The Internet of Things (IoT) is filled with billions of devices: sensors, meters, robots, and mobile devices that constantly produce data. Think of it like Twitter (now X, of course), with all those people (and bots) tweeting out about all different topics all the time… It’s chaos!
MQ Telemetry Transport is like the social media platform itself, giving you the option to efficiently organize and deliver notifications to users who choose to follow specific people. Born in the late‑1990s for oil‑pipeline telemetry, the MQTT protocol now sits at the center of any physical object connected to the internet such as warehouse robots, smart fridges, and cars, precisely because it moves data quickly without hogging our precious bandwidth.
Understanding MQTT
What is MQTT?
MQTT is a lightweight, open-standard messaging protocol built around a publish-subscribe model. Instead of every device calling every other device, senders publish messages to a broker, and receivers subscribe only to the topics that interest them. This simple design choice makes MQTT highly efficient, scalable, and simple to manage.
Key Features of MQTT
- Lightweight: MQTT’s minimal packet size is perfect for devices with limited memory and processing capabilities.
- Publish-subscribe model: Clearly separates message senders from receivers, improving scalability and simplicity.
- Low bandwidth usage: Optimizes data transfers even over restricted network connections.
- Low overhead: Minimal network overhead helps lower latency and improve responsiveness.
Core Components of an MQTT System
1. Brokers
The broker in some ways is like X’s central server. Every message passes through it, and the broker decides which subscribers should see what. This centralized method removes a bit of the chaos by adding standards, rules, and security in one place.
2. Publishers & Subscribers
- Publishers are like X users creating tweets. It could be anything generating data, such as soil moisture readings from vineyard sensors, battery levels from electric vehicles, or autopilot flight data from drones.
- Subscribers, similar to X followers, include things like mobile apps, analytic dashboards, or actuators. They follow particular topics, for example, "field/alpha/moisture," and then act based on only those incoming messages.
3. Topics & Topic Filters
Topics act as hashtags on Twitter. A topic labeled "sensor/42/temperature" can be selectively received by subscribers following either all sensors ("temperature/#") or just that particular sensor. MQTT's topic structure, with its wildcards and hierarchical naming, creates orderly, targeted message distribution even among millions of connected subscribers.
Why MQTT Matters in Real‑Time IoT
Internet‑of‑Vehicles (IoV)
Volkswagen uses MQTT to stream diagnostics, map updates, and infotainment cues to connected cars without overwhelming mobile networks. When a vehicle needs a critical software patch on the highway, every millisecond counts.
Drone Telemetry
Matternet tracks altitude, heading, and battery health via MQTT feeds. Operators can intervene if a drone deviates by a single degree, because the data arrived fast enough to matter.
Smart Grids
Power utilities put voltage and load readings through MQTT so they can rebalance the grid before a brown‑out spreads. The protocol’s low overhead makes it possible to assess thousands of transformers in near real time.
Technical Advantages of MQTT in IoT
Efficiency for Constrained Devices
Small microcontrollers (think 32 kB of RAM) and slow links (think NB‑IoT) appreciate MQTT’s bite‑sized frames. Less airtime means longer battery life and cheaper data plans.
Scalability in Massive Deployments
Because publishers never need to know how many subscribers exist, adding ten thousand new sensors is as simple as pointing them at the right broker. Cloud brokers routinely juggle millions of topics without noticeable delay.
Hardware Offloading Bonus
SmartNICs and FPGA‑based accelerators can now terminate TCP or even run an entire network stack on the card, trimming publish‑to‑deliver latency. In our research, offloading sequence‑number translation alone shaved several microseconds per packet, enough to matter when drones or autonomous vehicles are the clients.
How MQTT Fits into TCP Offloading
When MQTT runs over TCP, it guarantees reliable, ordered data transmission. However, TCP processing can itself cause latency, making it a bottleneck for real-time IoT applications. One solution we propose is TCP offloading, where specialized hardware, like SmartNICs and Data Processing Units (DPUs), takes over some network processing tasks from the server's CPU, reducing delays.
TCP monitoring with SmartNIC offload for MQTT
In our research, we've initially explored how using SmartNICs for TCP offloading, focusing specifically on accelerating MQTT Publish packet distribution, can significantly reduce latency. Our research demonstrated that even a basic offloading approach, like TCP monitoring, which intercepts and translates TCP sequences, can lead to reduced latency.
The results were promising enough to justify further development of the following proofs of concept:
- Network Stack Integration: Implementing an entire network stack directly on the SmartNIC, allowing it to independently handle MQTT Publish packets.
- Socket Interception: Redirecting network socket interactions to the SmartNIC’s internal stack, cutting out unnecessary server-side processing steps.
Our testing shows real results. By offloading tasks onto SmartNICs, we observed significant improvements in MQTT message delivery speeds, making it especially useful for scenarios where latency matters, such as autonomous drones, autonomous vehicles, and smart grids.
If you want to read more about how we did it and see the initial results for yourself:
