Rate control technique for layered architectures with multiple transmit and receive antennas

• US 20030076797A1
• Filed: 10/18/2001
• Published: 04/24/2003
• Est. Priority Date: 10/18/2001
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Lozano, Angel
• Granted Patent: US 7,116,652 B2
• Time in Patent Office: Days
• US Class Current: 370/334
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• 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: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0027 Scheduling of signalling, e.g. occurrence thereof

Abstract

In a wireless communication system using multiple antennas at the transmitter and multiple antennas at the receiver, with a sufficiently large number of antennas and/or diversity order, the same performance that is obtainable when employing instantaneous rate indication feedback can be attained without any such short-term feedback by adjusting the data rate of each transmit antenna according to a prescribed function. The prescribed function does not depend on the short-term state of the channel, but instead only depends on its long-term statistics, which may be fed back from the receiver to the transmitter at relatively lengthy intervals.

Claims

1. A transmitter of a multiple-input multiple-output (MIMO) system for transmitting a plurality of data substreams derived from a data stream, comprising

means for obtaining a long term parameter;

and

a rate controller that develops a rate for each transmit data substream as function of at least said long term parameter and no short term parameters.

2. The invention as defined in claim 1 wherein said transmitter is a wireless transmitter and each of said substreams is transmitted by a separate antenna.

3. The invention as defined in claim 1 wherein said long term parameter is a signal-to-noise ratio (SNR).

4. The invention as defined in claim 1 wherein said long term parameter is supplied by a receiver coupled via a channel to said transmitter.

5. The invention as defined in claim 1 wherein said long term parameter is developed at said transmitter.

6. The invention as defined in claim 1 wherein said long term parameter is characteristic of a channel between said transmitter and a receiver.

7. The invention as defined in claim 1 wherein said rate controller determines an approximation of the optimal rate for each transmit data substream.

8. The invention as defined in claim 7 wherein said optimal rate for each transmit data substream is given by

9. The invention as defined in claim 1 wherein said rate controller determines said rate for each transmit data substream also as a function of fixed parameters.

10. The invention as defined in claim 1 wherein said rate controller determines said rate for each transmit antenna also as a function of the ratio of transmit data substream and receive branches β

, where

11. The invention as defined in claim 1 wherein said data substreams are transmitted via a channel impaired by additive white Gaussian noise (AWGN), and said rate controller determines said rates by computing

12. The invention as defined in claim 1 wherein said transmitter is a wireless transmitter and each of said substreams is transmitted by a separate antenna over a channel to a receiver having a plurality of receive antennas, and wherein said rate controller develops each rate for each of said transmit data substream using a derivative of asymptotic capacity of said system.

13. A transmitter of a multiple-input multiple-output (MIMO) system for transmitting a plurality of data substreams derived from a data stream, comprising

means for obtaining a long term parameter;

and

means for developing a rate for at least one transmit data substream as function of at least said long term parameter and no short term parameters.

14. A wireless transmitter of a multiple-input multiple-output (MIMO) system for transmitting wirelessly a plurality of data substreams derived from a data stream, each of said data substreams being transmitted via an antenna of said wireless transmitter, said data substreams being for receipt at a receiver having a plurality of receive antennas, said transmitter comprising

means for obtaining a long term parameter;

and

a rate controller that develops a rate for each transmit data substream as function of at least said long term parameter and no short term parameters;

said data substreams being transmitted via a channel impaired by additive white Gaussian noise (AWGN), and said rate controller determines said rates by computing

$R<br><br>\left(b\right)={\log }_2(\hspace{1em}<br><br><br><br>1+\frac{\mathrm{SNR}}{\mathrm{\beta <br><br>}}-{\frac{1}{4}<br><br>\left[\sqrt{1+\frac{\mathrm{SNR}}{\mathrm{\beta <br><br>}}<br><br>{\left(1+\sqrt{\mathrm{\beta <br><br>}-b}\right)}^2}-\sqrt{1+\frac{\mathrm{SNR}}{\mathrm{\beta <br><br>}}<br><br>{\left(1-\sqrt{\mathrm{\beta <br><br>}-b}\right)}^2}\right]}^2)$$\mathrm{where}$$\mathrm{\beta <br><br>}=\frac{N}{M},$

N is the number transmit antennas,

M is the number of receive antennas,

SNR is the long-term average signal-to-noise ratio, and

b is n/M, where n is the index of the transmit antennas.

15. A method for use in transmitter of a multiple-input multiple-output (MIMO) system that is transmitting a plurality of data substreams derived from a data stream, the method comprising the steps of:

obtaining a long term parameter; and

determining a rate for each transmit data substream as function of at least said long term parameter and no short term parameters.

16. The invention as defined in claim 15 further comprising the step of:

transmitting each of said data substreams at said rate determined therefor.

17. The invention as defined in claim 15 wherein said data substreams are transmitted via a channel impaired by additive white Gaussian noise (AWGN), and said rate controller determines said rates by computing

18. A method for use in transmitter of a multiple-input multiple-output (MIMO) system that is transmitting a plurality of data substreams derived from a data stream, the method comprising the step of transmitting each of a plurality of data substreams at respective rates which are each function of at least a long term parameter and no short term parameters.