Method and apparatus for reducing current consumption

• US 6,330,234 B1
• Filed: 04/27/2000
• Issued: 12/11/2001
• Est. Priority Date: 04/27/2000
• Status: Expired due to Term

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Prairiecomm Inc. (NXP Semiconductors NV)
• Inventors: Bradley, Wayne H., Tomasi, Peter A., Zhao, Tong, St. Angel, Lindo, Schellinger, Michael J., Nguyen, Dien N.
• Primary Examiner(s): Patel, Ajit
• Assistant Examiner(s): NGUYEN, HANH N
• Application Number:
  US09/559,675
• Time in Patent Office: 593 Days
• Field of Search: 370/311, 370/324, 370/350, 370/335, 370/342, 370/503, 370/510, 370/320, 370/336, 370/333, 370/329, 370/328, 370/515, 370/441, 455/574
• US Class Current: 370/342
• CPC Class Codes: H04B 1/1615 Switching on; Switching off, e.g. remotely battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/10 Code generation
• CPC Class Codes: H04W 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus reduces current consumption of a mobile communication unit, such as a cellular or mobile telephone that communicates with a base station by disabling a temperature controlled crystal oscillator and a code generator while the mobile communication unit is in a sleep mode of operation, thereby reducing the sleep mode current consumed by the mobile communication unit. Prior to entering sleep mode, the mobile communications unit stores the state of the code generator and disables the temperature controlled crystal oscillator. Upon waking from sleep mode, the mobile communication unit calculates what the state of its code generator would have been if its temperature controlled crystal oscillator had not been disabled, and uses this calculated state to achieve synchronization with a code generator in the base station.

Claims

1. A method of reducing current consumption in a mobile communication unit having an oscillator driving a first pseudorandom code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second pseudorandom code generator, the method comprising the steps of:

storing a first state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first pseudorandom code generator are stopped;

entering an awake mode wherein the oscillator and the first pseudorandom code generator are started;

calculating a second state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a second time, wherein the second state of the first pseudorandom code generator is calculated based on the first state of the first pseudorandom code generator;

determining an estimated error between the second state of the first pseudorandom code generator and a state of the second pseudorandom code generator at the second time; and

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first pseudorandom code generator and the state of the second pseudorandom code generator at the second time to synchronize the first pseudorandom code generator to the second pseudorandom code generator.

2. The method of claim 1, further comprising the step of updating the first pseudorandom code generator to the second state, thereby substantially synchronizing the first pseudorandom code generator with the second pseudorandom code generator at the second time.

3. The method of claim 1, wherein the step of calculating the second state of the first pseudorandom code generator comprises multiplying the first state by a transformation matrix.

4. The method of claim 1, wherein the step of entering the sleep mode for the predetermined period of time comprises entering the sleep mode for approximately 1.28 seconds.

5. The method of claim 1, wherein the step of entering the sleep mode for the predetermined period of time comprises entering the sleep mode for approximately 2.56 seconds.

6. The method of claim 1, wherein the step of entering the awake mode comprises entering the awake mode for approximately 20 milliseconds to determine if a page is received from the base station.

7. The method of claim 6, further comprising the step of returning to the sleep mode if no page is received from the base station at the mobile unit.

8. The method of claim 1, wherein the step of determining an estimated error comprises determining an estimated error based on a slot cycle index.

9. The method of claim 1, wherein the step of determining an estimated error comprises determining an estimated error based on jitter of a sleep reference clock.

10. The method of claim 1, wherein the step of determining an estimated error comprises determining an estimated error based on propagation delay and multipath fading.

11. A method of reducing current consumption in a mobile communication unit having an oscillator driving a first code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second code generator, the method comprising the steps of:

storing a first state of the first code generator that is substantially synchronized to the second code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first code generator are stopped;

entering an awake mode wherein the oscillator and the first code generator are started;

calculating a second state of the first code generator that is substantially synchronized to the second code generator at a second time by multiplying the first state by a transformation matrix wherein the second state of the first code generator is calculated based on the first state of the first code generator;

determining an estimated error between the second state of the first code generator and a state of the second code generator at the second time; and

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first code generator and the state of the second code generator at the second time to synchronize the first code generator to the second code generator by searching a range two times the estimated error.

