Remote Wireless Infrastructure

 

CBRS Architecture

 

Citizen Broadband Radio Service (CBRS) is an opened up 150Mhz channel for spectrum sharing, that was otherwise mainly used by military ships, ground radars, and fixed satellites. CBRS operates in the 3.5 GHz spectrum (3550 – 3700 MHz) which is part of the C-band spectrum.

 

CBRS (Citizens Broadband Radio Service) at 3.5 GHz should not be confused with CB Radio (Citizens Band Radio) which is a two-way voice system at 27 MHz typically used by truckers.

 

Rfwel engineering is a certified professional installer (CPI) of CBRS systems. You can contact us to know how best to deploy CBRS fixed wireless project like:

  • Campus hotspots
  • Personal and small business hotspots
  • Backhaul and other Fixed Wireless Access applications

 

When CBRS is used for Private LTE, it is similar to traditional LTE in that it uses Evolved packet core (EPC) to access the provider’s services. This includes the mobile mobility equipment (MME), Service gateways (S-GW), and home subscriber station (HSS). The only difference comes in communication between the eNodeB (CBRSDs) and the user equipment (UE) or end user devices (EUDs).

 

In LTE, each provider uses its own unique frequency bands and cannot share infrastructure. For CBRS, a common 3.5 GHz spectrum is used in a dynamic shared spectrum set up (similar in some ways to TV White Space (TVWS) or to Licensed Shared Access (LSA) in Europe).

 

There are three tiers in the CBRS shared spectrum:

 

CBRS Tiers

 

  • Incumbent: They have been using this spectrum and have priority over all other tiers. They can use all the channels (10 MHz channels).
  • Priority access licensed: These are licensed providers, they use 3550 -3650 MHz, and can only use 7/10 channels. They have priority over GAA.
  • General authorized access: The channels are for the general public. They can use all the available channels not in use by the higher tiers. Example uses includes private LTE, Campus hotspots, Personal and small business hotspots, Backhaul, and Wireless broadband services.

 

CBRS spectrum

 

CBRS has 3 key components.

  • Spectrum access system (SAS): Maintains the database of the spectrum usage (like Geolocation database in TVWS).
  • Environmental sensing capability: Collection of sensors that detect incumbent usage and alert SAS. Mostly deployed along coast to detect radars.
  • CBSD (CBRS Devices): These are devices operating in the CBRS frequency range (3550-3700 MHz). They include antennas and the end user devices.

 

You can view some of CBRS devices here and sample CBRS antennas depending on your application.

 

There are 2 categories of CBSD

  • Category A CBSD: Has max EIRP of 30 dBm and can be used indoors or outdoors. If outdoors antenna must be less than 6 meters HAAT.
  • Category B CBSD: Has max EIRP of 47 dBm and can only be used outdoors. Antenna must be less than 6 meters HAAT. Must be installed by a CBRS Certified Professional Installer (CPI) – Rfwel Engineering is a CBRS CBI ( to learn more).
  • End user device (EUD): has max EIRP of 23 dBm. Eg smartphones operating in the 3.5Ghz range.

 

See below sample CBRS architecture:

 

CBRS Architecture

 

CBRS devices must generally follow the rules below:

  • It must comply to instructions from SAS within 5mins of receipt
  • If it changes location, must communicate to SAS within 60s
  • Must be capable two-way communications on the authorized frequencies.
  • Can only be installed by CPI (Rfwel Engineering is a licensed CBRS CPI)
  • On power up, CBSD must report to SAS its GPS location, Elevation, its category, and FCC ID, PAL or GAA

 

CBRS Overview
 
 

CBRS for private LTE is based on TD-LTE with one different being different spectrum emissions mask requirements. The CBRS band is . The UL/DL TDD configuration needs to be localized because of possibly non-planned deployments.

 

Contact an RfWeL CBRS Certified Professional Installer (CPI) to learn more about how you can use CBRS on your next fixed-wireless access project. You may also reach us at +1.480.218.1877 Option 2.

 

  • Order CBRS OnGo antennas for fixed wireless sites:
  • View CBRS Devices and other In-Building Fixed Installations:
  • CBRS Alliance (OnGo) Information:
  • FCC Information: