Introduction to the Internet of Things (IoT)

IoT comprises things that have unique identities and are connected to internet. By 2020 there will be a total of 50 billion devices /things connected to internet. IoT is not limited to just connecting things to the internet but also allow things to communicate and exchange data.

Definition:

A dynamic global n/w 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 information n/w, often communicate data associated with users and their environments.

Characteristics:

1) Dynamic & Self Adapting: IoT devices and systems may have the capability to dynamically adapt with the changing contexts and take actions based on their operating conditions, user‗s context or sensed environment.

Eg: the surveillance system is adapting itself based on context and changing conditions.

2) Self Configuring: allowing a large number of devices to work together to provide certain functionality.

3) Inter Operable Communication Protocols: support a number of interoperable communication protocols and can communicate with other devices and also with infrastructure.

4) Unique Identity: Each IoT device has a unique identity and a unique identifier (IP address).

5) Integrated into Information Network: that allow them to communicate and exchange data with other devices and systems.

Applications of IoT:

1) Home

2) Cities

3) Environment

4) Energy

5) Retail

6) Logistics

7) Agriculture

8) Industry

9) Health & Life Style

The things in IoT refers to IoT devices which have unique identities and perform remote sensing, actuating and monitoring capabilities. IoT devices can exchange data with other connected devices applications. It collects data from other devices and process data either locally or remotely. An IoT device may consist of several interfaces for communication to other devices both wired and wireless. These includes (i) I/O interfaces for sensors, (ii) Interfaces for internet connectivity (iii) memory and storage interfaces and (iv) audio/video interfaces.

2) IoT Protocols:

a) Link Layer : Protocols determine how data is physically sent over the network‗s physical layer or medium. Local network connect to which host is attached. Hosts on the same link exchange data packets over the link layer using link layer protocols. Link layer determines how packets are coded and signaled by the h/w device over the medium to which the host is attachedProtocols:

 802.3-Ethernet: IEEE802.3 is collection of wired Ethernet standards for the link layer.

Eg: 802.3 uses co-axial cable; 802.3i uses copper twisted pair connection; 802.3j uses fiber optic connection; 802.3ae uses Ethernet over fiber.

 802.11-WiFi: IEEE802.11 is a collection of wireless LAN(WLAN) communication

standards including extensive description of link layer. Eg: 802.11a operates in 5GHz band, 802.11b and 802.11g operates in 2.4GHz band, 802.11n operates in 2.4/5GHz band, 802.11ac operates in 5GHz band, 802.11ad operates in 60Ghzband.

 802.16 - WiMax: IEEE802.16 is a collection of wireless broadband standards including

exclusive description of link layer. WiMax provide data rates from 1.5 Mb/s to 1Gb/s.

 802.15.4-LR-WPAN: IEEE802.15.4 is a collection of standards for low rate wireless personal area network(LR-WPAN). Basis for high level communication protocols such as ZigBee. Provides data rate from 40kb/s to250kb/s.

 2G/3G/4G-Mobile Communication: Data rates from 9.6kb/s(2G) to up to100Mb/s(4G).

B) Network/Internet Layer: Responsible for sending IP datagrams from source n/w to destination n/w. Performs the host addressing and packet routing. Datagrams contains source and destination address. Protocols:

 IPv4: Internet Protocol version4 is used to identify the devices on a n/w using a hierarchical addressing scheme. 32 bit address. Allows total of 2**32addresses.

 IPv6: Internet Protocol version6 uses 128 bit address scheme and allows 2**128 addresses

 6LOWPAN:(IPv6overLowpowerWirelessPersonalAreaNetwork)operates in

2.4 GHz frequency range and data transfer 250 kb/s.

C) Transport Layer: Provides end-to-end message transfer capability independent of the

underlying n/w. Set up on connection with ACK as in TCP and without ACK as in UDP.

Provides functions such as error control, segmentation, flow control and congestion control.

Protocols:

 TCP: Transmission Control Protocol used by web browsers(along with HTTP and

HTTPS), email(along with SMTP, FTP). Connection oriented and stateless protocol. IP

Protocol deals with sending packets, TCP ensures reliable transmission of protocols in

order. Avoids n/w congestion and congestion collapse.

 UDP: User Datagram Protocol is connectionless protocol. Useful in time sensitive

applications, very small data units to exchange. Transaction oriented and stateless

protocol. Does not provide guaranteed delivery.

D) Application Layer: Defines how the applications interface with lower layer protocolsto

send data over the n/w. Enables process-to-process communication using ports.

Protocols:

 HTTP: Hyper Text Transfer Protocol that forms foundation of WWW. Follow request response model Stateless protocol.

 CoAP: Constrained Application Protocol for machine-to-machine (M2M) applications with constrained devices, constrained environment and constrained n/w. Uses client server architecture.

 WebSocket: allows full duplex communication over a single socket connection.

 MQTT: Message Queue Telemetry Transport is light weight messaging protocol based on publish-subscribe model. Uses client server architecture. Well suited for constrained environment.

 XMPP: Extensible Message and Presence Protocol for real time communication and streaming XML data between network entities. Support client-server and server-server communication.

 DDS: Data Distribution Service is data centric middleware standards for device-to-device or machine-to-machine communication. Uses publish-subscribe model.

 AMQP: Advanced Message Queuing Protocol is open application layer protocol for business messaging. Supports both point-to-point and publish-subscribe model