Radiotelephone and method for clock calibration for slotted paging mode in a CDMA radiotelephone system

Claim 3

A method as recited in claim 1 wherein step (b) comprises the step of inactivating the fine resolution clock.

Claim 4

A method as recited in claim 2 wherein the method further comprises the step of activating the fine resolution clock at a time sufficiently before step (d) to allow the fine resolution clock to stabilize.

Claim 5

A method as recited in claim 1, further comprising the steps of: storing an offset time corresponding to a difference between timing of the system timing indicator and timing of the coarse resolution clock; determining a wakeup time; at a prewake time corresponding to the difference in the wakeup time and the offset time, starting a reference timer which expires at the wakeup time; and in response to expiration of the reference timer, exiting the low power sleep mode.

Claim 6

A method as recited in claim 4 further comprising the step of configuring the reference timer to expire substantially synchronously with a next received system timing indicator.

Claim 9

A method as recited in claim 6 wherein the step of measuring timing accuracy comprises the steps of: summing reference clock edges; summing sleep clock edges; and relating sleep clock edges to reference clock edges to estimate the timing accuracy of the sleep clock signal.

Claim 10

A method as recited in claim 7 wherein the step of relating comprises multiplying the first clock rate by a ratio of sleep clock edges to reference clock edges to form an estimate of the second clock rate.

Claim 11

A method as recited in claim 6 wherein the method further comprises the steps of producing one or more output timing signals synchronized to the system timing indicator.

Claim 12

A method as recited in claim 6 wherein the mobile station includes a reference oscillator for producing the reference clock signal and wherein the step of entering a low power sleep mode comprises inactivating the reference oscillator.

Claim 13

A radiotelephone configured for operation in a code division multiple access (CDMA) radiotelephone system including a plurality of base stations, transmitting a short pseudorandom noise (PN) sequence including a system timing indicator comprising a PN roll boundary of the short PN sequence, the radiotelephone comprising: a PN code generator providing a short PN sequence to align with the system timing indicator; a reference oscillator for generating a reference clock signal synchronized to the system timing indicator using the short PN sequence from the PN code generator at a first rate; a sleep clock generator for generating a sleep clock signal; a reference timer for counting periods of the reference clock signal; a sleep timer for counting periods of the sleep clock signal; a controller for determining timing accuracy of the sleep clock generator by relating the periods of the sleep clock signal to the periods of the reference clock signal, the controller determining an offset between the reference clock signal and the sleep clock signal; and a sleep time controller for placing the radiotelephone in a low power sleep mode having a duration based on the timing accuracy of the sleep clock generator, the sleep time controller adjusting the duration by combining timing of the sleep clock signal and the offset.

Claim 14

A radiotelephone configured for operation in a code division multiple access (CDMA) radiotelephone system including a plurality of base stations, transmitting a short pseudorandom noise (PN) sequence including a system timing indicator comprising a PN roll boundary of the short PN sequence, the radiotelephone comprising: a PN code generator providing a short PN sequence to align with the system timing indicator; a reference oscillator for generating a reference clock signal synchronized to the system timing indicator using the short PN sequence from the PN code generator at a first rate; a sleep clock generator for generating a sleep clock signal; a reference timer for counting periods of the reference clock signal; a sleep timer for counting periods of the sleep clock signal; a controller for determining timing accuracy of the sleep clock generator by relating the periods of the sleep clock signal to the periods of the reference clock signal, the controller determining an offset between the reference clock signal and the sleep clock signal; and a sleep time controller for placing the radiotelephone in a low power sleep mode having a duration based on the timing accuracy of the sleep clock generator, the sleep time controller adjusting the duration by combining timing of the sleep clock signal and the offset.

Claim 15

The radiotelephone of claim 11, further comprising a timing controller for producing an output timing signal synchronized to the system timing indicator.

Claim 16

A radiotelephone as recited in claim 12 further comprising: a sleep latch coupled to the sleep timer for storing contents of the sleep timer at a first predetermined time; a reference latch coupled to the reference timer for storing contents of the reference timer at the first predetermined time; and an offset latch coupled to the reference timer for storing contents of the reference timer at a second predetermined time, the offset latch storing a time from a last received system timing reference to the second predetermined time.

Claim 17

A code division multiple access (CDMA) radiotelephone operable in a CDMA radiotelephone system including a plurality of base stations, transmitting a short pseudorandom noise (PN) sequence including a system timing indicator comprising a PN roll boundary of the short PN sequence, the CDMA radiotelephone comprising: a sleep clock which produces a coarse resolution clock signal; a PN code generator providing a short PN sequence which is aligned with the system timing indicator; an oscillator which produces a fine resolution clock signal, the oscillator being synchronized to the system timing indicator using the short PN sequence from the PN code generator; a timing controller which places a portion of the CDMA radiotelephone including the oscillator in a low power sleep mode, the timing controller determining an offset between the fine resolution clock signal and the coarse resolution clock signal, the timing controller timing duration of the low power sleep mode in response to the coarse resolution clock signal adjusted by combining the coarse resolution clock signal and the offset; and a clock edge synchronizer which synchronizes timing of the CDMA radiotelephone to the system timing indicator of the CDMA radiotelephone system using the fine resolution clock signal, the clock edge synchronizer removing the portion of the CDMA radiotelephone from the low power sleep mode synchronized with the system timing indicator.

Claim 18

A code division multiple access (CDMA) radiotelephone operable in a CDMA radiotelephone system including a plurality of base stations, transmitting a short pseudorandom noise (PN) sequence including a system timing indicator comprising a PN roll boundary of the short PN sequence, the CDMA radiotelephone comprising: a sleep clock which produces a coarse resolution clock signal; a PN code generator providing a short PN sequence which is aligned with the system timing indicator; an oscillator which produces a fine resolution clock signal, the oscillator being synchronized to the system timing indicator using the short PN sequence from the PN code generator; a timing controller which places a portion of the CDMA radiotelephone including the oscillator in a low power sleep mode, the timing controller determining an offset between the fine resolution clock signal and the coarse resolution clock signal, the timing controller timing duration of the low power sleep mode in response to the coarse resolution clock signal adjusted by combining the coarse resolution clock signal and the offset; and a clock edge synchronizer which synchronizes timing of the CDMA radiotelephone to the system timing indicator of the CDMA radiotelephone system using the fine resolution clock signal, the clock edge synchronizer removing the portion of the CDMA radiotelephone from the low power sleep mode synchronized with the system timing indicator.

Claim 19

A CDMA radiotelephone as recited in claim 14 wherein the clock edge synchronizer comprises: an offset register for storing an offset time corresponding to a difference between timing of a received system timing indicator and timing of the coarse resolution clock signal; a sleep timer for timing duration of the low power sleep mode and producing a match signal at a prewake time; and a reference timer which times the offset time after the sleep timer produces the match signal, the clock edge synchronizer removing the portion of the CDMA radiotelephone from the low power sleep mode upon expiration of the reference timer.

Claim 20

A CDMA radiotelephone as recited in claim 15 further comprising: a modem for detecting system timing indicators transmitted by the CDMA radiotelephone system, the offset time corresponding to a difference between timing of a last received system timing indicator and a last edge of the coarse resolution clock signal.

Claim 21

A CDMA radiotelephone as recited in claim 16 wherein the reference timer expires substantially synchronously with a next received system timing indicator.