The Evolution of Bluetooth: Leading the Wireless Future

01

The Origin of the Bluetooth Name

This derives from a little story, in the years 940-985 AD, Harald Blatand, later known as Harald Bluetooth, unified the entire Denmark. His name “Blatand” may have been derived from two ancient Danish words. “bla” means dark-skinned, and “tan” means great person. Like many kings, Harald expanded far and wide, waging wars for political, economic, and honor. In 960 AD, Harald reached the pinnacle of his power, conquering all of Denmark and Norway. Bluetooth is the nickname of this Danish king Viking because he loved blueberries, and his teeth turned blue, hence the nickname “Bluetooth.”

The current Bluetooth logo is a combination of runes from the later Futhark script, combining the initials “H” and “B” of King Harald’s name, forming the blue emblem that people are now familiar with.

02

The Origin of Bluetooth Technology

The “Bluetooth” technology originated in 1989. Dr. Nils Rydbeck and Dr. Johan Ullman from Ericsson Mobile wanted to develop wireless headphones to replace wired ones. Dr. Jaap Haartsen joined the project later and, within just five years, made a breakthrough by proposing the first protocol. In 1999, at the Las Vegas Computer Show, they showcased the world’s first hands-free Bluetooth headphones, earning accolades.

03

Bluetooth Technology Definition

Bluetooth is a global standard for open wireless data and voice communication. It is a special form of short-range wireless technology that enables low-cost, close-proximity wireless connections between both fixed and mobile devices. As a wireless radio technology that supports short-distance communication between devices, Bluetooth facilitates low-cost, low-power, convenient, and quick data and voice communication.

Bluetooth technology has become ubiquitous in our daily lives. We can see it in our use of true wireless earphones for calls, Bluetooth speakers for music playback, and interaction with vehicles through in-car Bluetooth systems. Almost all smartphones, tablets, laptops, cars, and even household devices come equipped with Bluetooth technology. Bluetooth technology is continually revolutionizing the way we interact with devices and how devices communicate with each other.

According to the latest data from market research firm ABI Research, in 2018, global Bluetooth device shipments were around 3.7 billion units, and by 2023, this number is projected to increase to 5.4 billion units.

Before delving into the history of Bluetooth technology, it’s important to understand the role of the Bluetooth Special Interest Group (SIG). The Bluetooth Special Interest Group is a trade association composed of leading companies in the telecommunications, computing, automotive manufacturing, industrial automation, and networking industries. It is a multinational organization dedicated to developing Bluetooth specifications and promoting Bluetooth technology. The SIG owns the Bluetooth trademark, certifies manufacturers, and authorizes them to use Bluetooth technology and the Bluetooth logo. However, it does not itself engage in the design, production, or sale of Bluetooth devices.

04

The Iterative History of Bluetooth Technology

Over the past two decades, from 1994 to the present, Bluetooth technology has faced numerous challenges, including competition from various other technology standards. It even disappeared from the limelight for a while. However, during this period of more than twenty years, Bluetooth technology has continually evolved and undergone five generations of technological updates. Despite numerous versions and challenges, it remains one of the most critical technology standards in the field of wireless communication today.

05

The First Generation of Bluetooth Technology

In 1998, Bluetooth technology was introduced with the 0.7 specification, supporting both Baseband and LMP (Link Manager Protocol) communication protocols. In 1999, subsequent versions were released, including 0.8, 0.9, and the 1.0 Draft. These versions completed the development of the SDP (Service Discovery Protocol) and TCS (Telephony Control Specification) protocols.

On July 26, 1999, the official release of version 1.0A was announced, which established the use of the 2.4 GHz frequency band for Bluetooth. Unlike infrared connections, Bluetooth devices could establish connections within their effective communication range without the need for direct line-of-sight interfaces.

In the latter half of 1999, a consortium of five companies, including Microsoft, Motorola, Samsung, Lucent, and a Bluetooth Special Interest Group, collectively formed the Bluetooth Technology Promotion Group. This move ignited a global wave of enthusiasm and interest in the emerging technology, popularly known as ‘Bluetooth’.

06

The First Generation of Bluetooth

1999: Bluetooth 1.0

In its early stages, Bluetooth 1.0 and its subsequent versions, 1.0A and 1.0B, faced several issues. Products from different manufacturers were not compatible with each other, causing interoperability problems. Additionally, during the process of connecting two devices, the Bluetooth hardware’s address (BD_ADDR) was transmitted, making it impossible to maintain anonymity at the protocol level, which posed a risk of data leakage. As a result, Bluetooth technology did not gain widespread adoption. Few electronic devices supported Bluetooth functionality, and they were relatively expensive.

2001: Bluetooth 1.1

Bluetooth 1.1 was officially incorporated into the IEEE 802.15.1 standard. It defined the physical layer (PHY) and media access control (MAC) specifications for wireless connections between devices, with a transmission rate of 0.7 Mbps. Due to its early design, it was susceptible to interference from products operating on the same frequency, affecting communication quality.

