DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
Internet of Things
Unit 1: Introduction to IoT (6)
Syllabus:
Definition, Applications and characteristics of IoT, Physical Design of IoT, Logical Design of
IoT, IoT Enabling Technologies, IoT Levels
Background:
What is IoT?
IoT is essentially a platform where embedded devices are connected to the internet, so they
can collect and exchange data with each other. It enables devices to interact, collaborate
and, learn from each other’s experiences just like humans do.
1. Definition of IoT:
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.
1.2 Applications of IoT
IoT applications promise to bring immense value into our lives. With newer wireless
networks, superior sensors and revolutionary computing capabilities, the Internet of
Things could be the next frontier in the race for its share of the wallet.
Details of
application read on last page.
1.3
Characteristics of IoT
• Dynamic & Self-Adapting
• Self-Configuring
• Interoperable Communication Protocols
• Unique Identity
• Integrated into Information Network
The fundamental characteristics of the IoT are as follows ,
Interconnectivity: With regard to the IoT, anything can be interconnected with the global
information and communication infrastructure. Things-related services: The IoT is capable
of providing thing-related services within the constraints of things, such as privacy
protection and semantic consistency between physical things and their associated virtual
things. In order to provide thing-related services within the constraints of things, both the
technologies in physical world and information world will change. Heterogeneity: The
devices in the IoT are heterogeneous as based on different hardware platforms and
networks. They can interact with other devices or service platforms through different
networks. Dynamic changes: The state of devices change dynamically, e.g., sleeping and
waking up, connected and/or disconnected as well as the context of devices including
location and speed. Moreover, the number of devices can change dynamically. Enormous
scale: The number of devices that need to be managed and that communicate with each
other will be at least an order of magnitude larger than the devices connected to the current
Internet. Even more critical will be the management of the data generated and their
interpretation for application purposes. This relates to semantics of data, as well as efficient
data handling. Safety: As we gain benefits from the IoT, we must not forget about safety. As
both the creators and recipients of the IoT, we must design for safety. This includes the
safety of our personal data and the safety of our physical well-being. Securing the endpoints,
the networks, and
the data moving across all of it means creating a security paradigm that will scale.
Connectivity: Connectivity enables network accessibility and compatibility. Accessibility is
getting on a network while compatibility provides the common ability to consume and
produce data.
1.4 Physical Design of IoT
• The "Things" in IoT usually refers to IoT devices which have unique identities and can
perform remote sensing, actuating and monitoring capabilities.
• IoT devices can:
• Exchange data with other connected devices and applications (directly or indirectly), or
• Collect data from other devices and process the data locally or
• Send the data to centralized servers or cloud-based application back- ends for
processing the data, or
• Perform some tasks locally and other tasks within the IoT infrastructure, based on
temporal and space constraints
Generic Block Diagram of an IoT Device:
• An IoT device may consist of several interfaces for connections to other devices, both
wired and wireless.
• I/O interfaces for sensors
• Interfaces for Internet connectivity
• Memory and storage interfaces
• Audio/video interfaces.
IoT Protocols:
Link Layer
• 802.3 – Ethernet
• 802.11 – WiFi
• 802.16 – WiMax
• 802.15.4 – LR-WPAN
• 2G/3G/4G
Network/Internet Layer
• IPv4
• IPv6
• 6LoWPAN
Transport Layer
• TCP
• UDP
Application Layer
• HTTP
• CoAP
• WebSocket
• MQTT
• XMPP
• DDS
• AMQP
1.5 Logical Design of IoT
• Logical design of an IoT system refers to an abstract representation of the entities and
processes without going into the low-level specifics of the implementation.
• An IoT system comprises of a number of functional blocks that provide the system the
capabilities for identification, sensing, actuation, communication, and management.
Request-Response communication model:
• Request-Response is a communication model in which the client sends requests to the
server and the server responds to the requests.
• When the server receives a request, it decides how to respond, fetches the data, retrieves
resource representations, prepares the response, and then sends the response to the client.
Publish-Subscribe communication model:
• Publish-Subscribe is a communication model that involves publishers, brokers and
consumers.
• Publishers are the source of data. Publishers send the data to the topics which are
managed by the broker. Publishers are not aware of the consumers.
• Consumers subscribe to the topics which are managed by the broker.
• When the broker receives data for a topic from the publisher, it sends the data to all the
subscribed consumers.
Push-Pull communication model:
• Push-Pull is a communication model in which the data producers push the data to queues
and the consumers pull the data from the queues. Producers do not need to be aware of the
consumers.
• Queues help in decoupling the messaging between the producers and consumers.
• Queues also act as a buffer which helps in situations when there is a mismatch between
the rate at which the producers push data and the rate rate at which the consumers pull
data.
Exclusive Pair communication model:
• Exclusive Pair is a bidirectional, fully duplex communication model that uses a persistent
connection between the client and server.
• Once the connection is setup it remains open until the client sends a request to close
the connection.
• Client and server can send messages to each other after connection setup.
REST-based Communication APIs:
• Representational State Transfer (REST) is a set of architectural principles by which you
can design web services and web APIs that focus on a system’s resources and how resource
states are addressed and transferred.
• REST APIs follow the request- response communication model.
