Citizens Broadband Radio System (CBRS), a shared spectrum initiative in the mid-band 3.5 GHz (3550-3700 MHz) range, will accelerate the deployment of private LTE networks in the coming years.
Private LTE networks are a boon to organizations setting up their own wireless networks. The appeal is that private LTE networks support new levels of connectivity, efficiency and productivity for the organizations that deploy them.
They are ideally suited for campuses (corporate, education, healthcare) and industrial vertical markets (mines, oilfields, utilities, ports/airports, manufacturing).
From an infrastructure perspective, a private LTE network has three distinguishing features: dedicated spectrum (leased or owned), dedicated LTE radios (leased or owned), and dedicated devices (smartphones, laptops, tablets, IoT sensors) that are programmed to operate only on that network. The Enhanced Packet Core (EPC), typically a big-ticket item, can be hosted by a third party or virtualized in the cloud. Private LTE networks generally serve hundreds or perhaps thousands of subscribers or devices compared to public cellular networks that serve millions of customers. As such, the capital costs to deploy a private LTE network are much less than the multi-millions invested in the public networks.
Access to spectrum is the linchpin for private LTE network operators. If they don’t own their own licenses, they must lease spectrum from those that do, namely, the MNOs. Up to now, private LTE network builds have been dependent upon the discretion of MNOs. Since MNOs hold the lion’s share of the licensed spectrum used for public cellular service, private network operators that do not own their own licenses are forced to lease spectrum from the license holders. Limited spectrum availability relegates private network use to where the MNOs allow it, not necessarily where it is needed to serve the greater good in wireless productivity and performance on a small scale. This point holds true for outdoor and in-building wireless applications.
CBRS lowers many barriers to spectrum access that MNOs pose. CBRS is a three-tiered spectrum access system for the highly-valued 3.5 GHz band, both for LTE and future 5G applications. The Tier 1 portion of the band is already used by U.S. military for radar stations and fixed satellite stations with the 3650-3700 MHz range used by wireless Internet service providers (WISPs). The system is designed to protect Tier 1 incumbents while allowing new users access under Tier 2 priority access licenses (PAL) and Tier 3 general authorized access (GAA).
Tier 2 PAL licenses in the 3550-3650 MHz portion will be awarded through the upcoming spectrum auction. Each PAL license covers a 10 MHz channel for a single census tract in over 70,000 census tracts in the US. In any census tract, an operator may be assigned up to seven PALs for a total of 70 MHz for a three-year period. MNOs are expected to bid big for PAL licenses.
Tier 3 GAA users have access to any portion of the 3.5 GHz band up to 80 MHz that is not already assigned to higher Tier uses. Though not licensed, GAA operators must coordinate their spectrum use with the FCC-designated Spectrum Access System (SAS). GAA offers smaller operators big opportunities to run their own networks.
Availability of large swaths of 3.5 GHz spectrum at nominal cost across the country will spawn new private LTE network deployments that will appeal to infrastructure product and service vendors.
By John Celentano, Inside Towers Contributing Analyst
December 20, 2019