12. A current consumption reduction system for use in a mobile communication unit having a processor and an oscillator driving a first pseudorandom code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second pseudorandom code generator, the current consumption reduction system comprising:

a memory;

instructions stored by the memory and adapted for execution by the processor, wherein the execution of the instructions causes the processor to perform the steps of;

storing a first state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first pseudorandom code generator are stopped;

entering an awake mode wherein the oscillator and the first pseudorandom code generator are started;

calculating a second state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a second time, wherein the second state of the first pseudorandom code generator is calculated based on the first state of the first pseudorandom code generator;

determining an estimated error between the second state of the first code pseudorandom generator and a state of the second pseudorandom code generator at the second time; and

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first pseudorandom code generator and the state of the second pseudorandom code generator at the second time to synchronize the first pseudorandom code generator to the second pseudorandom code generator.

13. The system of claim 12, wherein the processor is further programmed to perform the step of updating the first pseudorandom code generator to the second state, thereby substantially synchronizing the first pseudorandom code generator with the second pseudorandom code generator.

14. The system of claim 12, wherein when the processor performs the step of calculating the second state of the first pseudorandom code generator, the processor multiplies the first state by a transformation matrix.

15. The system of claim 12, wherein the step of entering the sleep mode for the predetermined period of time comprises entering the sleep mode for approximately 1.28 seconds.

16. The system of claim 12, wherein the step of entering the sleep mode for the predetermined period of time comprises entering the sleep mode for approximately 2.56 seconds.

17. The system of claim 12, wherein the step of entering the awake mode comprises entering the awake mode for approximately 20 milliseconds to determine if a page is received from the base station.

18. The system of claim 17, wherein the processor is further programmed to return to sleep mode if no page is received.

19. The system of claim 12, wherein the step of determining an estimated error comprises determining an estimated error based on a slot cycle index.

20. The system of claim 12, wherein the step of determining an estimated error comprises determining an estimated error based on jitter of a sleep reference clock.

21. The system of claim 12, wherein the step of determining an estimated error comprises determining an estimated error based on propagation delay and multipath fading.

22. A current consumption reduction system for use in a mobile communication unit having a processor and an oscillator driving a first code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second code generator, the current consumption reduction system comprising:

a memory;

instructions stored by the memory and adapted for execution by the processor, wherein the execution of the instructions causes the processor to perform the steps of;

storing a first state of the first code generator that is substantially synchronized to the second code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first code generator are stopped;

entering an awake mode wherein the oscillator and the first code generator are started;

calculating a second state of the first code generator that is substantially synchronized to the second code generator at a second time, wherein the second state of the first code generator is calculated based on the first state of the first code generator by multiplying the first state by a transformation matrix;

determining an estimated error between the second state of the first code generator and a state of the second code generator at the second time;

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first code generator and the state of the second code generator to synchronize the first code generator to the second code generator at the second time by searching a range two times the estimated error.

23. A current consumption reduction system for use in a communication unit having a processor and an oscillator driving a first pseudorandom code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second pseudorandom code generator, the current consumption reduction system comprising:

a memory;

a first software routine stored on the memory and adapted to be executed by the processor to store a first state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a first time;

a second software routine stored on the memory and adapted to be executed by the processor to enter a sleep mode for a predetermined period of time during which the oscillator and the first pseudorandom code generator are stopped;

a third software routine stored on the memory and adapted to be executed by the processor to enter an awake mode wherein the oscillator and the first pseudorandom code generator are started;

a fourth software routine stored on the memory and adapted to be executed by the processor to calculate a second state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a second time, wherein the second state is calculated based on the first state;

a fifth software routine stored on the memory and adapted to be executed on the processor to determine an estimated error between the second state of the first pseudorandom code generator and a state of the second pseudorandom code generator at the second time; and

a sixth software routine stored on the memory and adapted to be executed on the processor to search a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first pseudorandom code generator and the state of the second pseudorandom code generator at the second time to synchronize the first pseudorandom code generator to the second pseudorandom code generator.

