How did Bluetooth technology come about?-EEWORLD

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During World War II, Hollywood actress Hedy Lamarr, who should have relied on her beauty to make a living, chose to rely on her strength to join hands with pianist George Antheil to study frequency hopping spread spectrum (FHSS) technology. According to relevant records, this technology was patented in August 1942. In the nearly half a century that followed, this technology was not taken seriously until the 1980s, when FHSS technology was used by the military for wireless communication systems on the battlefield. Later, FHSS technology was introduced to the mass market and also affected the development of wireless technologies such as Bluetooth and WiFi.

Times have changed, and the Bluetooth technology based on FHSS has also undergone tremendous changes. Its standard has been upgraded from Bluetooth 1.0 to Bluetooth 5.0 and then to LE Audio. In the process of this technological change, what has changed in Bluetooth?

The origin of Bluetooth technology

Bluetooth technology can be traced back to 1994. Ericsson started to study Bluetooth technology as an alternative to RS-232 data lines. RS-232 is one of the commonly used serial communication interface standards. It was jointly formulated by the American Electronics Industry Association (EIA) and Bell System, modem manufacturers and computer terminal manufacturers in 1970. The RS-232 bus specifies 25 lines, including two signal channels, namely the first channel (called the main channel) and the second channel (called the secondary channel). RS-232 uses a point-to-point connection, and usually one serial port can only connect to one peripheral. Bluetooth technology can connect multiple devices, thus overcoming the problem of data synchronization. Therefore, Bluetooth technology is regarded as a low-power, low-cost wireless communication connection method between mobile phones and other accessories.

In 1997, Ericsson approached mobile device manufacturers with this concept to discuss the cooperative development of its project and obtain support. In 1998, five companies including Ericsson, Nokia, Toshiba, IBM and Intel established the predecessor of the Bluetooth Technology Alliance, the "Special Interest Group" (SIG), whose goal was to develop a low-cost, high-efficiency Bluetooth technology standard that can be connected wirelessly at will within a short range. In the process, an interesting thing happened about the naming of Bluetooth. At that time, the contract framework of SIG was nearly completed, but the official name of this short-distance wireless connection technology had not yet been determined. Its alternative name PAN had a high traffic in the Internet search engine at that time because it was biased towards buzzwords. Therefore, the trademark search did not pass. Jim Kardach of Intel suggested using Bluetooth as a temporary code name. Later, someone quoted Kardach as saying: "King Harald Bluetooth is famous for uniting Scandinavia, just as we intend to combine the PC and cellular industries through short-distance wireless links."

Version 0.7 is the first standard version of Bluetooth, which supports Baseband and LMP communication protocols. Later, SIG was established and successively released Bluetooth versions 0.8, 0.9, 1.0 Draft, 1.0a and 1.0B. In the second half of 1999, Microsoft, Motorola, Samsung, Lucent and the Bluetooth Special Group jointly established the Bluetooth Technology Promotion Organization, which set off a Bluetooth craze around the world.

The evolution of Bluetooth standards drives changes in terminal applications

Amid this Bluetooth craze, the Bluetooth standard has also changed along with the needs of technology terminal applications.

Bluetooth 1.0, launched in 1999, was not immediately widely used because of technical data leakage issues. In addition, there were few types of electronic devices with Bluetooth functions at the time, and Bluetooth devices were very expensive, which was also one of the reasons why Bluetooth was not widely adopted. It was not until 2001 that Bluetooth 1.1 was launched as the first commercial version to the market. This version of the Bluetooth standard was also officially included in the IEEE standard, also known as IEEE 802.15.1. In the same year, the number of SIG member companies exceeded 2,000.

