BLE- An overview
What is BLE? What does it stand for?
BLE stands for Bluetooth Low Energy (Bluetooth LE, and marketed as Bluetooth Smart). Bluetooth Low Energy (BLE), sometimes referred to as “Bluetooth Smart”, is a light-weight subset of classic Bluetooth
and was introduced as part of the Bluetooth 4.0 core specification.
BLE is a form of wireless communication designed especially for short-range communication. BLE is very similar to Wi-Fi in the sense that it allows devices to communicate with each other. However, BLE is meant for situations where battery life is preferred over high data transfer speeds. For example, say you want to broadcast marketing campaigns in the close proximity of a newly launched headphone. The amount of data you need to transfer to a visitor’s smartphone is extremely small, hence BLE compatible beacons do the job quickly without draining the battery.
How does BLE technology work?
BLE data transfer is essentially a one-way communication. Let’s take an example of BLE beacons trying to communicate with a smartphone in close proximity — a Bluetooth Low Energy beacon broadcasts packets of data at regular intervals of time. These data packets are detected by app/pre-installed services on smartphones nearby. This BLE communication triggers actions such as, pushing a message or promoting an app.
BLE devices all operate on 40 channels spread in the 2.4GHz range. Three of these channels are dedicated to advertisement, the rest are for data exchange. There’s only one general type of packet, specialized into advertisement and data types, which you pretty much don’t need to care about. Depending on the transmission power/reception sensitivity, the usable range will vary between 30 meters (a transmitter at 0.01mW and receiver with -70dBm sensitivity) and 100 meters (tx at 10mW and rx -90dBm).
To save energy and provide higher data transfer speed, the entire BLE communication framework consists of 40 frequency channels, separated by 2MHz. 3 of these channels are the primary advertisement channels while the remaining 37 channels are secondary channels, also known as data channels. The Bluetooth communication starts with the 3 primary advertisement channel and then offloads to the secondary channels.
BLE Platform Support
Support for Bluetooth 4.0 and Bluetooth Low Energy (which is a subset of BT 4.0) is available on most major platforms
as of the versions listed below:
– iOS5+ (iOS7+ preferred)
– Android 4.3+ (numerous bug fixes in 4.4+)
– Apple OS X 10.6+
– Windows 8 (XP, Vista and 7 only support Bluetooth 2.1)
– GNU/Linux Vanilla BlueZ 4.93+
Some Key Technical Terms
First, let’s write down all the key components we have on bluetooth in a short and concise definition to get a feel of what we have to do.
GAP: Is an acronym for the Generic Access Profile, and it controls connections and advertising in Bluetooth. GAP is what makes your device visible to the outside world, and determines how two devices can (or can’t) interact with each other.
GATT: Generic Attribute Profile to define how to exchange data using predefined attributes.
Central: the Computer/Tablet/Mobile device, also referred as GATT client. Scans, requests and uses the data given by the peripheral.
Peripheral: the device broadcasting the data, also referred as GATT server. The data is structured as definitions of how to interact with it’s ‘database’.
Services: set of provided features and associated behaviors to interact with the peripheral. Each service contains a collection of characteristics.
Characteristics: definition of the data divided into declaration and value. Using permission properties (read, write, notify, indicate) to get a value.
Descriptor: an optional attribute nested in a characteristic that describes the specific value and how to access it.
UUID: Universally Unique ID that are transmitted over the air so a peripheral can inform a central what services it provides.
Bluetooth classic vs Bluetooth Low Energy
What is Bluetooth? How is Bluetooth Low Energy (BLE) different?
There are two major technologies within the Bluetooth core specification — Bluetooth classic and Bluetooth Smart (Bluetooth Low Energy). The major difference between the two lies in the power consumption in each case. However, there are other factors why Bluetooth Smart is being pulled in for interesting technology applications.
Power consumption
This is what makes BLE so special! Businesses can use just four batteries to power Bluetooth devices for several months or years. However, for classic Bluetooth, given the higher data throughput, its power consumption can be really high.
Applications
Classic Bluetooth is great for applications that require continuous streaming of data, for example, headphones. However, BLE is suited for applications that work well with a periodic transfer of data, and hence reduces a significant amount of battery usage. This makes BLE suitable for IoT and proximity marketing-related applications.
Simultaneous connections
BLE can establish up to 20 connections simultaneously. It supports more simultaneous connections because it transfers small data packets and establishes quick connections. Classic Bluetooth on the hand can initiate only 7 simultaneous connections.
I hope this blog helped you to understand the basics of BLE technology. Follow me on Medium and lets share the knowledge together!!!
Cheers!!!
Riyas.
BLE- An overview
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