Bluetooth Low Energy (BLE)

Bluetooth Low Energy (BLE)ProtocolBluetooth Low Energy (BLE)Ultra-low energy connectivity for wearables and proximityView profile is the low-power version of Bluetooth, designed to send small amounts of data while running for long periods on small batteries. It first appeared in Bluetooth Core 4.0, works in the 2.4 GHz band and is maintained by the Bluetooth SIG. In IoTITermIoT (Internet of Things)The IoT (Internet of Things) is the network of physical objects with sensors, software and connectivity that collect and exchange data and act autonomously.View profile, BLE connects sensors, beacons and wearables to phones or gateways over short distances.

How BLE works

BLE uses 40 channels with 2 MHz spacing in the 2.4 GHz ISM band: 3 for advertising and 37 for data. Devices communicate in two main ways:

• Advertising: a device broadcasts short packets that any nearby scanner can read without connecting. Beacons and many sensors use it to send data one-to-many.
• Connections: a central (a phone or a gateway) connects to a peripheral (the sensor) for a one-to-one exchange.

Once connected, data is organized with GATTGTermGATTGATT (Generic Attribute Profile) is BLE's data model: it organizes information into services and characteristics a client reads, writes or is notified about.View profile: the device that holds the data acts as a server and exposes services, and each service groups characteristics such as a temperature reading or a battery level. BLE also supports mesh, in addition to point-to-point and broadcast.

BLE range, data rate and versions

Bluetooth range is not a fixed number. The Bluetooth SIG puts it anywhere from less than a meter to more than a kilometer, depending on the physical layer (PHY), receiver sensitivity, transmit power, antenna gain and obstacles. The PHY sets the trade-off between range and speed:

• LE 1M: 1 Mb/s.
• LE 2M: 2 Mb/s, added in Bluetooth 5 for higher throughput.
• LE Coded: 500 kb/s or 125 kb/s, also from Bluetooth 5. It uses error correction to reach roughly four times the range of Bluetooth 4.0 without more transmit power.

Bluetooth Core 6.0 added Channel Sounding, which securely measures the distance between two devices. If you are choosing between BLE and Wi-Fi for a sensor, see Bluetooth Low Energy vs Wi-Fi.

BLE and Cloud Studio IoT

BLE devices reach Cloud Studio IoT through a gateway, not directly. The gateway receives the data over BLE and forwards it to the platform, for example over MQTTProtocolMQTTThe standard pub/sub protocol of IoTView profile to your instance's MQTT server (TLS on port 8883) or through the HTTP API. Wi-Fi devices, by contrast, can send MQTT or HTTP directly.