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In addition to abiding by FCC rules and actively supporting WInnForum and OnGo Alliance standards, CommScope has developed custom features to help our customers install and operate their CBRS networks more efficiently and cost-effectively. One such feature is our ‘quick grant authorization’ for CBRS radio devices.
A fundamental requirement of CBRS regulations is that a CBRS device (Citizen’s Broadband Radio Device, or CBSD) must receive a successful spectrum grant authorization from the Spectrum Access System (SAS) before it can start radio transmissions over the air. This ensures all interference protection rules for PAL and incumbent users are analyzed and verified before the CBSD starts transmissions.
The SAS must perform this analysis for the CBSDs it locally manages, and also to include the interference contribution from CBSDs managed by other SASs. Thus, all SASs must exchange basic CBSD data with each other to accurately perform these computations. In scenarios where incumbents are present, a CBSD that requests a new channel from a typical SAS must wait for the nightly Coordinated Periodic Activities among SASs (CPAS) synchronization between all SASs before a channel is authorized.
This poses an operational challenge to CBRS network operators, as field crews installing CBSDs must wait until the next day before a site can come on-air and allow them to confirm a successful installation, prompting multiple site visits and adding cost to the process. At CommScope, we’ve worked with our lead CBRS customers to mitigate this challenge. Specifically, CommScope enhanced its SAS by introducing a quick grant authorization feature that makes use of interference headroom margin computed during the prior CPAS sync. This enables the feature to almost immediately authorize a grant.
How does this work?
Essentially, the initial grant request is briefly suspended while potential interference is checked against available margins. If there is sufficient margin, the CBSD grant is authorized. In rare cases in which there is not enough margin to provide full power as requested, the CBSD grant may be authorized at a slightly lower transmit power until the nightly CPAS can be executed to assess the requested power. The result is almost immediate feedback, meaning a CBSD can initiate transmission during installation – while the crew is still on-site.
Using this feature, the CommScope SAS authorizes a grant within the next ‘heartbeat’ message – typically less than 4 minutes – around 98% of the time, rather than having to wait overnight for the CPAS sync. These results highlight how the quick grant authorization feature provides significant value to our SAS customers by saving installation time and costs.
Real-world CBRS deployments are still relatively new, so it’s critical for vendors and users to identify and proactively tackle obstacles. Quick grant authorization is one example of this. We welcome input from customers on other challenges they are experiencing, so that we can continue to innovate and enhance the value of CBRS networks.