Why 450 MHz LTE is ideal for critical communication
The advantages include the physics of sub-GHz LTE signals, existing base station networks, and new hardware.
When disaster strikes, reliable communication is critical. Emergency responders need to be able to exchange information to coordinate their response. Government authorities need to be able to manage critical infrastructure. Power utilities need to be able to control the electric grid. And with the growing importance of connectivity in smart cities, smart power grids, and smart utility networks, resilient cellular connectivity will only become more urgent as time goes on – not only in times of disaster, but simply to keep critical infrastructure up and running reliably day to day.
In Europe, for instance, the communication networks used to control components of the power grid – and all other critical infrastructure – are required by mandate to remain operational for at least 24 hours in the event of a power failure – well beyond what most commercial cellular networks can offer. The solution the region’s energy industry lobbied for and, ultimately, won: privileged access to the 450 MHz frequency band, which was opened up for low power wide area (LPWA) LTE communication in 3GPP Release 16 using voice communication, standard LTE, and LTE-M and NB-IoT.
Around the world, national authorities are auctioning off frequency bands around 400 MHz – specifically, bands 31, 72, 73, 87, and 88 – to mobile network operators to enable either public or private cellular networks for critical communications, based on LTE or on the legacy CDMA technology that LTE is replacing. The Netherlands, Poland, Ireland, the Czech Republic, and Estonia, several South American countries, South Africa, and the Middle East have all been early adopters. And more European countries are likely to follow.
The benefits of the 450 MHz band
A key differentiator of the 450 MHz band is its long range. Most commercial LTE bands are situated somewhere upwards of 1 GHz. Up and coming 5G networks reach as far north as 39 GHz. High frequencies deliver higher data rates, enabling, for example, the concurrent streaming of high-resolution video to any number of smart devices. But these high data rates come at the cost: rapid signal attenuation, which requires dense base station networks.
The 450 MHz band (like its neighbors) sits on the other side of the spectrum. While a country the size of the Netherlands might require a few tens of thousands of base stations to achieve full geographical coverage of commercial LTE signals, the increased range of 400 MHz signals means that it only takes a few thousand base stations to achieve the same coverage. As a result, a much more manageable number of base stations need to be kept up and running using backup power to continue to connect critical devices in a power failure.
The reduced attenuation suffered by RF signals in the 450 MHz band is also behind its increased penetration through walls and other solid materials. Particularly for smart meters and connected sensors deployed indoors, underground, and in other hard-to-reach locations, the 450 MHz band’s superior penetration power brings obvious advantages.
Finally, there’s a practical benefit: existing infrastructure. The 450 MHz band has a long history, first serving professional analog mobile radio (PAMR) networks, then evolving to serve CDMA-based networks, often to reach far-flung corners of sparsely populated countries such as those in northern Europe or rural Africa. Because of that, a lot of countries already have enough cellular base stations on the ground to run the network.
A growing list of use cases
With resilient cellular communication networks tailored to the needs of mission- and business-critical use cases, there has been a surge of interest in expanding their scope to serve a growing list of use cases. In Poland, for example, frequency bands in the 450 MHz range will form a private wireless network to connect millions of smart meters and tens of thousands of SCADA systems used to control wind turbines and other applications.
In Germany, the network will offer a resilient cellular communication channel for voice and data serving a broad range of public and private utilities, including gas and heat distribution networks, in addition to the millions of devices needed to manage loads in smart power grids. And while energy-related use cases will receive the highest priority to use the network, other users, such as emergency or healthcare services, may be able to tap into the frequency bands when there is free capacity.
Peering further into the future, it’s likely that the 450 MHz band will serve a growing variety of use cases that depend on a resilient cellular network. Smart city and traffic control infrastructure, for example, both need to keep delivering when the power goes out. The same is true for smart healthcare devices that protect vulnerable individuals and security services that protect valuable property.
Designed for critical communications
To communicate over the 450 MHz spectrum, end devices – smart meters, smart lights, and other connected sensors and actuators – all need to make themselves heard by the network. To achieve this, the 3GPP has allowed them to shout louder than in other frequency bands, using a stronger 26 dBm power class (Power Class 2) than in other frequency bands, which can go up to 23 dBm (Power Class 3).
The u‑blox SARA-R540S module, which is based on u‑blox’s own UBX-R5 cellular LTE-M and NB-IoT chipset offers support for both Power Class 3 and Power Class 2 over the 450 MHz frequency bands. Supporting both private and public bands in the 400 MHz range in addition to a broad spectrum of standard LTE-M and NB-IoT bands, the module offers active antenna tuning to optimize performance across the entire breadth of the LTE spectrum.
SARA-R540S enables full end-to-end security, leveraging a hardware-based root of trust and a lightweight pre-shared key management system with u‑blox IoT Security-as-a-Service functionality.
Designed to meet the long lifetime requirements of many of its target use cases, the module runs on less than 1 μA of current in power save mode (PSM) and has a ‘last-gasp’ function to send a final message before losing its power supply, for example, during a power outage or in case of a tampering event.
To learn more about the SARA-R540S and how it can help you develop connected solutions for business- and mission-critical use cases, head over to the product page, reach out to our sales team, or get in touch via LinkedIn
Senior Principal Application Marketing EMEA, Energy and Industry 4.0, u‑blox
Courtesy of u-blox