2003: Bluetooth 1.2

Bluetooth 1.2 addressed the security issues of the 1.0 version, improving anonymity by introducing a feature that shielded the hardware addresses of devices, protecting users from identity sniffing attacks and tracking while remaining backward compatible with 1.1. It also introduced four new features:

1. Adaptive Frequency Hopping (AFH) technology, reducing interference issues with other wireless communication devices.
2. Extended Synchronous Connection-Oriented Links (eSCO) technology for providing Quality of Service (QoS) in audio transmission, catering to the needs of advanced voice and audio products.
3. Faster Connection feature, which shortened the time required for reconnection, making the connection process more stable and swift.
4. Support for stereo audio transmission requirements, albeit in a simplex mode.

07

The Second Generation of Bluetooth

2004: Bluetooth 2.0

Bluetooth 2.0 introduced Enhanced Data Rate (EDR) technology, which increased the capability of multitasking and running multiple Bluetooth devices simultaneously, enabling Bluetooth devices to achieve a transmission rate of up to 3 Mbps. Bluetooth 2.0 supported full-duplex mode, allowing for voice communication and document/image transmission simultaneously. By reducing the workload cycling, lowered power consumption. With the increased bandwidth, Bluetooth 2.0 could connect more devices and achieve a transmission speed over three times faster than its predecessor. This made it suitable for transferring larger files and particularly well-suited for use in headphones, as it could handle high-capacity audio files like CDs. The lower current consumption significantly extended the battery life and standby time of headphones. However, Bluetooth 2.0 had limitations, including a short range for data transmission. For Apple devices to use Bluetooth headphones, they require MFI (Made for iPhone/iPad) certification, which could be costly.

2007: Bluetooth 2.1

Bluetooth 2.1 introduced power-saving features by extending the time interval for sending mutual confirmation signals between devices from the old 0.1-second interval to approximately 0.5 seconds, significantly reducing the workload of Bluetooth chips. It also introduced Secure Simple Pairing (SSP) to improve the pairing experience of Bluetooth devices while enhancing security. Additionally, it supported Near Field Communication (NFC), enabling devices with embedded NFC chips to pair effortlessly. When two Bluetooth devices with NFC chips came close to each other, pairing passwords could be transmitted through NFC, eliminating the need for manual input.

08

The Third Generation of Bluetooth

2009: Bluetooth 3.0

Bluetooth 3.0 introduced the ‘High-Speed’ feature, which allowed Bluetooth to leverage 802.11 WiFi for high-speed data transmission, achieving rates of up to 24 Mbps. This was eight times faster than Bluetooth 2.0, making it easy to transfer data between devices like camcorders and HDTVs or PCs and printers. The core of Bluetooth 3.0 was the AMP (Generic Alternate MAC/PHY), a new alternate radio technology that enabled the Bluetooth protocol stack to dynamically select the correct radio frequency for any given task. In terms of power consumption, Bluetooth 3.0 introduced EPC (Enhanced Power Control) technology, combined with 802.11, which significantly reduced idle power consumption. Additionally, the new specification incorporated UCD (Unicast Connectionless Data) technology for one-way broadcast data, enhancing the responsiveness of Bluetooth devices.

09

The Fourth Generation of Bluetooth

2010: Bluetooth 4.0

Bluetooth 4.0 marked the first comprehensive Bluetooth protocol specification, integrating three modes into one. The most significant change was the introduction of Bluetooth Low Energy (BLE), offering three modes:

1. High-speed Bluetooth focused on data exchange and transmission.
2. Traditional Bluetooth, emphasizes information communication and device connections.
3. Bluetooth Low Energy is primarily designed for devices that do not require large bandwidth, with a 90% reduction in power consumption compared to older versions.

BLE originated from Nokia’s Wibree technology and was adopted by the Bluetooth Special Interest Group (SIG) and renamed Bluetooth Low Energy. Bluetooth 4.0 had two chip modes: Single mode, which could only transfer data to other Bluetooth 4.0 devices and was not compatible with previous versions, and Dual mode, which could be backward compatible with 3.0/2.1/2.0 versions.

2013: Bluetooth 4.1

Bluetooth 4.1 brought significant software improvements. This update made Bluetooth Smart technology a core driver for the development of the Internet of Things (IoT). It introduced automatic coordination of data transmission when Bluetooth and LTE wireless signals transmitted data simultaneously, reducing interference. Customizable reconnection intervals for Bluetooth devices added flexibility. Support for cloud synchronization was introduced with a dedicated IPv6 channel, allowing data to sync with the cloud through IPv6 when connected to internet-enabled devices. It also supported role swapping between extended devices and central devices, enabling devices to communicate directly without the need for a smartphone, tablet, or PC as a data hub.

2014: Bluetooth 4.2

Compared to Bluetooth 4.0, Bluetooth 4.2 brought several enhancements:

1. Faster data transfer: Under the Bluetooth 4.2 standard, data transfer speeds between devices increased by approximately 2.5 times compared to Bluetooth 4.1, and Bluetooth Smart data packets could carry about 10 times more data.
2. Improved security: Bluetooth 4.2 enhanced security, preventing Bluetooth signals from attempting to connect to or track user devices without user permission. It also enabled smart positioning.
3. Enhanced functionality: The new standard introduced the process of integrating the IPv6 protocol into the Bluetooth standard. Bluetooth 4.2 devices could directly connect to the internet via IPv6 and 6LoWPAN and supported low-power IP connections.

