BLE beacons, Eddystone and Physical Web: an introduction. Alessio Cucini, Samuele Forconi BlueUp Srls

Transcription

1 BLE beacons, Eddystone and Physical Web: an introduction Alessio Cucini, Samuele Forconi BlueUp Srls

2 Contents The origin of (radio) beacons Bluetooth 4.0 and Bluetooth Low Energy Bluetooth LE protocol Android Bluetooth LE API Bluetooth LE beacons ibeacon Eddystone Google Beacon API Physical Web Web Bluetooth

3 What is a (radio) beacon? A radio beacon is a transmitter at a known location, which transmits a continuous or periodic radio signal with limited information content (for example its identification or location), on a specified radio frequency. Occasionally the beacon function is combined with some other transmission, like telemetry data or meteorological information. (source: Wikipedia)

4 Beacons and mobile Radio beacons are a well known and estabilished technology (especially in aviation, navigation). A few events renewed the interest: Bluetooth Low Energy (or Smart) included in Bluetooth 4.0 specifications Support of Bluetooth 4.0 in smartphones and mobile OS (ios, Android, Windows, Blackberry) Launch of ibeacon (Apple)

5 Bluetooth 4.0 Starting from Version 4.0 of Bluetooth Core Specification, a new extension has been included, called Bluetooth Low Energy (BLE), also known as Bluetooth Smart. Bluetooth Low Energy is a power- and applicationfriendly version of Bluetooth, especially built for the Internet of Things (IoT). Bluetooth Smart was originally introduced under the name Wibree by Nokia in 2006.

6 The Bluetooth 4.0 Ecosystem (Source: Bluetooth SIG)

7 Vs. Low consumption ( low energy ) Short connection and comunication time Low complexity Asymmetric architecture Simple, cheap, batterypowered peripheral Complex central Non-negligible energy consumption Long discovering and pairing time Medium complexity Limited visibility and discovery Stream-oriented Message-oriented

8 BLE Roles GAP (Generic Access Profile) controls connections and advertising in Bluetooth: determines how two devices can (or can't) interact with each other. GAP defines various roles for devices. Two key concepts are: Peripheral devices are small, low power, resource contrained devices that advertise to connect to a much more powerful central device. Central devices are usually (but not necessarily) a mobile phone or tablet with far more processing power and memory.

9 BLE Services and Characteristics GATT (Generic ATTribute profile) defines how two BLE devices transfer data back and forth using concepts called Services and Characteristics: Services are logic entities, and contain specific chunks of data called characteristics; Characteristics incapsulate a single data point Services and Char's are identified by 16-bit or 128-bit UUID's

10 Generic BLE connection GATT Server GATT Client GAP = Generic Access Profile GATT = Generic ATTribute Profile

11 Android Bluetooth LE API GATT Client (App) GATT Server Class: BluetoothLeScanner Method: startscan (List<ScanFilter> filters, ScanSettings settings, ScanCallback callback) A ScanFilter allows clients to restrict scan results to only those that are of interest to them: Service UUIDs which identify the GATT services running on the device Name of remote Bluetooth LE device MAC address of the remote device. Service data which is the data associated with a service. Manufacturer specific data which is the data associated with a particular manufacturer.

12 Android Bluetooth LE API GATT Client (App) GATT Server Class: BluetoothDevice Method: connectgatt (Context context, boolean autoconnect, BluetoothGattCallback callback) Connect to GATT Server hosted by this device. The callback is used to deliver results to Caller, such as connection status as well as any further GATT client operations.

13 Android Bluetooth LE API GATT Client (App) GATT Server Class: BluetoothGatt Method: discoverservices() Discovers services offered by a remote device as well as their characteristics and descriptors.

14 BLE Beacon Smartphone Beacon BLE-beacon technology uses only a portion of the Bluetooth LE protocol: Broadcast advertising

15 BLE Beacons Timeline Apple launches ibeacon technology iphone 4S First smartphone with Bluetooth 4.0 support Physical Web support on Google Chrome ver. 49 for Android Google launches Eddystone specifications Android 4.3 supports Bluetooth 4.0

16 ibeacon technology ibeacon technology (May 2013) defines advertising packet format. ibeacon advertising packet includes an unique numeric identifier of the beacon, coded by three numbers (proximity-uuid, major number, minor number) Specifications requires also: Advertising interval equal to 100msec Non-connectable advertising packet

17 ibeacon Advertising Packet 1 2 FL FT fl 4 5 FL FT Mnf. data Proximity UUID M 04 1A FF 4C Fixed FL = Field Length FT = Field Type fl = LE and BR/EDR flag Mnf. data = manufacturer data (fixed) Proximity UUID = unique identifier of proximity region (16 bytes) M = major number (2 bytes) m = minor number (2 bytes) R = RSSI (Received Signal Strength Indicator) at 1mt [used to estimate proximity (immediate, near, far, unknown) and accuracy] m R

18 Proximity Immediate (< 0.2 m) Near (< 2/3 m) Far (< 30/35 m) Unknown

19 Accuracy Definition (Apple CoreLocation Framework): Indicates the one sigma horizontal accuracy in meters. Use this property to differentiate between beacons with the same proximity value. Do not use it to identify a precise location for the beacon. Accuracy values may fluctuate due to RF interference. A negative value in this property signifies that the actual accuracy could not be determined. Accuracy is associated to a probability to be within a certain distance from the beacon. It is NOT a distance.

