ble beacons, eddystone and physical web: an … beacons, eddystone and physical web: an introduction...

BLE beacons, Eddystone and Physical Web: an introduction

Alessio Cucini, Samuele ForconiBlueUp Srls

BlueUp Srls, 2016, All right reserved

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

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)



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)


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 application-friendly version of Bluetooth, especially built for the Internet of Things (IoT).

Bluetooth Smart was originally introduced under the name Wibree by Nokia in 2006.


The Bluetooth 4.0 Ecosystem

(Source: Bluetooth SIG)

● Non-negligible energy consumption

● Long discovering and pairing time

● Medium complexity● Limited visibility and

discovery● Stream-oriented


Vs.

● Low consumption (“low energy”)

● Short connection and comunication time

● Low complexity● Asymmetric architecture

● Simple, cheap, battery-powered peripheral

● Complex central ● Message-oriented


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.


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

GAP = Generic Access ProfileGATT = Generic ATTribute Profile

Generic BLE connection


GATT Client GATT Server

Android Bluetooth LE API


Class: BluetoothLeScannerMethod: 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.

GATT Client (App) GATT Server



Class: BluetoothDeviceMethod: 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.





Class: BluetoothGattMethod: discoverServices()Discovers services offered by a remote device as well as their characteristics and descriptors.

BeaconSmartphone

BLE Beacon


BLE-beacon technology uses only a portion of the Bluetooth LE protocol:

Broadcast advertising

2011 2012 2013 2014 2015 2016

BLE Beacons Timeline

iPhone 4SFirst smartphone with Bluetooth 4.0 support

Android 4.3 supports Bluetooth 4.0

Apple launches iBeacon technology

Google launches Eddystone specifications

Physical Web support on Google Chrome ver. 49 for

Android


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

iBeacon technology


FL = Field LengthFT = Field Typefl = LE and BR/EDR flagMnf. 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]

1 2 3 4 5 6-9 10-25 26-27 28-29 30

FL FT fl FL FT Mnf. data Proximity UUID M m R

02 01 04 1A FF 4C 00 02 15

Fixed

iBeacon Advertising Packet


Far (< 30/35 m)

Near (< 2/3 m)

Unknown

Immediate (< 0.2 m)

Proximity


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.


Accuracy

Reflections, diffractions, absorptions, ect., impact on radio signal propagation


Ranging with RSSI

0 2 4 6 8 10 12 14 16 18 20

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

Distance (m)

RSSI (dBm)

Log-distance path-loss modelRSSI = RSSI0 -10 n log10(d/d

0) + Xg

n = 1.7 (in-building LOS)

n = 2 (free space)

n = 5 (in-building NLOS)

Two-ray model

normal random variable with zero mean and standard deviation in dB

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

Eddystone specifications


FL = Field LengthFT = Field Typefl = LE and BR/EDR flagCL = Complete list of service UUIDSD = Service DataE-UUID = Eddystone UUID (0xFEAA)

1 2 3 4 5 6-7 8 9 10 11

FL FT fl FL CL E-UUID FL SD E-UUID

02 01 06 03 03 AA FE 0xnn 0x16 AA FE

1 … 11 12 … max (31)

02 … FE depends on frame type

Eddystone Advertising Packet


12 13 14-23 24-29 30 31

FT RD Namespace ID Instance ID RFU

00

FL = 0x17 (23)FT = Frame TypeRD = 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

Eddystone-UID


12 13 14 15 +

FT RD US Encoded URL

01

FL = variable, depends on URL lengthFT = Frame TypeRD = Ranging Data (RSSI at 0mt)US = URL Scheme prefix (0x00 = http://www.; 0x01 = https://www.; 0x02 = http://; 0x03 = https://.Encoded URL = up to 17 bytes (usually compact URL)

Eddystone-URL


FL = 0x11 (17)FT = Frame TypeVer. = TLM-frame version (currently 0x00)VBATT = battery voltage (mV) – 2 bytesTEMP = beacon temperature (°C) – 2 bytesADV_CNT = advertising packet counter from power-up (units) – 4 bytesSEC_CNT = time counter from power-up (0.1sec) – 4 bytes

12 13 14-15 16-17 18-21 22-25

FT Ver. VBATT TEMP ADV_CNT SEC_CNT

02 00

Eddystone-TLM


UID vs URL


UID

URL

ID

ID http://example.com

http://example.com

http://example.comhttp://example.com

Google Beacon API


(Source: Google Inc.)

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.

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.

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

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.

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.

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: https://www.w3.org/community/web-bluetooth/)

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


● Android API for Blueooth Low Energyhttp://developer.android.com/guide/topics/connectivity/bluetooth-le.html

● Open-source Android library for iBeaconhttps://github.com/AltBeacon/android-beacon-library

● Eddystone Beacons Google Developer sitehttps://developers.google.com/beacons/

● Open-source Eddystone libraryhttps://github.com/google/eddystone

● The Physical Web project libraryhttps://github.com/google/physical-web

● Web Bluetooth https://developers.google.com/web/updates/2015/07/interact-with-ble-devices-on-the-web

Resources


● Alessio CuciniBlueUp Srls, Managing DirectorE-mail: [email protected]

● Samuele ForconiBlueUp Srls, SW Development ManagerE-mail: [email protected]

Contacts

ble beacons, eddystone and physical web: an … beacons, eddystone and physical web: an introduction...

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