10

The Fifth Generation of Bluetooth

2016: Bluetooth 5.0

Bluetooth 5.0 offered faster and longer-range transmission capabilities in low-power mode. It doubled the data transmission rate compared to Bluetooth 4.2 (with a maximum speed of 2 Mbps), quadrupled the effective transmission range (theoretically up to 300 meters), and increased the data packet capacity eightfold. It supported indoor positioning and navigation functions, and optimized the underlying layers for the Internet of Things (IoT) with lower power consumption and improved performance, making it well-suited for smart homes.

2019 (January): Bluetooth 5.1

Bluetooth 5.1 introduced direction-finding technology, enhancing Location Services. It achieved centimeter-level accuracy. Bluetooth 5.1 used two antenna-based direction-finding technologies: Angle of Arrival (AoA) and Angle of Departure (AoD). AoA required two or more receiving antennas, and AoD required two or more transmitting antennas. Devices with Direction Finding support sent/received data packets containing Constant Tone Extension (CTE). The receiver calculated the phase difference of radio waves through IQ sampling, determining the angle of arrival or departure based on the phase difference, wavelength, and antenna spacing.

2019 (December): Bluetooth 5.2

Bluetooth 5.2 introduced a new generation of Bluetooth audio technology standards called Low-Energy Audio (LE Audio). LE Audio not only delivered higher audio quality but also provided different audio transmission mechanisms, including redefined ISO channels for connection and broadcasting, creating more diverse applications. Version 5.2 added three new features for Bluetooth Low Energy: LE Isochronous Channels, Enhanced ATT, and LE Power Control.

2021: Bluetooth 5.3

Bluetooth 5.3 focused on improving transmission efficiency, security, and stability. It addressed issues from the 5.2 version, enabling the transmission of low-speed data, enhancing encryption control, and improving periodic broadcasting. It also enhanced the periodic broadcasting, connection updates, and channel classification for Bluetooth Low Energy, further increasing communication efficiency, reducing power consumption, and improving the wireless coexistence of Bluetooth devices. It also introduced changes to device roles, renaming the Master device as Central and the Slave device as Peripheral. Additionally, it supported periodic broadcasting with Additional Data Information (ADI). The filtering of periodic broadcasting containing duplicate data reduced unnecessary data exchange, improving communication efficiency. It added an LE Enhanced Connection Update feature, greatly improving the time required to update effective connection intervals in established connections. It also introduced the LE Channel Classification feature, enabling Peripheral devices to regularly report the availability of each channel to Central devices for future hop map updates, reducing mutual interference and improving wireless communication coexistence. The High-Speed (HS) configuration was removed from the Bluetooth core specification.

2023 (January): Bluetooth 5.4

Bluetooth 5.4 introduced updates in broadcast data encryption, broadcast encoding selection, with-response periodic broadcasting, and LE GATT security level characteristics. It further enhanced the security of Bluetooth wireless communication technology, improving the user experience of Bluetooth Mesh networks and various Bluetooth applications based on GATT, and laid the foundation for developing new Bluetooth application specifications based on these new features.

11

The Upcoming Bluetooth Version

The next Bluetooth version, currently in development (the version number is subject to the future announcement by the Bluetooth Special Interest Group), introduces Bluetooth Low Energy (BLE) Channel Sounding to provide precise distance and location solutions. Channel Sounding uses both phase measurement and Round-Trip Time (RTT) measurements for distance estimation and mutual correction, offering higher accuracy and security features.

Although the Bluetooth version incorporating channel-sounding (abbreviated as CS) functionality has not been officially released, the Bluetooth SIG published a technical specification draft in November 2022 (Change Request r02). The public can download the draft specification from the Bluetooth Special Interest Group’s official website: Bluetooth SIG Draft Specification. Please note that the final technical specification may differ from the pre-released draft.

Channel Sounding, previously known as High Accuracy Distance Measurement (HADM), represents a fundamental improvement over traditional Bluetooth distance and location measurement techniques, which rely on Received Signal Strength Indicator (RSSI) and Angle of Arrival/Angle of Departure (AoA/AoD) technologies.

Compared to earlier Bluetooth location technologies, Bluetooth-based Channel Sounding offers higher security and accuracy. When combined with its low-power configuration, it becomes highly suitable for applications such as digital car keys, industrial/warehouse/consumer asset tracking, and real-time sports/fitness tracking, among other general applications.

The history and development of Bluetooth technology demonstrate its significance in the Internet of Things (IoT). With its low power consumption, high-speed transmission, and robust security features, Bluetooth is poised to extend its reach into various fields, making smart living more convenient and efficient.

Related:

1. Bluetooth vs WiFi in IoT: What’s the Real Difference?
2. Bluetooth Protocols: 1.0 to 6.0 Key Innovations
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