System, method, apparatus, and computer program for wireless communication

• US 20050249303A1
• Filed: 12/01/2004
• Published: 11/10/2005
• Est. Priority Date: 05/10/2004
• Status: Active Grant

• Current Assignee: Redwood Technologies, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takano, Hiroaki
• Granted Patent: US 7,627,045 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04B 7/0862 receiver computing weights based on information from the transmitter
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: H04L 2025/03808 Transmission of equaliser coefficients
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

The disclosed invention enhances transmission efficiency by decreasing regions of reference signals which are attached to transmit packets from a transmitter during bidirectional SVD-MIMO communication. The transmitter transmits user data following a reference signal. At the other end, the receiver acquires a channel matrix, based on the reference signal attached preceding the user data, receives the user data, while weighting the data with receive weights derived from the channel matrix, adaptively estimates the channel matrix H as long as the user data is being received, and obtains transmit weights V′ for transmitting user data in the reverse direction from an adaptively estimated channel matrix H′.

Claims

1. A wireless communication system which carries out data transmission, using multiple spatially multiplexed communication channels between a transmitter and a receiver, wherein:

the transmitter transmits user data following a reference signal for channel matrix acquisition, wherein the user data and the reference signal are weighted and transmitted over the spatially multiplexed channels; and

the receiver acquires a channel matrix H, based on the reference signal attached preceding the user data, receives the user data, while weighting the data with receive weights derived from the channel matrix H, and adaptively estimates the channel matrix H as long as the user data is being received.

2. The wireless communication system according to claim 1, wherein both said transmitter and said receiver are equipped with multiple antennas, said transmitter allocates transmit data to multiple streams, weights the streams, and transmits the weighted streams from the transmit antennas, and said receiver weights the streams received by the receive antennas.

3. The wireless communication system according to claim 1, wherein said receiver obtains transmit weights V′

for transmitting user data in the reverse direction to said transmitter from an adaptively estimated channel matrix H′

.

4. The wireless communication system according to claim 1, wherein said transmitter obtains transmit weights V for transmitting user data in the forward direction to said receiver beforehand, weights the reference signal and the user data by V, and transmits the user data following the reference signal over the spatially multiplexed channels.

5. The wireless communication system according to claim 4, wherein said receiver derives HV as a channel matrix from the reference signal weighted by V and continues to perform adaptive estimation of H′

V as a channel matrix during the reception of the user data transmitted in the forward direction from said transmitter, and, when transmitting user data in the reverse direction, following the reception of the user data, predetermines weights V′

for data transmission in the reverse direction by obtaining H′

by multiplying H′

V by V^H and by singular value decomposition of a transposed matrix of H′

.

6. A wireless communication apparatus which receives data transmitted from a transmitting end, using multiple spatially multiplexed communication channels, said wireless communication apparatus comprising:

a channel matrix acquisition unit which acquires a channel matrix in the forward direction from said transmitting end;

a receiving section which receives user data transmitted in the forward direction from said transmitting end and weights the user data with receive weights derived from the acquired channel matrix;

a channel matrix adaptive estimation unit which adaptively estimates the channel matrix H during reception of the user data transmitted in the forward direction from said transmitting end;

a reverse transmit weight determination unit which determines transmit weights for transmitting user data in the reverse direction to said transmitting end, based on the adaptively estimated channel matrix; and

a transmitting section which weights user data with the thus determined transmit weights and transmits the user data in the reverse direction to said transmitting end.

7. The wireless communication apparatus according to claim 6, wherein:

said transmitting end transmits user data following a reference signal for channel matrix acquisition, wherein the user data and the reference signal are weighted and transmitted over the spatially multiplexed channels; and

said channel matrix acquisition unit acquires the channel matrix H, based on the reference signal attached preceding the user data.

8. The wireless communication apparatus according to claim 6, wherein:

said transmitting end obtains transmit weights V for transmitting user data in the forward direction to the receiver beforehand, weights the reference signal and the user data by V, and transmits the user data following the reference signal over the spatially multiplexed channels;

said channel matrix acquisition unit derives HV as a channel matrix from the reference signal weighted by V;

said channel matrix adaptive estimation unit continues to perform adaptive estimation of H′

V as a channel matrix during the reception of the user data transmitted in the forward direction from said transmitting end; and

said reverse transmit weight determination unit, when the apparatus is transmitting user data in the reverse direction, following the reception of the user data in the forward direction, predetermines weights V′

for data transmission in the reverse direction by obtaining H′

by multiplying H′

V by V^H and by singular value decomposition of a transposed matrix of H′

.

9. A wireless communication method for receiving data transmitted from a transmitting end, using multiple spatially multiplexed communication channels, said wireless communication method comprising the steps of:

acquiring a channel matrix in the forward direction from said transmitting end;

receiving user data transmitted in the forward direction from said transmitting end and weights the user data with receive weights derived from the acquired channel matrix;

adaptively estimating the channel matrix H during reception of the user data transmitted in the forward direction from said transmitting end;

determining transmit weights for transmitting user data in the reverse direction to said transmitting end, based on the adaptively estimated channel matrix;

weighting user data with the thus determined transmit weights and transmitting the user data in the reverse direction to said transmitting end.

10. A computer program coded in a computer readable form to perform a process on a computer system for receiving data transmitted from a transmitting end, using multiple spatially multiplexed communication channels, said computer program comprises the steps of:

acquiring a channel matrix in the forward direction from said transmitting end;

adaptively estimating the channel matrix H as long as user data transmitted in the forward direction from said transmitting end is being received, while weighting the data with receive weights derived from the acquired channel matrix; and

determining transmit weights for transmitting user data in the reverse direction to said transmitting end, based on the adaptively estimated channel matrix.