24. The system of claim 23, further comprising a seventh software routine stored on the memory and adapted to be executed on the processor to update the first pseudorandom code generator to the second state, thereby substantially synchronizing the first pseudorandom code generator with the second pseudorandom code generator at the second time.

25. The system of claim 24, wherein the fourth software routine multiplies the first state by a transformation matrix.

26. The system of claim 23, wherein the fifth software routine is stored on the memory and adapted to be executed on the processor to determine an estimated error based on a slot cycle index.

27. The system of claim 23, wherein the fifth software routine is stored on the memory and adapted to be executed on the processor to determine an estimated error based on jitter of a sleep reference cycle.

28. The system of claim 23, wherein the fifth software routine is stored on the memory and adapted to be executed on the processor to determine an estimated error based on propagation delay and multipath fading.

29. A current consumption reduction system for use in a mobile communication unit having an oscillator driving a first pseudorandom code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second pseudorandom code generator, the current consumption reduction system comprising:

a logic device programmed to perform the steps of;

storing a first state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first pseudorandom code generator are stopped;

entering an awake mode wherein the oscillator and the first pseudorandom code generator are started;

calculating a second state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a second time, wherein the second state of the first pseudorandom code generator is calculated based on the first state of the first pseudorandom code generator;

determining an estimated error between the second state of the first code pseudorandom generator and a state of the second pseudorandom code generator at the second time; and

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first pseudorandom code generator and the state of the second pseudorandom code generator at the second time to synchronize the first pseudorandom code generator to the second pseudorandom code generator.

30. The system of claim 29, wherein the logic device is further programmed to perform the step of updating the first pseudorandom code generator to the second state, thereby substantially synchronizing the first code pseudorandom generator with the second pseudorandom code generator at the second time.

31. The system of claim 30, wherein when the logic device performs the step of calculating the second state of the first pseudorandom code generator, the logic device multiplies the first state by a transformation matrix.

32. A current consumption reduction system for use in a mobile communication unit having an oscillator driving a first code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second code generator, the current consumption reduction system comprising:

a logic device programmed to perform the steps of;

storing a first state of the first code generator that is substantially synchronized to the second code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first code generator are stopped;

entering an awake mode wherein the oscillator and the first code generator are started;

calculating a second state of the first code generator that is substantially synchronized to the second code generator at a second time, wherein the second state of the first code generator is calculated based on the first state of the first code generator by multiplying the first state by a transformation matrix;

updating the first code generator to the second state, thereby substantially synchronizing the first code generator with the second code generator at the second time;

determining an estimated error between the second state of the first code generator and a state of the second code generator at the second time;

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first code generator and the state of the second code generator at the second time to synchronize the second code generator by searching a range two times the estimated error.

33. A method of reducing current consumption in a mobile communication unit having an oscillator driving a first pseudorandom code generator, wherein the mobile communication unit is adapted to communicate with a base station having a second pseudorandom code generator, the method comprising the steps of:

storing a first state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a first time;

entering a sleep mode for a predetermined period of time during which the oscillator and the first pseudorandom code generator are stopped;

entering an awake mode wherein the oscillator and the first pseudorandom code generator are started;

recalling the first state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a first time; and

calculating a second state of the first pseudorandom code generator that is substantially synchronized to the second pseudorandom code generator at a second time, wherein the second state of the first pseudorandom code generator is calculated based on the first state of the first pseudorandom code generator by multiplying the first state by a transformation matrix;

determining an estimated error between the second state of tie first pseudorandom code generator and a state of the second pseudorandom code generator at the second time; and

searching a range of pseudorandom noise (PN) states dependent on the estimated error between the second state of the first pseudorandom code generator and the state of the second pseudorandom code generator at the second time to synchronize the first pseudorandom code generator to the second pseudorandom code generator.

34. The method of claim 33, further comprising the step of updating the first pseudorandom code generator to the second state, thereby substantially synchronizing the first pseudorandom code generator with the second pseudorandom code generator at the second time.