MB Radio State

  • Article

Overview

This topic describes the operations that are used to set and read an MB device's radio power state(s). These states can be controlled through software (airplane mode) or hardware (if the appropriate switch is present). This topic explains how the radio power states are controlled, how to test radio power state functionality, and how to investigate radio power state issues.

Terminology

System Radio State - System Radio State is a system-wide state. It is the most evident indicator of airplane mode state. System Radio State is managed by the Radio Management Service (RmSvc).

Radio Manager - RmSvc iterates several RadioManagers (MediaManagers) in the system like WlanRadioManager, BlueTooth, and WwanRadioManager. WwanRadioManager(.lib) is hosted in RmSvc.dll and manages the wwan side of the radio logic. WwanRadioManager uses the WWAN Service (WwanSvc) RPC to:

  1. Query and set cellular radio.
  2. Control the flow before and after airplane mode.

Radio Instance - Each RadioManager can include multiple radio instances. For example, WwanRadioManager can have two radio instances if there are two cellular modems in the system. Each radio instance is an abstract object and should map to one hardware radio module. In most cases, each radio instance maps to one cellular modem.

Relevant Services and Drivers

RmSvc.dll - Manages system-wide radio events like airplane mode. It also hosts all radio managers, including WwanRadioManager.

WwanSvc.dll - Cellular modems are managed by WwanSvc. Therefore, commands (OID/CID) are issued via WwanSvc. External requests from RmSvc or other components (UI) go via the WwanSvc RPC to query or set cellular radio state.

MbbCx.sys - The kernel-mode driver that manages device power state especially between D0 and Dx transition. On some system setups, the device is allowed to transition to Dx state and recover to D0 only when needed. MbbCx.sys manages the logic and control of radio state recovery before D0 and Dx.

Architecture/Flows

Radio Control from WwanSvc to Modem Hardware

Flowchart showing radio control from WwanSvc to modem hardware.

SET Radio via WwanSvc API

Flowchart illustrating SET Radio process via WwanSvc API.

Initial Radio State upon Device Arrival

Flowchart depicting initial radio state upon device arrival.

MBIM_CID_RADIO_STATE

As seen in the above diagrams, the CID used in airplane mode operations is MBIM_CID_RADIO_STATE. This CID sets or returns information about a MB device's radio power state.

Query

The InformationBuffer on MBIM_COMMAND_MSG is not used. MBIM_RADIO_STATE_INFO is returned in the InformationBuffer of MBIM_COMMAND_DONE.

Set

The InformationBuffer on MBIM_COMMAND_MSG contains MBIM_SET_RADIO_STATE. MBIM_RADIO_STATE_INFO is returned in the InformationBuffer of MBIM_COMMAND_DONE.

Unsolicited Event

The Event InformationBuffer contains an MBIM_RADIO_STATE_INFO structure.

Parameters

Set Query Notification
Command MBIM_SET_RADIO_STATE Empty N/A
Response MBIM_RADIO_STATE_INFO MBIM_RADIO_STATE_INFO MBIM_RADIO_STATE_INFO

Data Structures

Set

Offset Size Field Type Description
0 4 RadioState MBIM_RADIO_SWITCH_STATE Sets the software controlled radio state. See table below.

MBIM_RADIO_SWITCH_STATE

Types Value
MBIMRadioOff 0
MBIMRadioOn 1

Query

The InformationBuffer will be null and InformationBufferLength will be zero.

Response

MBIM_RADIO_STATE_INFO

Offset Size Field Type Description
0 4 HwRadioState MBIM_RADIO_SWITCH_STATE The state of the W_DISABLE switch. If the device does not have a W_DISABLE switch, the function must return MBIMRadioOn in this field.
4 4 SwRadioState MBIM_RADIO_SWITCH_STATE Software configured radio state.

Notification

See the MBIM_RADIO_STATE_INFO table above.

Status Codes

This CID only uses Generic Status Codes.

Testing

Cellular Radio Tests

Function Name Description
CellularRadioWinrtTest::VerifyCellularModemExistence Assert winrt api can query cellular modem and radio state
CellularRadioWinrtTest::VerifyCellularRadioToggle Assert winrt api can toggle radio state on each wwan adapter
CellularRadioRecoveryTest::VerifyCellularRadioRecoveryToOnAfterAPM Assert cellular radio states are recovered to On when leaving Airplane Mode
CellularRadioRecoveryTest::VerifyCellularRadioRecoveryToOffAfterAPM Assert cellular radio states remain off when leaving Airplane Mode
CellularRadioRecoveryTest::VerifyCellularRadioAcrossSvcRestart Assert cellular radio states stay consistent across WwanSvc restarting
CellularRadioRecoveryTest::VerifyCellularRadioAcrossDevNodePnp Assert cellular radio states stay consistent across device arrival/removal

CellularRadioTest.dll contains these tests.

Hardware Lab Kit (HLK) Tests

See Steps for installing HLK.

In HLK Studio connect to the device Cellular modem driver and run these tests:

Alternatively you can run the TestRadioStateHardware and TestRadioStateSoftware HLK testlist by netsh-mbn and netsh-mbn-test-installation.

netsh mbn test feature=radio testpath="C:\data\test\bin" taefpath="C:\data\test\bin" param="AccessString=internet"

The two files showing the HLK test results should have been generated in the directory that the 'netsh mbn test' command was ran from: TestRadioStateSoftware.htm and TestRadioStateHardware.htm.

Logs can be collected and decoded using these instructions: MB Collecting Logs.

Analyzing Logs

Useful keywords/regexp for filtering traces

  • OID_WWAN_RADIO_STATE

  • CWwanRadioInstance::OnSysRadioChange

  • Entering CUIRadioManager::_SetSysRadio

  • Leaving CUIRadioManager::_SetSysRadio

  • CWwanRadioInstance::_SetSoftwareRadioState

  • [WwanRadioManager]

  • PostD0Entry: previousPowerState

  • CWwanRadioManager::OnSystemRadioStateChange(.)+sysradiostate

  • RMAPI(.)+OnSystemRadioStateChange

  • RMAPI(.)+OnSystemRadioStateChange

  • Wwan-svc(.)+radio

  • mbbcx(.)+radio

Investigation tips

  • Identify whether this is a global (system-wide) or local (cellular-only) radio issue.
  • Differentiate device power state (D0-Dx) from radio state. They are different concepts but highly-correlated.
  • Ensure necessary ETW providers are included in the log.
  • Narrow down the area by using the scenario. For example:
    • If it's related to airplane mode, focus on RmSvc and WwanRadioManager.
    • If it's related to D0<->Dx, hibernation, or sleep transitions, focus on MBBCx.
    • If it's related to UI displays or state out-of-sync, start with WwanSvc.

WinRT API

Windows.Devices.Radios

Windows.Devices.Radios is owned by the Radio Management Service which manages all radio managers and instances. For the WWAN side, the RadioKind is RadioKind::MobileBroadband.

  • GetRadiosAsync( )
  • SetStateAsync( )

Windows.Networking.NetworkOperators

Windows.Networking.NetworkOperators documentation page

The only useful utility under this namespace for radio management is MobileBroadbandDeviceInformation.CurrentRadioState.

See Also

OID_WWAN_RADIO_STATE