One of the wasted opportunities of spectrum regulation has been the failure to make full use of the frequencies between 400 MHz and 450 MHz, despite their excellent propagation characteristics. The 450 MHz band was originally assigned for analog mobile, and then half-heartedly adopted for GSM and LTE, mainly in rural areas. In recent months, however, these very low frequencies have gained increasing prominence, especially in Europe, in the thinking about 4G-based networks for the IoT and for critical communications.
This has been helped by the recent harmonization of the band plan for 410-430 MHz, by Europe’s CEPT, the pan-EU body which coordinates telecoms authorities in the region. This section of the sub-450 MHz spectrum has been assigned to mobile broadband, primarily for critical communications use cases, but also for future evolution of other services that currently use PMR (private mobile radio) technologies such as Tetra.
Jumping on the harmonization of this band in Europe, Czech MNO Nordic Telecom is developing an LTE network that will provide critical communications – including voice, data and machine-to-machine – for emergency responders, public utilities and other industries.
In parallel with the 3GPP-compliant roll-out, Nordic is also developing specific functions for rescue and public safety agencies, which are not delivered by vanilla 4G, even with the critical comms enhancements which were added in the Release 14 standards. The MNO says its new network supports encryption of all communications, high availability service level agreements, and near-universal geographic coverage in the Czech Republic. It can also support prioritizated access for selected user groups, such as police and firefighters.
Nordic and its suppliers have tested the LTE network in the 410-430 MHz band, and will start to deploy it commercially later this year.
The operator says it is using chips from suppliers in Japan, Israel and South Korea, in order to avoid any components from Chinese vendors, given the current disputes in Europe over potential cybersecurity risks from Chinese equipment in critical infrastructure. Late last year, the Czech cybersecurity agency, Nukib, issued a warning about this potential risk, naming Huawei and ZTE; and mandated all Czech companies to undertake a risk analysis if they provide critical services. Since then, local reports indicate that CETIN, the country’s largest telco, has concluded that any risks related to Huawei technology are “manageable”, without the need for a ban.
In the CEPT decision of November 2018, the 410-430 MHz band was added as one option for public safety services, although this band, along with spectrum in 440-450 MHz and 450-470 MHz, was also approved for low power WAN IoT, LTE land mobile, digital PMR and Tetra services.
These low power, high availability applications, most of which require high mobility and near-ubiquitous coverage, may drive a revival of interest in spectrum below 5 GHz for 4G, and even future 5G, especially as specialized M2M and critical comms systems are phased out (though the repeated delays to the timescale to switch off the UK’s Tetra network, which will be replaced by the cellular Emergency Services Network, shows just how hard it is to make this transition without significant trade-offs, especially in the quality and reliability of voice).
To date, the main cellular technology to live in this area of the spectrum has been CDMA450. Several countries, especially in the north and east of Europe, assigned national mobile broadband licences in this band, but there has been limited migration to LTE, because of the limited capacity in such low frequency spectrum, and the shortage of mainstream devices.
Thomas Weber, spectrum manager at CEPT’s European Communications Office, believes the IoT will create a new demand for LTE450, with NB-IoT and Cat-M both able to run in the 450 MHz band, and potentially in 410-430 MHz too. In that case, the countries with ageing CDMA450 networks may well be the first to jump on the ability of the low frequency spectrum to support very wide coverage at affordable cost, because of its large cell sizes and good penetration through walls and other obstacles. Apart from Czech Republic, those countries are The Netherlands, Austria, Germany, Latvia, Russia, Sweden, Norway, Denmark, Finland and Hungary.
The first LTE450 network, dedicated to IoT applications, was launched by Finland’s Ukkoverkot (Ukko Mobile) in 2015, working with Huawei to migrate from a legacy CDMA system. Ukko is focusing on business and vertical data services, not costly consumer propositions, targeting field and home workers, public sector agencies and the transport sector.
Antti Pellinen, the operator’s CEO, said at the time of launch: “The coverage properties are truly impressive, with a countrywide network across the whole of Finland (about 340,000 square kilometers) successfully achieved with only a few hundred sites.” A 450 MHz base station covers about twice the area of an 800 MHz version, and up to 20 times that of a 2.6 GHz site.
Huawei said at the time: “We look forward to cooperating with many more operators to deploy LTE 450 MHz commercial networks and bring ubiquitous connection for M2M or things-to-things”.
Also in the Nordic region, Swedish challenger Net 1 (owned by Teracom) uses the band for rural services and M2M. Using CDMA, it achieved 96% geographic reach in 2012 with 400 base stations for coverage and another 100 for additional capacity.
In the USA, the 406-420 MHz band is one of the areas of the spectrum which a group of utilities are lobbying to have earmarked for their networks. The Utilities Technology Council wants its members to be able to build their own networks to support critical comms and smart grid.