Internet of Things
CS631P
IoT – Definition & Characteristics
• A dynamic global network infrastructure with
self-configuring capabilities based on standard
and interoperable communication protocols
where physical and virtual “things” have
identities, physical attributes, and virtual
personalities and use intelligent interfaces,
and are seamlessly integrated into the
information network, often communicate data
associated with users and their environments.
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Dynamic & Self-adapting
Self configuring
Interoperable communication protocols
Unique identity
Integrated into information network
Physical Design of IoT
• Things in IoT
– Unique identity
– Sensing, Actuating, Monitoring
– Exchange data, process data, send to server/cloud
Connectivity
Processor
USB Host
Ethernet
CPU
Audio/Video
Interfaces
HDMI
3.5 mm audio
RCA video
WIFI/Bluetooth
I/O Interfaces
(for sensors,
actuators etc.
UART
SPI
Memory
Interfaces
Graphics
I2C
SD
NAND/NOR
GPU
DDR1/2/3
Storage
Interfaces
MMC
SDIO
Fig: Generic block diagram for IoT Device
CAN
Physical Design of IoT
• IoT Protocols
– Link Layer
– Network Layer
– Transport Layer
– Application Layer
HTTP
Application Layer
CoAP
MQTT
WebSockets
XMPP
DDS
AMQP
Transport Layer
UDP
TCP
Network Layer
IPv4
IPv6
6LoWPAN
Link Layer
802.3 - Ethernet
802.16 - WiMax
802.11- WiFi
802.15.4 – LR-WPAN
Fig: IoT Protocols
2G/3G/4G/LTE
- Cellular
Link Layer
• Scope of link layer is the local network
connection to which the host is attached.
– Hosts on the same link exchange data packets
over the link layer using link layer protocols.
– Determines how the packets are coded and
signaled over the medium.
IoT Link Layer protocols
• IEEE 802.3 Ethernet
– Collection of wired Ethernet standards.
– Data rates – 10 Mbps to 40 Gbps and higher.
– Medium – Coaxial, Twisted pair, Optical fiber.
• IEEE 802.11 – Wifi
– Collection of wireless LAN communication
standards.
– Data rates – 1Mbps to 6.75 Gbps and higher.
– Radio waves
• IEEE 802.16 – WiMax
– Worldwide Interoperability for Microwave Access
– Collection of wireless broadband standards.
– Data rates – 1.5Mbps to 1 Gbps.
• IEEE 802.15.4 – LR-WPAN
– Collection of standard for Low-rate wireless
personal area networks.
– Forms the basis for Zigbee, WirelessHART, Thread
etc.
– Data rate – 40 Kbps to 250Kbps
– Low cost and low speed communication for power
constrained devices.
• 2G/3G/4G – Cellular Communication
– 2G - GSM,CDMA
– 3G – UMTS, CDMA2000
– 4G – LTE
– Data rate – 9.6 Kbps(2G) upto 100 Mbps (4G)
• Bluetooth and BLE
– transmit small packets of data consuming
significantly less power
Network/Internet Layer - IoT
• Responsible for sending IP datagrams from
source network to destination network.
• Addressing and Routing
• IPv4, IPv6,6LoWPAN
• 6LoWPAN
– IPv6 over Low power Wireless Personal Area
Networks.
– Works with IEEE 802.15.4 link layer protocol
– Data rate – 250 Kbps
Transport Layer - IoT
• TCP
– Connection Oriented
– Reliable
– Slow
• UDP
– Connectionless
– Unreliable
– Fast
Application Layer
• Defines how applications interface with the
lower layer protocols.
• Process to process communication
• Port numbers for application addressing
Application Layer Protocols - IoT
• HTTP
– Request-response model
– Stateless protocol
– Commands –
GET,PUT,POST,DELETE,HEAD,TRACE,OPTIONS
– Runs on top of TCP.
• CoAP
– Constrained Application Protocol
– Meant for constrained devices and networks.
– Request-response model
– Runs on top of UDP
– Can easily interface with HTTP and supports
methods such as GET,PUT,POST,DELETE.
