All devices and device drivers are required to support system suspend mode. This mode is also known as stand-by or sleep mode.
After the device is attached to the system, the system may go into suspend mode. While the system is in this sleep mode, there are a number of ways to wake-up the system. One is by initiating a remote wake-up event at the USB Device.
If the USB device supports remote wake-up, the device must be able operate after it issues the remote wake-up.