LTE and 5G for industrial IoT: What are private networks, and how do they work?
Private cellular networks are standard 3GPP-based cellular networks offering a combination of low-power wide-area (LPWA), broadband LTE, and even ‘massive’-scale, ultra-reliable 5G connectivity for exclusive use by private parties.
They are deployed and managed separately of public cellular networks, but function in the same way. They make use of micro towers and small cells just like public networks – and, like public indoor and outdoor networks, the numbers, positions, and settings of these base stations are adjusted for each deployment.
In most cases, private networks will be deployed to enable a higher degree of control and reliability than public networks, whether they run the networks themselves, or outsource their management to systems integrators, and even back to traditional mobile operators.
Their communications and applications are effectively isolated from the chatter of public communications networks, and they can divine their own security and service guarantees. Often, the critical applications that drive the demand for private networks will also require low latencies, which are achievable with LTE and 5G, and further tuneable as private variants.
Private networks exist in three ways: in licensed spectrum, shared spectrum, and unlicensed spectrum.
In the first case, operators dedicate a portion of their licensed spectrum, otherwise used for public mobile services, in a specific geographical area. Third parties are able to license their spectrum in these locales, and build or manage their networks, as required.
Public cellular coverage remains unavailable in these vicinities, unless it is operating in a different band. But in general, the business case to deploy a public network was not apparent in the first place, and therefore public connectivity is absent. Private arrangements can bring new income to traditional cellular operators, especially from their ongoing management.
In the second case, enterprises can operate private networks in “lightly licensed” spectrum that has been organised by a regulator for shared usage, and is made available via a sub-licensing arrangement. In the third case, enterprises or carriers can operate private networks alone in unlicensed spectrum.
There are certain developments to note around spectrum regulation and licensing, which are driving the market for private networks. One is with the CBRS band (3550-3700 MHz) in the US.
The Federal Communications Commission (FCC) has set up a three-tiered sharing framework for the CBRS band. The first is for incumbent user, already in the band, including the navy and some terrestrial and satellite internet providers. Their usage, in certain geographies, will be protected from interference.
The FCC has introduced two new spectrum tiers in order to make unlicensed CBRS spectrum available to enterprises under terms of shared access, dubbed General Authorized Access (GAA), and private access, which will see it licensed to multiple third parties at auction under a Priority Access License (PAL) scheme.
GAA deployments are gearing up now (Q2, 2019); timing of the PAL auction is still to be set by the FCC.
Regulators in other geographies are seeking to break up traditional monopolies around cellular spectrum, to drive innovation in the field, and economic growth at large. In the Netherlands, ports are already making private use of Band 41/42 (3400-3600 MHz) spectrum for LTE set-ups to control cranes and automated guided vehicles, as well as low-level LTE-based tracking.
Germany’s Federal Network Agency has just confirmed it will award spectrum for the provision of local 5G services in the second half of this year. German companies will be able to apply for spectrum in the 3.7-3.8 GHz band. So-called ‘C-Band’ spectrum as low as 3.4 GHz will be auctioned for 5G. Siemens et al are in the wings.
A final word on the standardisation process. The MulteFire Alliance has specified LTE for standalone usage in unlicensed spectrum. The 1.0 version, released last December (2018), specifies mobile broadband-like LTE connectivity in the global 3.5 GHz and 5 GHz bands.
The new 1.1 specification, scheduled for release this summer (2019), adds new spectrum bands (2.4 GHz, sub-1GHz, plus the 1.9 GHz DECT band in Japan) and new LPWA capabilities. It means MulteFire-flavoured LTE is now tuned for private deployments of LTE-M and NB-IoT, as well as higher bandwidth LTE services.
But the MulteFire workload, which has existed outside of 3GPP circles, is coming back ‘in-house’ as the telecoms market recognises the demand for privately controlled LTE networks. At the back-end of 2018, a new 3GPP work item proposed a pathway to make cellular technologies work in the unlicensed 5 GHz and 6 GHz bands.