• The REST architectural constraints apply to the components, connectors, and data
elements, within a distributed hypermedia system.
WebSocket-based Communication APIs:
• WebSocket APIs allow bi- directional, full duplex communication between clients and servers.
• WebSocket APIs follow the exclusive pair communication model
Exclusive Pair communication model:
• Exclusive Pair is a bidirectional, fully duplex communication model that uses a
persistent connection between the client and server.
• Once the connection is setup it remains open until the client sends a request to close
the connection.
• Client and server can send messages to each other after connection setup. 1.6
IOT Levels
An IoT system comprises of the following components:
• Device: An IoT device allows identification, remote sensing, actuating and remote
monitoring capabilities. You learned about various examples of IoT devices in section •
Resource: Resources are software components on the IoT device for accessing, processing,
and storing sensor information, or controlling actuators connected to the device. Resources
also include the software components that enable network access for the device.
• Controller Service: Controller service is a native service that runs on the device and
interacts with the web services. Controller service sends data from the device to the web
service and receives commands from the application (via web services) for controlling the
device.
• Database: Database can be either local or in the cloud and stores the data generated by the
IoT device.
• Web Service: Web services serve as a link between the IoT device, application, database
and analysis components. Web service can be either implemented using HTTP and REST
principles (REST service) or using WebSocket protocol (WebSocket service). • Analysis
Component: The Analysis Component is responsible for analyzing the IoT data and generate
results in a form which are easy for the user to understand. • Application: IoT applications
provide an interface that the users can use to control and monitor various aspects of the IoT
system. Applications also allow users to view the system status and view the processed
data.
IoT Level-1
• A level-1 IoT system has a single node/device that performs sensing and/or actuation,
stores data, performs analysis and hosts the application
• Level-1 IoT systems are suitable for modeling low- cost and low- complexity solutions
where the data involved is not big and the nalysis requirements are not computationally
intensive.
Let us now consider an example of a level-I loT system for home automation, system
consists of a single node that allows controlling the lights and appliances in a remotely. The
device used in this system interfaces with the lights and appliances inin, electronic relay
switches. The status information of each light or appliance is maintained; a local database.
REST services deployed locally allow retrieving and updating the sink or each light or
appliance in the status database. The controller service continuously m • the state of each
light or appliance (by retrieving state from the database) and triggers% relay switches
accordingly. The application which is deployed locally has a user interface for controlling the
lights or appliances. Since the device is connected to the Internet, application can be
accessed remotely as well.
IoT Level-2
• A level-2 IoT system has a single node that performs sensing and/or actuation and local
analysis.
• Data is stored in the cloud and application is usually cloud- based.
• Level-2 IoT systems are suitable for solutions where the data involved is big, however, the
primary analysis requirement is not computationally intensive and can be done locally
itself.
Let us consider an example of a level-2 IoT system for smart irrigation. The consists of a
single node that monitors the soil moisture level and controls the irrigation system. The
device used in this system collects soil moisture data from sensors. controller service
continuously monitors the moisture levels. If the moisture level below a threshold, the
irrigation system is turned on. For
controlling the irrigation system actuators such as solenoid valves can be used. The
controller also sends the moisture data the computing cloud. A cloud- based REST web
service is used for storing and retrieving in moisture data which is stored in the cloud
database. A cloud-based application is used for visualizing the moisture levels over a period
of time, which can help in making decisions irrigation schedules.
IoT Level-3
• A level-3 IoT system has a single node.
Data is stored and analyzed in the cloud
and application is cloud- based.
• Level-3 IoT systems are suitable for solutions where the data involved is big and the
analysis requirements are computationally intensive.
IoT Level-4
• A level-4 IoT system has multiple nodes that perform local analysis. Data is stored in
the cloud and application is cloud-based.
• Level-4 contains local and cloud- based observer nodes which can subscribe to and
receive information collected in the cloud from IoT devices.
• Level-4 IoT systems are suitable for solutions where multiple nodes are required, the data
involved is big and the analysis requirements are computationally intensive.
IoT Level-5
• A level-5 IoT system has multiple end nodes and one coordinator node.
• The end nodes that perform sensing and/or actuation.
• Coordinator node collects data from the end nodes and sends to the cloud. •
Data is stored and analyzed in the cloud and application is cloud-based.
• Level-5 IoT systems are suitable for solutions based on wireless sensor networks, in
which the data involved is big and the analysis requirements are computationally intensive.
IoT Level-6
• A level-6 IoT system has multiple independent end nodes that perform sensing
and/or actuation and send data to the cloud.
• Data is stored in the cloud and application is cloud-based.
• The analytics component analyzes the data and stores the results in the cloud
database.
• The results are visualized with the cloud-based application.
• The centralized controller is aware of the status of all the end nodes and sends
control commands to the nodes.
Let us consider an example of a level-6 loT system for weather monitoring.
The system consists of multiple nodes placed in different locations for monitoring
temperature, humidity and pressure in an area. The end nodes are equipped with various
sensors (temperature. pressure and humidity). The end
nodes send the data to the cloud in real time using a WcbSocket service. The data is stored
in a cloud database. The analysis of data is done in the cloud to aggregate the data and make
predictions. A cloud-based application is used for visualizing the data.
