Modulation scheme management

• US 20050064890A1
• Filed: 06/01/2004
• Published: 03/24/2005
• Est. Priority Date: 09/08/2003
• Status: Active Grant

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Dayong, Chen, Johan, Axnas, Stephen, Craig, Stefan, Eriksson
• Granted Patent: US 7,471,928 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/206 for modulated signals
• CPC Class Codes: H04W 52/262 taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001

Abstract

The invention involves selection of modulation scheme for a mobile unit (100) having access to a link quality enhancing algorithm (130) operable only on data modulated using a subset of the available modulation schemes. The mobile unit (100) performs signal quality measurements on a communications link (410), over which data modulated with a first modulation scheme is communicated. A link quality measure is then determined for this first modulation. A quality enhancement due to operation of the algorithm (130) is also determined. This quality measure and the quality enhancement are used for generating decision information, which is reported to the network (200). There the information is used for estimating link quality measure(s) of currently non-employed modulation(s) for the mobile unit (100). The selection of a modulation scheme for the communications link is then performed based on the decision information and the estimated quality measure(s).

Claims

1. A method of generating information for selection of a modulation scheme from multiple modulation schemes available for a mobile unit in a radio communications system, said mobile unit being adapted for employing a performance enhancing algorithm for enhancing the link quality of a communications link employing a subset of said available modulation schemes, said method comprising the steps of:

said mobile unit determining a first modulation-scheme-dependent link quality for said communications link employing a first modulation scheme of said scheme subset;

said mobile unit generating a representation of a link quality performance enhancement caused by said performance enhancing algorithm; and

generating said information for selection of a modulation scheme based on said first link quality and said enhancement representation.

2. The method according to claim 1, wherein said determining step comprises the steps of:

said mobile unit performing measurements of data modulated with said first modulation scheme and received on said communications link;

said mobile unit determining said first link quality based on said measurements.

3. The method according to claim 1, wherein said enhancement representation generating step comprises the steps of:

said mobile unit estimating a second modulation-dependent link quality for said first modulation scheme without usage of said performance enhancing algorithm; and

said mobile unit determining said enhancement representation based on said first link quality and said second link quality.

4. The method according to claim 1, wherein said enhancement representation generating step comprises the step of said mobile unit determining a rate of usage of said performance enhancing algorithm, said enhancement representation comprises said determined usage rate.

5. The method according to claim 1, wherein said performance enhancing algorithm is an interference suppressing algorithm.

6. The method according to claim 1, further comprising the step of said mobile unit reporting said first link quality and said enhancement representation to a modulation scheme selecting unit in said radio communications system.

7. The method according to claim 1, wherein each of said multiple modulation schemes is associated with a unique transmission power level used for communicating data on said communications link to said mobile unit, said method comprising the steps of:

determining a first transmission power level currently associated with said first modulation scheme;

determining a corresponding second transmission power level associated with at least a second modulation scheme,

wherein said information for selection of a modulation scheme comprises at least one of;

said first transmission power level and said second transmission power level; and

a quantity derived from said first transmission power level and said second transmission power level.

8. A mobile unit adapted for generating decision information for selection of a modulation scheme from multiple available modulation schemes in a radio communications system, said mobile unit comprising:

performance enhancing means for enhancing the link quality of a communications link employing a subset of said available modulation schemes;

means for determining a first modulation-scheme-dependent link quality for said communications link employing a first modulation scheme of said scheme subset;

means for generating a representation of a link quality performance enhancement caused by operation of said performance enhancing means; and

means for generating said decisions information based on said first link quality and said enhancement representation.

9. The mobile unit according to claim 8, further comprising means for receiving data modulated with said first modulation scheme on said communications link, wherein said determining means is configured for performing link quality measurements of said received and modulated data.

10. The mobile unit according to claim 8, further comprising means for estimating a second modulation-dependent link quality for said first modulation scheme without operation of said performance enhancing means, wherein said enhancement representation generating means is configured for determining said enhancement representation based on said first link quality and said second link quality.

11. The mobile unit according to claim 8, wherein said enhancement representation generating means is configured for determining a rate of activation of said performance enhancing means, said enhancement representation comprises said determined activation rate.

12. The mobile unit according to claim 8, wherein said performance enhancing means is configured for enhancing the enhancing the link quality using an interference suppressing algorithm.

13. The mobile unit according to claim 8, further comprising:

means for receiving a link quality measurement request from a modulation scheme selecting unit in said radio communications system; and

means for reporting said generated information for selection of a modulation scheme to said modulation scheme selecting unit upon reception of said request.

14. A modulation scheme managing unit adapted for generating decision information for selection of a modulation scheme from multiple available modulation schemes for a mobile unit in a radio communications system, said unit comprising:

means for providing a modulation-scheme-dependent link quality for a communications link of said mobile unit employing a first modulation scheme;

means for generating a representation of a link quality performance enhancement caused by operation of a performance enhancing algorithm adapted for enhancing the link quality of said communications link employing a subset of said available modulation schemes, said scheme subset comprises said first modulation scheme; and

means for generating said decisions information based on said first link quality and said enhancement representation.

15. The unit according to claim 14, further comprising means for receiving data modulated with said first modulation scheme on said communications link, wherein said providing means is configured for determining said link quality based on link quality measurements of said received and modulated data.

16. The mobile unit according to claim 14, further comprising means for estimating a second modulation-dependent link quality for said first modulation scheme without operation of said performance enhancing algorithm, wherein said enhancement representation generating means is configured for determining said enhancement representation based on said first link quality and said second link quality.

17. The mobile unit according to claim 14, wherein said enhancement representation generating means is configured for determining a rate of activation of said performance enhancing algorithm, said enhancement representation comprises said determined activation rate.

18. A modulation scheme selecting unit arranged in a radio communications system for selecting a modulation scheme from multiple modulation schemes available for a mobile unit adapted for employing a performance enhancing algorithm for enhancing the link quality of a communications link employing a subset of said available modulation scheme, said unit comprising:

means for receiving decision information originating from said mobile unit, said decision information comprises a first modulation-scheme-dependent link quality for said communications link employing a first modulation scheme of said scheme subset and a representation of a link quality performance enhancement caused by said performance enhancing algorithm; and

means for selecting a modulation scheme for usage for said communications link to said mobile unit based on said received decision information.

19. The unit according to claim 18, further comprising means for estimating a second modulation-scheme-dependent link quality for at least a second modulation scheme based on said received decision information, wherein said selecting means is configured for selecting a modulation scheme based on said second link quality and said received decision information.

20. The unit according to claim 19, wherein said estimating means is configured for determining said second link quality from a table mapping link qualities for different modulation-schemes employing said received decision information.

21. The unit according to claim 19, wherein each of said multiple modulation schemes is associated with a unique transmission power level used for communicating data on said communications link to said mobile unit, said unit comprising means for receiving, from a base station communicating said data to said mobile unit, a transmission power measure selected from at least one of:

a first transmission power level currently associated with said first modulation scheme and a second transmission power level associated with at least a second modulation scheme; and

a quantity derived from said first transmission power level and said second transmission power level, wherein said estimating means is configured for estimating said second link quality based on said received transmission power measure.