Satellite-Enabled LPWAN: What Network To Choose, When, and Why

LPWAN – Low Power Wide Area Networks – enable users to connect sensors / endpoints over large distances. They’re lower cost and consume less power than cellular, and while their data capacity rates are lower, there’s enough bandwidth for most IoT applications.

This article focuses on satellite-enabled LPWAN. Satellite comes into the equation when the sensors you’re connecting are so remote there’s no cellular infrastructure at all. At the moment, that leaves you with two options:

1. Use an unlicensed LPWAN technology such as LoRaWAN, mioty or Sigfox to connect your sensors, then backhaul the aggregated gateway data via a satellite transceiver;
2. Or, connect your sensors individually to a satellite transceiver.

The Differences Between Licensed and Unlicensed LPWAN

Before we settle into the main topic, some readers may find a quick explanation of licensed / unlicensed LPWAN helpful. The former leverages licensed radio frequency spectrum, which means connections use dedicated frequencies, making them more reliable. They also offer higher data capacity rates than unlicensed spectrum. Currently the best known networks – NB-IoT, LTE-M – rely on cellular infrastructure. Because of this dependency, they’re not used for extremely remote applications.

However, satellite LPWAN also falls into this category – services like Iridium’s Short Burst Data (SBD) and Certus 100, and Inmarsat/Viasat’s IsatData Pro (IDP) and BGAN M2M, all leverage licensed spectrum. Satellite LPWAN has no dependency on terrestrial infrastructure, so is usually deployed where there isn’t any – i.e. outside of population centers.

Unlicensed networks share frequencies with all other unlicensed users, so reliability in high-traffic areas may be an issue. They also have capacity issues because of the frequency spectrum they operate in – which is only suitable for very small amounts of data (LoRa has a maximum data rate of 50 Kbps). However, unlicensed LPWAN is lower cost, and devices generally require a little less power than networks operating in a licensed spectrum, although both perform well. For example, NB-IoT devices will typically operate for up to 10 years, and LoRa devices for up to 15 years, using battery power.

How Unlicensed LPWAN Works with Satellite

While there are many options for unlicensed LPWANs, because of its dominance, we’re focusing on LoRa.

LoRa networks require a gateway, or several gateways, depending on the size of the network, where the sensor data is aggregated. If the gateway is within cellular coverage, cellular can be used for data backhaul, but in remote applications, satellite is the best option for backhauling the aggregated sensor data. Co-locating your gateway(s) with a satellite transceiver like RockREMOTE ensures you can communicate with your sensors from anywhere on the planet, as long as you have a clear view of the sky.

The RockREMOTE series is particularly well suited to this pairing as it features edge computing capabilities. This enables systems integrators and developers to optimize their data transmissions to send only what’s needed, keeping the airtime cost down. It can also send your data via TCP/IP, or the more efficient messaging service, IMT. The Cobham Explorer 540, is another solid choice; this uses the BGAN M2M service which is wholly TCP/IP based, and is very cost effective if you need an IP-based transmission. If you have mains power, and need to move a lot of data – MBs rather than KBs – Starlink is also worth exploring.

NB: LoRa is a communication technology. LoRaWAN is a media access control (MAC) layer protocol which makes it easier and more secure to manage communication between gateways and endpoint devices (read a better explanation). So while LoRa can be, and is, used without the MAC layer, in the context of a wide area network, LoRaWAN is far more likely to be utilized.

When to use Individually Connected Devices

The main advantage of LoRaWAN is that it’s very low cost, but that cost increases if you’re using a commercially operated LoRaWAN. If you don’t, you’ll need to build the network yourself, which involves purchasing gateways and a network server, writing firmware, and creating the connections (read how to build a private LoRa network).

This could well be worth the effort, but it depends on the number of sensors you’re connecting, and their location. LoRaWAN is a ‘single-hop’ technology; each connected sensor communicates directly with the gateway or hub. If there’s a long distance between device and hub, or there are geographical features like mountains or forests, this can impede the signal. So, there are instances where individually connecting sensors to a satellite modem is faster, more reliable, quite possibly cheaper when time and expertise is factored in, and more efficient.

