Small cell support

Devices launched with Android 11 or higher can provide support for closed subscriber groups (CSGs) through methods in the cell identification APIs that get information about a cell's CSG information. This is useful for mobile network operators (MNOs) that manage small cells through closed subscriber groups. Information about CSGs is represented in the ClosedSubscriberGroupInfo class.


To support CGGs on devices running Android 11 or higher, implement the following functions in radio/1.5/types.hal.

  • ClosedSubscriberGroupInfo: Included optionally with every CellIdentity instance. This structure is used to provide details about the closed subscriber group to which a cell belongs, if any. This is commonly used to identity small cells such as personal LTE devices. It can also be used in deployments such as CBRS LTE.
  • CellIdentityLte: Supports a list of additional PLMN-IDs.
  • CellIdentityWcdma: Supports a list of additional PLMN-IDs.
  • CellIdentityTdscdma: Supports a list of additional PLMN-IDs.
  • RegStateResult: Includes an updated CellIdentity structure and a field to indicate the RPLMN.


To test your implementation, run the following CTS test: CellInfoTest.