September 2012

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Bluetooth Smart and Bluetooth Smart Ready

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Bluetooth Smart and Bluetooth Smart Ready

Even the most energy-frugal Bluetooth devices typically require a charge at least every 48 hours. But with the introduction of Bluetooth Low Energy (BLE), devices can communicate for months or years on a coin cell battery. This shift allows long term connectivity in devices that had previously been impractical.

BLE works by engaging in brief bursts of data transmission, as opposed to the continuous operation of devices like wireless headsets. In low energy communication, devices share attribute data that is smaller in size. While previous Bluetooth versions have required about 100 milliseconds (100 ms) to establish a connection, transmit data, and terminate the connection, BLE devices reportedly can achieve the same results in 3 ms (for previously established connections). By drastically reducing the time spent at peak power consumption, BLE devices can operate for significantly longer periods of time with the same total power usage.

The Bluetooth SIG has created two new Bluetooth classifications to illustrate compatibility among Bluetooth devices: Bluetooth Smart and Bluetooth Smart Ready. Smart Ready devices are considered dual-mode devices because they can communicate with both BLE devices and classic Bluetooth devices. Bluetooth Smart devices are considered single-mode devices because they cannot communicate with classic Bluetooth devices. Smart devices always enjoy the benefits of low-energy operation. Classic Bluetooth remains unchanged.

The two most common roles for BLE devices are central and peripheral. In BLE, the central role acts as a hub to one or more peripheral devices. Two central devices cannot directly communicate, and neither can two peripheral devices except as mediated by a central device.

Theoretically, a device in the central-role is capable of connecting to over a million peripherals. Central devices are typically configured via a profile to acquire and use status data from a peripheral. Devices in the peripheral role may act as information gatherers that transmit their status to the central device. Central devices may then display, re-route, or store gathered data.

While both Smart and Smart Ready devices can act in either central or peripheral roles, some compelling use cases arise when a Smart Ready device (particularly a mobile phone) is central, and can share its resources with a small network of Smart devices.

In a commonly cited use case, a Bluetooth Smart heart monitor collects data on a patient’s vitals and transmits that data to a device in the central mode – in this example, a Smart Ready mobile phone. In this use case, the heart monitor (with its low-energy wireless communications) can potentially go years without a battery change. The Smart monitor’s job is simple, specific, and only requires one connection at a time, ideal for the peripheral role. Also, the Smart Ready phone may communicate simultaneously with other medical devices that require its advanced resources. Most importantly, data from the heart monitor, a glucose monitor, or other devices may be sent to a physician over the Smart Ready phone’s internet connection. Smart Ready devices in this way can provide Smart Devices with a gateway to the entire internet’s resources.

Ultimately, the introduction of BLE signals a major scale-down of the requirements of Bluetooth hardware configurations leading to devices that are smaller, cheaper, and easier to embed into other products. Low power profiles means that a device’s battery may outlive the device itself; Bluetooth Smart chips can be embedded securely without the need for a battery access.