System and method for reducing power consumption for wireless communications by mobile devices

• US 20030064744A1
• Filed: 10/01/2001
• Published: 04/03/2003
• Est. Priority Date: 10/01/2001
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Zhu, Ji, Zhang, Qian, Zhang, Ya-Qin, Zhu, Wenwu
• Granted Patent: US 7,096,034 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/54 Signalisation aspects of the TPC commands, e.g. frame structure

Abstract

A power control scheme for a wireless network communication system that includes a base station and multiple wireless mobile device dynamically adjusts transmission power of a mobile device in conjunction with adjusting its bit allocation in source coding and channel coding to minimize its total power consumption while maximizing the system capacity in terms of the total effective transmission rates received by the base station. The base station sets a target signal quality value for each mobile station, and the target values are determined by the base station such that the total effective data rate from all the mobile devices is maximized under constraints of the total received power and the error protection level requirements for the mobile devices. The base station periodically measures a signal quality value, such as a signal-to-interference ratio (SIR), from transmissions received by the base from each mobile device, compares it with the measured signal quality value for that mobile device, and sends a control signal instructing the mobile device to increase or decrease its transmission power based on the result of the comparison. When the mobile device receives the control signal, it determines an amount of adjustment to its transmission power by performing a minimum calculation under constraints on the total data distortion and the maximum transmission rate to adjust the parameters for source coding, channel coding, and transmission under the constraints to result in a redistribution of power between the components that provides the minimized total power consumption.

Claims

1. A computer-readable medium having computer-executable instructions for performing steps of a power control scheme for network communications between a base station and a plurality of mobile devices, the steps comprising:

setting, by the base station, a target signal quality value for each of the mobile devices through a constrained maximization calculation to maximize a total effective data rate of wireless transmissions from the mobile devices;

periodically deriving, by the base station, a measured value of a signal quality parameter for each mobile device based on transmissions received from said each mobile device;

comparing, by the base station, the measured values of the signal quality parameter for said each mobile device to the target signal quality value for said each mobile device;

transmitting, by the base station, an instruction signal to said each mobile device to adjust a transmission power of said each mobile device;

determining, by said each mobile device in response to the instruction signal from the base station, an amount of adjustment to a transmission power of said each mobile device based on a constrained minimization calculation to minimize a total power consumption of said each mobile device via a reallocation of power among the transmission power and coding components of the total power consumption; and

adjusting, by said each mobile device, the transmission power by said amount of adjustment in conjunction with the reallocation of power to the coding components of the total power consumption.

2. A computer-readable medium as in claim 1, wherein the signal quality parameter is a signal-interference ratio.

3. A computer-readable medium as in claim 1, wherein the coding components include a source coding component and a channel coding component, and the reallocation of power includes changing bit rates of source coding and channel coding and adjusting transmission bit energy.

4. A computer-readable medium as in claim 1, wherein the constrained maximization calculation maximizes the total effective data rate under constraints imposed by a total received transmission power and error protection levels specified by the mobile devices.

5. A computer-readable medium as in claim 1, wherein the constrained minimization calculation minimizes the total power consumption of said each mobile device under constraints imposed by a total data distortion level and a maximum transmission rate of said each mobile device.

6. A computer-readable medium as in claim 1, wherein the reallocation of power results in a changed error protection level of said each mobile device, the computer-readable medium including further computer-executable instructions for said each mobile device to send an information packet to the base station specifying the changed error protection level of said each mobile device.

7. A computer-readable medium as in claim 6, wherein the base station repeats the step of setting based on the changed error protection level of said each mobile device.

8. A computer-readable medium as in claim 1, wherein the step of determining by said each mobile device includes deriving a bit error rate from wireless transmissions received from the base station.

9. A computer network comprising:

a base station;

a plurality of mobile devices communicating with the base stations by wireless transmissions,

the base station being programmed to perform to set a target signal quality value for each of the mobile devices through a constrained maximization calculation to maximize a total effective data rate of wireless transmissions from the mobile devices, periodically derive a measured value of a signal quality parameter for each mobile device based on transmissions received from said each mobile device, compare the measured values of the signal quality parameter for said each mobile device to the target signal quality value for said each mobile device, and transmit an instruction signal to said each mobile device to adjust a transmission power of said each mobile device;

said each mobile device being programmed to determine, in response to the instruction signal from the base station, an amount of adjustment to a transmission power of said each mobile device based on a constrained minimization calculation to minimize a total power consumption of said each mobile device via a reallocation of power among the transmission power and coding components of the total power consumption, and adjust the transmission power by said amount of adjustment in conjunction with the reallocation of power to the coding components of the total power consumption.

10. A computer network as in claim 9, wherein the signal quality parameter is a signal-interference ratio.

11. A computer network as in claim 9, wherein the coding components include a source coding component and a channel coding component, and the reallocation of power includes changing bit rates of source coding and channel coding.

12. A computer network as in claim 9, wherein the constrained maximization calculation maximizes the total effective data rate under constraints imposed by a total received transmission power and error protection levels specified by the mobile devices.

13. A computer network as in claim 9, wherein the constrained minimization calculation minimizes the total power consumption of said each mobile device under constraints imposed by a total data distortion level and a maximum transmission rate of said each mobile device.

14. A computer network as in claim 9, wherein the reallocation of power results in a changed error protection level of said each mobile device, and wherein said each mobile device is programmed to send an information packet to the base station specifying the changed error protection level of said each mobile device.

15. A computer network as in claim 14, wherein the base station resets the target values of the signal quality parameter for the mobile devices based on the changed error protection level of said each mobile device.

16. A computer network as in claim 9, wherein said each mobile device derives a bit error rate from wireless transmissions received from the base station for determining the amount of adjustment to the transmission power thereof.