Bluetooth low energy (BLE) beacon deployment is gaining
Traditional Bluetooth is intended as a cable replacement for popular applications such as wireless audio streaming. Bluetooth core specification version 2.1, referred to as BR/EDR (Basic Rate/Enhanced Data Rate) is optimised for sending a steady stream of high-quality data in a power-efficient way while also making it easier for consumers to connect Bluetooth devices.
Bluetooth 4.0/4.1/4.2, also known as Bluetooth Smart, adopted Bluetooth low energy (BLE), which is the power version of Bluetooth that was built for the Internet of Things (IoT). Bluetooth low energy (BLE) was created to provide wireless sensor connectivity for coin-cell battery powered applications. Bluetooth 4.0 low energy (BLE) technology allows for short bursts of long-range radio connections and is ideal for applications that need long battery life and intermittent low throughput streaming data.
Proximity detection features of wearable and wireless devices are widely deployed. GPS satellite wireless technology for proximity detection and directional navigation is a mature standard. However, proximity detection utilising Bluetooth’s low energy (BLE) features is emerging with the deployment of beacons in a wide-range of consumer, retail, and industrial application.
This article covers the following BLE topics:
- brief summary of Bluetooth, including Bluetooth low energy (BLE) and beacons.
- some beacon application ideas.
- beacon emerging standards
- discuss beacon design considerations
- And provide details on a vendor’s designer’s BLE support package
Bluetooth BLE Overview
Bluetooth® technology is a de jure standard regulated by the Bluetooth Special Interest Group (SIG), a not-for-profit trade association, which facilitates the promotion of Bluetooth Technology. Bluetooth® technology is a connectivity component of the Internet of Things (IoT), which is enabling a global vision to connect more devices in more places.
Traditional Bluetooth is optimised for sending a steady stream of high-quality data in a power-efficient way. Bluetooth is intended as a cable replacement for popular applications such as wireless audio streaming using Bluetooth version feature called BR/EDR (Bit Rate/Enhanced Data Rate).
Bluetooth 4.0, also known as Bluetooth Smart, was created to provide wireless sensor connectivity for coin-cell battery powered applications. Bluetooth low energy (BLE) technology allows for short bursts of long-range radio connections and is ideal for applications that need long battery life and intermittent low throughput streaming data. Bluetooth low energy consumes 10 to 20 times less power than its previous version and is able to transmit data 50 times quicker than conventional Bluetooth solutions.
The Bluetooth Smart specification supports both single and dual-mode devices. Single-mode (BLE, Bluetooth Smart) device is a device that implements BLE that can communicate with single-mode and dual-mode devices, but not with devices supporting BR/EDR only. Dual-mode (BR/EDR/LE, Bluetooth Smart Ready) device is a device that implements both BR/EDR and BLE, which can communicate with any Bluetooth device.
Bluetooth Smart Ready will refer to devices that use a dual-mode radio, which can handle both the 4.0 technology, as well as classic Bluetooth abilities, such as transferring files or connecting to a hands-free device. For example, the iPhone 4S, a Bluetooth Smart Ready smartphone, can connect to the Bluetooth Smart heart rate monitor with Bluetooth 4.0, but it will also work with classic Bluetooth devices, such as hands-free kits or your car’s stereo.
Bluetooth low energy (BLE) operates in the 2.4 GHz ISM (Industrial Scientific Medical) band (2402 MHz - 2480 MHz), which is license-free in most countries. The BLE specification defines 40 RF channels with 2 MHz channel spacing. Figure 1 shows there are three designated advertising channels (37, 38, & 39 shown in green) used for device discovery, connection establishment, and broadcast. The advertising channel frequencies are selected to minimise interference from IEEE 802.11 channels 1, 6 and 11, which are commonly used in several countries.
Figure 1. BLE channels and Frequencies
All physical channels use GFSK (Gaussian Frequency Shift Keying) modulation. In Bluetooth 4.0, 4.1 and 4.2 specifications the physical layer data rate is 1 Mbps. Typical data throughput is typically less than or equal to 100 kbps due to small packets. The recent changes in the Bluetooth and regulatory standards allow low energy Bluetooth devices to transmit up to 100mW (20 dBm) transmit power. The typical range for Bluetooth low energy radios is:
The Bluetooth 5.0 standard is planned to introduce additional improvements for increased data throughput, improved sensitivity, and longer range connections. Bluetooth 5.0 will provide up to 4x the range, 2x the speed and 8x the broadcasting message capacity, along with enhancements that increase functionality for the Internet of Things (IoT).
The basic BLE functions performed in a beacon application by the OSI link layer operations include Advertising, Scanning, and Connection establishment.
Advertisement is one of the most fundamental operations in Bluetooth low energy wireless technology. Advertisement provides a way for devices to broadcast their presence, allow connections to be established, and optionally broadcast data like the list of supported services, or the device name and TX power level.
