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

• US 7,116,652 B2
• Filed: 10/18/2001
• Issued: 10/03/2006
• 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
• Primary Examiner(s): Ngo, Ricky Q.
• Assistant Examiner(s): Wong, Warner
• Application Number:
  US09/999,442
• Publication Number:
  US 20030076797A1
• Time in Patent Office: 1,811 Days
• Field of Search: 370/252, 370/465, 370/468, 370/328, 455/101, 375/299, 375/295, 375/377, 375/267
• 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;

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.

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

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

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

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

6. 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 1 wherein said rate controller determines said rate for each transmit data substream also as a function of fixed parameters.

9. 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 substreams and receive antennas β

, where

$\mathrm{\beta <br><br>}=\frac{N}{M},$

N is the number transmit antennas and M is the number of receive antennas.

7. 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;

wherein said rate controller determines an approximation of the optimal rate for each transmit data substream and said optimal rate for each transmit data substream is given by

$R_n={\log }_2<br><br>\left(1+{h_n^H<br><br>\left(H_n<br><br>H_n^H+\frac{N<br><br><br><br>{\mathrm{\sigma <br><br>}}^2}{P}<br><br>I\right)}^{-1}<br><br>h_n\right)$

where

n is a data substream index;

h_n=[h_I,n . . . h_M,n]^T is the complex M-dimensional channel vector for transmit substream, with h_m,n being the channel transfer coefficient between transmit substream n and receiver branch m;

X^T indicates the matrix transpose operation for matrix X;

H_n=[h_n+1 h_n+2 . . . h_N], an M-by-(N-n) matrix;

P represents the total radiated power;

X^H indicates the Hermitian transpose operation for matrix X;

I the M-by-M identity matrix; and

σ

² is the noise variance.

10. 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;

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

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

N is the number transmit data substreams,

M is the number of receive branches,

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

h is n/M, where n is the index of the transmit data substreams.

11. 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

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

N is the number transmit antennas,

M is the number of receive antennas,

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

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

12. 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;

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

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

N is the number transmit data substreams,

M is the number of receive branches,

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

h is n/M, where n is the index of the transmit data substreams.