Many ask the question, when developing their data transmission systems: “Which is better, Sub-1GHz or 2.4GHz”?

Let’s try to figure it out, and everyone will choose their own path.

Let’s start with the fact that the range of microcontrollers with these frequency ranges is quite wide. There is a great variety of development and debugging tools, as examples of implementation of various devices too. It is difficult for developers to find an advantage if thay are just starting to develop and have not yet decided on the microcontroller’s core.

Let’s highlight the main criteria to a table and try to analyze it.

Compatibility A wide variety of manufacturers, a difference in the set of modulation methods, completeness of the description of the programming of the transceiver. The need to develop your own data transfer protocol or use the protocols of the manufacturers of the transceiver. Division into 3 classes:- Wi-Fi compatible (the TCP / IP stack is implemented in the microcontroller);- BlueTooth / BLE compatible (the protocol is implemented in software mainly);- Software implementations of protocols like ZigBee (without Wi-Fi / BlueTooth / BLE support)
Size of antennaLarger antennas and PCB antennas with a large footprint are possible.In most cases, miniature PCB antennas can be used.
Density of ether. A small number of devices simultaneously transmitting.Ease of predicted transmitting times.A huge number of devices in transmission mode (Wi-Fi / BlueTooth) is compensated by data transmission protocols.Complexity of predicted transmitting times.
Data transfer in indirect visibility conditionsSub-1GHz radio waves hase a very good ability to bend around obstacles.Low ability to bend around obstacles. Small objects create obstacles.
AutonomyAutonomy time work can be very long.A lot of energy goes into creating a connection. There is almost no possibility of a long-term standby mode.

Let’s discuss: 

– Compatibility.

The Sub-1GHz range is losing its appeal in the development of devices such as the Internet of Things (IoT).  In most cases, these will be devices with a narrow range of purposes and operating in their own environment. Perhaps it will be one control device and a number of performers devices, or Mesh technology will be used. Video transmission not possible.

2.4GHz devices can use the Internet in general and the IoT.

– Size of antenna

The situation is twofold. Size of antenna for Sub-1GHz is much larger than for 2.4GHz. But if need to transmit data over long distances for the 2.4GHz frequency, may need to install a repeater. And then the advantage in size of antenna becomes questionable.

– Density of ether.

In the modern world, we are constantly surrounded by various devices (mobile phones, wireless headphones, Internet routers, TVs with SMART function, refrigerators, robotic vacuum cleaners and even sockets and lighting lamps) that work with Wi-Fi, BlueTooth or BLE. All of them are constantly in touch. Collisions that arise in this case are resolved by the corresponding protocols.

In Sub-1GHz, everything is much simpler. Communication sessions are shorter. The size of the messages is small and, with the help of the confirmation of received data system, ensures the reliability of the data.

In addition, it should be noted that for the full operation of the Wi-Fi / BlueTooth / BLE protocols, it is necessary to ensure “pairing” (acquaintance) of subscribers with an “access point”. There are times when this procedure is difficult to implement. And in an open space, for example, in a field, mountains, on water, a rather complex infrastructure for building an “access point” will be required. The absence of high-level protocols in Sub-1GHz allows building a radio network of peer subscribers and providing data transmission over long distances.

– Autonomy.

As you already understand, almost all devices using 2.4GHz will function on some existing network and will always keep the connection. At the same time, Sub-1GHz devices can go into a fairly deep sleep and get in touch only as needed. For example, Texas Instruments microcontrollers based on the MSP430 core can sleep for years.

What to choose? You need to decide based on the goals of the project. The existing TiTAN and TiTAN-I boards based on MSP430 core offer a Sub-1GHz frequency range for use. But very soon TiTAN-Project LLC will release new TiTAN boards based on MSP432. And then our consumers will have a full choice of Sub-1GHz or 2.4GHz.