Physical and Logical Design of Internet of Things (IoT)

 In this article, we discuss the Physical and Logical Design of IoTPhysical Design of IoT systems refers to IoT Devices and IoT Protocols. Things are Node device which has unique identities and can perform remote sensing, actuating and monitoring capabilities. Communication established between things and cloud-based servers over the Internet by various IoT protocols. The logical design of IoT systems refers to an abstract representation of the entities & processes without going into the low-level specifies of the implementation.


Physical and Logical Design of IoT


Physical Design of IoT

Physical Design of IoT refers to IoT Devices and IoT Protocols. Things are Node device which has unique identities and can perform remote sensing, actuating and monitoring capabilities. IoT Protocols helps Communication established between things and cloud-based servers 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 the main part of IoT applications. IoT Devices can be various types, 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.



For example, Temperature data generated by a Temperature Sensor in a Home or other place, when processed can help in determining temperature and take action according to users.

The above picture shows a generic block diagram of an IoT device. It may consist of several interfaces for connections to other devices. IoT Device has I/O interface for Sensors, Similarly for Internet connectivity, Storage and Audio/Video.

IoT devices collect data from onboard or attached Sensors and Sensed data communicated either to other devices or Cloud-based server. Today many cloud servers available for especially IoT systems. These Platforms are known as the IoT platforms. Actually, these clouds especially design for IoT purposes. So here we can analyze and processed data easily.

How it works? For example, if relay switch connected to an IoT device can turn On/Off an appliance on the commands sent to the IoT device over the Internet.

IoT Protocols

IoT protocols help to establish communication between IoT devices (Node Device) and Cloud-based Server over the Internet. It helps to sent commands to IoT devices and received data from an IoT device over the Internet. An image is given below. By this image, you can understand which protocols used.



Link Layer


Link-layer protocols determine how data is physically sent over the network’s physical layer or medium (Coaxial cable 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. coaxial cable).

Here we explain some Link Layer Protocols:

802.3 – Ethernet: Ethernet is a set of technologies and protocols that are used primarily in LANs. It was first standardized in the 1980s by IEEE 802.3 standard. 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 classified into two categories: classic Ethernet and switched Ethernet.

For more information visit Tutorialspoint https://www.tutorialspoint.com/ieee-802-3-and-ethernet) (Source)

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.

For more info visit Wikipedia https://en.wikipedia.org/wiki/IEEE_802.11 (Source)

802.16 – Wi-Max : The standard for WiMAX technology is a standard for Wireless Metropolitan Area Networks (WMANs) that has been developed by working group number 16 of IEEE 802, specializing in point-to-multipoint broadband wireless access. Initially, 802.16a was developed and launched, but now it has been further refined. 802.16d or 802.16-2004 was released as a refined version of the 802.16a standard aimed at fixed applications. Another version of the standard, 802.16e or 802.16-2005 was also released and aimed at the roaming and mobile markets.

For more information visit this https://www.electronics-notes.com/articles/connectivity/wimax/what-is-wimax-802-16-technology-basics.php (Source)

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 cellular networks.


Network Layer


Responsible for sending IP datagrams from the source network to the destination network. The network layer performs the host addressing and packet routing. We used IPv4 and IPv6 for Host identification. IPv4 and IPv6 are hierarchical IP addressing schemes.

IPv4 :

An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: host or network interface identification and location addressing.

Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. However, because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP (IPv6), using 128 bits for the IP address, was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s.

IPv6: Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion. IPv6 is intended to replace IPv4. In December 1998, IPv6 became a Draft Standard for the IETF, which subsequently ratified it as an Internet Standard on 14 July 2017. IPv6 uses a 128-bit address, theoretically allowing 2128, or approximately 3.4×1038 addresses.  Source – Wikipedia

for more detail https://en.wikipedia.org/wiki/IPv6

6LoWPAN: 6LoWPAN is an acronym of IPv6 over Low-Power Wireless Personal Area Networks.6LoWPAN is the name of a concluded working group in the Internet area of the IETF. 6LoWPAN is a somewhat contorted acronym that combines the latest version of the Internet Protocol (IPv6) and Low-power Wireless Personal Area Networks (LoWPAN). 6LoWPAN, therefore, allows for the smallest devices with limited processing ability to transmit information wirelessly using an internet protocol. 6LoWPAN can communicate with 802.15.4 devices as well as other types of devices on an IP network link like WiFi.

For more details visit this https://iotbyhvm.ooo/6lowpan-zigbee/


Transport Layer


This layer provides functions such as error control, segmentation, flow control, and congestion control. So these layer protocols provide end-to-end message transfer capability independent of the underlying network.

TCP: TCP (Transmission Control Protocol) is a standard that defines how to establish and maintain a network conversation through which application programs can exchange data. TCP works with the Internet Protocol (IP), which defines how computers send packets of data to each other. Together, TCP and IP are the basic rules defining the Internet. The Internet Engineering Task Force (IETF) defines TCP in the Request for Comment (RFC) standards document number 793.

Source – For more detail:  https://searchnetworking.techtarget.com/definition/TCP

UDP: User Datagram Protocol (UDP) is a Transport Layer protocol. UDP is a part of the Internet Protocol suite, referred to as UDP/IP suite. Unlike TCP, it is an unreliable and connectionless protocol. So, there is no need to establish a connection prior to data transfer. Read more here https://www.geeksforgeeks.org/user-datagram-protocol-udp/


Application Layer


Application layer protocols define how the applications interface with the lower layer protocols to send over their network.

