Method and system for criterion based adaptive power allocation in a communication system with selective determination of modulation and coding

• US 6,385,462 B1
• Filed: 05/26/2000
• Issued: 05/07/2002
• Est. Priority Date: 05/26/2000
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Classon, Brian Keith, Sartori, Philippe Jean-Marc, Fry, Theresa Ann, Baum, Kevin Lynn
• Primary Examiner(s): Kincaid, Lester G.
• Assistant Examiner(s): ZEWDU, MELESS NMN
• Application Number:
  US09/579,984
• Time in Patent Office: 711 Days
• Field of Search: 455/13.4, 455/38.3, 455/62, 455/63, 455/67.1, 455/67.3, 455/69, 455/421, 455/423, 455/424, 455/450, 455/455, 455/452, 455/522, 455/44, 375/342, 370/342
• US Class Current: 455/522
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04W 52/262 taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS

Abstract

A method and system (102) for providing criterion based adaptive power allocation with selective determination of modulation and coding is provided. A method is presented which consists of providing adaptive power allocation with a target signal quality for each link based on a system criterion, and a modulation/coding rate for each link based on a signal quality associated with the transmit power of each link. A further method is provided which may alternatively, or additionally, consist of APA in which the transmit power for each link is assigned in an attempt to obtain a signal quality for each link within a range between or equal to a minimum and maximum. An additional method is disclosed consisting of APA in which the transmit power for each link is assigned in an attempt to obtain a signal quality for each link as close as possible to a common signal quality, when the power allocation method has a limited dynamic range. The method and system (102) of the present invention may be implemented in a wireless communication system (100) in any number of formats, such as code division multiple access or time division multiple access.

Claims

1. A method for transmitting signals in a communication system comprising the steps of:

determining a reference signal quality associated with a reference transmit power for each planned link of a plurality of planned links in the communication system to produce a plurality of reference signal qualities;

determining a target signal quality for each planned link of the plurality of planned links based on the plurality of reference signal qualities and on a system criterion that incorporates an ability of the system to support variable modulation/coding rates;

selecting a combination of a transmit power and a modulation/coding rate for each planned link of the plurality of planned links based on the target signal quality associated with the planned link and a set of possible modulation/coding rates; and

assigning the selected transmit powers and modulation/coding rates to each of the corresponding planned links.

2. The method as recited in claim 1 wherein the step of determining a target signal quality comprises the step of choosing a common target signal quality for each planned link of the plurality of planned links based on the plurality of reference signal qualities and on the system criterion.

3. The method as recited in claim 1 wherein the step of selecting a combination of a transmit power and a modulation/coding rate for each planned link comprises the step of selecting a common modulation/coding rate for all planned links of the plurality of planned links in the system.

4. The method as recited in claim 3 wherein the common modulation/coding rate is selected from a finite set of modulation/coding rates.

5. The method as recited in claim 1 wherein the signal quality is a bit error rate.

6. The method as recited in claim 1 wherein the signal quality is a carrier to interference ratio.

7. The method as recited in claim 1 wherein the signal quality is a carrier to interference plus noise ratio.

8. The method as recited in claim 1 wherein the signal quality is a ratio of wanted to unwanted signal energy.

9. The method as recited in claim 1 wherein the reference transmit power is a total system transmit power divided by a number of planned links.

10. The method as recited in claim 1 wherein the plurality of planned links comprises currently active links and wherein the reference transmit power for a planned link is the transmit power currently assigned to the active link.

11. In a wireless communication system, a method for transmitting signals comprising the steps of:

determining a reference signal quality associated with a reference transmit power for each planned link of a plurality of planned links to produce a plurality of reference signal qualities;

determining a target signal quality for each planned link of the plurality of planned links based on the plurality of reference signal qualities and a system criterion that incorporates an ability of the system to support variable modulation/coding rates;

determining a minimum desired signal quality and a maximum desired signal quality for the plurality of planned links based on one or more system criteria;

selecting a combination of a transmit power and a modulation/coding rate for each planned link of the plurality of planned links based on the target signal quality determined for the planned link, a set of modulation/coding rates, and the minimum and maximum desired signal qualities; and

assigning the determined transmit powers and modulation/coding rates to each of the corresponding planned links.

