LTE-M: Licensed Spectrum vs Unlicensed Spectrum

As LPWA (low-power, wide area) networks come into their own as an IoT technology, it’s important to look at what the different options are and how they can impact your deployment, both now and in the future. There are two main categories of LPWA technologies: those deployed on licensed radio spectrum and those deployed on unlicensed radio spectrum.   

LPWA on the licensed spectrum

MNO’s (Mobile Network Operators) procure licenses to operate within dedicated parts of the radio spectrum. This mean that no one else is allowed to use that part of the spectrum unless the operator allows them to. Since the operator have full control, they can provide high transmission quality, data security, stability, scalability and speed. In addition, they ensure that the quality remains over time, by tweaking the network as the subscriber’s usage patterns evolve. 

There are two key types of LPWA technologies deployed on licensed spectrumLTE-M and NB-IoT Both are acknowledged as the technologies that will be part of the 5G mMTC (Massive Machine Type Communications) standard which will enable massive IoT, with LTE-M in particular emerging as the strongest option for migrating legacy 2G and 3G devices, and also supporting new applications that require higher bandwidth along with lower power consumption and extended battery life. 

LTE-M and NB-IoT are both based on standards set by 3GPP, the organization that defines standard for technologies used within the telecom industry. More than 900 mobile operators around the world support 3GPP standards, covering the majority of the globe where businesses operate. These standards make it easy for devices to seamlessly roam from one network to another, making it possible to create one device that can work on network across the globe. The standard also ensures the longevity of a technology, a very important aspects when deploying an IoT solution that is meant to last for many years. 

LPWA on the unlicensed spectrum

Unlicensed spectrum isn’t owned by anyone and can be used free of charge, without any rules on how to get access at any given time. This allows for a lot of flexibility, but since it doesn’t require a license or fee it can become crowded. Everything from WiFi routers to cordless telephones and other communication devices also use unlicensed spectrum, meaning that IoT solution deployed in the unlicensed spectrum run the very real risk of interference. Technologies such as LoRa and Sigfox are based on unlicensed spectrum.  

While you might see upsides to these technologies, such as deceptively cheap devices, it’s important to consider the whole picture. Basing an IoT solution on these technologies often mean that you need spend money to procure and operate your own radio network, since most countries in the world does not have nationwide LPWA networks on the unlicensed spectrum.  

With the unlicensed part of the radio spectrum open for anyone, it makes it easy for anyone to establish their own private network. However, there is the risk that anyone else can do the same, resulting in interferencebetween networks. This is the same phenomenon that you might have experienced with your home Wi-Fi. When you first set it up it works great and provide high speeds, but 6 months later the neighbor buys a new Wi-Fi router, and all of a sudden you have a hard time getting a reliable connection since you are now (unwillingly) sharing the same part of the unsilenced spectrum.   

Let’s look at it another way

Think of licensed and unlicensed spectrum as the difference between an elegant dinner party at an exclusive restaurant and a party you might have attended back at university. Both start pretty much the same way: people arrive, there is plenty of room to move around, you can hear each other talk, and when the music comes on there’s room to dance. Fast forward a few hours, though, and things have changed: those who are at the dinner party are still able to converse and there’s plenty of elbow room at the table. At the university party, however, loads of people have crashed, everyone is shouting over the music, and if you try to dance there’s a good chance you’ll knock people over the second you break out your moves. Licensed spectrum is the elegant dinner party, where only the people invited are there and things are under control. Unlicensed spectrum is the frat party, where the lines to the bathroom are long and no one can hear what anyone is saying.  

What happens as the parties evolve? If new guests show up to the dinner party at the restaurant it’s not a problem because the restaurant staff are experienced and prepared – they’ll just bring an extra table and some chairs, and things will carry on as before. At the frat party, on the other hand, you don’t even know how many people will show and there’s a good chance endless strangers will crash the party and chaos will ensue.  

So, how does this relate to radio spectrum?  If you use unlicensed spectrum you have no idea who is joining the party – you might be one of the early arrivals but in a year or two there could be all sorts of devices crowding into your space, which would greatly reduce your ability to have efficient and IoT connectivity.  Using licensed spectrum, on the other hand, means you always have a professional taking care of the space your devices are communicating within, so you never have to worry that the service is being degraded.  

If you would like to learn more about how IoT can enable your business, please get in touch.

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