- The wireless network connection is dropped.
- You experience poor performance.
Note You may also experience these issues when you connect a Windows-based mobile PC to a wireless access point (AP) in a small office/home office (SOHO) environment or in an enterprise environment.
This issue occurs because of the power saving features that are included in Windows. The default power plan that Windows uses for a mobile PC is the Balanced power plan. The following is true for mobile PCs that are configured to use the Balanced power plan:
- When the mobile PC is plugged into a power source, the wireless network adapter is configured to use Maximum Performance mode. This turns off 802.11 power save mode.
- When the mobile PC is running on battery power, the wireless network adapter is configured to use Medium Power Saving mode. This uses the 802.11 power save mode.
- When the wireless AP receives the frames that have the power save option set, the wireless AP determines that the client network adapter that sent the frames wants to enter a power saving state.
- The wireless AP then buffers packets that are destined for the client network adapter.
- When the radio of the client network adapter turns on, the client network adapter then communicates with the AP to retrieve the buffered packets.
If the wireless AP does not support this feature correctly, the wireless AP continues to send packets to the client network adapter even if the client network adapter radio is turned off. Therefore, these packets are lost. In this scenario, the symptoms that you experience may vary depending on the phase of the wireless connection in which these packets are lost.
Method 1: Connect the mobile PC to a power sourceWhen you plug the mobile PC into a power source, Windows switches the wireless network adapter power setting in the default power plan from the Medium Power Saving setting to the Maximum Performance setting. This turns off the 802.11 power save mode.
Method 2: Modify the default power saving power planModify the default on-battery power setting for the wireless network adapter. Configure the wireless network adapter to use the Maximum Performance setting when Windows is configured to use the Balanced power plan or the Power saver power plan. To do this, follow these steps:
Windows Vista and Windows 7
Windows 8 and Windows 8.1
Method 3: Use the "High performance" power planIf the computer is running on a power plan other than the High performance power plan when you connect to a wireless network, manually change the power plan to High performance. To do this, follow these steps:
Windows Vista and Windows 7
Windows 8 and Windows 8.1
Method 4 (for advanced users): If "Wireless Power Setting" can't be customized in the User Interface as described in Method 3, here is how to implement the same change using the PowerCfg command
Windows 8 or 8.1
The workaround documented for Windows 8.1 is to change the Balanced power plan, Wireless Adapter Settings power saving mode for "On battery" to "Maximum performance". This has the same effect as the following command, when issued from an Admin command prompt:
powercfg -setdcvalueindex 381b4222-f694-41f0-9685-ff5bb260df2e 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a 0
It is possible that the system may not be using the Balanced power mode The following steps should be followed to make thsi change:
1. Run "powercfg /l" to find a list of power plans, and confirm that "Balanced" is the default. For example:
Existing Power Schemes (* Active)
Power Scheme GUID: 381b4222-f694-41f0-9685-ff5bb260df2e (Balanced) *
Power Scheme GUID: 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c (High performance)
Power Scheme GUID: a1841308-3541-4fab-bc81-f71556f20b4a (Power saver)
2. Then, set the DC Power Saving Mode to "Maximum Performance" for the Wireless Adapter by running the following command:
powercfg -setdcvalueindex 381b4222-f694-41f0-9685-ff5bb260df2e 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a0
-setdcvalueindex [...] 0 - sets the "Current DC Power Setting Index" to "0", where 0 = Maximum Performance
381b4222-f694-41f0-9685-ff5bb260df2e - is the Balanced power plan. If your system is not using the Balanced power plan, change this value to the "* Active" plan you're using
19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 - Wireless Adapter Settings
12bbebe6-58d6-4636-95bb-3217ef867c1a - Power Saving Mode
Note This change may not be reflected in original equipment manufacturer (OEM) versions of Windows that may be installed on mobile PCs. Computer manufacturers may change the default Windows power settings according to their guidelines.
You may also experience this issue when you connect to a Wi-Fi hot spot by using a Microsoft Windows XP-based computer. This issue is less likely to occur in Windows XP because the default power saving mode in Windows XP does not turn on the 802.11 power save mode of the wireless network adapter. However, if you do experience this issue in Windows XP, you can modify the power saving settings of the wireless network adapter to work around this issue. To do this, follow these steps:
- Click Start, click Run, type ncpa.cpl, and then click OK.
- In the Network Connections dialog box, right-click the wireless network adapter, and then click Properties.
- Click Configure under the name of the network card.
- Click the Advanced tab, and then modify the power management settings. For example, click Power Management in the Property list, drag the Value slider to the power management setting that you want to use, and then click OK.
Note These settings may differ depending on the manufacturer of the wireless network adapter.
ID articol: 928152 - Ultima examinare: 30 iun. 2015 - Revizie: 1