12. The method as recited in claim 11 wherein the step of selecting comprises the steps of:

if the target signal quality of one of the planned links is less than or equal to the minimum desired signal quality, selecting a smallest possible transmit power as the transmit power for the one of the planned links such that the signal quality of the one of the planned links when transmitted is greater than, or equal to the minimum desired signal quality;

if the target signal quality of the one of the planned links is greater than or equal to the maximum desired signal quality, and if there is enough dynamic range, selecting a greatest possible transmit power as the transmit power for the one of the planned links such that the signal quality of the one of the planned links when transmitted is lower than, or equal to the maximum desired signal quality;

if the target signal quality of the one of the planned links is greater than or equal to the maximum desired signal quality, and if there is not enough dynamic range such that the signal quality of the one of the planned links when transmitted is lower than, or equal to the maximum desired signal quality, selecting a minimum strictly positive power value for the transmit power for the one of the planned links; and

if the target signal quality of the one of the planned links is greater than the minimum desired signal quality and less than the maximum desired signal quality, selecting a transmit power for the one of the planned links such that the signal quality of the one of the planned links is as close as possible to the target signal quality.

13. The method as recited in claim 12 comprising the step of:

if there is not enough dynamic range to select a transmit power of a planned link such that the signal quality of the planned link, when transmitted, is greater than or equal to the minimum desired signal quality, removing that planned link from the plurality of planned links.

14. The method as recited in claim 11 wherein the signal quality is a carrier to interference ratio.

15. The method as recited in claim 11 wherein the signal quality is bit error rate.

16. In a wireless communication system, a system for transmitting signals comprising:

a transmit power unit for determining a reference transmit power for each planned link of a plurality of planned links and for determining a transmit power for the planned link based on the reference transmit power, a target signal quality determined by a signal quality unit, and a set of possible modulation/coding rates;

a signal quality unit for determining a reference signal quality associated with the reference transmit power determined for each planned link of the plurality of planned links to produce a plurality of reference signal qualities and for determining a target signal quality for each planned link of the plurality of planned links based on the plurality of reference signal qualities and on a system criterion that incorporates an ability of the system to support variable modulation/coding rates;

a modulation/coding rate unit for assigning a modulation/coding rate to each planned link of the plurality of planned links based on the target signal quality associated with the planned link and the transmit power determined for the planned link; and

a transceiver unit for transmitting each planned link of the plurality of planned links at the transmit power determined for the planned link and with the modulation/coding rate assigned to the planned link.

17. The system as recited in claim 16 wherein the target signal quality for each of the planned links is a common target signal quality for all of the planned links, and wherein the modulation/coding rate unit assigns a common modulation/coding rate to all planned links based on the target signal quality.

18. The system as recited in claim 16 wherein the signal quality unit comprises:

a range unit for determining minimum and maximum desired signal qualities for the planned links, and for determining the target signal quality for each of the planned links based on one or more system criteria, and

wherein the transmit power unit selects the transmit power for each of the planned links based on the minimum and maximum desired signal qualities and the target signal quality of each of the planned links.

19. The system as recited in claim 18 wherein the transmit power unit comprises:

a power selection unit for selecting a smallest possible transmit power as the transmit power for one of the planned links such that the signal quality of the one of the planned links when transmitted is greater than or equal to the minimum desired signal quality, if the target signal quality of the one of the planned links is less than or equal to the minimum desired signal quality;

for selecting a largest possible transmit power as the transmit power for the one of the planned links such that the signal quality of the one of the planned links when transmitted is lower than or equal to the maximum desired signal quality if the power selection unit has enough dynamic range and if the target signal quality of the one of the planned links is greater than or equal to the maximum desired signal quality;

for selecting a minimum strictly positive possible value for the transmit power for the one of the planned links if the selection unit does not have enough dynamic range such that the signal quality of the one of the planned links when transmitted is lower than or equal to the maximum desired signal quality and if the target signal quality of the one of the planned links is greater than or equal to the maximum desired signal quality; and

for selecting a transmit power for the one of the planned links such that the signal quality of the one of the planned links is as close as possible to the target signal quality, if the target signal quality of the one of the planned links is greater than the minimum desired signal quality and less than the maximum desired signal quality.

20. The system as recited in claim 19, wherein the power selection unit, if there is not enough dynamic range to select a transmit power of a planned link such that the signal quality of the planned link, when transmitted, is greater than or equal to the minimum desired signal quality, removes that planned link from the plurality of planned links.