Transmission mode and rate selection for a wireless communication system

• US 8,355,372 B2
• Filed: 05/08/2009
• Issued: 01/15/2013
• Est. Priority Date: 05/07/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Abraham, Santosh, Meylan, Arnaud, Walton, Jay Rodney
• Primary Examiner(s): Aminzay, Shaima Q
• Application Number:
  US12/463,078
• Publication Number:
  US 20090290655A1
• Time in Patent Office: 1,348 Days
• Field of Search: 370/329, 370/200, 370/203, 370/208, 370/334, 370/335, 370/339, 342/367, 342/368, 375/260, 455/67, 455/13, 455/63.1, 455/92, 455/151.1, 455/562.1, 700/53, 700/46
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0421 utilizing implicit feedback, e.g. steered pilot signals
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

To select a transmission mode to use for a data transmission via a MIMO channel from station A to station B, station A obtains channel information used for spatial processing and determines the age of this information. Station A selects one of multiple transmission modes based on the age of the channel information and possibly other information (e.g., the fading characteristic of the MIMO channel). To select rate(s) to use for the data transmission, station A obtains channel state information (CSI) indicative of the received signal quality for the MIMO channel, e.g., received SNRs or “initial” rates. Station A determines the age of the CSI and selects one or more “final” rates based on the CSI, the age of the CSI, the selected transmission mode, and possibly other information. Station A processes data in accordance with the selected transmission mode and final rate(s) and transmits the processed data to station B.

Claims

1. A method of selecting a transmission mode for data transmission in a wireless communication system, comprising:

determining the age of channel information available for use to transmit data via a wireless channel;

comparing the age of the channel information against a threshold, and selecting a steered mode when the age of the channel information is less than or equal to the threshold and selecting an unsteered mode when the age of the channel information is greater than the threshold; and

processing data in accordance with the selected transmission mode wherein the channel information is used for processing when the steered mode is selected and the channel information is not used for processing when the unsteered mode is selected.

2. The method of claim 1, further comprising:

obtaining eigenvectors used to transmit data on a plurality of orthogonal spatial channels of a multiple-input multiple-output (MIMO) channel, wherein the channel information comprises the eigenvectors.

3. The method of claim 1, further comprising:

determining the age of a pilot used to derive the channel information, wherein the age of the channel information is determined based on the age of the pilot.

4. The method of claim 1, further comprising:

determining the threshold based on a function of a time variant characteristic of the wireless channel.

5. An apparatus in a wireless communication system, comprising:

a controller to determine the age of channel information available for use to transmit data via a wireless channel, compares the age of the channel information against a threshold, and selects a steered mode when the age of the channel information is less than or equal to the threshold and selects an unsteered mode when the age of the channel information is greater than the threshold; and

to select a transmission mode from among a plurality of transmission modes based on the age of the channel information; and

a spatial processor to spatially process data in accordance with the selected transmission mode wherein the spatial processor uses the channel information for spatial processing when the steered mode is selected and the spatial processor does not use the channel information for spatial processing when the unsteered mode is selected.

6. The apparatus of claim 5, wherein the controller determines the age of a pilot used to derive the channel information and determines the age of the channel information based on the age of the pilot.

7. An apparatus in a wireless communication system, comprising:

means for determining the age of channel information available for use to transmit data via a wireless channel;

means for comparing the age of the channel information against a threshold, and selecting a steered mode when the age of the channel information is less than or equal to the threshold and selecting an unsteered mode when the age of the channel information is greater than the threshold; and

means for processing data in accordance with the selected transmission mode wherein the channel information is used for processing when the steered mode is selected and the channel information is not used for processing when the unsteered mode is selected.

8. The apparatus of claim 7, further comprising:

means for determining the age of a pilot used to derive the channel information, wherein the age of the channel information is determined based on the age of the pilot.

9. A computer program product, comprising:

a non-transitory computer-readable medium comprising code for causing a computer to;

determine the age of channel information available for use to transmit data via a wireless channel;

compare the age of the channel information against a threshold, and select a steered mode when the age of the channel information is less than or equal to the threshold and select an unsteered mode when the age of the channel information is greater than the threshold; and

process data in accordance with the selected transmission mode wherein the channel information is used for processing when the steered mode is selected and the channel information is not used for processing when the unsteered mode is selected.

10. The computer program product of claim 9, wherein the computer-readable medium further comprises code for causing the computer to determine the age of a pilot used to derive the channel information, wherein the age of the channel information is determined based on the age of the pilot.