Reduction of power consumption with increased standby time in wireless communications device

• US 6,397,053 B1
• Filed: 12/30/1999
• Issued: 05/28/2002
• Est. Priority Date: 12/30/1999
• Status: Expired due to Term

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Ghiazza, Jean-Yves
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): Nguyen, Thuan T.
• Application Number:
  US09/475,889
• Time in Patent Office: 880 Days
• Field of Search: 455/343,572,573,574,334,522
• US Class Current: 455/343.1
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus for reducing power consumption of a receiver of a communications device that does not change the global hardware of the device and uses the current master clock to lower the clock frequency. In an example embodiment, a method directed to reducing power consumption of a receiver of a communications device during an idle state. The receiver has an internal power source and a corresponding base unit. The method includes generating a clock signal that has an output frequency that varies, the frequency being higher in an active state and lower in an inactive state, such that the receiver consumes more power during the active state then when in the inactive state. Power consumption by the receiver is reduced by dynamically and synchronously switching the clock frequency to a lower clock frequency. Receiver power consumption is a function of the power consumed during the active and inactive states and the duration of the idle state.

Claims

1. A method of reducing power consumption of a receiver of a communications device, the receiver having an internal power source and a corresponding base unit, the receiver adapted to receive a transmitted signal in the form of a data stream, the data stream defined by a plurality of frames, each of the frames including a synchronization sub-frame, the method comprising the steps of:

detecting the activity status of the receiver with respect to the transmitted signal, the receiver being in an idle state when not receiving a transmitted signal, the idle state defined by a predetermined number of frames that include a set of active state frames and inactive state frames that combine to define a duration of the idle state;

generating a clock signal that has an output frequency that varies as a function of the active and inactive frames, the clock frequency being higher in the active state and lower in the inactive state, such that the receiver consumes more power during the active state then when in the inactive state;

synchronizing the receiver with the sub-frame of the transmitted signal during the idle state; and

reducing power consumption of the receiver by reducing the clock frequency as the number of inactive frames within the idle state are increased, power consumption being a function of the power consumed during the active and inactive states and the duration of the idle state.

2. The method of claim 1, wherein the step of reducing power consumption includes decreasing the number of active frames.

3. The method of claim 1, wherein the idle period length remains unchanged irrespective of the clock frequency output.

4. The method of claim 1, wherein the frames of the idle state have a frame boundary with a programmable length.

5. The method of claim 4, wherein the active and inactive frames start and stop on the frame boundary.

6. The method of claim 1, wherein the clock frequency is decreased during the inactive state by a factor of N, where N is a number greater than 1.

7. The method of claim 1, further including the step of synchronizing a frame counter of the receiver with a frame counter of the base unit at the end of the inactive state.

8. The method of claim 7, further including the step of synchronizing a multiframe counter of the receiver with a multiframe counter of the base unit at the end of the inactive state.

14. The method of claim 7, wherein the clock frequency is decreased during the inactive state by a factor of N, where N is an integer greater than 1.

9. A method for reducing power consumption of a receiver of a communications device during an idle state, the receiver having an internal power source and a corresponding base unit, the receiver adapted to receive a transmitted signal in the form of a data stream defined by a plurality of frames, the idle state defined by a predetermined number of frames that include a set of active state frames and inactive state frames that combine to define a duration of the idle state, the method comprising the steps of:

generating a clock signal that has an output frequency that varies as a function of the active and inactive frames, the clock frequency being higher in the active state and lower in the inactive state, such that the receiver consumes more power during the active state then when in the inactive state;

synchronizing the receiver with the sub-frame of the transmitted signal during the idle state; and

reducing power consumption of the receiver by dynamically and synchronously switching to a low clock frequency corresponding to the inactive state as the number of inactive frames within the idle state are increased, power consumption being a function of the power consumed during the active and inactive states and the duration of the idle state.

10. The method of claim 9, wherein the step of reducing overall power consumption includes decreasing power consumption by decreasing the number of active frames.

11. The method of claim 9, wherein the idle state duration remains unchanged irrespective of the clock frequency output.

12. The method of claim 9, wherein the frames of the idle state have a frame boundary with a programmable length.

13. The method of claim 12, wherein the active and inactive frames start and stop on the frame boundary.

15. The method of claim 9, further including the step of synchronizing a frame counter of the receiver with a frame counter of the base unit at the end of the inactive state.

16. The method of claim 15, further including the step of synchronizing a multiframe counter of the receiver with a multiframe counter of the base unit at the end of the inactive state.

17. A system for reducing power consumption of a receiver of a communications device, the receiver having an internal power source and a corresponding base unit, the receiver adapted to receive a transmitted signal in the form of a data stream, the data stream defined by a plurality of frames, each of the frames including a synchronization sub-frame, the method comprising the steps of:

detector means for detecting the activity status of the receiver with respect to the transmitted signal, the receiver being in an idle state when not receiving a transmitted signal, the idle state defined by a predetermined number of frames that include a set of active state frames and inactive state frames that combine to define a duration of the idle state;

a clock signal generator for generating a clock signal with an output frequency that varies as a function of the active and inactive frames, the clock frequency being higher in the active state and lower in the inactive state, such that the receiver consumes more power during the active state then when in the inactive state;

synchronizing circuitry, coupled to the receiver and the clock signal generator, for synchronizing the receiver with the sub-frame of the transmitted signal during the idle state and for reducing overall power consumption of the receiver, reducing power consumption by reducing the clock frequency as the number of inactive frames within the idle state are increased, power consumption being a function of the power consumed during the active and inactive states and the duration of the idle state.

18. An apparatus for reducing power consumption of a receiver of a communications device during an idle state, the receiver having an internal power source and a corresponding base unit, the receiver adapted to receive a transmitted signal in the form of a data stream defined by a plurality of frames, the idle state defined by a predetermined number of frames that include a set of active state frames and inactive state frames that combined define a duration of the idle state, the method comprising the steps of:

clock means for generating a clock signal that has an output frequency that varies as a function of the active and inactive frames, the clock frequency being higher in the active state and lower in the inactive state, such that the receiver consumes more power during the active state then when in the inactive state;

means for synchronizing the receiver with the transmitted signal during the idle state, synchronizing means coupled to the receiver and the clock signal generator; and

means for reducing power consumption of the receiver by dynamically and synchronously switching to a lower clock frequency corresponding to the inactive state and increasing the number of inactive frames within the idle state, power consumption being a function of the power consumed during the active and inactive states and the duration of the idle state.

19. The apparatus of claim 18 wherein power consumption reduction means further including means for synchronizing a frame counter of the receiver with a frame counter of the base unit at the end of the inactive state.

20. The apparatus of claim 19 wherein power consumption reduction means further including means for synchronizing a multiframe counter of the receiver with a multiframe counter of the base unit at the end of the inactive state.