Power management for wireless transmissions

• US 8,792,930 B1
• Filed: 03/29/2010
• Issued: 07/29/2014
• Est. Priority Date: 01/22/2010
• Status: Expired due to Fees

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Gopalakrishnan, Varadarajan, Bowen, James Samuel, Hyun, In Chul, Woo, David
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US12/748,641
• Time in Patent Office: 1,583 Days
• Field of Search: 455/522, 455/550.1, 455/553.1, 455/556.1, 455/575.6, 455/117, 455/127.2
• US Class Current: 455/522
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use
• CPC Class Codes: H04W 52/18 TPC being performed according to specific parameters
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range

Abstract

A user device receives a command to transmit information at a transmit power level specified by a wireless carrier. The user device makes a determination as to whether transmitting the information at the specified transmit power level will cause the user device to violate a condition. When it is determined that transmitting the information at the specified transmit power level will cause the user device to violate the condition, the user device dynamically computes a new transmit power level that is lower than the specified transmit power level. The user device then transmits the information at the new transmit power level.

Claims

1. A method, implemented by a user device programmed to perform the following, comprising:

receiving, by the user device, a command to transmit information at a specified transmit power level;

computing, by the user device, a moving sum of transmit power levels used to transmit information within a moving window, wherein the moving sum of the transmit power levels is a summed total of the transmit power levels used within the moving window, and wherein the moving window spans a time period extending backward in time from a current time at which the moving sum is computed to a previous time that is a specified temporal distance from the current time;

determining, by the user device, whether transmitting the information at the specified transmit power level will cause the moving sum to exceed a particular percentage of a maximum accumulated power level; and

responsive to determining that transmitting the information at the specified transmit power level will cause the moving sum to exceed the particular percentage of the maximum accumulated power level, computing a new transmit power level that is lower than the specified transmit power level, and transmitting the information at the new transmit power level, wherein a difference between the new transmit power level and the specified transmit power level is based at least in part on the particular percentage of the maximum accumulated power level.

2. The method of claim 1, wherein the specified transmit power level is specified by a wireless carrier.

3. The method of claim 1, further comprising:

identifying the particular percentage based on an active application.

4. The method of claim 1, further comprising:

determining whether transmitting the information at the specified transmit power level will cause interference with a wireless connection.

5. The method of claim 1, further comprising:

estimating one or more future transmit power levels that the wireless communication system will specify for information to be transmitted in the future; and

computing the new transmit power level based on the moving sum and on the estimated one or more future transmit power levels.

6. The method of claim 5, wherein estimating the one or more future transmit power levels comprises:

determining a signal to noise ratio for transmissions;

computing a moving average of the transmit power levels used to transmit the information within the moving window;

extrapolating the moving average into the future; and

applying the determined signal to noise ratio and the extrapolated moving average to a future transmit power level estimation algorithm.

7. The method of claim 1, wherein the moving sum of transmit power levels comprises transmit power levels of a plurality of radios of the user device over the moving window, wherein each of the plurality of radios is associated with a different wireless communication protocol.

8. The method of claim 1, wherein the maximum accumulated power level based on an amount of radiation permitted to be absorbed by a user.

9. The method of claim 8, further comprising:

detecting whether a portion of the user'"'"'s body is within a predetermined distance from an antenna of the user device; and

determining whether transmitting the information at the specified transmit power level will cause the moving sum to exceed the particular percentage of the maximum accumulated power level when the portion of the user'"'"'s body is detected.

10. The method of claim 1, further comprising:

identifying a minimum transmit power level below which the information will not be successfully transmitted to a wireless communication system; and

ensuring that the new transmit power level is at least the minimum transmit power level.

11. The method of claim 1, wherein computing the new transmit power level comprises:

incrementally reducing the new transmit power level from the specified transmit power level until the new transmit power level will not cause the moving sum to exceed the particular percentage of the maximum accumulated power level.

