METHOD AND APPARATUS TO IMPROVE THE ROBUSTNESS OF A WIRELESS COMMUNICATION LINK

• US 20110143805A1
• Filed: 02/10/2010
• Published: 06/16/2011
• Est. Priority Date: 12/14/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Vasudevan, Srinivasan, Sebeni, Johnson O., Ramasamy, Venkatasubramanian, Narang, Mohit, Deivasigamani, Giri Prassad, Xing, Longda
• Granted Patent: US 8,554,259 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/22 taking into account previous information or commands
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/346 distributing total power among users or channels

Abstract

A method and apparatus to improve the robustness of a wireless communication link between a base station and a mobile communication device. The method increases power selectively on portions of an uplink communication signal transmitted from the mobile communication device to the base station. The method monitors a quality metric value at the mobile communication device and sets the transmit power level of the first portion of an uplink communication signal to the first power level, if the monitored quality metric value is in a first range of quality values, or sets the transmit power level of the first portion of the uplink communication signal to a second power level, if the monitored quality metric value is in a second range of quality values. The first portion of the uplink communication signal includes control signals used by a base station to maintain connection of the wireless communication link.

Claims

1. A method for improving robustness of a wireless communication link between a mobile communication device and a base station, the method comprising:

adapting transmit power levels of the mobile communication device in accordance with a quality metric value associated with the wireless communication link.

2. The method as recited in claim 1, further comprising:

monitoring the quality metric value at the mobile communication device; and

adaptively setting a transmit power level of a first portion of an uplink communication signal transmitted on the wireless communication link from the mobile communication device to the base station in accordance with the monitored quality metric value.

3. The method as recited in claim 2, wherein adaptively setting the transmit power level of the first portion of the uplink communication signal comprises

setting the transmit power level of the first portion of the uplink communication signal to a first transmit power level value if the monitored quality metric value is within a first range of quality metric values, and

setting the transmit power level of the first portion of the uplink communication signal to a second transmit power level value if the monitored quality metric value is within a second range of quality metric values,

wherein the second transmit power level value is greater than the first transmit power level value, thereby improving the robustness of the wireless communication link.

4. The method as recited in claim 3 further comprising

initializing the transmit power level of the first portion of the uplink communication signal to the first transmit power level value, and

repeatedly monitoring the quality metric value and adaptively setting the transmit power level of the first portion of the uplink communication signal in accordance with the monitored quality metric value while the wireless communication link is connected.

5. The method as recited in claim 3, wherein the first portion of the uplink communication signal includes control signals used by the base station to maintain connection of the wireless communication link between the base station and the mobile communication device.

6. The method as recited in claim 3 further comprising:

monitoring a power storage metric value of the mobile communication device; and

setting the second transmit power level value based on the monitored power storage metric value.

7. The method as recited in claim 3 wherein the quality metric value is a power control level value set by the base station.

8. The method as recited in claim 3 wherein the quality metric value is a timing advance value set by the base station.

9. The method as recited in claim 3 wherein the quality metric value is a received downlink transmission quality metric value measured by the mobile communication device.

10. The method as recited in claim 3 further comprising:

adaptively setting a transmit power level of a second portion of the uplink communication signal in accordance with the monitored quality metric value;

wherein the transmit power level of the second portion of the uplink communication signal is set to the first power level value if the monitored quality metric value is in the first range of quality values, and

the transmit power level of the second portion of the uplink communication signal is set to a third power level value if the monitored quality metric value is in the second range of quality values;

wherein the third power level value is less than the first power level value.

11. The method as recited in claim 10 further comprising

initializing the transmit power level of the second portion of the uplink communication signal to the first power level value;

and

repeatedly monitoring the quality metric value and adaptively setting the transmit power level of the second portion of the uplink communication signal in accordance with the monitored quality metric value.

12. The method as recited in claim 10 wherein the total average transmit power across the first and second portions of the uplink communication signal when the first portion is set to the second power level value and the second portion is set to the third power level value is no more than when the first and second portions are set to the first power level value.

13. A mobile communication device, comprising:

a processor, wherein when the mobile communication device is in wireless communication with a base station over a wireless link, the wireless link comprising an uplink communication signal transmitted from the mobile communication device to the base station, the processor adapts transmit power levels of the mobile communication device by

monitoring a quality metric value; and

adaptively setting a transmit power level of a first portion of the uplink communication signal in accordance with the monitored quality metric value.

