How Do IoT Devices Communicate With Each Other?


The Internet of Things is considered one of the most promising and powerful technologies in the IT industry. Why? Due to global connectivity. IoT allows any device from a smart bulb to a complex industrial machine to connect and communicate to share information. 

As a result, it’s possible to automate many time-consuming processes with sensors, scanners, wearables, and other connected instruments. 

So, the question arises — how do IoT devices communicate with each other? In this post, you will find the explanation. 

What Is an IoT Device?

Let’s start with the basics — what is the Internet of Things?

Simply saying, IoT was developed to connect everything in the world. Based on the special IoT communication protocols, certain devices can collect and exchange information. The data processing system or application gathers data, analyzes it, and performs actions using prewritten scripts. 

An IoT device stands for any specialized physical object connected to a network that gathers and exchanges data with other devices and systems without human intervention.

Examples of IoT devices include:

  • smart home appliances (e.g., thermostats, lighting systems, security cameras);
  • wearables (e.g., fitness trackers, smartwatches);
  • industrial sensors (e.g., temperature sensors);
  • medical devices (e.g., pacemakers, insulin pumps).

These days, such devices help improve employees’ efficiency and automate routine tasks. On the other hand, IoT technology brings concerns around privacy, security, and data protection since the collected information may be sensitive and valuable.

How Do IoT Devices Work?

Considering the IoT communication process, five main components can be distinguished — sensors, connectivity protocols, application protocols, cloud services, and user interfaces. 

#1. Sensors

The primary goal of any IoT device is data collection. That’s why they are equipped with various sensors that detect changes in the environment (temperature, humidity, and pressure) or the device’s status (battery levels) and trigger specific actions.

Let’s consider an example — IoT in the supply chain. Commercial carriers can install the Electronic Logging Device (ELD) on the track. These devices are connected to the Engine Control Unit (ECU) and get information from the engine, brakes, and transmission. 

#2. Connectivity protocols

Remote IoT devices require wireless communication channels in the form of physical layer communication protocols.  

The most used connectivity technologies/protocols:

  • Wi-Fi
  • Bluetooth
  • Cellular networks (4G/5G)
  • LoRaWAN
  • Zigbee

In the case of a tiny connectivity range, NFC and RFID can also be used.

These connectivity protocols allow for exchanging data and commands with other instruments and systems, allowing for real-time monitoring and control.

#3. Application Protocols

There are some application layer IoT communication protocols and standards such as MQTT, CoAP, and HTTP that operate on top of connectivity technologies and ensure a seamless communication process between applications running on the IoT devices.

These protocols define how applications exchange data and commands, which data format is used, and how to handle different data types.

#4. Data Processing Services

IoT devices can process the information in the cloud or on-premises, depending on the company’s requirements and business specifications.

Cloud-based solutions offer a high flexibility level. It’s possible to store, process, analyze, and access information from various devices. Cloud platforms provide a scalable and secure way to manage large volumes of IoT information.

#5. User Interface

To interact with the device, monitor its status, and configure its settings, customers need to use a user interface for IoT devices.

In most cases, the Internet of Things device has a supporting mobile app or web interface. Some devices can have a dedicated interface.

How Do IoT Devices Communicate: Application Layer Protocols

MQTT (MQ Telemetry Transport) is a high-level lightweight messaging protocol designed for clients with limited processing power and battery life, being operated in unreliable, high-latency, and low-bandwidth network conditions. In particular, MQTT is well-suited for scenarios with connection problems.

For example, MQTT Last Will refers to a feature meant to send a message when the device (connected to an MQTT broker) unexpectedly disconnects or goes offline. This message can be pre-chosen by the device or user and sent to a specific topic, therefore notifying all other clients subscribed to this topic of the device disconnection.

How Do IoT Devices Communicate: Physical Layer (Connectivity) Protocols

Below you can find the most common methods used for IoT device communication:

#1. Wi-Fi

Wi-Fi networks are commonly used to connect IoT devices since they are widely available and provide medium-range communication.

The 802.11 standard offers a larger data range in comparison to other protocols. It allows for managing a large amount of information. Wi-Fi covers an area of around 50 meters. Of course, transmitters can extend this range, but the speed of data transferring might be lower. 

#2. Bluetooth

Bluetooth is perfect for short-range communication between devices. It is a low-power wireless IoT communication technology that can connect small devices like smartphones and wearables.

There is also Bluetooth Low Energy which was specifically designed for IoT world and therefore provides many opportunities for devices with small battery capacity. However, the range is even less than Bluetooth has. Information exchange speed is suitable only for relatively small pieces of information.

#3. LoRaWAN

LoRaWAN was specifically designed to support IoT devices and allow for long-range communication with small battery-powered devices using as little energy as possible.

LoRaWAN stands for Long Range Wide Area Network and is based on the LoRa modulation technology. This IoT communication protocol is scalable, secure, and reliable, making it ideal for a wide range of IoT applications. The most prominent advantage of LoRaWAM is its long communication range which is often measured in kilometers. However, it offers very slow data rates in comparison to other protocols. 

#4. Cellular networks (4G/5G)

IoT devices can also communicate with each other using cellular networks. With the 5G technology, IoT got unlimited capabilities. The information transmission is very fast and reliable even with previous network generation. Moreover, in comparison to other protocols, a larger number of devices can be supported simultaneously.

But everything has its price. This IoT communication protocol tends to be the most expensive, so companies often look for a cheaper alternative. In addition, cellular networks typically consume more power. 

To summarize, IoT devices use various communication methods and combinations of protocols to ensure uninterrupted communication.


Author‘s Bio: As an accomplished technology enthusiast, Laurenz Dallinger has a strong interest in digital transformation, with a particular focus on IoT. His commitment to advancing the field of device communication is evident in his work as a speaker and exhibitor at events like the Ars Electronica museum. As a valued member of the Cedalo team, the company behind the top MQTT broker, Laurenz is passionate about sharing his knowledge and ideas with developers seeking new and efficient ways of communicating with devices.