Choose CBSD channels

This document provides information about how to choose the best channels for a Citizens Broadband Radio Service Device (CBSD). The Google Spectrum Access System (SAS) Portal offers channel guidance to help you maximize the Citizens Broadband Radio Service (CBRS) spectrum and manage interference.

In the SAS Portal, the Coex tab shows a ranked recommendation of channels for a CBSD. These recommendations are based on channel availability and the SAS assessment of channel quality. Channel quality is a combination of the level of interference and the Effective Isotropic Radiated Power (EIRP) available.

The Coex tab is available for all registered CBSDs. It is also available for unregistered CBSDs in a Ready for CPI or Pending Registration configuration state.

Channel quality

The channel quality score is a number between 0 (zero) and 100. The channel quality varies based on a CBSD's configuration and its surrounding environment.

For all CBSDs, channel quality is affected by the following:

  • The maximum EIRP available 24 hours after you request the spectrum grant.

    To protect incumbents, SAS does not offer full power in certain areas.

  • Google's estimate of the interference caused by other CBSDs inside and outside your network.

    Based on configuration and active grants of surrounding CBSDs along with terrain and clutter data, the interference estimate takes into account all Category A CBSDs within one kilometer and Category B CBSDs within 10 kilometers.

  • Interference and SINR estimation by using a generic antenna pattern based on the beamwidth information.

    For CBSDs in a frequency management group, SAS assumes that CBSDs in the same Frequency Reuse Group (FRG) don't interfere with each other when they use the same channel.

For fixed wireless networks, SAS assumes the following channel quality:

  • The CPE-CBSDs and Base Station-CBSDs in the same sector don't interfere with each other.

  • The CPE-CBSDs and Base Station-CBSDs in one sector interfere with CPE-CBSDs and Base Station-CBSDs in other sectors, unless they're in the same FRG.

Channel ranking

Channel ranking is the list of all available channels for the CBSD sorted from the highest quality to the lowest.

For fixed wireless networks, SAS assumes the following channel ranking:

  • For a CPE-CBSD that has been specified as an SFG, SAS recommends the channels that are used by the Base Station-CBSD in the SFG. SAS shows these channels at the top of the list regardless of quality scores.

  • For a Base Station-CBSD, SAS recommends the channels with the highest scores. It might recommend the same channels for all the CBSDs in the same FRG.

For mobile networks, SAS recommends the channels with the highest scores. It might recommend the same channels for all the CBSDs in the same FRG.

To view the channel recommendation for a CBSD, follow these steps:

  1. Go to the SAS Portal.
  2. Click View deployments.
  3. Select the deployment, and then click Open.
  4. In the Channel recommendations list, do one of the following:
  5. Select the CBSD. On the right, the CBSD page opens.
  6. Click the Coex tab. For a new CBSD, wait for four hours to see the Coex tab.

  7. To review the channels with the highest quality scores, use the channel ranking.

  8. Request a new grant from your CBSD or Domain Proxy (DP) and specify the channels that you identified in the previous step. You might have to relinquish the previous grant.

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