14. The mobile communication device as recited in claim 13, wherein adaptively setting the transmit power level of the first portion of the uplink communication signal comprises:

setting the transmit power level of the first portion of the uplink communication signal to a first transmit power level value if the monitored quality metric value is within a first range of quality metric values, and

setting the transmit power level of the first portion of the uplink communication signal to a second transmit power level value if the monitored quality metric value is within a second range of quality metric values,

wherein the second transmit power level value is greater than the first transmit power level value.

15. The mobile communication device as recited in claim 14, wherein the processor further adapts transmit power levels of the mobile communication device by:

initializing the transmit power level of the first portion of the uplink communication signal to the first transmit power level value, and

repeatedly monitoring the quality metric value and adaptively setting the transmit power level of the first portion of the uplink communication signal in accordance with the monitored quality metric value while the wireless communication link is connected.

16. The mobile communication device as recited in claim 14, wherein the first portion of the uplink communication signal includes control signals used by the base station to maintain connection of the communication link between the base station and the mobile communication device.

17. The mobile communication device as recited in claim 14, wherein the processor further adapts transmit power levels of the mobile communication device by:

monitoring a power storage metric value of the mobile communication device; and

setting the second transmit power level value based on the monitored power storage metric value.

18. The mobile communication device as recited in claim 14 wherein the quality metric value is a power control level set by the base station.

19. The mobile communication device as recited in claim 14 wherein the monitored quality metric value is a timing advance set by the base station.

20. The mobile communication device as recited in claim 14 wherein the monitored quality metric value is a received downlink transmission quality metric value measured by the mobile communication device.

21. The mobile communication device as recited in claim 14, wherein the processor further adapts transmit power levels of the mobile communication device by:

adaptively setting a transmit power level of a second portion of the uplink communication signal in accordance with the monitored quality metric value;

wherein the transmit power level of the second portion of the uplink communication signal is set to the first power level value if the monitored quality metric value is in the first range of quality values, and

the transmit power level of the second portion of the uplink communication signal is set to a third power level value if the monitored quality metric value is in the second range of quality values;

wherein the third power level value is less than the first power level value.

22. The mobile communication device as recited in claim 21, wherein the processor further adapts transmit power levels of the mobile communication device by:

initializing the transmit power level of a second portion of the uplink communication signal to the first power level value; and

repeatedly monitoring the quality metric value and adaptively setting the transmit power level of the second portion of the uplink communication signal in accordance with the monitored quality metric value.

23. The mobile communication device as recited in claim 21, wherein the total average transmit power across the first and second portions of the uplink communication signal, when the first portion is set to the second power level value and the second portion is set to the third power level value, is no more than when the first and second portions are set to the first power level value.

24. A computer readable medium for storing computer code executed by a processor for improving robustness of a wireless communication link between a mobile communication device and a base station, the computer readable medium comprising:

computer program code for monitoring a quality metric value at the mobile communication device; and

computer program code for increasing a transmit power level of a first portion of an uplink communication signal transmitted on the wireless communication link from the mobile communication device to the base station based on the monitored quality metric value.

25. The computer readable medium as recited in claim 24, wherein the quality metric value measures indirectly a signal quality of uplink communication signals received at the base station from the mobile communication device, and the first portion of the uplink communication signal includes control signals used by the base station to maintain connection of the wireless communication link between the base station and the mobile device.

26. The computer readable medium as recited in claim 24 wherein the quality metric value is a power control value set by the base station.

27. The computer readable medium as recited in claim 24 wherein the quality metric value is a timing advance value set by the base station.

28. The computer readable medium as recited in claim 24 wherein the quality metric value is a received downlink transmission quality metric value measured by the mobile communication device.

29. The computer readable medium as recited in claim 24 further comprising

computer program code for decreasing a transmit power level of a second portion of the uplink communication signal transmitted on the wireless communication link from the mobile communication device to the base station based on the monitored quality metric value.

30. The computer readable medium as recited in claim 29, wherein the decreased transmit power level of the second portion of the uplink communication signal balances the increased transmit power level of the second portion of the uplink communication signal, so that the average transmit power level of the uplink communication signal is approximately unchanged.