Wireless telephone that rapidly reacquires a timing reference from a wireless network after a sleep mode

Abstract

A method for rapidly reacquiring a timing reference after a sleep period in a wireless telephone receiving pilot signals from one or more base stations in a wireless network, wherein the wireless telephone has a master timer (local time reference), a fast, accurate clock source, a slow, less accurate but power efficient clock source and a memory. The method includes the steps of entering the sleep period by storing one or more parameters related to the pilot signals and how the pilot signals are changing over time, calculating a prediction of the parameters of the pilot signals after a sleep period based on the stored parameters, storing the prediction, starting the slow clock, and stopping the master timer (local time reference) and fast clock source. The method further includes the steps of ending the sleep period by generating a wake-up interrupt by the slow clock after the sleep period, restarting the master timer and fast clock source responsive to the wake-up interrupt, and reacquiring pilot signals using the predictions stored previously. A time correction factor can then be computed that closely aligns the received pilot signals on the prediction which is then weighted and the master timer is adjusted by the weighted time correction.

Dependencies are inferred from the claim text.