Bluetooth is a standard wire-replacement communications protocol primarily designed for low power consumption, with a short range based on low-cost transceiver microchips in each device.[29] Because the devices use a radio (broadcast) communications system, they do not have to be in visual line of sight of each other; however, a quasi optical wireless path must be viable.[30]
Bluetooth Classes and power use[edit]
| Class | Max. permitted power | ||
|---|---|---|---|
| (mW) | (dBm) | ||
| 1 | 10 — 100 | +10 — +20 | |
| 1.5* | 2.5 — 10 | +4 — +10 | |
| 2 | 1 — 2.5 | 0 — +4 | |
| 3 | 0.01 — 1 | -20 — 0 | |
| * Class 1.5 included in class 1 for BR/EDR | |||
| Source:BT 5.3 Vol 6 Part A Sect 3 and V2 PA S3, Bluetooth Technology Website | |||
Historically, the Bluetooth range was defined by the radio class, with a lower class (and higher output power) having larger range.[2] The actual range achieved by a given link will depend on the qualities of the devices at both ends of the link, as well as the air and obstacles in between. The primary hardware attributes affecting range are the data rate, protocol (Bluetooth Classic or Bluetooth Low Energy), the transmitter power, the receiver sensitivity, and the gain of both antennas.[31]
The effective range varies depending on propagation conditions, material coverage, production sample variations, antenna configurations and battery conditions. Most Bluetooth applications are for indoor conditions, where attenuation of walls and signal fading due to signal reflections make the range far lower than specified line-of-sight ranges of the Bluetooth products.
Most Bluetooth applications are battery-powered Class 2 devices, with little difference in range whether the other end of the link is a Class 1 or Class 2 device as the lower-powered device tends to set the range limit. In some cases the effective range of the data link can be extended when a Class 2 device is connecting to a Class 1 transceiver with both higher sensitivity and transmission power than a typical Class 2 device.[32] Mostly, however, the Class 1 devices have a similar sensitivity to Class 2 devices. Connecting two Class 1 devices with both high sensitivity and high power can allow ranges far in excess of the typical 100m, depending on the throughput required by the application. Some such devices allow open field ranges of up to 1 km and beyond between two similar devices without exceeding legal emission limits.[33][34][35]
Bluetooth profile[edit]
To use Bluetooth wireless technology, a device must be able to interpret certain Bluetooth profiles, which are definitions of possible applications and specify general behaviors that Bluetooth-enabled devices use to communicate with other Bluetooth devices. These profiles include settings to parameterize and to control the communication from the start. Adherence to profiles saves the time for transmitting the parameters anew before the bi-directional link becomes effective. There are a wide range of Bluetooth profiles that describe many different types of applications or use cases for devices.[36]
List of applications[edit]
- Wireless control and communication between a mobile phone and a handsfree headset. This was one of the earliest applications to become popular.[37]
- Wireless control of and communication between a mobile phone and a Bluetooth compatible car stereo system (and sometimes between the SIM card and the car phone[38][39]).
- Wireless communication between a smartphone and a smart lock for unlocking doors.
- Wireless control of and communication with iOS and Android device phones, tablets and portable wireless speakers.[40]
- Wireless Bluetooth headset and intercom. Idiomatically, a headset is sometimes called "a Bluetooth".
- Wireless streaming of audio to headphones with or without communication capabilities.
- Wireless streaming of data collected by Bluetooth-enabled fitness devices to phone or PC.[41]
- Wireless networking between PCs in a confined space and where little bandwidth is required.[42]
- Wireless communication with PC input and output devices, the most common being the mouse, keyboard and printer.
- Transfer of files, contact details, calendar appointments, and reminders between devices with OBEX[a] and sharing directories via FTP.[43]
- Triggering the camera shutter of smartphone using bluetooth powered selfie stick.[44]
- Replacement of previous wired RS-232 serial communications in test equipment, GPS receivers, medical equipment, bar code scanners, and traffic control devices.
- For controls where infrared was often used.
- For low bandwidth applications where higher USB bandwidth is not required and cable-free connection desired.
- Sending small advertisements from Bluetooth-enabled advertising hoardings to other, discoverable, Bluetooth devices.[45]
- Wireless bridge between two Industrial Ethernet (e.g., PROFINET) networks.
- Game consoles have been using Bluetooth as a wireless communications protocol for peripherals since the seventh generation, including Nintendo's Wii[46] and Sony's PlayStation 3 which use Bluetooth for their respective controllers.
- Dial-up internet access on personal computers or PDAs using a data-capable mobile phone as a wireless modem.
- Short-range transmission of health sensor data from medical devices to mobile phone, set-top box or dedicated telehealth devices.[47][48]
- Allowing a DECT phone to ring and answer calls on behalf of a nearby mobile phone.
- Real-time location systems (RTLS) are used to track and identify the location of objects in real time using "Nodes" or "tags" attached to, or embedded in, the objects tracked, and "Readers" that receive and process the wireless signals from these tags to determine their locations.[49]
- Personal security application on mobile phones for prevention of theft or loss of items. The protected item has a Bluetooth marker (e.g., a tag) that is in constant communication with the phone. If the connection is broken (the marker is out of range of the phone) then an alarm is raised. This can also be used as a man overboard alarm.
- Calgary, Alberta, Canada's Roads Traffic division uses data collected from travelers' Bluetooth devices to predict travel times and road congestion for motorists.[50]
- Wireless transmission of audio (a more reliable alternative to FM transmitters)
- Live video streaming to the visual cortical implant device by Nabeel Fattah in Newcastle university 2017.[51]
- Connection of motion controllers to a PC when using VR headsets
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