Lecture 2 – IoT Architecture and TCP/IP Model

The structure of IoT architecture and its relation to the TCP/IP model. Explore four IoT layers, key protocols, and a practical lab on layer mapping.

Understanding IoT Architecture

The Internet of Things (IoT) architecture defines how connected devices interact, process data, and communicate across networks. It consists of multiple layers each responsible for specific tasks like data collection, transmission, processing, and presentation.

In simple terms, IoT architecture acts as a bridge between the physical and digital worlds, enabling machines to sense the environment and send data to the cloud for analysis and automation.

Four-Layer IoT Architecture

The modern IoT stack is often explained using a four-layer architecture that aligns closely with the traditional TCP/IP model.

IoT Layer	Purpose	Examples of Technologies and Protocols
Perception Layer	Collects data from sensors and actuators in the physical world.	RFID, Sensors, Actuators, Camera Modules
Network Layer	Transmits data securely to servers and cloud platforms.	Wi-Fi, BLE, ZigBee, 6LoWPAN, LoRaWAN, IP Protocols
Middleware Layer	Manages data processing, storage, and connectivity between devices and applications.	MQTT, CoAP, HTTP, Node-RED, Edge Computing
Application Layer	Provides user interfaces and domain-specific services.	Smart Home Apps, Health Dashboards, IoT Analytics

How IoT Maps to the TCP/IP Model

IoT Stack Layer	Equivalent TCP/IP Layer	Example Protocols Used in IoT
Perception	Physical + Data Link	IEEE 802.15.4, BLE, ZigBee
Network	Network	IPv6, 6LoWPAN
Middleware	Transport + Session	TCP, UDP, MQTT, CoAP
Application	Application	HTTP, MQTT, CoAP, AMQP

The TCP/IP model (Transport Control Protocol / Internet Protocol) provides the foundation for IoT communication.
Each IoT layer depends on TCP/IP to transmit data from the sensing device all the way to the application server or dashboard.

Common IoT Protocols

Protocol	Purpose	Where Used
MQTT	Lightweight publish/subscribe messaging for small devices.	Middleware & Application Layers
CoAP	Resource-constrained REST-like protocol.	Middleware Layer
HTTP/HTTPS	Web communication between IoT and servers.	Application Layer
LoRaWAN	Long-range low-power communication.	Network Layer
6LoWPAN	IPv6 over Low-Power Wireless Networks.	Network Layer

Laboratory Exercise Layer Mapping with Real Examples

Hardware Required

Component	Purpose
Arduino UNO or ESP32	The brain of your IoT system it reads sensor data and sends it to the network.
Wi-Fi Module (ESP8266 optional)	Connects your device to the internet or local network.
DHT22 Sensor	Measures temperature and humidity your data source.
Laptop with Arduino IDE and Node-RED	Used to program, process, and visualize data.

ESP32 has built-in Wi-Fi, so you don’t need a separate Wi-Fi module if you’re using it.

Step-by-Step Procedure

Step 1: Identify the Perception Layer

This is where data is collected from the physical world.
Connect your DHT22 sensor to the ESP32 and upload a simple Arduino sketch to read temperature and humidity values.

#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
}

void loop() {
  float t = dht.readTemperature();
  float h = dht.readHumidity();
  Serial.print("Temp: "); Serial.print(t); Serial.print("°C  ");
  Serial.print("Humidity: "); Serial.print(h); Serial.println("%");
  delay(2000);
}

You’ve just worked on the Perception Layer the point where the IoT system senses its environment.
(In the TCP/IP model, this corresponds to the Physical + Data Link Layers.)

Lecture 1 – Introduction to the Internet of Things (IoT)

Step 2: Map the Network Layer

Now your ESP32 needs to transmit this data across the network.
Use Wi-Fi to send your sensor data to your computer running Node-RED on the same local network.

In Arduino IDE, add Wi-Fi credentials and confirm successful connection via Serial Monitor.

You’re now interacting with the Network Layer responsible for data transfer using IP protocols like IPv4 or IPv6.
(In TCP/IP, this matches the Network Layer.)

Step 3: Define the Middleware Layer

At this stage, your system must manage communication between devices.
Use MQTT (Message Queuing Telemetry Transport) a lightweight IoT protocol to publish your sensor data to a broker (like Mosquitto).

Node-RED can subscribe to this data and process it in real time.

You’re working within the Middleware Layer, which ensures reliable messaging and data flow.
(This aligns with the Transport and Session Layers in TCP/IP.)

Step 4: Visualize the Application Layer

Finally, make your IoT project come alive visually!
In Node-RED, create a dashboard that shows real-time temperature and humidity readings from your ESP32.
You can even add gauges, graphs, or alerts when the temperature crosses a threshold.

This is the Application Layer, where users interact with data through applications and dashboards.
(This corresponds to the Application Layer in the TCP/IP model.)

Understanding the Layer Mapping

IoT Architecture Layer	Your Example	Equivalent TCP/IP Layer
Perception Layer	DHT22 Sensor	Physical + Data Link
Network Layer	Wi-Fi (ESP32/ESP8266)	Network
Middleware Layer	MQTT Broker (Mosquitto, Node-RED)	Transport + Session
Application Layer	Node-RED Dashboard	Application

The approach followed at E Lectures reflects both academic depth and easy-to-understand explanations.

Summary

In this lecture, you learned how IoT architecture mirrors the TCP/IP model. You now understand how data flows from the Perception Layer (sensors) to the Application Layer (user interface).
This layered understanding forms the basis for designing scalable and secure IoT systems an essential skill for your future projects.

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