Scanning is the operation where a scanner is listening for incoming advertisement in order to discover, discover and connect, or simply to receive the data broadcast by the advertising devices. Two types of scanning modes are passive and active scanning. In active scanning mode the scanner listens for incoming advertisement packets and, upon receiving one, sends an additional scan request packet to the advertiser in order to learn more about it. In passive scanning mode, the scanner simply listens for incoming advertisement packets. The scanner cycles through each advertisement channel in a round-robin fashion, listening to one channel at a time.
Connections allow application data to be transmitted in a reliable and robust manner, as Bluetooth low energy connections use CRCs, acknowledgements, and retransmissions of lost data to ensure correct data delivery.
There are five Network Topologies Device roles in a Bluetooth low energy communication. Figure 2 illustrates the network device roles in the network.
- Advertiser: device that broadcasts advertisement packets, but is not able to receive them. It can allow or disallow connections.
- Scanner: device that only listens for advertisements. It can connect to an advertiser.
- Slave: device connected to a single master (BT 4.0) or multiple masters (BT 4.1 and newer).
- Master: device that is connected to one or more slaves. A master can have an unlimited number of slave devices connected to it but in practice, the master can connect 4-8 slaves at a time.
- Hybrid: it is possible for a device to advertise and scan at the same time or be connected to a master and advertise or scan simultaneously. This is, however, vendor-specific, and the exact features that are supported should be checked with the vendor.
Figure 2. Connection, transmission, and connection termination
What is a Beacon?
A beacon is a small, battery-powered wireless device that uses Bluetooth low energy (Bluetooth Smart) to advertise its presence and services by broadcasting a beacon identifier to compatible devices. Beacons are used for proximity awareness to create interactive experiences with smartphone and tablet users in a particular area. Bluetooth BLE beacons will provide proximity awareness to growing population that carries smartphones.
Fixed Beacon - The fixed beacon scenario can be a fixed location or on a fixed movable object. A BLE smartphone can correlate the proximity, detect entry and exit from an area, and process the conditional response such as offering contextually-relevant content. The other fixed model uses a fixed wireless node to monitor beacons on objects that pass by monitoring area. This model is ideal for asset tracking.
Proximity –Aware applications a user smartphones that come into proximity of a beacon. In the second scenario, beacons come into contact with beacon-monitoring node. Beacons distributed in various locations in a retail store allow loyalty apps to offer customised coupons and messaging to shoppers. Vending machine and point-of-sale apps to advertise favourite items or menu options.
Drive-Through - The same vending solution can be applied for the drive-through point-of-sale. The same application can be optimised to perform inventory management. Asset tracking such as toolkit check-out and return are industrial applications. The addition benefit of beaconing applications is indoor navigation relevant content in large buildings.
There are non-beaconing Bluetooth low energy applications in which advertising packets provide identifying information about the advertiser’s services and are then followed by a period of time in which the advertiser actively listens for a connection requests from scanners want access to those services. This form of one-time messaging allows the beacon radio to be shut down after transmitting the advertising message thus conserving battery life.
Beacon Emerging Standards
The Bluetooth SIG does not oversee a BLE beacon standard. There are three BLE leadership vendors that derived a vendor specific beacon de facto, pseudo-standard.
Apple’s iBeacon allows vendors who want to sell iBeacon products to use of the logo and free license. iBeacon specifies a 30-byte packet and 100ms broadcast intervals. Monitoring works when the user has enabled iOS Location Services for the corresponding app.
Eddystone is Google’s open-source, cross-platform beacon format that supports Android and iOS devices using a UID which broadcasts a unique beacon ID, TLM telemetry data about the beacon and broadcasts Uniform Resource Locators. A URL frame allows mobile platforms to offer web proximity content that allows proximity tracking without an app installed.
Radius Networks defined the AltBeacon specification which creates an OS-agnostic, open-source standard that doesn’t favour a specific vendor and is freed to use without royalties or licensing fees.
Beacon design considerations
OEMs who have never used wireless technology before are now adopting Bluetooth and adding beacons to their products. BLE beacon designer needs to consider:
- battery life
- security and privacy
- the vendor
Designers from vending machines to appliances are designing beacon products. Designers must consider hardware, software, battery life and beacon provisioning schemes. Security and privacy are also important to successful beacon deployment.
Design complexity associated with initial product launch can be reduced by selecting a vendor with pre-certified Bluetooth SMART BLE modules, which avoids RF regulatory compliance complications and reduces RF certification costs. Selecting a wireless module vendor with a field proven Bluetooth stack is recommended. A beacon typically broadcasts its advertising packets for about 1% of its life. The vast majority of the remaining 99% are spent in deep sleep mode. A beacon’s average battery life is determined by its transmit power and its transmit vs. sleep duty cycle. Having a proven, energy efficient stack is very important.
Silicon Labs offers a BGM11x Bluetooth BLE module family that provides the connectivity solution for BLE beacon applications. A high-level API programming language for beacon application code development is also recommended. Silicon Labs offer BG Script, a high-level, BASIC-like programming language that allows developers to quickly develop their Bluetooth applications. Silicon Labs also provides example beacon scripts that will assist designers in getting started with their beacon design.