Duty cycling to reduce average transmit power

• US 9,295,004 B2
• Filed: 07/15/2014
• Issued: 03/22/2016
• Est. Priority Date: 01/22/2010
• Status: Active Grant

• 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:
  US14/331,985
• Publication Number:
  US 20140329552A1
• Time in Patent Office: 616 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: 1/1
• 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 determines whether transmitting the information at the specified transmit power level using a first duty cycle will cause the user device to violate a condition. Responsive to determining that transmitting the information at the specified transmit power level using the first duty cycle will cause the user device to violate the condition, the user device determines a new duty cycle that is lower than the first duty cycle, and transmits the information using the new duty cycle.

Claims

1. A method comprising:

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

computing, by the user device, a moving sum of transmit power levels used to transmit previous 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 using a first duty cycle will cause the moving sum to exceed a predetermined percentage of a maximum accumulated power level, wherein the predetermined percentage is less than 100% of the maximum accumulated power level, the maximum accumulated power level representing a maximum amount of radiation that the user device will expose a user to in a specified time period, wherein the first duty cycle comprises a first ratio of active periods during which the user device is to transmit data to inactive periods during which the user device is not to transmit data;

responsive to determining that transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level, performing the following comprising;

determining a new duty cycle that is lower than the first duty cycle, wherein the new duty cycle comprises a second ratio of the active periods during which the user device is to transmit data to the inactive periods during which the user device is not to transmit data, and wherein the second ratio is lower than the first ratio; and

transmitting the information using the new duty cycle

detecting whether a portion of a 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 using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level when the portion of the user'"'"'s body is detected.

2. The method of claim 1, further comprising

responsive to determining that transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level, computing a new transmit power level that is lower than the specified transmit power level, wherein the information is transmitted at the new transmit power level using the new duty cycle.

3. A user device comprising:

a memory;

a processor, coupled to the memory, to;

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

compute a moving sum of transmit power levels used to transmit previous 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;

determine whether transmitting the information at the specified transmit power level using a first duty cycle will cause the moving sum to exceed a predetermined percentage of a maximum accumulated power level, wherein the predetermined percentage is less than 100% of the maximum accumulated power level; and

determine a new duty cycle that is lower than the first duty cycle responsive to a determination that transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level;

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

determine whether transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level within a specified time period when the portion of the user'"'"'s body is detected; and

an antenna, coupled to the processor, to transmit the information using the new duty cycle.

4. The user device of claim 3, wherein the first duty cycle comprises a first ratio of active periods during which the user device is to transmit data to inactive periods during which the user device is not to transmit data, and wherein the new duty cycle comprises a second ratio of the active periods during which the user device is to transmit data to the inactive periods during which the user device is not to transmit data, the second ratio being lower than the first ratio.

5. The user device of claim 3, wherein the specified transmit power level is specified by a wireless carrier.

6. The user device of claim 3, wherein the processor is further to:

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

determine the new duty cycle based at least in part on the moving sum and on the estimated one or more future transmit power levels.

7. The user device of claim 3, wherein the maximum accumulated power level is based on an amount of radiation absorbed by a user.

8. The user device of claim 3, wherein the processor is further to

responsive to determining that transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level, compute a new transmit power level that is lower than the specified transmit power level, wherein the information is transmitted at the new transmit power level using the new duty cycle.

9. The user device of claim 8, wherein the processor is further to

incrementally reduce 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 predetermined percentage of the maximum accumulated power level.

10. A non-transitory computer readable medium including instructions that, when executed by a processor of a user device, cause the processor to perform operations comprising:

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

computing, by the processor, a moving sum of transmit power levels used to transmit previous 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 processor, whether transmitting the information at the specified transmit power level using a first duty cycle will cause the moving sum to exceed a predetermined percentage of a maximum accumulated power level, wherein the predetermined percentage is less than 100% of the maximum accumulated power level;

responsive to determining that transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level, determining a new duty cycle that is lower than the first duty cycle, and transmitting the information using the new duty cycle;

detecting whether a portion of a 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 using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level when the portion of the user'"'"'s body is detected.

11. The computer readable medium of claim 10, the operations further comprising:

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

determining the new duty cycle based at least in part on the moving sum and on the estimated one or more future transmit power levels.

12. The computer readable medium of claim 10, wherein the maximum accumulated power level is based on an amount of radiation absorbed by a user.

13. The computer readable medium of claim 10, the operations further comprising

responsive to determining that transmitting the information at the specified transmit power level using the first duty cycle will cause the moving sum to exceed the predetermined percentage of the maximum accumulated power level, computing a new transmit power level that is lower than the specified transmit power level, wherein the information is transmitted at the new transmit power level using the new duty cycle.

14. The computer readable medium of claim 10, wherein the first duty cycle comprises a first ratio of active periods during which the user device is to transmit data to inactive periods during which the user device is not to transmit data, and wherein the new duty cycle comprises a second ratio of the active periods during which the user device is to transmit data to the inactive periods during which the user device is not to transmit data, the second ratio being lower than the first ratio.