Citizen Broadband Radio Service (CBRS) is considered as a modern alternative to distributed antenna systems (DAS), which is basically a way to improve indoor coverage for mobile operators utilizing some shared resources.
But CBRS also presents additional use cases, some of which are extremely attractive to CLECs, ISPs and a slew of vertical applications such as smart-city, transportation, education, and more. These parties can now leverage the economy of scale of LTE RAN and LTE backhaul for their bread-and-butter applications.
But wait, what is CBRS?
CBRS is an innovative designation of a frequency band at 3.5GHz (3550MHz – 3700MHz) for shared commercial use. This band, previously occupied by “incumbent users” (Tier-1 users) for US military radars (on-ground and ship-borne) and satellite communications solutions, is now shared with additional users – Priority Access License (PAL: Tier-2 users) that acquire up to 7x10MHz channels and General Authorized Access (GAA: Tier-3 users) that use this band as a license-exempt band.
This hybrid usage is based on a dynamic spectrum coordination mechanism (spectrum access system - SAS), which verifies that each tier does not experience interference from a lower-tier application. For GAA users, this presents a huge opportunity to become an LTE network operator and to leverage the great benefits of this technology.
The LTE opportunity
As mentioned above, indoor coverage is not the only use case of CBRS. In fact, Verizon sees outdoor small cells as its first CBRS use case. While the Verizon use case is aimed at offloading hotspot traffic from its valuable lower spectrum bands, a CLEC, an ISP or even a municipality can turn to CBRS to improve its competitiveness and enhance its service offering.
By utilizing the economy of scale of LTE (in general and specifically CBRS), these service providers may find outdoor CBRS small cell an extremely efficient way to provide fixed-broadband services to hot-spots, business customers and, in some cases, even residential customers.
In this way, CLECs and ISP can avoid the use of proprietary solutions and of the highly-congested WIFI spectrum.
The LTE challenge
While using CBRS outdoor small cells as a fixed-access network holds many benefits, it also poses some challenges that operators should handle in order to leverage the full potential of CBRS.
The main challenge is creating an end-to-end ecosystem that ensures coherent network performance in both the access network and the wireless backhaul in terms of capacity and availability.
CBRS small cell backhaul
The nature of CBRS small cells calls for a high-capacity, license-exempt, cost-effective, and all-outdoor wireless backhaul.
The reason for this is that the backhaul must not add a constraint to the end-to-end ecosystem – not in terms of performance (i.e. capacity), reliability and availability, and spectrum-acquisition or site-acquisition.
In light of the above, the best backhaul solution for this use case is one that is based on millimeter-wave. E-Band and V-Band solutions (described in previous posts) provide a high-capacity solution with a small form-factor, which makes it very easy to deploy them in cases where spectrum is lightly-licensed (required coordination only). This ensures high availability with no spectrum-acquisition costs.
To learn about Ceragon’s small-cell backhaul solutions, visit http://www.ceragon.com/small-cells
