Physical Design of IOT

Physical Design of IOT

• It refers to IoT Devices and IoT Protocols.
• Things are Node device which have unique identities and can
perform remote sensing, actuating and monitoring
capabilities.
• IoT Protocols helps Communication established between
things and cloud based server over the Internet.
 Things
• Basically Things refers to IoT Devices which have unique
identities and can perform remote sensing, actuating and
monitoring capabilities. Things are main part of IoT
Application. IoT Devices can be various type, Sensing
Devices, Smart Watches, Smart Electronics appliances,
Wearable Sensors, Automobiles, and industrial machines.
These devices generate data in some forms or the other
which when processed by data analytics systems leads to
useful information to guide further actions locally or
remotely.
Universal Asynchronous Receiver-
Transmitter (UART)
• UART stands for universal asynchronous receiver/transmitter and is a
simple, two-wire protocol for exchanging serial data.
• Asynchronous means no shared clock, so for UART to work, the same
bit or baud rate must be configured on both sides of the connection.
• Start and stop bits are used to indicate where user data begins and
ends, or to “frame” the data.
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I2C) Protocol
• Controller Area Network (CAN)
 IoT Protocols
• IoT protcols help to establish Communication between IoT
Device (Node Device) and Cloud based Server over the
Internet.
• It help to sent commands to IoT Device and received data
from an IoT device over the Internet.
IOT Protocols
 IOT Protocols
• Link Layer
• Link layer protocols determine how data is physically sent
over the network’s physical layer or medium (Coxial calbe or
other or radio wave).
• Link Layer determines how the packets are coded and
signaled by the hardware device over the medium to which
the host is attached (eg. coxial cable).
 802.3 – Ethernet
• IEEE 802.3 defines the physical layer and the medium access
control (MAC) sub-layer of the data link layer for wired
Ethernet networks.
• Ethernet is a set of technologies and protocols that are used
primarily in LANs.
 802.11 – WiFi
• IEEE 802.11 is part of the IEEE 802 set of LAN protocols, and
specifies the set of media access control (MAC) and physical
layer (PHY) protocols for implementing wireless local area
network (WLAN) Wi-Fi computer communication in various
frequencies, including but not limited to 2.4 GHz, 5 GHz, and
60 GHz frequency bands.
 802.15.4 -LR-WPAN
• A collection of standards for Low-rate wireless personal area
network.
• The IEEE’s 802.15.4 standard defines the MAC and PHY layer
used by, but not limited to, networking specifications such as
Zigbee®, 6LoWPAN, Thread, WiSUN and MiWi protocols.
• The standards provide low-cost and low-speed communication
for power-constrained devices.
2G/3G/4G- Mobile Communication :
• These are different types of telecommunication generations.
IoT devices are based on these standards can communicate
over the celluer networks.
 Application Layer
• Application layer protocols define how the applications
interface with the lower layer protocols to send over ther
network.
MQTT

Introduction to Internet of Things 3

 Introduction
✓Message Queue Telemetry Transport.
✓ISO standard (ISO/IEC PRF 20922).
✓It is a publish‐subscribe‐based lightweight
messaging protocol for use in conjunction with the
TCP/IP protocol.
✓MQTT was introduced by IBM in 1999 and
standardized by OASIS in 2013.
✓Designed to provide connectivity (mostly
embedded) between applications and
middle‐wares on one side and networks and
communications on the other side.
Source: “MQTT”, Wikipedia (Online)

Introduction to Internet of Things 4

✓A message broker controls the publish‐subscribe
messaging pattern.
✓A topic to which a client is subscribed is updated
in the form of messages and distributed by the
message broker.
✓Designed for:
▪ Remote connections
▪ Limited bandwidth 5

▪ Small‐code footprint
Source: “MQTT”, Wikipedia (Online) Introduction to Internet of Things
 MQTT Components

Publishers • Lightweight sensors

Subscribers • Applications interested in sensor data

Brokers • Connect publishers and subscribers

• Classify sensor data into topics

Source: “MQTT”, Wikipedia (Online)

Introduction to Internet of Things 6

 MQTT Methods
Connect
Disconnect
Subscribe
Unsubscribe
Publish

Source: “MQTT”, Wikipedia (Online)

Introduction to Internet of Things 7

 8
Introduction to Internet of Things

Source: “MQTT 101 – How to Get Started with the lightweight IoT Protocol”, HiveMQ (Online)
 Communication
✓The protocol uses a publish/subscribe
architecture (HTTP uses a request/response
paradigm).
✓Publish/subscribe is event‐driven and enables
messages to be pushed to clients.
✓The central communication point is the MQTT
broker, which is in charge of dispatching all
messages between the senders and the rightful
receivers.
✓Each client that publishes a message to the broker,
includes a topic into the message. The topic is the
routing information for the broker.
Source: “MQTT 101 – How to Get Started with the
lightweight IoT Protocol”, HiveMQ (Online)
✓Each client that wants to receive messages
subscribes to a certain topic and the broker delivers
all messages with the matching topic to the client.
✓Therefore the clients don’t have to know each
other. They only communicate over the topic.
✓This architecture enables highly scalable solutions
without dependencies between the data producers
and the data consumers.

Source: “MQTT 101 – How to Get Started with the lightweight IoT Protocol”, HiveMQ (Online)

Introduction to Internet of Things 10

MQTT Topics
✓A topic is a simple string that can have more
hierarchy levels, which are separated by a slash.
✓A sample topic for sending temperature data of
the living room could be
house/living‐room/temperature.
✓On one hand the client (e.g. mobile device) can
subscribe to the exact topic or on the other hand, 11

it can use a wildcard.

Source: “MQTT 101 – How to Get Started with the lightweight IoT Protocol”, HiveMQ (Online)
 ✓The subscription to house/+/temperature would
result in all messages sent to the previously
mentioned topic house/living‐ room/temperature, as
well as any topic with an arbitrary value in the place
of living room, such as house/kitchen/temperature.
✓The plus sign is a single level wild card and only
allows arbitrary values for one hierarchy.
✓If more than one level needs to be subscribed, such
as, the entire sub‐tree, there is also a multilevel
wildcard (#).
✓It allows to subscribe to all underlying hierarchy
levels.
✓For example house/# is subscribing to all topics
beginning with
house.
Source: “MQTT 101 – How to Get Started with the lightweight IoT Protocol”, HiveMQ (Online)

Introduction to Internet of Things 12

 Applic ations
✓Facebook Messenger uses MQTT for online chat.
✓Amazon Web Services use Amazon IoT with
MQTT.
✓Microsoft Azure IoT Hub uses MQTT as its main
protocol for telemetry messages.
✓The EVRYTHNG IoT platform uses MQTT as an
M2M protocol for millions of connected products.
✓Adafruit launched a free MQTT cloud
service for IoT experimenters called Adafruit
IO.
Introduction to Internet of Things 13
 SMQTT
✓Secure MQTT is an extension of MQTT which
uses encryption based on lightweight attribute
based encryption.
✓The main advantage of using such encryption is
the broadcast encryption feature, in which one
message is encrypted and delivered to multiple
other nodes, which is quite common in IoT
applications.
✓In general, the algorithm consists of four main
stages: setup, encryption, publish and
decryption.
Source: M. Singh, M. Rajan, V. Shivraj, and P. Balamuralidhar, "Secure MQTT for Internet of Things (IoT)," in Fifth International Conference on Communication Systems
and Network Technologies (CSNT 2015), April 2015, pp. 746‐751

Introduction to Internet of Things 14

✓In the setup phase, the subscribers and publishers register
themselves to the broker and get a master secret key
according to their developer’s choice of key generation
algorithm.
✓When the data is published, it is encrypted and published
by the broker which sends it to the subscribers, which is
finally decrypted at the subscriber end having the same
master secret key.
✓The key generation and encryption algorithms are not
standardized.
✓SMQTT is proposed only to enhance MQTT security 15

features.
CoAP

Introduction to Internet of Things 2

 Introduction
✓CoAP – Constrained Application Protocol.
✓Web transfer protocol for use with constrained nodes
and networks.
✓Designed for Machine to Machine (M2M) applications
such as smart energy and building automation.
✓Based on Request‐Response model between end‐points
✓Client‐Server interaction is asynchronous over a
datagram oriented transport protocol such as UDP
Source: Z. Shelby , K. Hartke, C. Bormann, “The Constrained Application Protocol (CoAP)”, Internet Engineering TasktoForce
Introduction (IETF),
Internet ofStandards
Things Track,
2014
 ✓The Constrained Application Protocol (CoAP) is a session
layer protocol designed by IETF Constrained RESTful
Environment (CoRE) working group to provide
lightweight RESTful (HTTP) interface.
✓Representational State Transfer (REST) is the
standard interface between HTTP client and servers.
✓Lightweight applications such as those in IoT, could
result in significant overhead and power consumption
by REST.
✓CoAP is designed to enable low‐power sensors to use
RESTful services while meeting their power constraints.
Source: Z. Shelby , K. Hartke, C. Bormann, “The Constrained Application Protocol (CoAP)”, Internet Engineering Task Force (IETF), Standards Track, 2014

