Why is Bluetooth called “Bluetooth”? An introduction to Bluetooth’s anti-interference solutions!

　　As a widely used technology, Bluetooth has long been embraced by modern residents. But have you ever pondered this question: Why is it called Bluetooth in the first place? What’s the origin behind Bluetooth’s name?

　　1. Why is Bluetooth called Bluetooth?

　　“Bluetooth” originally referred to a king from the 10th century who united Denmark and brought together what were then Sweden, Finland, and Denmark. Naming this new technology standard after him carries the implicit meaning of unifying a fragmented landscape. Bluetooth technology employs advanced techniques such as high-speed frequency hopping (FH) and time-division multiple access (TDMA) to wirelessly connect several digital devices—including various mobile devices, fixed communication equipment, computers and their peripherals, diverse digital data systems like digital cameras and digital video cameras, and even household appliances and automated devices—in a mesh network at short ranges and at relatively low cost. Bluetooth technology will serve as a unified bridge for interfacing various peripheral devices within a network, eliminating the need for physical cables between devices and replacing them with wireless connections.

　　Bluetooth is a short-range wireless communication technology that allows electronic devices to connect with each other wirelessly, eliminating the need for traditional cables. Equipped with Bluetooth-enabled chips and wireless receivers, electronic devices can communicate with one another within a range of up to ten meters, with data transfer rates reaching as high as one megabyte per second. In the past, infrared interfaces required electronic devices to be within line-of-sight distance from each other; however, with the advent of Bluetooth technology in 2012, this inconvenience has been completely eliminated.

　　II. The main issues with Bluetooth technology are as follows:

　　(1) The Bluetooth connection is very complicated.

　　The Bluetooth connection process involves multiple information transmissions and authentication procedures. On the surface, users don't perceive the complexity of the connection process. However, for device calibration resources, the authentication processing—performed repeatedly for each connection through redundant data encoding and decoding—is identical, and the resulting waste cannot be overlooked.

　　(2) Bluetooth power consumption issue

　　Bluetooth does not frequently transmit data and consumes very little energy during data transmission. However, to respond promptly to connection requests, the polling access that waits for connections can consume a significant amount of energy.

　　(3) Security Issues with Bluetooth

　　Bluetooth pairing requires users to verify using a PIN code. The PIN code typically consists of digits only and has a few digits, usually ranging from 4 to 6 digits.

　　(4) Bluetooth’s interference resistance issue

　　In some cases, the Bluetooth signal transmission process can be interfered with, which in turn affects the stability and reliability of Bluetooth communication.

　　III. Several Solutions for BLE Anti-Interference

　　As we learned from the previous section, Bluetooth transmission has certain issues in terms of anti-interference. So, what are some of the better anti-interference solutions currently available?

　　As the number of networked devices in the market continues to grow, the signal transmission environment is becoming increasingly complex, posing significant challenges to the stability and reliability of Bluetooth transmissions. Particularly in high-traffic areas such as airports, train stations, and shopping malls, these environments are also saturated with powerful Wi-Fi signals. Since both Bluetooth and Wi-Fi operate in the 2.4 GHz frequency band, they can interfere with each other intensely, potentially causing Bluetooth connections to drop or disconnect altogether.

　　In this regard, Yang Yueming believes that interference is unavoidable, and it can be broadly categorized into co-channel interference and adjacent-channel interference. At the chip level, to address co-channel interference, the primary approach is to improve the demodulation threshold; however, such improvements are generally rather limited. For adjacent-channel interference, the main solution lies in enhancing the filtering performance of the filters. At the protocol and application levels, too, the focus is largely on these measures—adopting techniques such as frequency hopping, channel sensing, retransmission, and power boosting—to enhance the user experience.

　　Niu Zhao stated that to address interference issues, we can take several approaches. One is to increase the transmission power in TWS headphones—when the headphones are close to the phone, boosting the signal can effectively eliminate connection drops. Another approach is to adopt a frequency-hopping mechanism. Additionally, reducing the data rate can also help mitigate connection drops. In smart home and IoT applications, the amount of data transmitted is relatively lower compared to audio, so lowering the data rate can enhance anti-interference capabilities and improve the success rate of data transmission.

　　David Su stated that Bluetooth technology already incorporates adaptive frequency-hopping functionality, which becomes effective when WiFi and Bluetooth are used on separate devices. In addition, when Bluetooth and WiFi are integrated into the same device, there is an industry-standard solution for harmonizing these two technologies—the so-called Bluetooth-WiFi coexistence feature. Atmosic supports both adaptive frequency-hopping and Bluetooth-WiFi coexistence. (Reprinted from 21ic.com)