Method of maximizing MIMO system performance by joint optimization of diversity and spatial multiplexing

• US 20060098760A1
• Filed: 11/08/2004
• Published: 05/11/2006
• Est. Priority Date: 11/08/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Niu, Huaning, Shen, Jun, Ngo, Chiu Y.
• Granted Patent: US 7,627,051 B2
• Time in Patent Office: Days
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 25/0224 using sounding signals

Abstract

A method of transmission in a wireless communication system having a transmitter and a receiver. In the transmitter: signals are encoded using a space-domain precoder for spatial multiplexing, time-domain variable delay is introduced at each signal communication path for time diversity, and the signal are transmitted to the receiver. In the receiver the signal transmissions from the transmitter are decoded using a space-domain decoder, wherein time diversity and spatial multiplexing are combined, to increase communication robustness and spectral efficiency.

Claims

1. A wireless communication system comprising:

a transmitter including a space-domain precoder, and a variable delay device that introduces time-domain variable delay at each signal communication path for time diversity;

a receiver including a space-domain decoder, the receiver receiving signal transmissions from the transmitter;

such that the transmitter and the receiver combine time diversity and spatial multiplexing, to increase communication robustness and spectral efficiency.

2. The system of claim 1, wherein the precoder and the decoder comprise a pair of linear matrices such that their entries are transformation optimized.

3. The system of claim 1, wherein the precoder and the decoder comprise a pair of linear matrices such that their entries are transformation optimized along with variable time delay for each communication path.

4. The system of claim 1 wherein:

the variable delay device, the precoder and the decoder are configured such that time diversity gain and spectral efficiency gain via spatial multiplexing are essentially jointly optimized.

5. The system of claim 1, wherein the wireless communication system comprises a multiple-input multiple-output (MIMO) system, such that the transmissions from the transmitter form multipaths.

6. The system of claim 1 wherein the variable delay device introduces delay in each path to modify the signal characteristics such that the signal along different paths are received with higher diversity order at the receiver.

7. The system of claim 6 wherein:

the receiver sends CSI back to the transmitter including eigenmode power distribution and precoder matrix, and

the variable delay device determines the variable delays based on the feedback from the receiver to provide substantially uncorrelated at the receiver.

8. A method of transmission in a wireless communication system including a transmitter and a receiver, comprising the steps of:

in the transmitter;

preceding signals using a space-domain precoder for spatial multiplexing;

introducing time-domain variable delay at each signal communication path for time diversity; and

transmitting the signals to the receiver; and

in the receiver;

decoding the signal transmissions from the transmitter using a space-domain decoder;

wherein time diversity and spatial multiplexing are combined, to increase communication robustness and spectral efficiency.

9. The method of claim 8, wherein the precoder and the decoder comprise a pair of linear matrices such that their entries are transformation optimized.

10. The method of claim 9, wherein the precoder and decoder comprise a pair of linear matrices such that their entries are transformation optimized along with variable time delay for each communication path.

11. The method of claim 8 wherein the variable delay device introduces variable time delays are introduced such that signal along different paths are received with higher diversity order at the receiver.

12. The method of claim 8 further comprising the steps of essentially jointly optimizing time diversity gain and spectral efficiency gain via spatial multiplexing.

13. The method of claim 8, wherein the wireless communication system comprises a multiple-input multiple-output (MIMO) system, such that the transmissions from the transmitter form multipaths.

14. The method of claim 13, wherein the step of joint optimization further includes the steps of:

computing singular value decomposition of a channel matrix H to obtain multiple data streams;

allocating eigenmodes to the data streams; and

providing diversity across the eigenmodes to maximize post-combination SNR of the data streams.

15. The method of claim 14, wherein the step of allocating the eigenmodes further includes the steps of:

determining the sum of the eigenvalues of all subcarriers for each eigenmode, and allocating the eigenmodes to different data streams as evenly as possible, using an iterative process.

16. The method of claim 15, wherein the step of allocating the eigenmodes further includes the steps of:

using diversity to protect small eigenvalues.