After a few years, Bluetooth became a must-have feature of electronic products, and its price dropped significantly due to the maturity of technology. In order to expand the application level and transmission speed of Bluetooth, SIG launched version 1.2 (this version added anti-interference frequency hopping function to solve the problem of easy interference) and version 2.0 in 2003 and 2004, and added many new features. According to Wikipedia, version 2.0 added EDR (Enhanced Data Rate, which increases the maximum transmission speed to 3Mbps in accordance with the technical standards of 2.0), A2DP (Advanced Audio Distribution Profile, a control track distribution technology, mainly used in stereo headphones), AVRCP (A/V Remote Control Profile), etc. Bluetooth 2.0 increased the transmission rate to 2Mbps and 3Mbps, which is much higher than the 1Mbps of version 1.x (actually about 723.2kbps). Bluetooth version 2.0 began to support duplex mode, that is, voice communication while transmitting data. It was also from this version that Bluetooth was recognized by the market. Subsequently, in mid-2007, SIG improved the existing problems and released Bluetooth 2.1. At this time, the emergence of Bluetooth technology enabled mobile phones to transmit audio, video, and pictures to each other. However, the way to connect mobile phones via Bluetooth was relatively cumbersome at the time. Both paired parties displayed a 6-digit number. The user had to check whether the numbers were consistent and enter Yes/No. If both ends said Yes, they could be paired. Although this method was cumbersome at the time, it could prevent man-in-the-middle attacks.

In 2009, Bluetooth 3.0 also began to be marketed, using a new alternating radio frequency technology and canceling the UMB application. In April of this year, the Bluetooth Technology Alliance promulgated the Bluetooth Core Specification Version 3.0 (3.0+HS), which is a new alternating radio frequency technology. Bluetooth 3.0+HS improves the data transmission rate, and the integrated 802.11PAL has a maximum speed of up to 24Mbps, which is 8 times the speed of Bluetooth 2.0. In addition, enhanced power control is introduced, and the actual idle power consumption is significantly reduced. This feature also adds closed-loop power control, which means that RSSI filtering can be carried out at the same time as the response is received. In addition, this version also adds a "go straight to maximum power" request to deal with the link loss of the headset, and traditional Bluetooth headsets are gradually entering the market.

In 2010, the release of Bluetooth 4.0 once again revolutionized Bluetooth technology. When this version was released, SIG also proposed three modes: "Bluetooth Low Energy", "Traditional Bluetooth" and "High-Speed Bluetooth". Among them, High-Speed Bluetooth focuses on data exchange and transmission; Traditional Bluetooth focuses on information communication and device connection; Bluetooth Low Energy, as the name suggests, focuses on device connection that does not require too much bandwidth. Its predecessor was actually the Wibree technology developed by NOKIA. It was originally a mobile wireless communication technology with extremely low power consumption developed specifically for mobile devices. After being accepted and standardized by SIG, it was renamed Bluetooth Low Energy (hereinafter referred to as Bluetooth Low Energy). These three protocol specifications can also be combined with each other to achieve a wider range of application modes. In addition, Bluetooth 4.0 also increases the transmission distance of Bluetooth to more than 100 meters (under low-power mode conditions). So far, the release of Bluetooth 4.0 has also laid the foundation for the development of the Internet of Things.

Then, at the end of 2013, the Bluetooth SIG launched the Bluetooth 4.1 specification, with the goal of making Bluetooth Smart technology the core driving force for the development of the Internet of Things. This version improves support for the coexistence of LTE and bulk data exchange rates, and helps developers innovate by allowing devices to support multiple roles at the same time. Through Bluetooth 4.1, headphones, watches, keyboards and mice that support this standard can send and receive data autonomously without going through data hubs such as PCs, tablets, and mobile phones. For example, smart watches and pedometers can bypass smartphones and communicate directly. In 2014, SIG updated the Bluetooth standard and launched Bluetooth 4.2, which not only increased the speed by 2.5 times, had higher privacy, but also could connect to the network through IPv6. This technology allows multiple Bluetooth devices to access the Internet or local area network through one terminal, so that most smart home products can abandon the relatively complex WiFi connection and use Bluetooth transmission instead, making the connection between personal sensors and homes more convenient and fast.

In 2016, the Bluetooth standard continued to evolve with the explosion of IoT applications. During this period, SIG released Bluetooth 5.0. Compared with Bluetooth 4.0, 5.0 has doubled the transmission speed, quadrupled the transmission distance, and increased the data transmission volume eightfold. At the same time, it can coexist with Wi-Fi without interfering with each other. In 2019, SIG launched Bluetooth 5.1, adding a direction-finding function, which improves the accuracy of Bluetooth positioning to the centimeter level, with lower power consumption, faster transmission, longer distance, and more accurate positioning. With the launch of the Bluetooth 5.1 standard, the industry has also seen the prospect of applying Bluetooth technology to indoor positioning, which is also one of the future development prospects of Bluetooth technology.

