Overview

Android provides a default Android framework implementation that includes support for various Wi-Fi protocols and modes, including:

  • Wi-Fi infrastructure (STA)
  • Wi-Fi hotspot (Soft AP) in either tethered or local-only modes
  • Wi-Fi Direct (p2p)
  • Wi-Fi Aware (NAN)
  • Wi-Fi RTT (IEEE 802.11mc FTM)

An application using Wi-Fi services directly communicates with the various Wi-Fi services through Binder. The Wi-Fi services run in the System Service and communicate with the HAL over HIDL. This diagram shows the general structure of the Android Wi-Fi stack.

Wi-Fi architecture

Figure 1. Android Wi-Fi architecture

Application framework

At the application framework level is application code, which uses the various android.net.wifi APIs to interact with the Wi-Fi framework and hardware. Internally, this code calls the Wi-Fi process through the Binder IPC mechanism.

Wi-Fi services

The Wi-Fi services run in the System Service, and are located in frameworks/opt/net/wifi. The Wi-Fi service communicates with the Wi-Fi HAL over HIDL.

There are various Wi-Fi services:

  • Wi-Fi Service: Primary mechanism for controlling Wi-Fi infrastructure modes (both STA and AP).
  • Wi-Fi P2P Service: Manages the Wi-Fi Direct mode.
  • Wi-Fi Aware Service: Manages the Wi-Fi Aware mode.
  • Wi-Fi RTT Service: Manages the IEEE 802.11mc FTM functionality.

The Wi-Fi framework also includes a stand-alone process, wificond, located at system/connectivity/wificond. The wificond process communicates with the Wi-Fi driver over standard nl80211 commands.

Wi-Fi HALs

The Wi-Fi framework has three Wi-Fi HAL surfaces represented by three different HIDL packages: Vendor HAL, Supplicant HAL, and Hostapd HAL.

For details about implementations of the various HALs, see Wi-Fi HAL.