1. Bluetooth Low Energy
Overview

2. What is BLE Wireless Personal Area Network technology
Target for healthcare, fitness, beacons, security and home entertainment
Provides considerably reduced power consumption
Low Energy requirements, operating for “months or years” on a button cell
Small size and low cost
Compatibility with large installed base
Starting point of automation in nearly all domain

3. Architecture Application / Profiles APIs Generic
Generic Attribute Profile ( GATT )
Security
Manager
( SM )
Generic
Access
Profile
( GAP )
Attribute Protocol ( ATT )
L2CAP
Link Layer
BLE Radio

4. BLE Radio Layer
Operates in 2.4 GHz ISM ( Industrial Scientific Medical ) band 2402 MHz – 2480 MHz
40 RF Channels with 2 MHz Spacing
3 out of 40 channels are advertising
Used for device discovery
connection establishment
broadcast
Advertising channel frequencies are selected to minimize the interference

5. BLE Radio Layer … All physical channels use GFSK
Gaussian Frequency Shift Keying modulation
Allows reduced peak power consumption
Physical layer data rate is 1 Mbps
Range is typically 0 – 50 meters from smart phone

6. BLE Link Layer
First level of control & data structure over raw radio operations
Bit stream transmission & Reception
State machine & state transitions
Data & Advertisement Packet formating
Link Layer operations
Connections, packet timings, retransmission
Link Layer level security

7. BLE - PDU

8. BLE L2CAP
Advertisement
Scanning
Connection Establishment

9. BLE L2CAP - Advertisement
Provides a way for devices to broadcast their presence
Allows connection to be established
Broadcast data like the list of supported services, device name and TX Power Level
Device will send advertising broadcast packets to one or multiple advertisement channels, which remote devices will pick up.

10. BLE L2CAP – Advertisement Passive Scanning

11. BLE L2CAP – Active Scanning

12. BLE Advertising Parameters
Values
Description
Advertisement Interval
20 mSec to mSec
Interval between advertisement packets
Advertisement channels
37, 38 & 39
RF Channel used to transmit
Discoverability Mode
Not Discoverable
Generic Discoverable
Limited Discoverable
Broadcast
How the advertiser visible to other devices
Connect ability mode
Not connectable
Directly connectable
Undirected connectable
Defines if advertiser can be connected or not
Payload
0 – 31 Byte
Data byte can be included in advertisement packet

13. BLE L2CAP – Connection

14. BLE L2CAP – Network Topology
Advertiser
Broadcasts advertisement packets
Scanner
Only listen for advertisements, can connect to advertiser
Slave
Device connected to master
Master
Device connected with one or more slaves
Master can connect upto 4 – 8 slaves at a time
Hybrid
Device advertise and scan at the same time
Connected to a master and advertise or scan simultaneously

15. BLE L2CAP – Connection

16. BLE L2CAP – Topology Change

17. BLE Generic Attribute Profile
Provides access to the link layer operations related to
Device discovery
Connection establishment & termination
Connection timing control
GAP defines roles
Broadcaster : Sends advertising & broadcast data
Observer : Listens for advertising events
Peripheral : Always slave, is connectable & advertising
Central : Always master, never advertise
Device can have more than one role, only one role can be adopted at a given time

18. BLE GAP Modes Connectable Discoverable Bondable Can make a connection.
Not connectable, connectable
Discoverable
Can be discovered ( is advertising )
None, limited, general
Bondable
If connectable, will pair with connected device for a long term connection
Bondable, Non Bondable

19. BLE GAP Procedures Name Discovery Device Discovery Link Establishment
Find the name of other device
Device Discovery
Find address and name of devices
Define device role
Link Establishment
Instruct link layer to send a CONNECT_REQ
Service discovery, device authentication
Service Discovery
Find services available on the peer devices

20. BLE Attribute Protocol
Defines communication between two devices playing the roles of server & client
ATT Protocol defines two roles
Server : device that stores the data as one or more attributes
Client : Collects the information for one or more servers

21. BLE ATT Data Transfer

22. BLE GATT Built on top of Attribute Protocol
Establishes common framework for data transported & stored
GATT defines two roles
Server
Client

23. BLE GATT Attributes Service Characteristics
Transported by Attribute protocol
Formatted as services & characteristics
Service
Contain collection of characteristics
Characteristics
Contain single value and any number of descriptors

24. BLE GATT Data Structure

25. BLE GATT Characteristics
Value used in a service
Expose and / or exchange the data
Control information
Well defined, known format
Information about how the value can be passed and security achievement
Contain descriptors describe the value or permit configuration or characteristics data indication

26. BLE Security Manager ( SM )
Ensure the trust, integrity, privacy and encryption of data
Security Manager responsible for
Pairing
Key distribution
Generating hashes and short term keys

27. BLE Security Model Pairing Bonding Device authentication Encryption
Process of creating shared keys
Bonding
Storing the keys created during pairing for later usage
Device authentication
Verification of stored keys
Encryption
Data confidentiality
Message Integrity
Protection against data alteration

28. Profiles – Health Care BLP – Blood Pressure Profile
HTP – Health Thermometer Profile
GLP – Glucose Profile
CGMP – Continuous Glucose Monitor Profile

29. Profiles – Sports & Fitness
BCS – Body Composition Service
CSCP – Cycling Speed and Cadence Profile
CPP – Cycling Power Profile
HRP – Heart Rate Profile
LNP – Location and Negotiation Profile
RSCP – Running Speed and Cadence Profile
WSP – Weight Scale Profile

30. Profiles … IPSP – Internet Protocol Support Suite
ESP – Environmental Sensing Profile
UDS – User Data Service
HOGP – HID over GATT Profile