Steve Rogerson looks for the answers to the most common IoT questions.

Is a tomato a fruit or a vegetable? Are facemasks really useful against infections? Will England ever again win a major football tournament? Some questions just keeping coming back.

The same is true, and always has been, in the IoT world, where the debate as to which flavour for which application continues. Should you use licensed or unlicensed spectrum? If you go for unlicensed, what are the differences between, say, Sigfox and LoRa?

Most of these questions have been answered many times over the years since IoT became a thing, but the landscape keeps changing as the technologies evolve and improve. It is thus nice to step back once in a while and go through it all again.

That is why I was pleased to listen to a keynote address last week by Fernando Llobregat, head of IoT sales for enterprises at BICS. He was speaking during the second of the IoT M2M Council’s IoT Days Summer online conferences about just that.

First, he said you needed to decide what was important for your IoT application and he split these roughly into four segments – coverage, cost, bandwidth and energy consumption. So, let’s start with coverage.

First, does the application requires national or international coverage? For just national coverage, the unlicensed LoRa and Sigfox are fine. They provide very good coverage in specific countries, cities or areas, and have proven they are simple to deploy and do the job.

However, he said from his experience when companies want worldwide coverage, they are more likely to investigate licensed technologies. The difficulty is that for full coverage, the likes of LTE-M and NB-IoT are still works in progress. But at least when they are fully set up, a single device should be able to deal with deployment worldwide.

On cost, he said generally he found the simplicity of LoRa and Sigfox gave them an advantage. But in the past couple of years, this has been changing as the volumes ramp up for licensed technologies. Another aspect on cost is network maintenance. If you deploy, say, a LoRaWan, there will be costs involved with deployment and maintenance, but if you choose NB-IoT or a satellite network, these ongoing costs are already included in the subscription.

For bandwidth, this will really depend on your use case. There is no technology that fits all, and if you do find one that does there are likely to be negatives in terms of cost and energy consumption. If you need high bandwidth, then you do need to look at licensed technologies. But with low bandwidth, you may have a choice between licensed and unlicensed, as they could provide a similar service and the cost difference is becoming negligible. However, if you need ultra-low bandwidth, he said the unlicensed technologies were probably best as they were simple and cheap.

Energy consumption is an area where you may have to make the most trade-offs. LoRaWan and Sigfox do have an advantage because of their simplicity, though they quickly reach their limits in terms of bandwidth. But the energy requirements of NB-IoT and LTE-M are coming down.

So, these are the outlines of what you should consider but obviously the next big question is will they be around next year, in five years, in ten years. Here, Llobregat admitted he did not have a crystal ball. On coverage, it is early days, as mentioned; the licensed companies are still rolling out, and he was encouraged by LoRa’s goals of being worldwide.

Taking the licensed route should guarantee at least some choice going forward in terms of supplier, as competition will be there. With unlicensed technology, you are at the mercy of the network supplier; there will be no real competition.

With licensed technology, you can expect improvements over time in coverage and bandwidth, and they will probably improve power consumption. With unlicensed, the simplicity probably means the bandwidth will stay the same, but if you have chosen that option, bandwidth is not a big issue. If you feel your bandwidth needs will increase over time, then unlicensed is maybe not the right choice.

There is of course the option of taking a multi-technology approach. There are some use cases where this could make sense, for example adding a low bandwidth technology to check if devices have been tampered with. But generally, multi-technology can be quite complex in terms of design, as well as struggling on the cost and energy consumption fronts.

In summary, the questions are still there and the answers are still really the same, it all depends on what you can do and want to do with the technology. So, start with looking at your application, deciding what coverage you need, how much bandwidth you want, how important is energy consumption, and then go through the options to find which technology best fits your needs.

On an easier question, a tomato is a fruit.