IoT Communication models and Control units

1. Chapter -2
Components of IoT
Control Units
Communication Modules
Bluetooth – Zigbee – Wifi - GPS
Dr. Y V Srinivasa Murthy
School of Computer Science & Engg. (SCOPE)
VIT Vellore

2. Outline
• Control units
• Communication modules
• Bluetooth
• Zigbee
• Wifi
• IoT Protocols

3. Control Units
• The Internet of Things is rarely discussed without the
conversation steering to data and the new Data
Economy.
• Sensors are the source of IoT data.
• Driven by new innovations in materials and
nanotechnology, sensor technology is developing at a
never before seen pace, with a result of increased
accuracy, decreased size and cost, and the ability to
measure or detect things that weren’t previously
possible.

4. Transducer
• A better term for a sensor is a transducer.
• Physical device that converts one form of energy into
another.
• The transducer converts some physical phenomenon
into an electrical impulse that can then be
interpreted to determine a reading.

5. Some Sensors

6. Actuators
• Another type of transducer that you will encounter
in many IoT systems is an actuator.
• In simple terms, an actuator operates in the reverse
direction of a sensor.
• It takes an electrical input and turns it into physical
action.
• For instance, an electric motor, a hydraulic system,
and a pneumatic system.

7. Sensor to Actuator Flow

8. Sensors and Actuators
• Humidity Sensor
• Level/tilt sensor
• Pressure sensor
• Temperature Sensor
• Motion sensor
• Proximity sensor
• Optical sensor
• Acceleration sensor
• Load sensor
• Vibration, chemical, flow…..
• LEDs
• Relays
• Motors
• Lasers
• Solenoids
• Speakers
• LCD displays

9. Communication Modules
• Bluetooth
• Zigbee
• Wifi

10. Short range wireless application areas
Voice Data Audio Video State
Bluetooth ACL/HS x Y Y x x
Bluetooth SCO/eSCO Y x x x x
Bluetooth low energy x x x x Y
Wi-Fi (VoIP) Y Y Y x
Wi-Fi Direct Y Y Y x x
ZigBee x x x x Y
ANT x x x x Y
10Low Power
State = low bandwidth, low latency data

11. How much energy does traditional Bluetooth use?
• Traditional Bluetooth is connection oriented. When a device is
connected, a link is maintained, even if there is no data flowing.
• Sniff modes allow devices to sleep, reducing power
consumption to give months of battery life
• Peak transmit current is typically around 25mA
• Even though it has been independently shown to be lower
power than other radio standards, it is still not low enough
power for coin cells and energy harvesting applications
11

12. What is Bluetooth Low Energy?
• Bluetooth low energy is a NEW, open, short range
radio technology
• Blank sheet of paper design
• Different to Bluetooth classic (BR/EDR)
• Optimized for ultra low power
• Enable coin cell battery use cases
• < 20mA peak current
• < 5 uA average current
12

13. Basic Concepts of Bluetooth 4.0
• Everything is optimized for lowest power
consumption
• Short packets reduce TX peak current
• Short packets reduce RX time
• Less RF channels to improve discovery and connection time
• Simple state machine
• Single protocol
• Etc.
13

14. Bluetooth low energy factsheet
Range: ~ 150 meters open field
Output Power: ~ 10 mW (10dBm)
Max Current: ~ 15 mA
Latency: 3 ms
Topology: Star
Connections: > 2 billion
Modulation: GFSK @ 2.4 GHz
Robustness: Adaptive Frequency Hopping, 24 bit CRC
Security: 128bit AES CCM
Sleep current: ~ 1μA
Modes: Broadcast, Connection, Event Data Models, Reads, Writes
14

15. ZigBee

16. Introduction
• ZigBee is a technological standard designed for
control and sensor networks
• Based on the IEEE 802.15.4 Standard
• Created by the ZigBee Alliance

17. Introduction
• Operates in Personal Area Networks (PAN’s) and
device-to-device networks
• Connectivity between small packet devices
• Control of lights, switches, thermostats, appliances,
etc.

18. History
• Developement started 1998, when many
enginereers realized that WiFi and Bluetooth were
going to be unsuitable for many applications
• IEEE 802.15.4 standard was completed in May 2003

19. ZigBee Alliance
• Organization defining global standards for reliable,
cost‐effective, low power wireless applications
• A consortium of end users and solution providers,
primarily responsible for the development of the
802.15.4 standard
• Developing applications and network capability
utilizing the 802.15.4 packet delivery mechanism

20. Characteristics
• Low cost
• Low power consumption
• Low data rate
• Relatively short transmission range
• Scalability
• Reliability
• Flexible protocol design suitable for many applications

21. Security
• Encryption specified for MAC, Network and APS
layers
• Encryprion/Authentication mode CCM(CTR +CBC-
MAC)
• CTR is a counter based encryption mode
• CBC-MAC provides data integrity
• All security is based on 128bit key and AES-128
block encryption method

22. Applications
PERSONAL
HEALTH CARE
ZigBee
LOW DATA-RATE
RADIO DEVICES
HOME
AUTOMATION
CONSUMER
ELECTRONICS
TV VCR
DVD/CD
Remote
control
security
HVAC
lighting
closures
PC &
PERIPHERALS
consoles
portables
educational
TOYS &
GAMES
INDUSTRIAL &
COMMERCIAL
monitors
sensors
automatio
n
control
mouse
keyboard
joystick
monitors
diagnostic
s
sensors

