Connecting the globe: seamless worldwide coverage with cellular and satellite technology

Connecting the globe: seamless worldwide coverage with cellular and satellite technology

Internet of Things (IoT) applications come in many forms, with varying bandwidth, mobility, power consumption, and lifetime requirements. It is often believed that many rely on cellular technology as the primary channel to transmit data, with availability on most continents and affordability as two key advantages.

But despite claims of 99% population coverage in Europe, North America, and Asia, cellular connectivity is not available in vast expanses of these continents. Typically, cellular technology poorly serves mountainous or remote areas with low population densities. At the other end of the spectrum are Africa and Australia, where cities and villages have access to good cellular coverage, but the situation changes drastically in less populated areas, where vast regions lack coverage.

Considering the entire world, including the oceans, we can estimate that cellular technology covers only 10% of the Earth's surface.

Houston, we have a global problem, especially for those IoT use cases that require ubiquitous connectivity. Classic examples include assets, vehicles, and goods that travel around the globe and need monitoring, such as the sweet mangoes from Latin America that people eat in Europe. The need for extended connectivity goes beyond mobile applications. Wind turbines or solar panels for power generation require constant monitoring. This infrastructure is usually located in remote places, such as offshore, on a mountaintop, in the countryside, or in the desert.

Satellite connectivity comes to the rescue...sort of

To date, the IoT use cases mentioned above have ensured extended global communication by complementing cellular with satellite technology. This is possible thanks to multiple satellite constellations and operators offering connectivity, platform management, and other services tailored for the IoT.

While these satellite solutions can provide users with global communication, they present cost inconveniences on two primary levels.

Nearly all multi-mode cellular and satellite solutions today use dual-core solutions: one for cellular and one for satellite. Each requires an entirely separate hardware section and RF via the communication antenna.

Using this dual-core approach to accessing cellular and satellite IoT non-terrestrial networks (IoT-NTN) significantly increases the overall cost of the solution, as hardware, certification, and device management contribute to the final price. In fact, multi-mode cellular and satellite terminals are expensive devices that only a small percentage of IoT users can afford. Investments in this technology are only made in specific cases, when, for instance, monitoring dangerous goods, expensive materials, and strategic infrastructure.

In addition to the terminal cost issue, another pain point with current satellite IoT solutions is that each satellite terminal is designed to operate with a specific satellite network. This means they must use well-defined and operator-approved hardware and software based on proprietary protocols.

So, whenever users need to switch from one satellite provider to another, they must replace all satellite terminals with a new series compatible with the new provider. This action requires a significant investment.

A solution on the horizon

Access barriers such as the ones described above have limited the adoption of satellite IoT to a small percentage of potential IoT users. Yet, this is about to change with the new 3GPP Release 17 standard for NTN. Many IoT users who have not had access to satellite technologies will now, thanks to this new global standard.

In response to the growing need for extended cellular connectivity, 3GPP* has adapted 5G New Radio (NR), as well as narrowband IoT (NB-IoT) and long-term evolution (LTE) for machine-type communications (LTE-M) for operation over satellite links, known as NR-NTN and IoT-NTN, respectively. Through these protocols, satellite-based communication at a lower cost is now possible.

3GPP Release 17 is a significant step toward integrating IoT cellular and satellite connectivity into a unified system by adopting a standard cellular communication protocol (NB-IoT, LTE-M, or 5G NR) that does not require different hardware components.

Although the conditions have been established (the NTN specification was launched in 2022), it will take time for an ecosystem to emerge. Satellite providers have a long way to go before providing full global coverage, obtaining landing rights**, and establishing comprehensive roaming agreements in multiple countries.

Today, some satellite operators (such as Skylo) have achieved significant operational capability with continental coverage through agreements with geostationary orbit (GEO) constellation owners and terrestrial cellular network operators. Skylo's IoT-NTN offering is entirely based on the 3GPP Rel 17 NB-IoT protocol.

This is not the only case. Other satellite operators, such as OQ Technology or Sateliot, are launching and expanding their low-Earth orbit (LEO) constellations to offer IoT-NTN connectivity via the NB-IoT protocol.

Main benefits

1. Compensation for errors

The 3GPP Release 17 introduces modifications to NB-IoT and LTE-M, enabling support for NTNs.

One of the main challenges for satellite communication systems is the management of round-trip delays and frequency changes caused by the movement of the satellite relative to Earth, known as Doppler shifts. The 3GPP solution addresses this issue by requiring user equipment (UE) to adjust for the service link delays and frequency shifts before connecting to the network.