Introduction to Internet of Things 4

✓Built over UDP, instead of TCP (which is commonly used with HTTP)
✓ and has a light mechanism to provide reliability.
✓CoAP architecture is divided into two main sub‐layers:
▪ Messaging
▪ Request/response.
✓The messaging sub‐layer is responsible for reliability and
duplication of messages, while the request/response sub‐layer is
responsible for communication.
✓CoAP has four messaging modes:
▪ Confirmable
▪ Non‐confirmable
▪ Piggyback Introduction to Internet of Things 5

▪ Separate
 CoAP Position

Application

Request
CoAP
Messages

UDP

Source: Z. Shelby , K. Hartke, C. Bormann, “The Constrained Application Protocol (CoAP)”, Internet Engineering Task Force (IETF), Standards Track,
2014

Introduction to Internet of Things

 CoAP Message Types

Message Types‐CoAP
Confimble

Non‐Confirmable

Piggyback

Separate

Source: Z. Shelby , K. Hartke, C. Bormann, “The Constrained Application Protocol (CoAP)”, Internet Engineering Task Force (IETF), Standards Track,
2014

Introduction to Internet of Things

 CoAP Request-Response Model

Source: V. Karagiannis, P. Chatzimisios, F. Vazquez‐Gallego, and J. Alonso‐Zarate, "A survey on application layer protocols for the internet of
things," Transaction on IoT and Cloud Computing, vol. 3, no. 1, pp. 11‐17, 2015

Introduction to Internet of Things

✓Confirmable and non‐confirmable modes represent the
reliable and unreliable transmissions, respectively, while
the other modes are used for request/response.
✓Piggyback is used for client/server direct communication
where the server sends its response directly after receiving
the message, i.e., within the acknowledgment message.
✓On the other hand, the separate mode is used when the
server response comes in a message separate from the
acknowledgment, and may take some time to be sent by
the server.
✓Similar to HTTP, CoAP utilizes GET, PUT, PUSH, DELETE
9

messages requests to retrieve, create, update, and delete,

respectively
 CoAP Request-Response Model

Source: V. Karagiannis, P. Chatzimisios, F. Vazquez‐Gallego, and J. Alonso‐Zarate, "A survey on application layer protocols for the internet of
things," Transaction on IoT and Cloud Computing, vol. 3, no. 1, pp. 11‐17, 2015

Introduction to Internet of Things

 Features
✓ Reduced overheads and parsing complexity.
✓ URL and content‐type support.
✓ Support for the discovery of resources provided by known
CoAP services.
✓ Simple subscription for a resource, and resulting push
notifications.
✓ Simple caching based on maximum message age.
Source: ”Constrained Application Protocol”, Wikipedia (Online)

Introduction to Internet of Things 11

XMPP

Introduction to Internet of Things 12

 Introduction

✓ XMPP – Extensible Messaging and Presence Protocol.

✓ A communication protocol for message‐oriented middleware
based on XML (Extensible Markup Language).
✓ Real‐time exchange of structured data.
✓ It is an open standard protocol.

Source: “XMPP”, Wikipedia (Online)

Introduction to Internet of Things 13

 ✓ XMPP uses a client‐server architecture.
✓ As the model is decentralized, no central server is required.
✓ XMPP provides for the discovery of services residing locally or
across a network, and the availability information of these
services.
✓ Well‐suited for cloud computing where virtual machines,
networks, and firewalls would otherwise present obstacles to
alternative service discovery and presence‐based solutions.
✓ Open means to support machine‐to‐machine or peer‐to‐peer
communications across a diverse set of networks.
Source: “XMPP”, Wikipedia (Online)

Introduction to Internet of Things 14

 Highlights

✓ Decentralization – No central server; anyone can run their

own XMPP server.
✓ Open standards – No royalties or granted permissions are
required to implement these specifications
✓ Security – Authentication, encryption, etc.
✓ Flexibility – Supports interoperability

Source: “XMPP”, Wikipedia (Online)

Introduction to Internet of Things 15

Source: “JabberNetwork.svg”, Wikimedia Commons (Online)

Introduction to Internet of Things 16

Core XMPP Technologies
Core
• information about the core XMPP technologies for XML streaming
Jingle
• multimedia signalling for voice, video, file transfer
Multi‐user Chat
• flexible, multi‐party communication
PubSub
• alerts and notifications for data syndication
BOSH
• HTTP binding for XMPP
Source: “XMPP: Technology Overview”, XMPP.org (Online)

Introduction to Internet of Things 17

Weaknesses

✓ Does not support QoS.

