What are the top protocols for IoT projects?

The Internet of Things (IoT) refers to a network of interconnected devices that communicate to perform specific tasks or applications. These devices are extensive and include vehicles, appliances, sensors, software, or web services. Effective communication is crucial in any IoT application, allowing these devices to work seamlessly.

In an IoT network, device-to-device communication is distinct. Most devices are low-power, resource-constrained, and driven by microcontrollers or microcomputers with limited memory and RAM. Typically, they’re insufficient for complex calculations or handling large amounts of data and must communicate over the Internet, which has the capacity for high-speed, high-bandwidth communication. Several specialized protocols have been developed to facilitate efficient communication between low-resource devices and the Internet.

To develop IoT projects, understanding the related protocols and their functions is crucial. The most common IoT protocols include MQTT, COAP, Zigbee, IMAP, XMPP, TCP, UDP, and SMTP. Each protocol is distinct, requiring different platforms and tools for implementation. For an IoT developer to design projects efficiently, a deep understanding of each protocol and how they are implemented on physical devices or within a network is essential.

This article will briefly discuss each of these protocols and highlight some impressive IoT projects that demonstrate their practical application. Let’s get started.

Message Queue Telemetry Transport (MQTT)

MQTT is a popular lightweight IoT protocol often used in IoT projects. Based on a publish-subscribe model, MQTT is ideal for low-bandwidth networks. This protocol is commonly implemented in sensor networks, industrial automation, asset tracking, home automation, and smart farming applications.

Implementing the MQTT protocol involves a crucial step: setting up communication between two MQTT clients using an MQTT broker. These clients can be computers, mobile devices, or microcontrollers. The MQTT protocol, facilitated by the broker, ensures secure and reliable data communication among devices that need to exchange frequent, low-bandwidth data.

The MQTT broker plays the most crucial role in an IoT project based on the MQTT protocol. There are a variety of both paid and free MQTT brokers available that can be used to implement an IoT project. Some popular MQTT brokers include EMQX, cloudMQTT, HiveMQ, Mosquitto, VerneMQ, and Adafruit IO. When using the MQTT protocol in an IoT project, one of the most common challenges is setting up MQTT data communication between two microcontrollers through the broker.

MQTT is an application layer protocol that can be implemented on the devices connecting to Internet through any physical layer protocol, such as Wi-Fi, Ethernet or Cellular. Once you have a good understanding of implementing the MQTT protocol with various brokers and Internet technologies, building an MQTT sensor network can be both a rewarding and enjoyable challenge.

Constrained Application Protocol (CoAP)

CoAP is a specialized web transfer protocol for resource-constrained devices and networks commonly used on the IoT. It is a lightweight protocol based on UDP that uses request methods and message formats similar to an HTTP protocol. Like HTTP, CoAP operates on a client-server model. CoAP’s adaptability to different IoT scenarios, especially when extremely constrained devices need to communicate over a low-bandwidth network, makes it the preferred choice for developers.

For an example of its application, check out this IoT project, where an LED attached to an ESP8266 microcontroller is controlled through the IoT using the CoAP protocol.

Extensible Messaging and Presence Protocol (XMPP)

XMPP is an instant messaging protocol that enables real-time messaging between users with an XMPP address on different platforms or servers. Originally developed as an open-source alternative to proprietary IM services like AOL Instant Messenger (AIM) and MSN Messenger, XMPP has evolved due to its flexibility. It’s now used for lightweight messaging in IoT applications. XMPP is useful for IoT projects that require real-time messaging between physical devices, making it ideal for executing time-critical applications.

Internet Message Access Protocol (IMAP)

IMAP is not an IoT-specifc protocol. Rather, it’s used to send emails and manage such accounts. IMAP allows email clients to retrieve, organize, and manage emails stored on a mail server, providing a two-way communication channel. This enables users to download and manipulate emails on a server (such as deleting or moving emails to a different folder). In some IoT projects, devices may need to send email notifications or read emails from a registered account. In these cases, IMAP provides devices with direct access to send or receive emails. You can even control IoT devices through emails using the IMAP protocol.

Simple Mail Transfer Protocol (SMTP)

SMTP is the standard protocol for sending emails over the Internet. After establishing a communication channel between an email client and a mail server, SMTP routes and delivers the email to the recipient’s server. SMTP is essential for ensuring the reliable and secure delivery of emails. While it is not generally used in IoT projects, projects that may require sedning email notifications could benefit from the SMTP protocol for secure and guaranteed email delivery. Check out this IoT project to see how a Raspberry Pi can capture images through its camera and email the captured images to the user via the SMTP protocol.

User Datagram Protocol (UDP)

UDP is a transport layer protocol. Its simplicity and speed make it well-suited for resource-constrained devices and widely used by IoT. Contrary to TCP, UDP is a connectionless protocol, meaning it doesn’t establish a handshaking process or guaranteed delivery of data packets. Instead, it sends data packets (datagrams) from a sender to a receiver while relying on the receiver to handle potential errors or missing data.

The connectionless nature of UDP eliminates the overhead of connection establishment or verification, making it ideal for applications where speed is a priority and reliable delivery isn’t critical. UDP is also extremely lightweight compared to the TCP protocol, making it suitable for low-power, resource-constraint devices. Check out this IoT project to learn how microcontroller devices communicate with UDP clients in an IoT network.

Transmission Control Protocol (TCP)

TCP also operates as a transport layer protocol and serves as the default Internet protocol for the World Wide Web, rather than an IoT-specific protocol. However, IoT projects often find it necessary to communicate with TCP clients due to project requirements. The TCP protocol may be used in an IoT application when speed is less critical but reliable delivery of messages from one device to another is required.

While message delivery may experience delays, TCP is a connection-oriented protocol that guarantees accurate delivery by establishing a connection between sender and receiver before data transmission. This initial handshake ensures both parties are ready and sets expectations for data flow. The protocol carefully manages data flow between sender and receiver to prevent overwhelming the receiver with data packets faster than it can process them. TCP excels over UDP and other IoT protocols for tasks such as to firmware updates, transmitting security-sensitive data, or mission-critical data delivery. Explore this IoT project to see how devices interact with an IoT server using TCP protocol.

Zigbee

Zigbee is a physical layer protocol and standard designed for low-power, low-data-rate communication within personal area networks (PANs). This protocol offers mesh-networking capabilities with resource-constraint IOT devices operating within a short range (10-100 m). Zigbee is often used in building automation, smart home projects, asset tracking, and industrial automation.

Due to its extremely low power consumption, Zigbee is well-suited for battery-powered devices. Its networks are highly secure and scalable, theoretically supporting up to 64,000 devices. However, practical limitations such as hub capacity, signal interference, and network performance typically constrain the number of devices. Generally, it’s recommended to include only 30 to 50 IoT nodes in a Zigbee network for optimal performance.

Zigbee is among the most widely used standards for building wireless sensor networks, along with Wi-Fi and Bluetooth. It can be used to set up communication between two devices or two computers in an IoT project and to remote-control other devices in the IoT network.

Conclusion

Internet protocols are critical for IoT, and mastering them is essential for establishing secure, fast, and reliable device-to-device communication within IoT networks. MQTT and CoAP are among the most widely used protocols in IoT projects. Additionally, SMTP and IMAP protocols are employed to send email notifications within IoT networks. XMPP is a valuable option when real-time messaging is required between IoT devices. Depending on application requirements, devices in an IoT project may also need to interact with UDP or TCP clients.

Learn all about iot from basics in details to get started on projects.