Today's article is for folks who want to know:
Why is my grant getting suspended due to DPA activation? My CBSD isn’t anywhere near the coast!
There are two primary reasons a CBSD that is very far from the coast would have its grant suspended due to DPA activation. Either the grant has not yet been held through CPAS yet, or the CBSD could be affected by a P-DPA.
Any CBSD registered within a certain proximity of a DPA is considered within its DPA Neighborhood. Per WInnForum requirements, all new grants within a DPA neighborhood that overlap with the DPA’s protected frequencies (generally 3550-3650 MHz) must be placed on one or all of that DPA’s movelists. A movelist is a list of grants per channel that the SAS has determined must be suspended to protect higher priority users from interference. This occurs when the SAS detects incumbent activity in that DPA on that channel. When the SAS does its interference calculations at CPAS, movelists are also recalculated. A grant that has gone through CPAS is likely to be removed from some or all of the movelists it was initially placed on. Grants that have not been held through CPAS are therefore more likely to be suspended due to DPA activation than grants that have. As a result, it is recommended that your CBSD hold its grants through CPAS even if they are getting suspended on the first day they were requested. This is especially the case if you think it is unlikely that your CBSD could generate interference for higher priority users near the coast. You can check the age of your suspended grant by looking at the information listed in the CBSD’s History tab in the SAS Portal. Any grant requested in the last 14 days will be listed.
To understand what a P-DPA is, it is helpful to first understand what an E-DPA is and how they differ. E-DPAs, otherwise known as ESC-controlled DPAs, are located along the entire coast of the contiguous United States. An ESC, or Environmental Sensing Capability, is used to monitor E-DPAs for incumbent user activity so that the SAS knows when they need to be protected. Conversely P-DPAs, or Portal DPAs, are only activated when an incumbent manually submits a request for interference protection. The activation of a P-DPA can cause suspensions in the bottom 100 MHz of the CBRS band (3550 MHz to 3650 MHz). They can also be located anywhere in the country, not just near the coasts.
You can check your grant in the SAS Portal to determine if it is on the movelist of a P-DPA. Simply select the device in the SAS Portal, open up the Status tab, and expand the grant you wish to investigate. If the grant is on any DPA movelists, they will be listed here by DPA name and frequency. If the name of the DPA does not conform with the following naming scheme: West1, West2, East1, East2, etc, then the DPA is likely a P-DPA. Alternatively, P-DPAs do not activate very often - it may be that the better solution is to accept the risk that the grant will occasionally be suspended in exchange for a more powerful grant.
For more information please read the following Help Center articles:
- Operate CBSDs near the coast
- Spectrum Access System sync
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