A wireless communication device calibrates a sleep clock with a fast clock and determines a quality of the calibration

摘要

When in a power saving sleep mode, a wireless communication device uses a low quality, low frequency sleep clock to time when the device should awaken. The sleep clock is calibrated using a fast clock of the device which functions when the device is awake. The device also determines the quality of the calibration. The device may be a user device or a base station. In one embodiment (Fig. 3B) the device compares the quality of a new calibration and the quality of an older calibration and uses the new calibration only if it has higher quality. The determination of quality may be based on the error caused by temperature drift or/and the error caused by the resolution of the fast clock (referred to as the phase error).