Dynamic thermal control for wireless transceivers

• US 20100091747A1
• Filed: 10/15/2008
• Published: 04/15/2010
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Athas, William C., Dorsey, John G.
• Granted Patent: US 8,170,606 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04B 1/036 Cooling arrangements
• CPC Class Codes: H04W 52/0251 using monitoring of local events, e.g. events related to user activity
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and apparatus for dynamic thermal management and control within, e.g., small form-factor wireless devices such as laptop computers or cellular “smartphones”. In one embodiment, a thermal management system monitors the temperature (or other relevant criteria) for one or more components, and implements different operating states within the wireless transceiver (e.g., Wi-Fi™ or WiMAX transceiver) so as to both reduce thermal output and minimize disruption to the wireless link and/or user experience. In another embodiment, a wireless client may communicate with other clients, and/or access points, so as to cooperatively provide more options for thermal management. In addition, methods and apparatus employing “high performance” (e.g., high power output or high data rate) radios within aggressively small industrial designs are also disclosed.

Claims

1. A method for providing dynamic thermal control for a wireless transceiver in a portable wireless device, the method comprising:

determining that the value of a first parameter associated with said portable wireless device in a first operating state exceeds a threshold value; and

switching said portable wireless transceiver from said first operating state to a second operating state based at least in part on said determining, said second operating state comprising one of a plurality of other operating states that generate less heat within at least a portion of said device than said first operating state.

2. The method of claim 1, wherein said first parameter comprises a temperature associated with at least one component of said device, or a voltage generated by a thermocouple associated with said at least one device, and said plurality of other operating states comprises a spatial multiplexing power save (SM PS) mode state, a reduced channel bandwidth mode state, and an alternate modulation and coding scheme (MCS) mode state.

3. The method of claim 1, wherein said value of said first parameter comprises a value measured from at least one thermocouple within said device.

4. The method of claim 1, wherein said threshold value comprises a value determined based on a plurality of different operating conditions for said portable wireless device.

5. The method of claim 1, wherein said steps of determining and switching are continued at least until said value no longer exceeds said threshold value.

6. The method of claim 5, wherein said continued determining and switching comprises utilizing operating states which have progressively lower heat generation rates.

7. The method of claim 5, wherein said switching comprises:

first reducing at least one of a modulation and coding scheme complexity;

next reducing the number of spatial streams used for communication; and

then reducing at least one channel bandwidth.

8. The method of claim 1, wherein said switching comprises forcing the transceiver to enter an idle state via at least traffic shaping.

9. The method of claim 1, wherein said switching comprises a sequence of successive steps, said sequence substantially mitigating step-changes in the performance of said wireless transceiver that would otherwise occur if said sequence were not followed.

10. A method for providing thermal management in a wireless device, the method comprising:

characterizing a plurality of adjustable operating parameters in terms of their disruption to a communications link when adjusted, said act of characterizing producing a listing ordered from least disruptive to most disruptive for said plurality of adjustable operating parameters;

evaluating a thermally-related parameter of the wireless device; and

when said thermally-related parameter exceeds a threshold, adjusting individual ones of said plurality of said operating parameters in said listing order so as to reduce said thermally-related parameter below said threshold.

11. The method of claim 10, wherein said thermally-related parameter comprises temperature, and said adjustable operating parameters relate to the operation of a wireless transceiver of said device.

12. The method of claim 11, wherein said adjustable operating parameters are selected from the group consisting of:

(i) at least one of modulation and coding scheme; and

(ii) spatial multiplexing.

13. The method of claim 11, wherein said temperature comprises the temperature within at least one portion of said wireless transceiver.

14. The method of claim 11, wherein said characterizing a plurality of adjustable operating parameters in terms of their disruption to a communications link when adjusted comprises evaluating a plurality of state changes for said wireless transceiver, said state changes comprising:

a state change from a multi-stream modulation to a single stream modulation;

a state change from one combination of modulation type and code rate to another combination of modulation type and code rate; and

a state change from a first channel bandwidth to a second channel bandwidth of lesser value.

15. A method of thermal management in a wireless device having a wireless transceiver, the method comprising:

determining whether a thermal value of said wireless device, when operating in conjunction with said wireless transceiver, exceeds a threshold value; and

adjusting one or more operating modes for said wireless transceiver by considering at least said determined thermal value and a current operating mode for said wireless transceiver.

16. The method of claim 15, wherein said wireless transceiver comprises an OFDM-based modulation scheme and multiple input, multiple output (MIMO) antenna functionality.

17. The method of claim 16, wherein said wireless transceiver comprises a transceiver compliant with IEEE Std. 802.11n, and said current operating mode comprises a modulation and coding scheme (MCS) index value which exceeds a predetermined index threshold value.

18. The method of claim 16, wherein said one or more of respective operating modes to be adjusted comprises the MCS index value, and said act of adjusting comprises repeating said acts of determining and adjusting until either said thermal threshold value is no longer exceeded, or said current MCS index no longer exceeds said index threshold value.

19. The method of claim 15, wherein said adjusting one or more operating modes for said wireless transceiver by considering at least said determined thermal value and a current operating mode for said wireless transceiver comprises evaluating the proximity of said determined thermal value to said threshold value.

20. The method of claim 15, wherein said thermal value comprises the time-rate-of-change of temperature (dT/dt) of at least one component of said device.

21. The method of claim 15, wherein said thermal value comprises a model obtained from a model or estimation of the temperature of one or more components of said device based at least in part on data obtained from a plurality of locations within said device, said plurality of locations not comprising said one or more components.

22. A thermal management system for use in a portable device having at least one wireless transceiver, the system comprising:

a controller;

a plurality of environmental sensors in operative communication with said controller; and

a storage device operatively coupled to said controller, said storage device comprising a computer program which, when executed by said controller, performs thermal management according to the method comprising;

evaluating signals from one or more of said sensors in relation to one or more first criteria; and

if said evaluating indicates that thermal management is required, causing said wireless transceiver to change states according to at least a first prescribed order until said thermal management is no longer required.

23. The system of claim 22, wherein said method further comprises selectively causing said wireless transceiver to change states according to at least a second prescribed order instead of said first prescribed order until said thermal management is no longer required.

24. The system of claim 23, wherein said second prescribed order comprises a more aggressive thermal reduction sequence than that of said first prescribed order, and said evaluating comprises determining that said more aggressive sequence is required.

25. The system of claim 24, wherein said first prescribed order is less disruptive to data communication over at least one channel of said wireless transceiver than said second prescribed order.

26. The system of claim 22, wherein:

said controller comprises a digital microcontroller;

said storage device comprises a RAM, ROM or FLASH memory;

said plurality of sensors comprises a plurality of thermocouples; and

said wireless transceiver comprises an OFDM modulation scheme and a spatially diverse antenna system.