With the Internet of Things (IoT) becoming immensely popular, companies are rapidly finding ways to use IoT and improve their efficiency. While IoT has several benefits, businesses are struggling to understand how to implement the technology in their work and day-to-day life. This article will look at the logical and physical design of IoT and explain the differences between them.

The logical design of IoT is an abstract representation of processes and entities without going into the lower-level details of the implementation. Logical design is less detailed than physical design and is more conceptual. It’s the basic outline of how you want all those devices to talk and exchange information, but it doesn’t specify a particular technology or product.

Physical design is more than creating products. It is about forming an overall intelligent system. The design must be oriented towards the end user’s needs. In logical design, one understands the logical relationship of the objects. However, in physical design, one understands the most effective method of storing and accessing those objects.

“Things” in IoT

Things refer to IoT devices with unique identities that have actuating, monitoring, and remote sensing capabilities. Things are the primary component of IoT applications.

IoT devices can be of various types, including smartwatches, sensing devices, smart electronics appliances, automobiles, wearable sensors, and industrial machines. IoT devices generate data in some form which leads to useful information when processed.

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Physical Design of IoT

A physical design of an IoT system refers to the individual node devices and their protocols that are utilised to create a functional IoT ecosystem.

Each node device can perform tasks such as remote sensing, actuating, monitoring, etc., by relying on physically connected devices. It may also be capable of transmitting information through different types of wireless or wired connections.

The things/devices in the IoT system are used for:

• Building connections
• Data processing
• Providing storage
• Providing interfaces
• Providing graphical interfaces

The devices generate data, and the data is used to perform analysis and do operations for improving the system. For instance, a moisture sensor is used to obtain the moisture data from a location, and the system analyses it to give an output.

Logical Design of IoT

A logical design for an IoT system is the actual design of how its components (computers, sensors, and actuators) should be arranged to complete a particular function. It doesn’t go into the depth of describing how each component will be built with low-level programming specifics.

IoT logical design includes:

1. IoT functional blocks:

   IoT systems include several functional blocks such as Devices, communication, security, services, and application. The functional blocks provide sensing, identification, actuation, management, and communication capability.These functional blocks consist of devices that handle the communication between the server and the host, enable monitoring control functions, manage the data transfer, secure the IoT system using authentication and different functions, and provide an interface for controlling and monitoring various terms.

2. IoT communications models

   There are multiple kinds of models available in an Internet of Things system that is used for communicating between the system and server, such as:

   • Request-response model
   • Push-pull model
   • Publish-subscribe model
   • Exclusive pair model

3. IoT communication APIs

   APIs are used to communicate between the server and system in IoT. Some API’s include:

   • REST-based communication APIs
   • Client-server
   • Stateless
   • Cacheable
   • Websocket based communication API

Generic Block Diagram of an IoT Device

IoT Protocols

The set of rules governing all direct or indirect exchange of data between computers on a network. These rules are formulated at the application level and are used collectively to define how devices communicate interoperably, irrespective of differences in their internal designs and operations.

IoT protocols help send commands and data between a network of devices controlled by sensors or other physical attributes like motion, temperature, or vibration. Network protocols help achieve reliable data transfer across all layers like the application, transport, network, and link layer.

Application Layer Protocols

On this layer, protocols use an application interface to define how the data can be sent over the network. These protocols include HTTP, XMPP, WebSocket,  DDS, MQTT, and AMQP.

Transport Layer Protocols

This layer is responsible for data flow control and error handling, ensuring that there are rules in place to deal with errors. This layer also provides end-to-end message transfer capability, independent of the underlying network infrastructure. It provides essential connectivity between the two nodes on either end of the point-to-send-point-receive model used by key protocols such as TCP/IP.

Network Layer

This layer is used to send data from a source network to a destination network. For this, IPv4 and IPv6 protocols are used for host identification, which transfers data in packets.

Link Layer

Link-layer protocols are the type of data transmission protocol used to help send data over the physical layer. They also determine how devices signal and code packets on the network.

Difference Between Physical and Logical Design of IoT

Physical Design	Logical Design
Physical design is highly detailed.	Logical design is a high-level design and doesn’t provide any detail.
Physical design is more graphical than textual; however, it can comprise both.	Logical design can be textual, graphic, or both.
A physical design focuses on specific solutions explaining how they are assembled or configured.	A logical design focuses on satisfying the design factors, including risks, requirements, constraints, and assumptions.

In this blog, we have tried to cover all the concepts related to IoT’s logical and physical design. We hope this write-up helped you gain a clear understanding of the fundamentals of IoT and its logical and physical design. Explore Airtel IoT to know more about business use cases.