✓ Text based communications induces higher network
overheads.
✓ Binary data must be first encoded to base64 before
transmission.

Introduction to Internet of Things 18

Applic ations

✓ Publish‐subscribe systems
✓ Signaling for VoIP
✓ Video
✓ File transfer
✓ Gaming
✓ Internet of Things applications
▪ Smart grid
▪ Social networking services

Introduction to Internet of Things 19

AMQP

Introduction to Internet of Things 2

 Introduction

✓ Advanced Message Queuing Protocol.

✓ Open standard for passing business messages between
applications or organizations.
✓ Connects between systems and business processes.
✓ It is a binary application layer protocol.
✓ Basic unit of data is a frame.
✓ ISO standard: ISO/IEC 19464
Source: “Advanced Message Queuing Protocol”, Wikipedia (Online)

Introduction to Internet of Things 3

Source: “The‐amqp‐model‐for‐wikipedia.svg”, Wikimedia Commons (Online)

Introduction to Internet of Things 4

AMQP Features

Organizations Technologies Time Space

Connects across

Introduction to Internet of Things 5

Features
Security
Reliability
Interoperability
Routing
Queuing

Open standard

Introduction to Internet of Things 6

 Message Delivery Guarantees

✓ At‐most‐once
▪ each message is delivered once or never
✓ At‐least‐once
▪ each message is certain to be delivered, but may do so multiple times
✓ Exactly‐once
▪ message will always certainly arrive and do so only once

Reference: "OASIS AMQP version 1.0, sections 2.6.12‐2.6.13". OASIS AMQP Technical Committee

Introduction to Internet of Things 7

 AMQP Frame Types
✓ Nine AMQP frame types are defined that are used to initiate, control and
tear down the transfer of messages between two peers:
▪ Open (connection open)
▪ Begin (session open)
▪ Attach (initiate new link)
▪ Transfer (for sending actual messages)
▪ Flow (controls message flow rate)
▪ Disposition (Informs the changes in state of transfer)
▪ Detach (terminate the link)
▪ End (session close)
▪ Close (connection close)
Source: O.S. Tezer, “An advanced messaging queuing protocol walkthrough ”, DigitalOcean (Online), 2013

Introduction to Internet of Things 8

 Components

Exchange • Part of Broker

• Receives messages and routes them to Queues

Queue • Separate queues for separate business processes

• Consumers receive messages from queues

Bindings • Rules for distributing messages (who can access

what message, destination of the message)

Source: O.S. Tezer, “An advanced messaging queuing protocol walkthrough ”, DigitalOcean (Online), 2013

Introduction to Internet of Things 9

 AMQP Exchanges
Direct
Fan‐out
Topic
Header
Source: O.S. Tezer, “An advanced messaging queuing protocol walkthrough ”, DigitalOcean (Online), 2013

Introduction to Internet of Things 10

 AMQP Features

✓ Targeted QoS (Selectively offering QoS to links)

✓ Persistence (Message delivery guarantees)
✓ Delivery of messages to multiple consumers
✓ Possibility of ensuring multiple consumption
✓ Possibility of preventing multiple consumption
✓ High speed protocol
Source: O.S. Tezer, “An advanced messaging queuing protocol walkthrough ”, DigitalOcean (Online), 2013

Introduction to Internet of Things 11

 Applic ations

✓ Monitoring and global update sharing.

✓ Connecting different systems and processes to talk to each other.
✓ Allowing servers to respond to immediate requests quickly and
delegate time consuming tasks for later processing.
✓ Distributing a message to multiple recipients for consumption.
✓ Enabling offline clients to fetch data at a later time.
✓ Introducing fully asynchronous functionality for systems.
✓ Increasing reliability and uptime of application deployments.
Source: O.S. Tezer, “An advanced messaging queuing protocol walkthrough ”, DigitalOcean (Online), 2013

Introduction to Internet of Things 12