초록 ▼

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 with

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.

대표청구항 ▼

What is claimed is: 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 fu

What is claimed is: 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. 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 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. 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 N is the number transmit antennas and M is the number of receive antennas. 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 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 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 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.