Satellite LPWAN:

• Works well in both mobile and stationary applications
• Has no limitation on the distance between your sensors – they can be positioned as far apart as your application requires
• Has a huge amount of flexibility in terms of data rates – up to 464 Kbps (although the lowest power consumption comes from the message-based services of Iridium Short Burst Data, and Inmarsat/Viasat IsatData Pro)
• Can operate on a solar powered battery for 10 years (depending on data rates and frequency of transmission)
• Is secure by design – it’s very hard to intercept the data while it’s in space, and firewalls, VPNs and private lines protect the data once it’s earth-bound again
• Has no dependency on terrestrial infrastructure
• Will work in any location, including mountains and forests, as long as there is a clear view of the sky
• Is not affected by extremes of temperature or adverse weather conditions.

Coming Soon: NTN NB-IoT

This is developing technology, with the goal of offering a single SIM to work on multiple cellular and satellite networks.

While the technology exists today to seamlessly switch between cellular and satellite networks, the devices enabled with this technology are using proprietary modems that only communicate with a single satellite network. Relatively few are produced, and they’re more expensive than their cellular-only counterparts. Moreover you’re tied into that satellite network, and if you wanted to use an alternative satellite network, you would need to buy a completely different device.

3GPP standardization is poised to disrupt this model. Firstly, there are many more cellular IoT-connected devices than there are satellite IoT-connected devices, and so production of these dual-function modems would benefit from economies of scale. They are likely to be lower cost than today’s proprietary satellite IoT modems.

The other potential benefit will be the ability to switch between satellite network operators in much the same way as you can switch between cellular networks today. Every satellite network that is 3GPP compatible with coverage in your area should be able to offer you service. It’s by no means certain, but we think this is likely to increase competition and lower pricing.

So, the impact will be to make NTN NB-IoT not just possible but also cost-competitive over the long term. That said, it will still be a more expensive solution than an unlicensed LPWAN – and for good reason, as it retains the higher data capacity rates and reliability benefits of licensed spectrum.

The lower cost modules may well move the tipping point between individually connected endpoints / sensors vs. building a LoRa network. Individually connected endpoints, as we’ve already discussed, have the benefit of being easy to set up, reliable and low latency. The number and location of the endpoints determine the choice of network today, and that will be true with NTN NB-IoT, too. But as the cost will be lower, the point at which it makes sense to use LoRa (or similar) will, we anticipate, come at a higher number of endpoints than it does today.

It may also open up new use cases for geographically dispersed endpoints that could utilize satellite IoT today, but the proprietary modems make this cost-prohibitive. Applications in Agriculture, Utilities, Mining and Oil & Gas are likely to emerge as the device and airtime costs decrease.

NTN NB-IoT:

• Has a maximum data rate of 159 Kbps up, 106 Kbps down
• Works well for stationary and slower-moving mobile applications
• Offers greater reliability as the network is more exclusive
• Strong support for user identity confidentiality, authentication and integrity
• Doesn’t require a gateway, but you will need – once available – a dual mode satellite and cellular SIM card in each device
• Will no longer need terrestrial cellular infrastructure once Satellite Network Operators (SNOs) make their satellites compatible with the 3GPP standard
• Should support route switching in the future, keeping costs low and predictable.

What’s Best for Your Remote Application?

There is a lot of hype around 3GPP standards-based technology, and when it comes to fruition, users will benefit from lower cost modems and possibly, because of increased competition, lower cost and more predictable airtime bills. Many major satellite network operators – Iridium, Inmarsat, Viasat, Starlink – have announced plans to support a form of this technology (either NTN NB-IoT or LTE) in the future.

There are companies already offering this service, but at the time of writing, they have patchy coverage, and data capacity rates are very low. The full value of this technology will be realized when there is global availability and multiple service providers – which is currently looking like 2026-27.

If you’re building your remote application right now, your choice of LPWAN depends on your application. If your devices are very widespread, LoRaWAN may not be your best choice given the higher risk of packet loss between the sensors and the gateway(s). It is cost-effective, particularly when paired with a satellite transceiver like RockREMOTE which supports edge computing, thus allowing you to optimize your transmissions. If you can manage with a degree of data delivery uncertainty (due to the capacity challenges in the unlicensed radio frequency spectrum), it’s a good choice.

For devices spread over a wide geographical area, connecting each sensor or sensor array to a satellite IoT transceiver ensures that you will receive your data, with no dependencies on terrestrial infrastructure, and no reliability issues due to contested spectrum. If you choose a service like Iridium Short Burst Data, or Inmarsat IsatData Pro, you’ll receive your data in close to real-time, too. Connecting sensors in this way costs more, but even now is less expensive than people imagine. For mission-critical applications, it’s the most reliable, fast and secure means of capturing your widespread remote sensor data.