You can test the interoperability of your Citizens Broadband Radio Service Device (CBSD) with
Spectrum Access System (SAS) and simulate different types of
[incumbents](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms#incubment).

To do this, the test SAS environment offers the following:

- [Federal Communications Commission (FCC)](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms#fcc) regulations
- A [suspension zone](https://docs.cloud.google.com/spectrum-access-system/docs/protected-entities#suspension-zone)
- [Priority Access License (PAL)](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms#pal) testing zones
- A [termination zone](https://docs.cloud.google.com/spectrum-access-system/docs/termination-zone)
- A [Grandfathered Wireless Protection Zone (GWPZ)](https://docs.cloud.google.com/spectrum-access-system/docs/protected-entities#gwpz)

## Suspension zone

The test SAS environment provides a suspension zone to help with
testing scenarios related to grant requests, grant authorization, and grant
suspension. This zone is defined as a rectangle with corners at the
following [locations](https://storage.googleapis.com/support-kms-prod/7FEG4C0UNXaVWxdW9dm0kl2JvGE8QWE8cvKR):

- 63° North, -156° East
- 62° North, -156° East
- 62° North, -155° East
- [63° North, -155° East](https://storage.googleapis.com/support-kms-prod/hBKwPcVsRNwcAA0uQGDIA3uTMlfVrJO3joXJ)

The frequency range associated with the suspension zone is from 3550 MHz to
3620 MHz. All grants, whether partially or fully overlapping this frequency
range, are affected by the suspension zone. The zone is active every hour
between 5--10, 15--25, and 35--50 minutes past the hour---for example, from
12:05 PM to 12:10 PM, 12:15 PM to 12:25 PM, and 12:35 PM to 12:50 PM.

## PAL testing zones

The test SAS environment provides zones to support PAL testing.
The equipment manufacturers receive information by email about the zone where
the testing takes place. SAS customers can only perform PAL
testing *after* their official PAL assignments are made public.

Some tests require a [CBSD configuration](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms#cbsdconfig)
with the intermittent PAL [user ID](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms#userid) called
`test_pal_user_id`. This ID is a special user ID that results in intermittent,
scheduled PAL behavior in specific geographic areas in the test environment.
During certain times of the day, CBSDs registered with
`test_pal_user_id` are PAL-qualified. At other times, these CBSDs
act as [GAA-only](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms#gaaonly).

The time schedule for the intermittent PAL user ID is as follows:

- Between 14:30 to 22:30 UTC, no PALs are associated with `test_pal_user_id`.
- At all other times of the day, the ID is linked with test PALs in specific South Dakota counties.

## Termination zone

The test SAS environment provides a periodic termination zone for
testing purposes. This zone is defined as a rectangle with corners at
the following [locations](https://storage.googleapis.com/support-kms-prod/S3Jl4c3vmgwPUPrMm2yhzPth7LIPHZjOyLon):

- 67° North, -159° East
- 66° North, -159° East
- 66° North, -158° East
- [67° North, -158° East](https://storage.googleapis.com/support-kms-prod/j73kOT0oaNlFBodFj6Z01NdxyHbOCyXZgTbX)

The frequency range associated with the termination zone is from 3550 MHz
to 3620 MHz. All grants partially or fully overlapping this frequency range
are affected by the zone. The termination zone is active every hour between
5--10, 15--25, and 35--50 minutes past the hour---for example, 12:05 PM to 12:10 PM,
12:15 PM to 12:25 PM, and 12:35 PM to 12:50 PM.

For CBSDs that have grants and are registered inside the termination zone,
SAS terminates *all* active grants that partially or fully
overlap with the 3550 MHz to 3620 MHz frequency range at 5, 15, and
35 minutes after every hour. SAS also suggests a new frequency
range from 3620 MHz to 3700 MHz in the heartbeat response, which
notifies the CBSD of grant termination. For example, if the
CBSD starts at minute 0 (zero), it receives a grant and a heartbeat.
At 5 minutes past the hour, SAS terminates the grant. The next
heartbeat response contains `responseCode 500` (`Terminated_grant`) and the
suggested operation parameters.

The following example shows a response:

```
"operationParam": {
   "operationFrequencyRange": {
     "lowFrequency": 3620000000,
     "highFrequency": 3700000000
    }
}
```

While the termination zone is active, any requested grants that partially or
fully overlap with the 3550 MHz--3620 MHz frequency range are
automatically rejected. This facilitates verification of correct
CBSD behavior through observation of the radio frequency output.

## GWPZ

An example of GWPZ defined in the test SAS environment is
available as a circle centered at [70° North, -162° East](https://storage.googleapis.com/support-kms-prod/ntHGf4LYG3aDoDdu5VlFhMS1jVCRUa0t5jQd)
with a radius of 18 km.

The frequency range associated with the GWPZ is from 3650 MHz to
3700 MHz. Unlike the other zones described in the test plan, the GWPZ is
*always* protected from interference.

## What's next

- Learn about [PAL interoperability test suite](https://docs.cloud.google.com/spectrum-access-system/docs/pal-iottest).
- Learn about [CBSD interoperability with SAS](https://docs.cloud.google.com/spectrum-access-system/docs/sas-iottest).
- Learn about [key SAS terms](https://docs.cloud.google.com/spectrum-access-system/docs/key-terms).
- [Troubleshoot SAS issues](https://docs.cloud.google.com/spectrum-access-system/docs/troubleshooting).