Bluetooth provides a system for wireless communication between different portable devices such as mobile phones, laptops or personal digital assistants (PDAs). The connection consists of a radio link between the devices' transmitters and receivers. Data is transmitted on the 2.4 GHz (gigahertz) band that is licence-exempt worldwide, at a data transfer speed of up to one megabit per second. The transmitting power of the interface is one watt. This allows a transmission range of around ten metres, which will be more than sufficient to link up individual devices inside a vehicle in future. One major advantage of the low transmission power is data security, as it prevents interception of data. It also means that interference from electromagnetic radiation is negligible. As further protection against interception of data transmission, every Bluetooth device is assigned a profile. This profile consists of an ID number which is guaranteed to be unique worldwide. This ID allows the devices that are linked up to identify each other. Encryption with a 128-bit code, which is randomly generated for each new communication process, provides an additional layer of protection when transmitting data.