• Websocket
– The WebSocket protocol enables interaction
between a web client (such as a browser) and a
web server with lower overheads.
– On top of TCP
• MQTT
– Message Queue Telemetry Transport
– Light weight protocol
– Publish-Subscribe model
– Suited for constrained environments
– MQTT Broker
• Broker: Broker controls the
distribution of information and
mainly responsible for
receiving all messages from
publisher, filtering them,
decide who is interested in it
and then sending the
messages to all subscribed
clients. It can do the following
things -Accept Client requests.
-Receives Published messages
by Users. -Processes different
requests like Subscribe and
Unsubscribe from Users. After receiving messages from
publisher sends it to the
interested Users.
MQTT Working
• XMPP
– Extensible Messaging Presence Protocol
– Protocol for streaming XML data
– Real-time communication
• DDS
– Data Distribution Service
– Publish-subscribe model
• AMQP
– Advanced Message Queuing Protocol
– Publish-Subscribe
– Interoperability
Logical Design of IoT
• Refers to an abstract representation of the
entities and processes without going in to the
low-level specifics of the implementation.
– IoT Functional Blocks
– IoT Communication Models
– IoT Communication APIs
IoT Functional Blocks
• Device
– Sensing, actuation, monitoring, control etc.
• Communication
– Handles communication for the IoT system
• Services
– Services for device monitoring, data publishing, device
discovery etc.
• Management
– Functions to govern and manage the IoT system
• Security
– Authentication, Authorization, integrity and security.
• Application
– Interface to the user to view/control/analyze.
Application
Services
Security
Management
Communication
Device
Fig: Functional Block of IoT
IoT Communication Models
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Request-Response
Publish-Subscribe
Push-Pull
Exclusive pair
Request-Response
Client
Server
Request
Sends
requests to
the Server
Response
Receives
requests from
client, processes
requests, looks
up/fetches
resources,
prepares
response and
sends response
to client
Resources
Publish-Subscribe
Publisher
Broker
Publish to
topic-1
Sends messages
to topics
Consumer-1
Topic-1
Subscribers:
Consumer-1,
Consumer-2
Consumer-2
Publish to
topic-2
Topic-2
Subscribers:
Consumer-3
Consumer-3
Push-Pull
Publisher
Queues
Consumer-1
Sends
messages
to the
Queue
Message
pushed to
Queues
Message
pulled from
Queues
Consumer-2
Exclusive Pair
Request to setup connection
Response accepting the request
Message from client to server
Client
Server
Message from server to client
Connection close request
Connection close response
IoT Communication APIs
• REST-based Communication APIS
• WebSocket-based Communication APIs
REST-based Communication APIS
• Representational State Transfer (REST) – A set
of architectural principles to design web
services and web APIs.
• Request-Response communication model
• On top of HTTP
• XML, JSON, YAML etc.
REST Architectural constraints
• Client-Server
– Separation of concerns
• Stateless
– No stored context in server
• Cache-able
– Data within a response should be labeled as
cache-able or non-cache-able.
• Layered System
– Each component cannot see beyond the
immediate layer with which it is interacting
REST Architectural constraints
• Uniform Interface
– Uniform method of communication
– Resources identified by URI (Uniform Resource
Identifier)
– Representation of the resource sent to the client
• Code on demand
– Optional
– Servers can provide executable codes or scripts for
clients to execute in their context.
Request-Response model used by REST
REST
Client
Server
Request(GET,PUT,UPDATE or DELETE) with
payload (JSON or XML)
Response (JSON or XML)
Request(GET,PUT,UPDATE or DELETE) with
payload (JSON or XML)
Response (JSON or XML)
HTTP Client
HTTP Packet
HTTP Server
HTTP Command
Rest-Aware
HTTP Client
GET
PUT
POST
DELETE
Authorization
REST-ful Web
Service
REST Payload
JSON
XML
Resources
URI
URI
Representations
Representations
Resources
Resources
Fig: Communication with REST APIs
WebSocket-based Communication
APIs
• Allow bi-directional, full-duplex communication
between clients and servers.
