According to the Centers for Disease Control (CDC), the number of telehealth visits increased by 50% in the first quarter of 2020. This is a result of greater demand for remote monitoring and early detection of health-related issues and health wearables used to monitor vital signs, track exposure and allow the integration with telehealth services.
Bluetooth Location Services
The Bluetooth Location Services market is also moving in the right direction. Expectations for the segment are to exhibit healthy medium-term expansion, with 32 percent CAGR in annual device shipments from 2021 to 2025.
According to the report, retail is the vertical taking the most significant advantage of Bluetooth Location Services, with 66 percent of all implementations currently supporting retail use cases. At the same time, 79 percent of Bluetooth Location Services solutions include indoor navigation properties. For example, 136 million Bluetooth RTLS tags and personal trackers will ship in 2021, the report claims, with 4 x growth in asset tracking tag shipments and 5 x growth in Bluetooth healthcare location services implementations predicted by 2025. The effects of the pandemic primarily spur the latter.
Virtual Reality and Augmented Reality devices will also be a source of growth as metaverse-related applications gather pace. The Bluetooth SIG says the number of compatible VR headsets will rise by 51% between 2022 and 2026, while AR units such as smart glasses will increase by 68%. Shipments of Bluetooth-enabled real time locating systems (RTLS) will increase threefold by 2026, reaching 250 million.
The ever-expanding categories of connected devices using Bluetooth ensures that this technology remains the number one technology for the Internet of Things. The widespread use of Bluetooth technology has demonstrated that anything can be a connected device, and the ability to collect data and turn used this information provides additional value for both businesses and consumers.