Bluetooth, also known as Bluetooth, is a new wireless transmission protocol. It was originally created by Ericsson and later developed the technical standard by the Bluetooth Special Interest Group. It is said that because this technology is still in its infancy, Bluetooth is commercially registered in Taiwan with the Chinese translation of "Bluetooth". However, according to the literal translation of the English meaning, "Bluetooth" is more appropriate.
History:
Bluetooth technology was originally created by Ericsson. On May 20, 1999, industry leaders such as Sony Ericsson, IBM, Intel, Nokia and Toshiba established the Bluetooth Special Interest Group to formulate Bluetooth technology standards. The name "Bluetooth" comes from the nickname of Harald Gormsson, King of Denmark in the 10th century. Harald, who was born into a pirate family, unified the fragmented countries of Northern Europe and became the king of the Viking Kingdom. Because he liked to eat blueberries, his teeth were often dyed blue, earning him the nickname "Bluetooth". At that time, blueberries were considered unfit for consumption because of their weird color. Therefore, this king who loved to try new things also became an innovative and brave king. Trying symbol. In 1998, Ericsson hoped that wireless communication technology could be unified and named "Bluetooth".
Recent developments:
The products currently on the market all use the 1.1 version standard. They are low-power wireless devices that use a low-cost microprocessor. Chip, completes information sending and receiving at short distances (10 to 100 meters).
Bluetooth is used to make wireless connections between different devices, such as connecting computers and peripherals, such as printers, keyboards, etc., or allowing a personal digital assistant (PDA) to communicate with other nearby PDAs or computers. communicate. There are currently a wide selection of mobile phones with Bluetooth technology on the market that can be connected to computers, PDAs and even hands-free handsets.
In fact, according to established standards, Bluetooth can support more powerful long-distance communications to form a wireless LAN. Each Bluetooth device can maintain 7 connections simultaneously. Each device can be configured to continuously announce its presence to nearby devices in order to establish connections. In addition, the connection between the two devices can be password-protected to prevent it from being received by other devices.
The standard of Bluetooth is IEEE 802.15, and the Bluetooth protocol operates in the 2.45GHz ISM frequency band that does not require a license. The maximum speed can reach 723.1 kb/s. To avoid interference with other protocols that may use 2.45GHz, the Bluetooth protocol divides the frequency band into 79 channels and can change channels up to 1,600 times per second.
It is inappropriate to compare Bluetooth with WiFi, because WiFi is a faster protocol with a larger coverage area. Although both use the same frequency range, they also require more expensive hardware. Bluetooth is supposed to be used to create wireless connections between different devices, while WiFi is a wireless LAN protocol. The purpose of the two is different.
Future development:
The Bluetooth Special Interest Group is developing versions 1.2 and 2.0.
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Version 1.2
This version is backward compatible with version 1.1. Its main improvements include:
Anonymous mode: shielding The hardware address of the device (BD_ADDR), protecting users from identity sniffing attacks and tracking. Hardware anonymity has been possible since version 1.1, but it has not been implemented, so this feature is still not available to ordinary consumers.
Adaptive Frequency Hopping (AFH): Improves resistance to radio interference by avoiding the use of crowded frequencies in hopping sequences.
Higher actual transmission speed
The L2CAP layer introduces flow control and error correction mechanisms
Version 2.0
Contents of version 2.0 There is no clear information yet, but Ericsson researchers have announced something:
The addition of a "Non-hopping narrowband channel" (Non-hopping narrowband channel).
Because there is no need to exchange acknowledgment signals with each device, this channel can be used to broadcast the Bluetooth service summary of various devices to a large number of Bluetooth devices simultaneously. The reply handshake process currently takes approximately one second.
Unencrypted information such as real-time bus schedules, basic traffic flow information and advanced traffic directional instructions can be sent to the device at high speeds.
Higher connection speeds
Supports multiple speed levels
Early Bluetooth:
Early 1.0 and 1.0B versions exist Multiple issues arise, with multiple manufacturers pointing out that their products are incompatible with each other. At the same time, during the "handshaking" process between two devices, the address of the Bluetooth hardware (BD_ADDR) will be sent out. Anonymity cannot be achieved at the protocol level, causing the risk of data leakage, which makes some users Hesitant.