Created by Raúl Alarcón – Hidroconta
The objective of this blog is not to technically explain how the different LPWAN technologies work. For that, anyone can find numerous articles on the web that will do so much more precisely than I can in these few lines. Rather, it is to share with the reader the experience I have accumulated in this type of deployment and thus establish simple guidelines that the uninitiated user can follow when selecting the technology that best suits their use case.
4 ASPECTS TO CONSIDER
1. Cobertura
Possibly one of the main factors is the availability of coverage in the deployment area.
Currently, in Spain, we can find fairly extensive operator coverage for both Sigfox and NBIoT, especially in population centers and their surroundings, with LoRaWAN being a bit behind in this regard.
An important factor to consider is the possibility of deploying coverage privately.
Both Sigfox and LoRaWAN operate on the 868MHz free band and allow the installer to deploy coverage, meaning anyone can buy a gateway and install it, providing coverage to an area that previously lacked it.
A point to clarify:
- Sigfox gateways connect directly to the operator’s backend. Therefore, paying for connectivity is inevitable. They also do not have a “white list” function to allow access only to elements of our network.
- LoRaWAN, on the other hand, allows us to deploy a fully private network (including the backend) without paying for connectivity.
If we choose this solution, we recommend also considering the following:
Due to the special modulation characteristics, both Sigfox and LoRaWAN signals behave differently depending on the scenario.
While Sigfox performs better over long distances in open fields, LoRa is superior in more indoor environments or those with more noise. This translates to deploying coverage with Sigfox in more rural scenarios where antenna visibility is better, as the greater communication distance requires fewer concentrators (urbanizations, low-rise areas, agricultural applications…). Conversely, in more urban environments (tall buildings), with more noise in the used band or more indoor locations, we prefer LoRa technology.
Regarding NBIoT, since it operates on licensed cellular bands, it totally depends on the availability provided by the operator. However, for this reason, it is not as limited in transmission power, making its performance in “deep-indoor” and very noisy environments much better than the other two.
2. Consumption
In applications powered by non-rechargeable batteries, a device’s consumption is directly linked to its useful life, as well as to the battery size it uses to achieve it.
Recently, these three technologies have significantly evolved in energy saving, allowing developers to design very small devices with several years of useful life.
If the size fits, what else should we consider?
Both LoRaWan and NB use “self-regulation” methods for transmission power. They reduce power when coverage is good, saving battery, and increase it in low coverage areas. This also means the battery life range is very broad and heavily depends on where the equipment is installed, potentially resulting in years of difference between two devices in the same installation.
Sigfox, on the other hand, does not use these energy-saving methods, so the life of devices using this option is more homogeneous.
3. Bidirectional Requirements
In this sense, Sigfox is undoubtedly the most restrictive technology. Its excellent long-distance performance is achieved, among other factors, by reducing the packet size, the number of packets that can be transmitted, and lastly, limiting bidirectionality. This characteristic practically excludes the use of Sigfox in applications requiring a high data exchange.
LoRaWAN, being a more open standard, is not as limited in this sense. However, when designing a network, we must consider that increasing the frame size and the need for bidirectionality also decreases communication distance, requiring more available concentrators.
Lastly, we have NBIoT, which is only limited by the maximum bandwidth of the technology, with no restrictions on size, direction, or the amount of data sent.
4. Communication Costs
To realistically calculate the communication costs of our network, we first need to clarify the amount of daily data we will transmit, number, frame size, and frequency. With this information, an operator can give us an exact price for communications per device per year.
If we opt to deploy a private network, keep in mind that LoRaWAN is the only technology that allows it. In this case, communications would be FREE, and the cost would only be linked to infrastructure maintenance, i.e., concentrators and servers.
I do not want to close this blog without briefly discussing the possibilities of GPRS.
As we all know, it is a very mature technology with very high energy consumption. However, this maturity is its main strength as it is widely spread, with very few shadow zones. In our opinion, GPRS continues to be an excellent option for providing remote reading to control points that, being especially remote and isolated, lack coverage from other technologies and do not justify the deployment necessary to obtain it.
