Maintain hotspots between driving sessions

This page describes how you can set up users to maintain hotspots between driving sessions, similar to the Wi-Fi driving experience in AAOS.

public class CarSettings {
  ...

  @SystemApi
  public static final class Global {
    ...

    /**
     * Enables persistent tethering when set to {@code "true"}.
     *
     * <p>When enabled, tethering is started when the car is started given
     * that the hotspot was enabled at shutdown and all tethering sessions
     * will remain on even if no devices are connected to it.
     *
     * <p>When disabled, hotspot will turn off automatically if no devices
     * are connected and will no longer persist through drives.
     *
     * @hide
     */
    @SystemApi
    public static final String ENABLE_PERSISTENT_TETHERING =
           "android.car.ENABLE_PERSISTENT_TETHERING";
  }
}

To persist tethering, use ENABLE_PERSISTENT_TETHERING through the Settings API, which can also be used to query.

Permissions

Use of the CarWifiManager API is restricted. This new permission is created to guard access.

public boolean canControlPersistApSettings() { ... }

Protection levels for this permission are:

New permission	Permission	Protection level
Yes	READ_PERSIST_TETHERING_SETTINGS	Signature | Privileged

The persist behavior defaults to not supported. A resource overlay (config_enablePersistTetheringCapabilities) is configured to block the ability to persist tethering. To intentionally persist tethering, set the value to true to enable the feature on top of the user preference opt-in since other system apps with the WRITE_SECURE_SETTINGS permission can also control this setting.

The following API determines if the behavior is enabled. Call this API before you change ENABLE_PERSISTENT_TETHERING.

/**
 * CarWifiManager provides API to allow for applications to perform Wi-Fi specific
 * operations.
 *
 * @hide
 */
@SystemApi
public final class CarWifiManager extends CarManagerBase {
 /**
  * Returns {@code true} if the persist tethering settings are able to be
  * changed.
  *
  * @hide
  */
 @SystemApi
 @RequiresPermission(Car.PERMISSION_READ_PERSIST_TETHERING_SETTINGS)
 public boolean canControlPersistApSettings() { ... }
}