Rate control technique for layered architectures with multiple transmit and receive antennas
AssigneeLucent Technologies Inc.
InventorAngel Lozano
Life of this patent
Estimating the term…
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.
Claims12
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.
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
-
- (
- 1
- +
- h
- n
- H
-
- (
- H
- n
-
- H
- n
- H
- +
- N
-
-
- σ
- 2
- P
-
- I
- )
- -
- 1
-
- h
- n
- )
- where
- n is a data substream index;
- hn=[hI,n . . . hM,n]T is the complex M-dimensional channel vector for transmit substream, with hm,n being the channel transfer coefficient between transmit substream n and receiver branch m;
- XT indicates the matrix transpose operation for matrix X;
- Hn=[hn+1 hn+2 . . . hN], an M-by-(N-n) matrix;
- P represents the total radiated power;
- XH indicates the Hermitian transpose operation for matrix X;
- I the M-by-M identity matrix;
- and
- σ2 is the noise variance.
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
-
- (
- b
- )
- =
- log
- 2
- (
-
- 1
- +
- SNR
- β
- -
- 1
- 4
-
- [
- 1
- +
- SNR
- β
-
- (
- 1
- +
- β
- -
- b
- )
- 2
- -
- 1
- +
- SNR
- β
-
- (
- 1
- -
- β
- -
- b
- )
- 2
- ]
- 2
- )
-
- where
-
-
- β
- =
- 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.
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
-
- (
- b
- )
- =
- log
- 2
- (
-
- 1
- +
- SNR
- β
- -
- 1
- 4
-
- [
- 1
- +
- SNR
- β
-
- (
- 1
- +
- β
- -
- b
- )
- 2
- -
- 1
- +
- SNR
- β
-
- (
- 1
- -
- β
- -
- b
- )
- 2
- ]
- 2
- )
-
- where
-
-
- β
- =
- 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.
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
-
- (
- b
- )
- =
- log
- 2
- (
-
- 1
- +
- SNR
- β
- -
- 1
- 4
-
- [
- 1
- +
- SNR
- β
-
- (
- 1
- +
- β
- -
- b
- )
- 2
- -
- 1
- +
- SNR
- β
-
- (
- 1
- -
- β
- -
- b
- )
- 2
- ]
- 2
- )
-
- where
-
-
- β
- =
- 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.
Dependencies are inferred from the claim text.