RATE SELECTION WITH MARGIN SHARING

• US 20090129454A1
• Filed: 11/13/2008
• Published: 05/21/2009
• Est. Priority Date: 05/12/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Medvedev, Irina, Walton, J. Rodney
• Granted Patent: US 8,855,226 B2
• Time in Patent Office: Days
• US Class Current: 375/227
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Rate selection with margin sharing in a system with independent data stream rates is presented. Signal-to-Noise Ratio (SNR) estimates are obtained for each stream. Rates are selected for the streams based on the SNR estimates, such that at least one data stream has an SNR margin below a threshold, each remaining data stream has an SNR margin above a respective threshold, and the total SNR margin for all streams is above a total threshold. For rate selection with margin sharing with a vector-quantized rate set, SNR estimates are obtained for usable transmission channels. The total SNR margin is determined for each rate combination based on the estimates. Each rate combination is associated with a specific number of data streams to transmit, a specific rate for each data stream, and a specific overall throughput. The combination with the highest overall throughput and non-negative total SNR margin is selected.

Claims

1. A method of performing rate selection for data transmission over a plurality of transmission channels in a communication system, comprising:

obtaining a signal-to-noise ratio (SNR) estimate for each of the plurality of transmission channels;

determining a total SNR margin for each of a plurality of rate combinations based on the SNR estimates for the plurality of transmission channels, wherein each rate combination is associated with a specific number of the data streams to transmit, a specific rate for each data stream, and a specific overall throughput; and

selecting a rate combination from among the plurality of rate combinations based on total SNR margins and overall throughputs for the plurality of rate combinations.

2. The method of claim 1, wherein the determining the total SNR margin for each rate combination comprises

determining an SNR margin for each data stream in the rate combination based on an SNR estimate for a transmission channel used for the data stream and a required SNR for the data stream, and

summing SNR margins for all data streams in the rate combination to obtain the total SNR margin for the rate combination.

3. The method of claim 1, further comprising:

removing each rate combination having at least one data stream with an SNR margin below a predetermined value.

4. The method of claim 1, wherein the selecting the rate combination from among the plurality of rate combinations comprises

selecting a rate combination having a highest overall throughput among the plurality of rate combinations.

5. The method of claim 4, wherein the selecting the rate combination from among the plurality of rate combinations further comprises

selecting a rate combination having fewer data streams if multiple rate combinations have the highest overall throughput.

6. The method of claim 4, wherein the selecting the rate combination from among the plurality of rate combinations comprises

selecting a rate combination having a larger total SNR margin if multiple rate combinations have the highest overall throughput.

7. The method of claim 1, further comprising:

selecting the plurality of rate combinations in a sequential order for evaluation, starting with rate combinations having fewest data streams and concluding with rate combinations having most data streams.

8. The method of claim 7, further comprising:

selecting rate combinations for a given number of data streams in a sequential order, starting with a rate combination having a lowest overall throughput and concluding with a rate combination having a highest overall throughput.

9. An apparatus for performing rate selection in a communication system that has a plurality of transmission channels usable for data transmission, comprising:

a channel estimator operative to obtain a signal-to-noise ratio (SNR) estimate for each of the plurality of transmission channels; and

a controller operative to determine a total SNR margin for each of a plurality of rate combinations based on the SNR estimates for the plurality of transmission channels, and to select a rate combination from among the plurality of rate combinations based on total SNR margins and overall throughputs for the plurality of rate combinations, wherein each rate combination is associated with a specific number of data streams to transmit, a specific rate for each data stream, and a specific overall throughput.

10. The apparatus of claim 9, wherein the controller is operative to determine an SNR margin for each data stream in each rate combination based on an SNR estimate for a transmission channel used for the data stream and a required SNR for the data stream, and to sum SNR margins for all data streams in each rate combination to obtain the total SNR margin for the rate combination.

11. The apparatus of claim 9, wherein the controller is operative to select a rate combination having a highest overall throughput among the plurality of rate combinations, and to select a rate combination having fewer data streams or a larger total SNR margin if multiple rate combinations have the highest overall throughput.

12. An apparatus for performing rate selection in a communication system that has a plurality of transmission channels usable for data transmission, comprising:

means for obtaining a signal-to-noise ratio (SNR) estimate for each of a plurality of transmission channels;

means for determining a total SNR margin for each of a plurality of rate combinations based on the SNR estimates for the plurality of transmission channels, wherein each rate combination is associated with a specific number of data streams to transmit, a specific rate for each data stream, and a specific overall throughput; and

means for selecting a rate combination from among the plurality of rate combinations based on total SNR margins and overall throughputs for the plurality of rate combinations.

13. The apparatus of claim 12, wherein the means for determining the total SNR margin for each rate combination comprises

means for determining an SNR margin for each data stream in the rate combination based on an SNR estimate for a transmission channel used for the data stream and a required SNR for the data stream, and

means for summing SNR margins for all data streams in the rate combination to obtain the total SNR margin for the rate combination.

14. The apparatus of claim 12, wherein the means for selecting the rate combination from among the plurality of rate combinations comprises

means for selecting a rate combination having a highest overall throughput among the plurality of rate combinations, and

means for selecting a rate combination having fewer data streams or a larger total SNR margin if multiple rate combinations have the highest overall throughput.

15. A processor readable media having stored therein processor-usable instructions for a processor, wherein said instructions when executed by the processor cause the processor to:

obtain a signal-to-noise ratio (SNR) estimate for each of a plurality of transmission channels;

determine a total SNR margin for each of a plurality of rate combinations based on the SNR estimates for the plurality of transmission channels, wherein each rate combination is associated with a specific number of data streams to transmit, a specific rate for each data stream, and a specific overall throughput; and

select a rate combination from among the plurality of rate combinations based on total SNR margins and overall throughputs for the plurality of rate combinations.

16. The processor readable media of claim 15, wherein said instructions when executed by the processor further cause the processor to:

determine an SNR margin for each data stream in the rate combination based on an SNR estimate for a transmission channel used for the data stream and a required SNR for the data stream, and

sum SNR margins for all data streams in the rate combination to obtain the total SNR margin for the rate combination.

17. The processor readable media of claim 15, wherein said instructions when executed by the processor further cause the processor to:

select a rate combination having a highest overall throughput among the plurality of rate combinations, and

select a rate combination having fewer data streams or a larger total SNR margin if multiple rate combinations have the highest overall throughput.