TRANSMISSION CONTROL FOR A SPECIFIC ABSORPTION RATE COMPLIANT COMMUNICATION DEVICE

• US 20110034135A1
• Filed: 08/05/2009
• Published: 02/10/2011
• Est. Priority Date: 08/05/2009
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Mobasher, Amin, Womack, James, Ali, Shirook, Kanj, Houssam
• Granted Patent: US 8,798,662 B2
• Time in Patent Office: Days
• US Class Current: 455/103
• 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

Abstract

Transmission of data from a portable communication device to a station via a radio frequency signal uses a protocol that has recurring frames, each having a plurality of transmission slots, different numbers of which can be used to transmit the data. When the portable communication device desires to send a data transmission, a first value is selected for either a power level for the radio frequency signal or the number of transmission slots to use. Then the first value is used to select a second value for the other one of the power level and the number of transmission slots. The first and second values are selected so that the data transmission at the selected power level using the selected number of transmission slots does not result in a specific absorption rate that is greater than a specific absorption rate limit.

Claims

1. A method for transmitting data from a portable communication device to a station via a radio frequency signal, wherein data is transmitted using a protocol that has recurring frames, each having a plurality of transmission slots different numbers of which can be used to transmit the data, the method comprising:

defining a relationship between variation of a power level for the radio frequency signal and the number of the transmission slots in a frame that may used by the portable communication device to transmit the data without the radio frequency signal resulting in a specific absorption rate limit being exceeded;

when desiring to transmit data, the portable communication device selecting a given power level for the radio frequency signal; and

the portable communication device using the given power level and the relationship to select a given number of transmission slots so that the data transmission does not result in a specific absorption rate that is greater than the specific absorption rate limit.

2. The method as recited in claim 1 further comprising the portable communication device requesting permission from the station to transmit the data using the given number of transmission slots.

3. The method as recited in claim 2 further comprising the station determining whether the given number of transmission slots is available for use by the portable communication device, and if not, the station changes the number of transmission slots that the portable communication device may use to transmit the data.

4. The method as recited in claim 3 further comprising the station sending a grant of permission to the portable communication device, wherein the grant designates a changed number of transmission slots.

5. The method as recited in claim 1 wherein the power level and the given number of transmission slots are selected so as to maximize the given number of transmission slots without the data transmission resulting in the specific absorption rate limit being exceeded.

6. The method as recited in claim 1 further comprising the portable communication device, responding to the given power level and the given number of transmission slots, by selecting one of a plurality of antennas from which to transmit data.

7. A method for transmitting data from a portable communication device to a station via a radio frequency signal, wherein the portable communication device has a first antenna and a second antenna, and wherein data is transmitted using a protocol that has recurring frames, each having a plurality of transmission slots, different numbers of which can be used to transmit the data, the method comprising steps of

(a) for each antenna defining a relationship between variation of a power level for the radio frequency signal and the number of the transmission slots in a frame that may used by the portable communication device to transmit the data without the radio frequency signal resulting in a specific absorption rate limit being exceeded;

(b) individually for each antenna selecting a given power level for the radio frequency signal and a given number of transmission slots based on an amount of data to be transmitted, thereby defining an preliminary transmission configuration for each antenna;

(c) deciding whether using the preliminary transmission configuration for the first antenna to transmit the data results in a specific absorption rate that is greater than the specific absorption rate limit for the first antenna, and if not, transmitting the data via the first antenna;

(d) if step (c) determines that use of the preliminary transmission configuration for the first antenna results in exceeding the respective specific absorption rate limit, then deciding whether using the preliminary transmission configuration for the second antenna to transmit the data results in a specific absorption rate that is greater than the specific absorption rate limit for the second antenna, and if not, transmitting the data via the second antenna;

(e) if step (d) determines that use of the preliminary transmission configuration for the second antenna results in exceeding the respective specific absorption rate limit, then selecting the one of the first and second antenna that has a preliminary transmission configuration that exceeds the respective specific absorption rate limit by a lesser amount;

(f) employing the relationship to select a final power level and a final number of the transmission slots for transmitting the data via the first or second antenna selected at step (e) without exceeding the respective specific absorption rate limit; and

(g) transmitting the data via the antenna selected at step (e).

8. The method as recited in claim 7 wherein defining an preliminary transmission configuration for each antenna comprises determining from the station whether the given number of transmission slots is available for use.

9. A method for transmitting data from a portable communication device to a station via a radio frequency signal, wherein data is transmitted using a protocol that has recurring frames, each having a plurality of transmission slots different numbers of which can be used to transmit the data, the method comprising:

defining a relationship between variation of a power level for the radio frequency signal and the number of the transmission slots in a frame that may used by the portable communication device to transmit the data without the radio frequency signal resulting in a specific absorption rate limit being exceeded;

the station performing steps of;

(a) selecting one of a plurality of power levels available to use for the radio frequency signal, thereby designating a given power level; and

(b) in response to the given power level and the relationship, selecting a given number of transmission slots in a frame, wherein transmission of the data by the portable communication device at the given power level and in the given number of transmission slots does not result in a specific absorption rate limit being exceeded.

10. The method as recited in claim 9 wherein selecting one of a plurality of power levels selects a power level that produces a radio frequency signal that has a predefined signal strength at the station.

11. The method as recited in claim 9 wherein defining a relationship for each of the plurality of power levels comprises designating a predefined number of transmission slots in a frame that can be used to transmit the data without exceeding the specific absorption rate limit.

12. The method as recited in claim 11 wherein selecting a given number of transmission slots, selects the predefined number of transmission slots in a frame designated for the given power level.

13. The method as recited in claim 11 wherein selecting a given number of transmission slots, selects a lesser one of the maximum number of transmission slots that actually are available to use in a transmission frame and the predefined number of transmission slots in a frame designated for the given power level.

14. The method as recited in claim 9 further comprising the station sending to the portable communication device a designation of the given power level and the given number of transmission slots that was selected.

15. The method as recited in claim 9 wherein the given power level and the given number of transmission slots are selected to maximize the given number of transmission slots without the data transmission exceeding the specific absorption rate limit.

16. The method as recited in claim 9 further comprising sending information related to the specific absorption rate limit from the portable communication device to the station.

17. A portable communication device that transmits data to a station via a radio frequency signal, wherein data is transmitted using a protocol that has recurring frames, each having a plurality of transmission slots different numbers of which can be used to transmit the data, the portable communication device comprising:

a control system having logic for;

storing a relationship between variation of a power level for the radio frequency signal and the number of the transmission slots in a frame that may used by the portable communication device to transmit the data without the radio frequency signal resulting in a specific absorption rate limit being exceeded;

selecting a given power level for the radio frequency signal; and

using the given power level and the relationship to select a given number of transmission slots so that the data transmission does not result in a specific absorption rate that is greater than the specific absorption rate limit.

18. The portable communication device as recited in claim 17 further comprising the control system requesting permission from the station to transmit the data using the given number of transmission slots.

19. The portable communication device as recited in claim 18 further comprising the logic responding to receipt of a response to requesting permission which response contains a revised the number of transmission slots that the portable communication device may use to transmit the data.

20. The portable communication device as recited in claim 17 wherein the power level and the given number of transmission slots are selected so as to maximize the given number of transmission slots without the data transmission resulting in the specific absorption rate limit being exceeded.

21. The portable communication device as recited in claim 17 further comprising the portable communication device, responding to the given power level and the given number of transmission slots, by selecting one of a plurality of antennas from which to transmit data.