BLE communication consists primarily of “Advertisements”, or small packets of data, broadcast at a regular interval by Beacons or other BLE enabled devices via radio waves.
BLE Advertising is a one-way communication method. Beacons that want to be “discovered” can broadcast, or “Advertise” self-contained packets of data in set intervals. These packets are meant to be collected by devices like smartphones, where they can be used for a variety of smartphone applications to trigger things like push messages, app actions, and prompts.
Apple’s iBeacon standard calls for an optimal broadcast interval of 100 ms. Broadcasting more frequently uses more battery life but allows for quicker discovery by smartphones and other listening devices.
Standard BLE has a broadcast range of up to 70 meters, which make Beacons ideal for indoor location tracking and awareness.
How does iBeacon use BLE communication?
For understanding purpose WalkN is an app that owns the Beacons with in a shopping center.
With iBeacon, Apple has standardized the format for BLE Advertising. Under this format, an advertising packet consists of four main pieces of information.
UUID: This is a 16 byte string used to differentiate a large group of related beacons. For example, WalkN maintains a network of beacons in a shopping center, all WalkN beacons would share the same UUID. This allows WalkN dedicated smartphone app to know which beacon advertisements come from WalkN-owned beacons.
Major: This is a 2 byte string used to distinguish a smaller subset of beacons within the larger group. For example, if WAlkN had four beacons in a particular store, all four would have the same Major. This allows WalkN to know exactly which store its customer is in.
Minor: This is a 2 byte string meant to identify individual beacons. Keeping with the WalkN example, a beacon at the front of the store would have its own unique Minor. This allows WalkN’s dedicated app to know exactly where the customer is in the store.
Tx Power: This is used to determine proximity (distance) from the beacon. How does this work? TX power is defined as the strength of the signal exactly 1 meter from the device. This has to be calibrated and hardcoded in advance. Devices can then use this as a baseline to give a rough distance estimate.
A beacon broadcasts the following packet
A device receiving this packet would understand it’s from the WalkN Sandton City (device owner) (UUID) in the the iStore (group of beacons) (Major) at the iPhone covers (single beacon)(Minor).