Because the UE compensates for round-trip delays and Doppler shifts, the base station (gNB) can maintain its assigned frequency. The time for uplink (UL) and downlink (DL) communications can be synchronized, mimicking the operation of a terrestrial network.

This new framework enables switching between terrestrial and non-terrestrial networks, much like how mobile devices can roam between different cellular networks when traveling internationally or moving between network coverage areas.

The use of satellite communication will most likely increase the cost per bit compared to terrestrial networks, although other factors may help minimize overall costs.

2. Similar performance at a lower cost

The primary advantage of cellular NTN will not be data speed or bandwidth. Regarding performance, IoT-NTN or NR-NTN will be similar to what users already experience with existing satellite operators.

The real benefit is that a satellite network would become an extension of the terrestrial cellular network, using the same protocols, routing procedures, network management rules, etc. This makes it possible to use regular cellular, low-cost IoT devices to connect to both networks.

Although IoT-NTN cellular devices must support three additional bands dedicated to NTN (B23, B255, and B256), the extra cost should not have a significant impact on the bill of materials. The cost of an NTN-compliant satellite terminal will be dramatically lower than that of a satellite device designed to connect to existing satellite systems. Most likely, the cost of an IoT-NTN device will be similar to that of a standard IoT device today that was designed for terrestrial cellular networks only.

Removing the cost barrier will lead the industry to adopt NTN-compatible IoT terminals. These devices may not often need to access satellite networking, but will have the ability to do so, if circumstances require it.

Some readers might have already thought of scenarios in which this could be a significant advantage. Consider what happened during the COVID-19 pandemic, when thousands of containers were lost at ports and in warehouses. This resulted in shortages of materials and factories that could not properly plan for incoming goods. But what if the tracking systems of those containers had had access to satellite connectivity?

3. Satellite roaming

Another barrier to accessing satellite communication, as mentioned above, is the need to commit to a specific satellite provider. Changing the satellite provider would require replacing the entire fleet of satellite equipment. With the new standardized approach, this is no longer an issue, allowing an IoT user to access the satellite network and roam from a terrestrial network.

Consider a hypothetical situation where a tracking application travels from Canberra to Perth through the central deserts of Australia, where cellular coverage is nonexistent. Assuming the IoT application has an NTN-enabled local SIM card, the IoT application could switch from, let's say, Telstra to an NTN satellite operator with a roaming agreement with Telstra. The switch would be seamless, and the IoT user would not need to take any action to manage it because it would be in roaming mode.

A second possible case could involve an IoT monitoring application for offshore wind turbines using a SIM card from an NTN satellite operator. In this case, the IoT device would be static and connected to a defined NTN satellite operator. Coverage issues, rates, and services might be reasons for the user to consider changing the operator. Setting aside the reason, the IoT user could simply replace the satellite operator SIM card with one for a different provider or update the SIM profile in the case of an eSIM/iSIM with remote SIM provisioning (RSP) capability.

In neither scenario does the user need to commit to a provider, as changing the SIM in a cellular device would automatically change the operator.

What the future holds

Cellular NTN will revolutionize the IoT ecosystem by fostering the convergence of terrestrial and satellite systems into a single standardized network. It will do so by removing the barriers that previously limited access to satellite IoT, such as its high costs.

With cellular NTN, satellite IoT access will be democratized. Standard applications based on standard hardware will be able to use it on demand. NTN users will benefit from the economies of scale offered by the vast IoT ecosystem. We can expect a dramatic drop in the cost of terminals, with simplified designs that reduce form factors by eliminating multiple parts.

We should not expect features such as bandwidth, data rate, or payload to change significantly. The initial cost per bit will likely be higher than cellular connectivity but may decrease as the satellite ecosystem expands.

At this point, very few NTN satellite operators can provide global connectivity. Roaming agreements between satellite and cellular operators are in their early stages, and most LEO constellations do not yet have the density of satellites required to offer a continuous service. Coverage is not global for GEO-based NTN operators, and connectivity is intermittent/periodic for LEO-based operators.

NTN is set to follow a similar path to other standardized technologies. Satellite IoT systems are converging, and constellations are set to use the same protocols, eventually resulting in interoperability…worldwide.

_{* The standards body for cellular communications.}

_{** Landing rights comprise the permissions granted to airlines so that they can land at specific airports or in certain countries.}

ValerioCarta

Senior Product Marketing Manager Cellular

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