Bluetooth is a standard and communications protocol primarily designed for low power consumption, with a short range (power-class-dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device.
Bluetooth enables these devices to communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, as long as the received transmission is powerful enough.
| Class | Maximum Permitted Power (mW/dBm) | Range (approximate) |
|---|---|---|
| Class 1 | 100 mW (20 dBm) | ~100 meters |
| Class 2 | 2.5 mW (4 dBm) | ~10 meters |
| Class 3 | 1 mW (0 dBm) | ~1 meter |
It has to be noted that in most cases the effective range of class 2 devices is extended if they connect to a class 1 transceiver, compared to pure class 2 network. This is accomplished by higher sensitivity and transmitter power of the Class 1 device. The higher transmitter power of Class 1 device allows higher power to be received by the Class 2 device. Furthermore, higher sensitivity of Class 1 device allows reception of much lower transmitted power of the Class 2 devices. Thus, allowing operation of Class 2 devices at much higher distances. Devices that use a power amplifier on the transmit, have improved receive sensitivity, and highly optimized antennas are available that routinely achieve ranges of 1km within the Bluetooth Class 1 standard.
| Version | Data Rate |
|---|---|
| Version 1.2 | 1 Mbit/s |
| Version 2.0 + EDR | 3 Mbit/s |
| WiMedia Alliance (proposed) | 53 - 480 Mbit/s |
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