Rate adaptation and parameter optimization for multi-band single carrier transmission

• US 20050276343A1
• Filed: 08/05/2005
• Published: 12/15/2005
• Est. Priority Date: 11/17/2000
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Jones, David Charles
• Granted Patent: US 7,512,186 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0016 involving special memory structures, e.g. look-up tables
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority

Abstract

A method for enhancing the bit rate and/or margin at which quadrature amplitude modulation (QAM) communication is performed over multiple bands of a communication link includes the steps of varying a spectral allocation and constellation size with which communication is performed, so as to define a combination of spectral allocation and constellation size at which the bit rate and/or margin are enhanced. The rate adaptation method identifies the spectral allocation and constellation size to use on each of the multiple bands that results in a total bit rate greater than or equal to the target bit rate, subject to specified constraints on SNR margin and/or BER limits. If more than one parameter set has this property, the rate adaptation method may for example select the spectral allocation and constellation size combination that maximizes the minimum SNR margin across the multiple bands.

Claims

1. A method for multi-band data communication, the method comprising:

defining an adjustable center frequency and constellation size for each of said multiple bands; and

varying the adjustable center frequency and constellation size for defining a combination of an optimum center frequency and an optimum constellation size at which data transmission is enhanced.

2. The method of claim 1 further comprising evaluating a response characteristic of each of said multiple bands, wherein the data transmission is enhanced in accordance with said response characteristic.

3. The method of claim 1 further comprising defining a total target bit rate for said multiple bands;

and defining a margin requirement for each of said multiple bands, wherein the combination of the optimum center frequency and the optimum constellation size is defined when the target bit rate and the margin are enhanced.

4. The method of claim 1 further comprising defining a plurality of spectral allocations for each of said multiple bands;

and evaluating a response characteristic of each of said multiple bands with respect to said plurality of spectral allocations.

5. The method of claim 4 further comprising determining a maximum constellation size for each of said plurality of spectral allocations in accordance with said response characteristic.

6. The method of claim 5 further comprising varying said maximum constellation size to increase a signal-noise-ratio margin without falling below a total target bit rate for said multiple bands.

7. A method for multi-band data communication, the method comprising:

varying a constellation vector including an adjustable center frequency and an adjustable constellation size for each of said multiple bands to increase a signal-noise-ratio margin without falling below a total target bit rate for said multiple bands; and

defining an optimal parametric set for which at least one of said constellation vector and said signal-noise-ratio margin is optimized.

8. The method of claim 7 further comprising evaluating a response characteristic of each of said multiple bands with respect to a parametric set, wherein the optimal parametric set is defined when the response characteristic allows optimization of at least one of said constellation vector and said signal-noise-ratio margin.

9. The method of claim 7 wherein the step of varying the constellation vector comprises:

varying the constellation vector while maintaining a substantially constant spectral allocation; and

repeating the constellation vector varying step at a plurality of different discrete spectral allocations.

10. The method of claim 8 wherein the step of evaluating a response characteristic of each of said multiple bands with respect to a parametric set comprises evaluating signal-to-noise-ratio.

11. The method of claim 8 further comprising the step of evaluating said response characteristic with respect to said optimal parametric set.

12. The method of claim 11 further comprising commencing a bidirectional data communication with said optimal parametric set if said response characteristic complies with a predetermined threshold.

13. The method of claim 8 further comprising adjusting said constellation vector in accordance with said response characteristic.

14. A method for multi-band data communication, the method comprising:

defining an adjustable center frequency for each of said multiple bands;

evaluating a response characteristic of each of said multiple bands with respect to said adjustable center frequencies;

determining a maximum constellation size for each of said adjustable center frequencies in accordance with said response characteristic; and

defining an optimal center frequency and constellation size in accordance with said constellation size.

15. The method of claim 14 wherein the step of defining an optimal center frequency and constellation size comprises:

defining a first subset containing center frequency and constellation size combinations for which a total bit rate delivered for each of said adjustable center frequencies and maximum constellation sizes is equal to or greater than a target bit rate;

varying said plurality of center frequencies within said first subset to increase said noise margin without falling below a total target bit rate for said multiple bands; and

defining said optimum center frequency and constellation size in accordance with said increased noise margin.

16. The method of claim 15 wherein the step of defining said optimum center frequency and constellation size in accordance with said increased noise margin comprises defining optimum center frequency and constellation size in accordance with largest minimum noise margin.

17. The method of claim 14 wherein the step of defining an optimal center frequency and constellation size comprises:

defining a first subset containing center frequency and constellation size combinations that provide a total bit rate that is less than a target bit rate;

identifying center frequency and constellation size combinations within said first subset that provide largest total bit rate; and

defining said optimum center frequency and constellation size in accordance with said noise margin.

18. A multi-band data communication system comprising:

means for defining an adjustable center frequency and constellation size for each of said multiple bands; and

means for varying the adjustable center frequency and constellation size for defining a combination of an optimum center frequency and an optimum constellation size at which data transmission is enhanced.

19. The system of claim 18 further comprising means for evaluating a response characteristic of each of said multiple bands, wherein the data transmission is enhanced in accordance with said response characteristic.

20. The system of claim 18 further comprising means for defining a total target bit rate for said multiple bands;

and means for defining a margin requirement for each of said multiple bands, wherein the combination of the optimum center frequency and the optimum constellation size is defined when the target bit rate and the margin are enhanced.