HTTP: Hypertext Transfer Protocol (HTTP) is an application-layer protocol for transmitting hypermedia documents, such as HTML. It was designed for communication between web browsers and web servers, but it can also be used for other purposes. HTTP follows a classical client-server model, with a client opening a connection to make a request, then waiting until it receives a response. HTTP is a stateless protocol, meaning that the server does not keep any data (state) between two requests. Though often based on a TCP/IP layer, it can be used on any reliable transport layer, that is, a protocol that doesn’t lose messages silently like UDP does. RUDP — the reliable update of UDP — is a suitable alternative.

CoAP: CoAP-Constrained Application Protocol is a specialized Internet Application Protocol for constrained devices, as defined in RFC 7252. It enables devices to communicate over the Internet. It is defined as a Constrained Application Protocol and is a protocol intended to be used in very simple hardware. The protocol is especially targeted for constrained hardware such as 8-bits microcontrollers, low power sensors, and similar devices that can’t run on HTTP or TLS. It is a simplification of the HTTP protocol running on UDP, that helps save bandwidth. It is designed for use between devices on the same constrained network (e.g., low-power, lossy networks), between devices and general nodes on the Internet, and between Devices on different constrained networks both joined by an internet. CoAP is also being used via other mechanisms, such as SMS on mobile communication networks.

Read more … https://iotbyhvm.ooo/what-is-coap-protocol/

WebSocket: The WebSocket Protocol enables two-way communication between a client running untrusted code in a controlled environment to a remote host that has opted-in to communications from that code. The security model used for this is the origin-based security model commonly used by web browsers. The protocol consists of an opening handshake followed by basic message framing, layered over TCP. The goal of this technology is to provide a mechanism for browser-based applications that need two-way communication with servers that do not rely on opening multiple HTTP connections (e.g., using XMLHttpRequest or <iframe>s and long polling).

MQTT :

MQTT is a machine-to-machine (M2M)/”Internet of Things” connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport and useful for connections with remote locations where a small code footprint is required and/or network bandwidth is at a premium. For example, it has been used in sensors communicating to a broker via satellite link, over occasional dial-up connections with healthcare providers, and in a range of home automation and small device scenarios.

MQTT protocol runs on top of the TCP/IP networking stack. When clients connect and publish/subscribe, MQTT has different message types that help with the handshaking of that process. The MQTT header is two bytes and the first byte is constant. In the first byte, you specify the type of message being sent as well as the QoS level, retain, and DUP (duplication) flags. The second byte is the remaining length field.

Read my article for more information https://iotbyhvm.ooo/mqtt/

XMPP: Extensible Messaging and Presence Protocol (XMPP) is a communication protocol for message-oriented middleware based on XML (Extensible Markup Language). It enables the near-real-time exchange of structured yet extensible data between any two or more network entities. Originally named Jabber, the protocol was developed by the eponymous open-source community in 1999 for near real-time instant messaging (IM), presence information, and contact list maintenance. Designed to be extensible, the protocol has been used also for publish-subscribe systems, signaling for VoIP, video, file transfer, gaming, the Internet of Things (IoT) applications such as the smart grid, and social networking services.

DDS: The Data Distribution Service (DDS™) is a middleware protocol and API standard for data-centric connectivity from the Object Management Group® (OMG®). It integrates the components of a system together, providing low-latency data connectivity, extreme reliability, and scalable architecture that business and mission-critical Internet of Things (IoT) applications need.

In a distributed system, middleware is the software layer that lies between the operating system and applications. It enables the various components of a system to more easily communicate and share data. It simplifies the development of distributed systems by letting software developers focus on the specific purpose of their applications rather than the mechanics of passing information between applications and systems.

Source – https://www.dds-foundation.org/what-is-dds-3/

AMQP: The AMQP – IoT protocols consist of hard and fast components that route and save messages within a broker carrier, with a set of policies for wiring the components together. The AMQP protocol enables patron programs to talk to the dealer and engage with the AMQP model. AMQP has the following three additives, which might link into processing chains in the server to create the favored capability.

  • Exchange: Receives messages from publisher primarily based programs and routes them to ‘message queues’.
  • Message Queue: Stores messages until they may thoroughly process via the eating client software.
  • Binding: States the connection between the message queue and the change.

Logical Design of IoT

In this article, we discuss the Logical design of the Internet of things. The logical design of IoT systems refers to an abstract representation of the entities & processes without going into the low-level specifies of the implementation. For understanding the Logical Design of IoT, we describe the given below terms.

  • IoT Functional Blocks
  • IoT Communication Models
  • IoT Communication APIs

IoT Functional Blocks


An IoT system comprises a number of functional blocks that provide the system the capabilities for identification, sensing, actuation, communication, and management.

functional blocks are:

Device: An IoT system comprises devices that provide sensing, actuation, monitoring, and control functions.

Communication: Handles the communication for the IoT system.

Services: services for device monitoring, device control service, data publishing services, and services for device discovery.

Management: this block provides various functions to govern the IoT system.

Security: this block secures the IoT system and by providing functions such as authentication, authorization, message and content integrity, and data security.

Application: This is an interface that the users can use to control and monitor various aspects of the IoT system. The application also allows users to view the system status and view or analyze the processed data.



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