20 Ranging with RSSI Reflections, diffractions, absorptions, ect., impact on radio signal propagation Distance (m) Two-ray model n = 1.7 (in-building LOS) RSSI (dbm) n = 2 (free space) n = 5 (in-building NLOS) Log-distance path-loss model RSSI = RSSI0-10 n log10(d/d0) + Xg normal random variable with zero mean and standard deviation in db

21 Eddystone specifications First-release Eddystone specifications (July 2015) defines 3 advertising packet formats: Eddystone-UID: similar to ibeacon (opaque unique identifier), but with a different ID structure Eddystone-URL: transmit an URL (Uniform Resource Locator) in compact form Eddystone-TLM: telemetry data (internal status) of the beacon (battery voltage, temperature, counters) This three packet formats share the first 11 bytes of the advertising packet

22 Eddystone Advertising Packet FE 12 max (31) depends on frame type FL FT fl FL CL E-UUID FL SD AA FE 0xnn 0x16 FL = Field Length FT = Field Type fl = LE and BR/EDR flag CL = Complete list of service UUID SD = Service Data E-UUID = Eddystone UUID (0xFEAA) E-UUID AA FE

23 Eddystone-UID FT RD Namespace ID Instance ID FL = 0x17 (23) FT = Frame Type RD = Ranging Data (RSSI at 0mt; = RSSI at 1mt + 41dB) Namespace ID, identifies a set of beacons (10 bytes) Instance ID, identifies a certain beacon within NID (6 bytes) RFU = Reserved for Future Use 31 RFU

24 Eddystone-URL FT RD US Encoded URL 01 FL = variable, depends on URL length FT = Frame Type RD = Ranging Data (RSSI at 0mt) US = URL Scheme prefix (0x00 = 0x01 = 0x02 = 0x03 = Encoded URL = up to 17 bytes (usually compact URL)

25 Eddystone-TLM FT Ver. VBATT TEMP ADV_CNT SEC_CNT FL = 0x11 (17) FT = Frame Type Ver. = TLM-frame version (currently 0x00) VBATT = battery voltage (mv) 2 bytes TEMP = beacon temperature ( C) 2 bytes ADV_CNT = advertising packet counter from power-up (units) 4 bytes SEC_CNT = time counter from power-up (0.1sec) 4 bytes

26 UID vs URL UID ID ID URL

27 Google Beacon API (Source: Google Inc.)

28 Proximity Beacon API / 1 The Proximity Beacon API is a cloud service that allows you to manage data associated with your BLE beacon fleet using a REST interface. You can associate data with registered beacons as attachments. Attachments are arbitrary blobs of data that are served back as messages to your Android and ios apps through the Nearby Messages API. You can update attachments remotely, eliminating the need to physically visit each beacon.

29 Proximity Beacon API / 2 You can monitor the health of your beacons (battery level, internal temperature,...) through the Proximity Beacon API's diagnostic endpoint (based on Eddystone-TLM) Also, when registering beacons with the Proximity Beacon API, the following fields are used as a signal by the Places API: Latitude and longitude coordinates. Indoor floor level. Place ID.

30 Physical Web The Physical Web is a project whose aim is to connect everyday physical objects to the web. This involves creating an open ecosystem where smart devices can broadcast URLs into the area around them. Any nearby display such as a smartphone or a tablet can then see these URLs and offer them up to the user. It mirrors the basic behavior we have today with a search engine. The backbone of Physical Web is Eddystone-URL format

31 Physical Web The user requests a list of what's nearby. A ranked list of URLs is shown. The user picks one. The URL is opened in a full screen browser window.

32 Physical Web With Physical Web you do not need an app to receive nearby objects URL's. A browser with embedded BLE beacon-scanning support is sufficient. Starting from Rel. 49.x, Google Chrome supports Physical Web (still some bugs to be fixed!) HTTPS is required Note: Opera browser supports Physical Web, too.

33 Web Bluetooth Web Bluetooth is a specification for Bluetooth API to allow websites to communicate with BLE devices, using the Generic Attribute Profile (GATT), in a secure and privacy-preserving way. A website, running in the Central role, can connect to remote GATT Servers over a BLE connection. You can interact with a BLE-enabled device from a website with a browser (no app required) (Source:

34 Live Demo Very simple demo: toggling a led on a BLE-enabled device, using Web Bluetooth API. We use: a browser a HTTPS site a BLE connection NO Internet connection is required on the BLE-enabled device side

35 Resources Android API for Blueooth Low Energy tooth-le.html Open-source Android library for ibeacon Eddystone Beacons Google Developer site Open-source Eddystone library The Physical Web project library Web Bluetooth ct-with-ble-devices-on-the-web

36 Contacts Alessio Cucini BlueUp Srls, Managing Director Samuele Forconi BlueUp Srls, SW Development Manager