Radio telephone and method for operating a radiotelephone in slotted paging mode

A method for operating a radiotelephone in a slotted paging mode in a Code Division Multiple Access (CDMA) radiotelephone system, the radiotelephone including a processor, a pseudorandom noise (PN) generator, and a receiver configured for communication with a base station, the method comprising the steps of:

• receiving a CDMA signal from the base station;
• identifying a wakeup time;
• detecting PN rollover boundaries in the CDMA signal;
• in response to a PN rollover boundary, resetting a sleep timer to synchronize the sleep timer with a system time;
• inactivating the processor, the PN generator, and the receiver, interrupting communication with the base station;
• generating local timing in response to a timing signal from the sleep timer to simulate system timing and synchronize local timing to the system time;
• when local timing corresponds to the wakeup time, activating the processor;
• aligning the PN generator to a current system time using a system timing offset;
• and
• upon reacquisition of the CDMA signal, resuming communication with the base station.

A radiotelephone operable in a slotted paging mode, the radiotelephone comprising:

• a modem for detecting pseudorandom noise (PN) roll boundaries in system timing;
• a call processor for controlling entry to a sleep mode by the radiotelephone, the call processor configured to calculate one or more wake up times for exiting the sleep mode;
• a timing controller including:
• registers for storing the one or more wakeup times;
• a sleep timer for generating local timing, the sleep timer synchronizing the local timing to system timing using the PN roll boundaries;
• a comparator for comparing local timing and the one or more wakeup times;
• and
• select logic for restarting portions of the radiotelephone when local timing matches a wakeup time.

A method for operating a radiotelephone system which includes at least one base station and at least one radiotelephone, the method comprising the steps of:

• at a base station,
• maintaining a system time;
• transmitting a code division multiple access (CDMA) signal including periodically timed PN rollover boundaries;
• at a radiotelephone,
• receiving the CDMA signal;
• detecting the PN rollover boundaries in the CDMA signal;
• in response to a PN rollover boundary, resetting a sleep timer to synchronize local timing with the system time;
• inactivating a portion of the radiotelephone, interrupting communication with the base station;
• generating local timing to simulate system timing;
• when local timing corresponds to the wakeup time, activating the portion of the radiotelephone;
• aligning local timing to a current system time using a system timing offset;
• and
• upon reacquisition of the CDMA signal, resuming communication with the base station.