In addition, with the advent of the era of the Internet of Everything, Bluetooth technology has also been absorbed and expanded. In addition to the Bluetooth 1, 2, 3, 4, and 5 series standards, the Bluetooth Technology Alliance officially announced in July 2017 that Bluetooth technology began to fully support Mesh mesh networks. It is reported that Bluetooth Mesh will be compatible with Bluetooth 4 and 5 series protocols. The new Mesh function provides many-to-many transmission between devices, and especially improves the communication capabilities of building large-scale network coverage. It is suitable for IoT solutions such as building automation and wireless sensor networks that require tens of thousands of devices to transmit in a reliable and secure environment. With the launch of Bluetooth Mesh, smart homes have been greatly developed, and this field is also regarded as another direction for the future development of Bluetooth. At the 2018 International Consumer Electronics Show, Alibaba and MediaTek announced that they would work together to promote Bluetooth Mesh technology, signed a cooperation agreement, and created the first Smartmesh wireless connection solution that supports Bluetooth Mesh technology.

The new Bluetooth standard will once again reform terminal applications

In January 2020, the Bluetooth SIG released its next-generation Bluetooth audio technology standard, LE Audio, at CES 2020 held in Las Vegas. This solution has attracted attention along with the explosion of TWS headsets. Therefore, some industry insiders believe that the LE Audio Bluetooth standard will once again have a significant impact on terminal applications.

As we all know, traditional Bluetooth headsets have not been widely used before because their sound quality and battery life are not satisfactory. TWS headsets that use the LE Audio Bluetooth standard can transmit better sound over longer distances with low energy consumption. According to the SIG official website, in terms of improving sound quality, the LE Audio Bluetooth standard includes a new high-quality, low-power audio codec, the Low Complexity Communication Codec (LC3). LC3 provides high quality even at low data rates, and it will bring great flexibility to developers, allowing them to make better design trade-offs between key product attributes such as audio quality and power consumption. According to relevant reports, the quality of LC3 has been improved by three times, while the energy consumption when transmitting audio has been reduced by three times.

According to relevant reports, SIG will launch the independent function of LE Audio this year, and SIG expects chip manufacturers to release new designs that support LE Audio within the next year to 18 months. This is because LE Audio requires the mobile phone to support the LE Audio standard first, and TWS headphones will make more sense. Therefore, in this case, TWS headphones are still some distance away from their real explosion period.

At the same time, SIG also introduced on its official website that LE Audio will not only bring development opportunities for TWS headphones, but this standard will also promote the development of other audio products. For example, LE Audio will promote the development of Bluetooth hearing aids, bringing all the benefits of Bluetooth audio to more and more people with hearing loss. LE Audio will also add broadcast audio, allowing audio source devices to broadcast one or more audio streams to an unlimited number of audio receiver devices. Broadcast audio provides important new opportunities for innovation, including enabling a new Bluetooth use case "audio sharing". Bluetooth audio sharing can be personal or location-based. With personal audio sharing, people will be able to share the Bluetooth audio experience with others around them; for example, share music in a smartphone with family and friends. With location-based audio sharing, public places such as airports, bars, stadiums, cinemas, and conference centers can now share Bluetooth audio, enhancing the experience of visitors.

Conclusion

The above data shows that Bluetooth has evolved from the initial audio transmission, image and text transmission, and video transmission to become the protagonist of IoT transmission. Especially in the past year, the development of Bluetooth technology has also driven changes in the TWS headset market. From the changes in Bluetooth technology, its development has a huge impact on downstream terminal products. With the diversification trend of terminal products in recent years, it has also brought new opportunities for the development of Bluetooth.

At the same time, as a member of wireless communications, Bluetooth technology also needs to compete with other wireless transmission technologies such as WiFi. How Bluetooth technology can maintain its advantage in this competition is worthy of attention from the industry.

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