12. The method of claim 1, where the user device is an electronic book reader and wherein the method further comprises transmitting additional information at the transmit power level specified by the wireless communication system, even when it is determined that transmitting the additional information at the specified transmit power level will cause the user device to exceed the particular percentage of the maximum accumulated power level, if the additional information is associated with an electronic book.

13. The method of claim 1, further comprising:

modifying a duty cycle for transmissions.

14. The method of claim 1, wherein the particular percentage is less than 100% of the maximum accumulated power level.

15. The method of claim 1, wherein a higher particular percentage of the maximum accumulated power level results in a larger difference between the new transmit power level and the specified transmit power level.

16. A user device comprising:

a memory;

a processor, coupled to the memory;

a transmit power manager, executed from the memory by the processor, to;

receive a message to transmit information at a specified transmit power level;

compute a moving sum of transmit power levels used to transmit information within a moving window, wherein the moving sum of the transmit power levels is a summed total of the transmit power levels used within the moving window, and wherein the moving window spans a time period extending backward in time from a first time at which the moving sum is computed to a previous second time that is a specified temporal distance from the first time;

determine whether transmitting the information at the specified transmit power level will cause the moving sum to exceed a particular percentage of a maximum accumulated power level; and

compute a new transmit power level that is lower than the specified transmit power level responsive to a determination that transmitting the information at the specified transmit power level will cause the moving sum to exceed the particular percentage of the maximum accumulated power level, wherein a difference between the new transmit power level and the specified transmit power level is based at least in part on the particular percentage of the maximum accumulated power level; and

an antenna, coupled to the processor, to transmit the information at the new transmit power level.

17. The user device of claim 16, further comprising:

the transmit power manager to estimate one or more future transmit power levels that the wireless communication system will specify for information to be transmitted in the future, and to compute the new transmit power level based on the moving sum and on the estimated one or more future transmit power levels.

18. The user device of claim 16, wherein the maximum accumulated power level is based on an amount of radiation permitted to be absorbed by a user.

19. The user device of claim 16, further comprising:

a sensor to detect a presence of a human body part;

wherein the transmit power manager is configured to compute the new transmit power level when the presence of the human body part is detected.

20. The user device of claim 16, further comprising:

the transmit power manager to identify a minimum transmit power level below which the information will not be successfully transmitted to a wireless communication system, and to ensure that the new transmit power level is at least the minimum transmit power level.

21. The user device of claim 16, wherein the transmit power manager to compute the new transmit power level by incrementally reducing the new transmit power level from the specified transmit power level until the new transmit power level will not cause the moving sum to exceed the particular percentage of the maximum accumulated power level.

22. A method, implemented by a user device programmed to perform the following, comprising:

receiving a command to wirelessly transmit information to a recipient by an application executing on the user device;

determining, by the user device, whether there are any power management conditions associated with the application; and

when the application is associated with a power management condition, and that power management condition is violated, initiating power throttling for wireless transmissions to the recipient, wherein at least one power management condition comprises a maximum accumulated power level, wherein;

determining whether the maximum accumulated power level is violated comprises computing a moving sum of transmit power levels used to transmit information within a moving window, wherein the moving window spans a time period extending backward in time from a first time at which the moving sum is computed to a previous second time that is a specified temporal distance from the first time, and wherein the moving sum of the transmit power levels is a summed total of the transmit power levels used within the moving window, and determining whether transmitting information at a specified transmit power level will cause the moving sum to exceed a particular percentage of the maximum accumulated power level, and

initiating the power throttling comprises, responsive to determining that transmitting the information at the specified transmit power level will cause the moving sum to exceed the particular percentage of the maximum accumulated power level, computing a new transmit power level that is lower than the specified transmit power level, and transmitting the information at the new transmit power level, wherein a difference between the new transmit power level and the specified transmit power level is based at least in part on the particular percentage of the maximum accumulated power level.