IoT Protocols Explained: MQTT, CoAP, LoRaWAN and HTTP
Devices in an Internet of Things system need a common language to talk to each other and to servers. These languages are IoT protocols. This guide explains what they do, compares four common ones and gives simple rules for choosing between them.
Key takeaways
- IoT protocols set how devices send data, how they connect and how they are secured.
- MQTT and CoAP are light messaging protocols, LoRaWAN is a long-range radio network and HTTP is the general web protocol.
- The right choice depends on range, power, data size and the network available.
- Standard protocols make devices from different makers work together.
What IoT protocols do
A protocol is a set of rules for sending data. It decides how a device connects, how a message is formatted, how it is acknowledged and how it is protected. Without a common protocol, every device would need a custom link to every other one. Standard protocols also add reliability and security.
MQTT, CoAP, LoRaWAN and HTTP compared
These four are used often in industry and cities.
| Protocol | Best for | Strengths | Limits |
|---|---|---|---|
| MQTT | Sensor data sent to a server | Light, reliable, publish and subscribe | Needs a broker and steady connection |
| CoAP | Small, low-power devices | Very light, similar to HTTP | Less common support in some tools |
| LoRaWAN | Long-range, low-power sensors | Reaches kilometres on small batteries | Low data rate, not for video |
| HTTP | Web services and apps | Universal and well known | Heavier for small devices |
How to choose a protocol
Start with the device. If it runs on a battery for years and sends small readings far, look at LoRaWAN. If it sends frequent data to a platform over Wi-Fi or cellular, MQTT is a common choice. For very small devices on constrained networks, CoAP is an option. Use HTTP where you integrate with web services. Read how smart city IoT solutions work for examples.
Security and compatibility
Choose protocols that support encryption and device authentication, and keep device software updated. Check that your platform supports the protocols you plan to use. See smart city IoT security, integration and cost challenges for what to plan.
IoT protocols and solutions from Suraj Informatics
Suraj Informatics builds IoT solutions for industry, ports and cities, choosing sensors, networks and protocols to fit the site, and connects them with the GATIVRA platform.
IoT protocols: common questions
What is MQTT?
A light messaging protocol in which devices publish data to a broker and other systems subscribe to it.
When should I use LoRaWAN?
When sensors are far apart, send small readings and must run on batteries for a long time.
Is HTTP suitable for IoT?
Yes for devices with enough power and bandwidth, and for linking to web services. It is heavier than MQTT or CoAP.
Can one project use several protocols?
Yes. A gateway or platform often translates between them.
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