23. ZigBee/IEEE 802.15.4
PHY
868MHz / 915MHz / 2.4GHz
MAC
Application
Network
Star / Mesh / Cluster-Tree
Security
32- / 64- / 128-bit encryption
API
ZigBee
Alliance
IEEE
802.15.4
Customer
ZigBee Alliance
-“the software”
-Network, Security & Application layers
-Brand management
IEEE 802.15.4
-“the hardware”
-Physical & Media Access Control layers

24. IEEE 802.15.4
• IEEE 802.15.4 Architecture
IEEE 802.15.4
868/915 MHz
PHY
IEEE 802.15.4
2400 MHz
PHY
IEEE 802.15.4 MAC
IEEE 802.2 LLC Other LLC
Data Link Controller (DLC)
Networking App Layer
ZigBee Application Framework

25. IEEE 802.15.4 Physical Layer
• PHY functionalities:
• Activation and deactivation of the radio transceiver
• Energy detection within the current channel
• Link quality indication for received packets
• Clear channel assessment for CSMA-CA
• Channel frequency selection
• Data transmission and reception

26. PHY frame structure
• PHY packet fields
• Preamble (32 bits) – synchronization
• Start of packet delimiter (8 bits) – shall be formatted as
“11100101”
• PHY header (8 bits) –PSDU length
• PSDU (0 to 127 bytes) – data field
Preamble
Start of
Packet
Delimiter
PHY Header
PHY Service
Data Unit (PSDU)
4 Octets
0-127 Bytes
Sync Header PHY Payload
1 Octets 1 Octets
Frame
Length
(7 bit)
Reserve
(1 bit)

27. Operating frequency bands
• The standard specifies two PHYs :
• 868 MHz/915 MHz direct sequence spread spectrum (DSSS)
PHY (11 channels)
• 1 channel (20Kb/s) in European 868MHz band
• 10 channels (40Kb/s) in 915 (902-928)MHz ISM band
868MHz/
915MHz
PHY
868.3 MHz
Channel 0 Channels 1-10
928 MHz902 MHz
2 MHz

28. Operating frequency bands
• 2450 MHz direct sequence spread spectrum (DSSS) PHY (16
channels)
• 16 channels (250Kb/s) in 2.4GHz band
2.4 GHz
Channels 11-26
2.4835 GHz
5 MHz
2.4 GHz
PHY

29. IEEE 802.15.4 MAC Layer
• Traffic Type
• Periodic data
• e.g. sensors
• Intermittent data
• e.g. light switch
• Repetitive low latency data
• e.g. mouse

30. IEEE 802.15.4 MAC Layer
• Device Classes
• Full function device (FFD)
• Can function in any topology
• Capable of being Network coordinator
• Can talk to any other device (FFD/RFD)
• Reduced function device (RFD)
• Limited to star topology
• Cannot become network coordinator
• Talks only to FFDs
• Address
• All devices must have 64 bit IEEE addresses
• Short (16 bit) addresses can be allocated to reduce
packet size

31. IEEE 802.15.4 MAC Layer
• Frame Types
• Data Frame
• used for all transfers of data
• Beacon Frame
• used by a coordinator to transmit beacons
• Acknowledgment Frame
• used for confirming successful frame reception
• MAC Command Frame
• used for handling all MAC peer entity control transfers

32. IEEE 802.15.4 MAC Layer
• Transmission Mode
• Slotted (Beacon enable mode )
• Periodic data and Repetitive low latency data using.
• Un-slotted (Non-Beacon enable mode)
• Intermittent data using.

33. ZigBee Network Topologies
Star
Mesh
Cluster Tree PAN coordinator
Full Function Device
Reduced Function Device

34. ZigBee Network Topologies
• Star Topology
• Advantage
• Easy to synchronize
• Low latency
• Disadvantage
• Small scale

35. ZigBee Network Topologies
• Mesh Topology
• Advantage
• Robust multihop communication
• Network is more flexible
• Lower latency
• Disadvantage
• Route discovery is costly
• Needs storage for routing table

36. ZigBee Network Topologies
• Cluster Tree
• Advantage
• Low routing cost
• Allow multihop communication
• Disadvantage
• Route reconstruction is costly
• Latency may be quite long

37. ZigBee and Bluetooth Comparison
• Optimized for different applications
• ZigBee
• Smaller packets over large network
• Mostly Static networks with many, infrequently used devices
• Home automation, toys, remote controls, etc.
• Bluetooth
• Larger packets over small network
• Ad‐hoc networks
• File transfer
• Screen graphics, pictures, handsfree audio, Mobile phones,
headsets, PDAs, etc.

38. ZigBee and Bluetooth Comparison
Feature(s) Bluetooth ZigBee
Power Profile days years
Complexity complex Simple
Nodes/Master 7 64000
Latency 10 seconds 30 ms – 1s
Range 10m 70m ~ 300m
Extendibility no Yes
Data Rate 1 Mbps 250 Kbps
Security 64bit, 128bit 128bit AES and
Application Layer

39. ZigBee and Bluetooth ComparisonSHORT<RANGE>LONG
LOW < DATA RATE > HIGH
PAN
LAN
TEXT GRAPHICS INTERNET HI-FI
AUDIO
STREAMING
VIDEO
DIGITAL
VIDEO
MULTI-CHANNEL
VIDEO
802.15.1
Bluetooth1
802.15.1
Bluetooth 2
802.15.4
ZigBee
802.11b
802.11a/HL2 & 802.11g