Choosing the communication technology is one of the first decisions in developing a connected product, and one of the hardest to change later. It affects the battery, the unit cost, the monthly cost and what the product can do. This is a practical comparison, from the point of view of the person designing the hardware.
The comparison in short
| LoRa | Cellular (LTE / NB-IoT) | BLE | Wi-Fi | |
|---|---|---|---|---|
| Range | Kilometers in open terrain | Anywhere with coverage | Tens of meters | Tens of meters |
| Data rate | Very low | High (LTE) to low (NB-IoT) | Medium | High |
| Power consumption | Very low | Medium to high | Very low | High |
| Monthly cost | None | SIM card | None | None |
| Infrastructure needed | Your own gateway | Cellular network | Phone or gateway | Router on site |
LoRa: long range, little data
LoRa fits devices spread over open terrain that send little data and run on batteries, for example agricultural sensors or units in a solar field. One gateway can serve tens to hundreds of units.
Note: in Israel LoRa operates at 917–920 MHz, and there is a limit on the percentage of time a device may transmit. That limit affects everything, including remote firmware updates, which become a process of hours. It has to be designed for from day one.
Cellular: works everywhere, costs every month
A cellular modem lets the device connect from anywhere with coverage, with no infrastructure of your own. LTE fits large data volumes, and NB-IoT or LTE-M fit low-power sensors. The downsides are a monthly cost per unit and higher power consumption.
BLE: the phone is the interface
BLE is perfect when the user is near the device: configuration, reading data, control from an app. Power consumption is very low. The downside is that without a nearby phone or gateway there is no cloud connection.
Wi-Fi: when there is a network and power
Wi-Fi fits devices at home, in an office or a factory, with a constant power supply. High data rate and no monthly cost, but power consumption is high, and installation requires connecting to the customer's network.
You can combine them
Many products combine two technologies. For example, end units on LoRa and one master unit with cellular or Wi-Fi to the cloud. Or a device with BLE for initial setup and Wi-Fi for everyday operation.
How to decide
Ask four questions: how much data must be sent and how often? What is the power source? Where is the device? And how much are you willing to pay per unit, once and every month? The answers usually narrow the choice to one or two options.
The communication choice also affects the board design and the firmware, so it is best decided by someone who designs both. Tell us about your product, and we'll help you choose.
Written by Roman Alperovich, founder and lead engineer at ProtoMakers.