From the first exposure to a piece of IoT asset tracking code, you are confronted by the barrage of terms, including MQTT, RTLS, RSSI, geofencing, and digital twin. This piece will provide clear explanations without any buzzwords or technical assumption. It will give practical examples to illustrate your understanding of each term.
01
MQTT
Protocol
An open communication protocol used for devices that have little bandwidth and computing power. All devices in the system broadcast messages on certain topics. The message is received by other connected systems interested in these topics.
Analogy
Imagine a radio station. The GPS tracker acts as the broadcaster. The broker functions as the radio tower, while your back end becomes the listening device on that frequency. The tracker doesn't matter who receives its transmissions as long as it is transmitting.
02
RSSI
Signal
The abbreviation for "Received Signal Strength Indicator". Indicates the strength of wireless signal received at a particular place, measured in dBm (always negative — more towards zero value indicates greater strength). Utilized in BLE indoor positioning technology to gauge the distance between the device and an antenna in a fixed location.
Analogy: Think of someone speaking in the same room. If their voice sounds more prominent, the chances are that they are standing closer to you. RSSI measures the same thing with radio waves.
03
Geofencing
Location
A zone established virtually based on a specific physical location that triggers an action once crossed. An asset that crosses this boundary either while leaving or entering this geofenced location will trigger an action event. There can be circular (based on center point and radius) and polygon geofences.
Analogy: You may draw a line on a map with a marker to represent your warehouse boundaries. Geofencing represents this line digitally — but invisibly and it notifies you instantly once anything enters this invisible zone.
04
Digital Twin
Architecture
It is an instance of a physical asset in a virtual world — that is, a digital entity which represents the exact current state of your physical asset through your backend system. Location, temperature, battery life, and status — everything gets updated as soon as the sensors update data. Your digital twin will always be in sync with your physical asset.
Analogy: The digital twin of your mobile device on the "Find my" app of your smartphone works in the same way, except that instead of a phone, your asset can be something like a fork lift or some medical equipment.
05
RTLS
System
Real-Time Locating System. An infrastructural technology used to track the location of the asset inside a building where global positioning systems cannot operate. Gateways or readers pick up signals from tags fitted on your assets and determine their position using RSSI, Ultra Wideband (UWB), and RFID.
Analogy: While GPS relies on satellites which are outside of the buildings, RTLS replaces the satellites with fixed anchors which can be inside of the building.
06
QoS (Quality of Service)
Protocol
In the MQTT protocol, QoS refers to the efforts that are put in by the broker in delivering the message. QoS 0 = fire and forget (message not guaranteed). QoS 1 = message delivery at least once (possible duplication). QoS 2 = exactly one-time message delivery (slowest but safest). Most asset management systems rely on QoS 1 for location pings and QoS 2 for alerts.
Analogy: QoS 0 – Texting without expecting to hear back (no confirmation of receipt). QoS 1 – Sending a message repeatedly until you are sure the receiver got it. QoS 2 – A registered letter; signed, sealed, and delivered precisely once.
07
Dead Letter Queue (DLQ)
Architecture
This is where the failed attempts at processing the messages end up when no more retries are possible. Rather than deleting the failed IoT messages (and losing the data silently), they are routed to a special queue for debugging purposes.
Analogy: It works just like the dead letter office in a post office; instead of deleting the mail that didn’t reach the receiver, it ends up here where the user can collect it and retry.
08
Edge Computing
Architecture
Processing of information locally in the device itself or at a gateway nearby without routing it to a distant cloud first. When talking about asset tracking, it allows a smart tag to check whether a temperature threshold is violated and to raise an alarm instantly within milliseconds, instead of waiting for the cloud round trip which would take several seconds.
Analogy: As opposed to contacting headquarters each time in order to get an answer to something trivial, edge computing is similar to empowering the people who are on site to be able to make decisions by themselves, leaving only critical cases for the higher-ups.
09
Telemetry
Data
The constant stream of data sent by a particular device to its backend infrastructure. Within the asset tracking domain, the information transmitted consists of location coordinates, sensor readings (temperature, humidity, shock), battery life, and overall health of the device – depending on the frequency of transmission.
Analogy: Telemetry feed of a race car consisting of speed, tyre pressure, fuel level, and engine temperature. Exactly the way your IoT device works, just applied to your assets.
10
Cold Start
Hardware
Time taken by the GPS equipment to initialize and receive a satellite fix from scratch. A cold start may take 30-90 seconds since there are no previous satellites in the device memory. This process is much quicker during a warm start, which takes 5-15 seconds. A hot start will only require a fraction of this time.
Analogy: Think of turning on your map application after being off for one week – it may take some time to determine your location. However, if you simply lock and unlock your device, it would show your location immediately.
Each of these 10 key concepts will pop up all the time once you get started building your asset tracking solution. The good news is that none of them will seem quite as scary at first glance as they do now – each is simply an analogy to something you probably already know about from web application development.
The best way to understand any new set of technology concepts is to see them put into practice – and that means checking out a real asset tracking platform.
AssetTrackPro uses MQTT for its telemetry ingest; RTLS and RSSI for locating assets; geofences for triggering notifications on the digital twin; and even has edge computing capabilities, in addition to everything else covered here. You can find all of that and more on assettrackpro.com.
See all of these concepts in action with AssetTrackPro's production IoT platform.
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