Finally, we come to Bluetooth 4.0 (also known as Smart and/or Low Energy) which introduces a new physical layer system altogether which enables super-low-powered devices that run for years off a single battery.

Bluetooth 3.0 bought the ability to use Bluetooth as a signalling channel to use Wi-Fi as a higher-speed transfer medium (although this functionality is often problematic). New pairing modes were introduced which simplified and secured pairing. Bluetooth 2.0 bought newer modulation modes which allow for higher speed data transfer and practical battery life savings for portable devices. The initial Bluetooth 1.0 was superseded by 1.1 which offered more robustness against interference through adaptive frequency hopping, and higher transfer rates in practice. Over the years, it has made the evolution through numerous revisions each with new benefits. This can be because of outdated software without profile support for newer devices, or a lack of software altogether, leaving the user to rely on the operating system’s default (and often somewhat limited) Bluetooth stack. While generally touted as easy to set up and get working, for a variety of reasons often related to the quality of the software Bluetooth stack provided with many USB Bluetooth devices, users have often found frustration in getting things beyond just basic file transfer working. Bluetooth is a short-range personal area network technology which is used for transferring files, contact information, connecting hands free sets and stereo headsets to mobile phones, tablets and PCs wirelessly.

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