• Follow the exclusive pair communication model.
• Persistent connection
– Do not require a new connection to be set up for each
message to be sent.
– Begins with WebSocket Handshake.
– Suitable for low-latency or high throughput
requirements.
Exclusive pair model used by
WebSocket APIs
WebSocket Protocol
Client
Server
Request to setup WebSocket Connection
Response accepting the request
Data Frame
Data Frame
Data Frame
Data Frame
Connection close request
Connection close response
IoT Enabling Technologies
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Wireless Sensor Networks
Cloud Computing
Big Data Analytics
Communication Protocols
Embedded Systems
Wireless Sensor Networks
WSN Protocol Stack
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Low cost - Sensors
Energy efficient
Computational power - Limited
Communication Capabilities – Radio waves,
Short range, bi-directional/uni-directional,
Robust/Secure.
• Security and Privacy
• Distributed sensing and processing
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Dynamic network topology
Self-organization
Multi-hop communication:
Application oriented
Small physical size
Cloud Computing
• On demand services
• Computing power, Storage, Services
Cloud Computing
• Infrastructure –as-a-Service(IaaS)
– Computing and Storage resources provided as
virtual machine instances and virtual storage.
– Can deploy OS and applications of choice.
– Pay-per-use billing model
– DigitalOcean, Linode, Rackspace, Amazon Web
Services (AWS), Cisco Metapod, Microsoft Azure,
Google Compute Engine (GCE) are some popular
examples of Iaas.
• Platform-as-a-Service(Paas)
– Development tools, APIs, Services, Libraries
– Provider manages the underlying cloud
infrastructure including servers, network, OS and
storage.
– Users responsible for developing, deploying,
configuring and managing applications.
– Examples: AWS Elastic Beanstalk, Windows Azure,
Heroku, Force.com, Google App Engine, Apache
Stratos.
• Software-as-a-Service(SaaS)
– Provides Complete software application or the UI to
the application.
– Provider manages the cloud infrastructure including
servers, network, OS, storage and the application
software
– User unaware of the underlying architecture.
– Applications are provided to user through thin client
interface like browser, app etc.
– Platform independent – Can be accessed from
anywhere using any device (Workstations, PCs,
Tablets, smart phones etc.) running on different OS.
– Examples- Google Apps, Dropbox, Salesforce, Cisco
WebEx, Concur, GoToMeeting
Big Data Analytics
• Data whose volume, velocity and variety is so
large that it is difficult to store, manage,
process and analyze it using traditional
database tools.
• Involves
– Data cleansing
– Data Munging (Data Wrangling)
– Data Processing
– Visualization
4 Vs
5 Vs
• Data cleansing or data cleaning is the process
of detecting and correcting (or removing)
corrupt or inaccurate records from a record
set, table, or database and refers to
identifying incomplete, incorrect, inaccurate
or irrelevant parts of the data and then
replacing, modifying, or deleting the dirty or
coarse data.
• Data wrangling, sometimes referred to as data
munging, is the process of transforming and
mapping data from one "raw" data form into
another format with the intent of making it
more appropriate and valuable for a variety of
downstream purposes such as analytics.
Big Data in IoT
• Sensor data generated by IoT systems such as
weather monitoring systems.
• Machine sensor data collected from sensors
embedded in industrial and energy systems
for monitoring their health and failure
patterns.
• Etc.
Communication Protocols
Embedded System
• An embedded system is some combination of
computer hardware and software, either fixed in
capability or programmable, that is designed for a
specific function or for specific functions within a larger
system.
• Industrial machines, agricultural and process industry
devices, automobiles, medical equipment, cameras,
household appliances, airplanes, vending machines
and toys as well as mobile devices are all possible
locations for an embedded system.
• Embedded systems can be microprocessor or
microcontroller based. In either case, there is
an integrated circuit (IC) at the heart of the
product that is generally designed to carry out
computation for real-time operations.