IoT Communication Models

IoT allows the connection of multiple devices (things) to communicate with each other. In this article, we’ll explore the major IoT communication models, how they work, and where they are best applied in real-world applications.

Why Communication Models Matter in IoT

IoT communication models play a critical role in ensuring reliable, real-time, and energy-efficient communication between sensors, actuators, and cloud services. Each communication model determines how data is exchanged, how often it’s transmitted, and device’s responses to changes.

Choosing the right model influences

  • system latency,
  • data volume,
  • power consumption,
  • Overall scalability and reliability.

Key IoT Communication Models

Here are the four primary communication models used in IoT systems:

1. Request-Response Model 

In IoT, the client device sends a request to the server. The request may be an upload or transfer of data. The Server responds to the request. The server may be remote or local and can handle the requests of multiple clients. The server receives the request, processes (decides) the response to that request, and fetches the data from resources (i.e., database).

IoT Request-Response Model

Note: The Request-Response model is stateless, independently handling each request.

Here is a table of advantages and disadvantages of the Request-Response Communication Model in IoT:

Aspect Advantages Disadvantages
Simplicity Easy to implement and understand May not be efficient for real-time or event-driven communication
Control Client has control over when requests are sent The server remains idle until a request is made
Statelessness Each request is independent, making scaling easier Requires the client to send full context with every request
Compatibility Widely supported by HTTP and RESTful APIs Not suitable for continuous data streams or real-time sensor updates
Security Easier to secure using HTTPS and standard authentication Each request must be individually secured, increasing overhead
Resource Usage Efficient for low-frequency communication Inefficient for high-frequency or continuous data exchange
Reliability Predictable and well-defined interactions No built-in mechanism for retrying or handling lost updates

2. Publisher-Subscriber Model

There are three essential elements in the publisher-subscriber Model, as given below.

  • Publisher: It transfers data to the broker. Publishers don’t know about consumers.
  • Broker: It accepts publisher data and sends it to the appropriate subscriber.
  • Subscriber: It consumes the topics that the broker manages.

A detailed diagram of the publisher-subscriber model is given below

Publisher - Subscriber Model

Real-life Example: Imagine a news App

  • Publisher: A user uploads an article to a news app.

  • Broker: The news app acts as the broker, storing and managing the article.

  • Subscriber: Another user, who has subscribed to that topic, receives a notification and reads the article.

Here are the advantages and disadvantages of the Publisher-Subscriber Model in IoT, in table form

Aspect Advantages Disadvantages
Scalability Works well when many devices need to send and receive messages It can be harder to manage with many devices
Real-Time Sends messages instantly when events happen May send too many messages to small or low-power devices
Loose Connection Devices don’t need to talk directly to each other Hard to track where messages are going or coming from
Flexibility Easy to add or remove devices from the system Needs a message broker (like MQTT), which adds complexity
Speed Fast communication with low delay Messages might get lost if quality settings are not managed
Saves Bandwidth Sends data only when needed, not all the time Harder to manage security for all devices

3 Push-Pull Model 

There are three essential elements in the Push-Pull Model, as given below

  • Publisher: It pushes the data into Message Queue
  • Message Queue: it is a buffer that stores data pushed by a publisher
  • Subscriber: It pulls data from the message queue.

Publishers and Subscribers are unaware of each other. The Push-Pull Model is explained under

Push-Pull Model

Here is a simple table showing the advantages and disadvantages of the Push-Pull Communication Model in IoT:

Aspect Advantages Disadvantages
Decoupling Producer and consumer work independently No real-time data delivery
Flexibility Consumers can pull data when ready May result in delays if the consumer pulls too late
Load Management Helps balance load by storing data temporarily in a buffer or a queue Buffer may overflow if the consumer is too slow
Scalability Supports different rates of data production and consumption Requires a queue or storage system (adds complexity)
Data Availability Data can be pulled anytime until it expires or is removed Risk of outdated data if pulled too late
Control Consumer controls when to fetch data The producer has no idea when or if the data is consumed

4. Exclusive Pair

It is a bi-directional (full duplex) combination model. In an exclusive pair, the client establishes a connection with the server by sending a request, and this connection remains open until the client sends a request to close the connection. A detailed diagram is given below.

Exclusive Pair Model

Here is a simple table of advantages and disadvantages of the Exclusive Pair Communication Model in IoT:

Aspect Advantages Disadvantages
Direct Connection Devices communicate directly with each other Not suitable for large-scale or multi-device communication
Low Latency Fast data transfer with minimal delay Connection setup may take time or resources
High Security Point-to-point connection allows strong encryption Each new connection must be separately secured
Reliable Exchange Ensures data is delivered and acknowledged between two specific devices No support for broadcasting or multicasting
Simplicity Easy to manage in small networks or one-to-one setups Complex to scale in larger IoT networks
Efficient Bandwidth No unnecessary data sharing; only two devices share the channel Limited flexibility for dynamic or event-driven communication

Choosing the Right Communication Model in IoT

Selecting the right communication model in an IoT system is essential for performance, reliability, and scalability. The best model depends on factors like:

  • Type of application or use case
  • Device limitations (power, memory, etc.)
  • Network availability and bandwidth
  • Timing needs (real-time vs. delay-tolerant)

Below is a table that matches common IoT scenarios with the most suitable communication model, along with a brief explanation:

IoT Use Cases and Recommended Communication Models

Use Case Recommended Model Why this model works best
Smart home automation Publish-Subscribe Devices (like lights or sensors) publish data, and other components subscribe to relevant topics. Enables real-time, event-driven communication.
Periodic sensor readings Request-Response Suitable for scheduled updates, such as temperature readings every 10 minutes. Simple and energy-efficient.
Live data streaming Push-Pull Data producers push content (e.g., video), and consumers pull it when ready. Helps manage speed mismatches between sender and receiver.
Real-time control systems Exclusive Pair Requires fast and secure direct communication (e.g., between a robotic arm and its controller). Ensures low latency and reliable delivery.