What is Bluetooth Smart: Bluetooth Low Energy, BLE
- Bluetooth Smart also called Bluetooth Low Energy, BLE, has been introduced to enable small battery run devices to utilise Bluetooth whilst still being able to support very long battery lifetimes.
Bluetooth Smart or Bluetooth Low Energy, BLE, is a form of Bluetooth technology that has been developed to provide effective connectivity for many forms of small devices, particularly those associated with the Internet of Things, IoT.
Bluetooth Smart is aimed at use in devices that may need to run of small batteries for long periods of time, while also being able to communicate with larger devices like smartphones or tablets.
Bluetooth Smart has the advantage that it is easy for developers and OEMs to develop products that will work with the Bluetooth enabled products that are already in existence today.
Bluetooth Smart was originally introduced under the name Wibree by Nokia in 2006. The name Wibree remained in use for a short while, but the standard was merged into the main Bluetooth standard in 2010 with the adoption of the Bluetooth Core Specification Version 4.0.
Bluetooth Smart overview
One of the key aspects of Bluetooth Smart or Bluetooth Low Energy, BLE, is that it is able to support devices running with very low levels of battery consumption whilst still being able to communicate with existing Bluetooth devices.
This means that many IoT style devices like sports & fitness devices, health care devices, keyboards and mice, beacons, wearables, along with small sensors and actuators that may need to be able to operate for a year or more on a single battery charge.
Along with previous versions of the specification, the Bluetooth Smart can be optimised according to the application, enabling the battery usage to be minimised when long ranges are not needed.
The classic Bluetooth implementations include a basic 10 metre or 30 foot range, but there is no limit imposed within the specification. For Bluetooth Smart devices, manufacturers may choose to optimize range to 200 feet or more. This can be particularly useful for in-home sensor applications where long range may be a necessity.
Bluetooth Smart features
For users and developers of Bluetooth Smart products, the highlight features of the technology can be summarised:
- Ultra-low peak, average and idle mode power consumption.
- Ability to run for years on standard coin-cell batteries:- this means that battery life of a year or more can often be achieved - a necessity for many applications where battery changes can be difficult.
- Lower implementation costs:- this is of great importance because many IoT devices will be very low cost.
- Multi-vendor interoperability:- a necessity as different Bluetooth Smart applications may include devices from many vendors.
- Enhanced range:- of key importance where some sensors may be located in remote areas where power and access are limited.
Bluetooth Smart compatibility
Bluetooth Smart compatibility is a major capability requirement. Although Bluetooth Smart is not backward-compatible with the Classic, Bluetooth protocol, the later Bluetooth 4.0 specification permits devices to implement either or both of the LE and Classic systems.
Despite the fact that Classic Bluetooth protocols are not able to link with Bluetooth Smart, mobile operating systems including Andriod, BlackBerry, iOS, Android, and Windows Phone as well as OS X, Linux, and Windows 8 / 10 (Note: XP, Vista and 7 only support Bluetooth 2.1), support Bluetooth Smart. Although this may appear to be a major issue, the Bluetooth SIG predicts that by 2018 more than 90% of Bluetooth-enabled smartphones will support Bluetooth Smart.
Bluetooth Smart technology highlights
Bluetooth Smart technical details include:
- Data transfer : Bluetooth Smart supports very short data packets (8 octet minimum up to 27 octets maximum) that are transferred at 1 Mbps. It is anticipated that data rates in excess of 1 Mbps are unlikely to be needed for Bluetooth Smart applications.
- Frequency hopping: Frequency hopping is a key element of Bluetooth technology and this capability is retained within Bluetooth Smart, Bluetooth Low Energy to ensure that interference to and from other users of the 2.4GHz ISM band is minimised
- Control functionality: In order to minimise the drain on power, as much of the processing as possible has been transferred from the remote device to the host. In this way, Bluetooth Smart, Bluetooth Low Energy is able to minimise the current drain on the battery powered device by transferred processing to the host which is likely to have easier access to power.
- Latency: For many control and monitoring situations, latency can be an issue. To ensure that Bluetooth Low Energy / Bluetooth Smart can accommodate the needs of users, the latency of Bluetooth Smart has been reduced so that it can support connection setup and data transfer as low as 3ms. This allows the system to set up a connection and then transfer authenticated data in few milliseconds for a short communication burst before quickly removing the connection to save power.
- Range: The range for Bluetooth Low Energy / Bluetooth Smart is an issue. With many remote sensing and control requirements, range may need to be in excess of that needed for other Bluetooth applications. As a result, Bluetooth Smart range can be in excess of 100 metres as a result of the increased modulation index.
- Robustness : To obtain the required level of robustness against interference for Bluetooth Low Energy, BLE, a 24 bit CRC is used on all packets.
- Security: Security is a major issue for any IoT application. To achieve this, full AES-128 encryption with CCM is used to provide strong encryption and authentication of data packets
- Topology: Bluetooth Smart / Bluetooth Low Energy, uses a 32 bit access address on every packet for each slave. This allows for a vast number of devices to be connected.
|Bluetooth Smart / Low Energy Specifications|
|Data rate (over the air)||1 Mbps|
|Application throughput||0.27 Mbps|
|Peak current consumption||< 15 mA|
|Robustness||Adaptive frequency hopping, Lazy Acknowledgement, 24-bit CRC, 32-bit Message Integrity Check|
|Power consumption||0.01W to 0.5W|
|Latency (from a non-connected state)||6 ms|
By Ian Poole
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