Rate-Adaptive Multiple Input/Multiple Output (MIMO) Systems

• US 20110176599A1
• Filed: 03/15/2011
• Published: 07/21/2011
• Est. Priority Date: 01/31/2003
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Inventors: Winters, Jack Harriman, Luo, Hui, Sollenberger, Nelson Ray
• Granted Patent: US 8,433,258 B2
• Time in Patent Office: Days
• US Class Current: 375/227
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

A rate-adaptive method of communicating over a multipath wireless communication system uses multiple links such that each end of a link uses multiple transmit and receive antennas. A number of independent streams that are to be transmitted for each link is determined based on an overall system performance measure. In addition, the system may also jointly determine the best modulation, coding, power control, and frequency assignment for each link, based on an overall system performance measure. In OFDM systems, the number of independent streams, as well as the modulation, coding, and power control, may be determined on a tone-by-tone basis based on an overall system performance measure.

Claims

1. A system that includes a first terminal, where said first terminal comprises:

N antennas, where N is at least one; and

a processor, responsive to M signals received from transmitting antennas of a second terminal by said N antennas, where M is greater than one, for

determining an overall measure of goodness in detecting information received from said second terminal,

determining attributes of preferred information transfer to said first terminal from said second terminal, in terms of

number of data streams,

modulation methods, and

coding type and rate that said second terminal is to employ in next frame communication to said first terminal, and

sending to said second terminal an instruction that specifies said number of data stream, modulation methods, and coding type and rate.

2. The system of claim 1 where said measure of goodness is based on overall system throughput over all links, where a link is channel from between one antenna of said N antennas of said first terminal and one said M antennas of said second terminal.

3. The system of claim 1 where said measure of goodness is based on signal-to-interference-and-Noise-Ratio (SINR) for at least one of link, where a link is channel from between one antenna of said N antennas of said first terminal and one said M antennas of said second terminal.

4. The system of claim 1 where said measure of goodness is based on minimum mean squared error for at least one link, where a link is channel from between one antenna of said N antennas of said first terminal and one said M antennas of said second terminal.

5. The system of claim 1 where said measure of goodness is based on a calculated data rate for at least one link, where a link is channel from between one antenna of said N antennas of said first terminal and one said M antennas of said second terminal.

6. The system of claim 1 where said measure of goodness is based on a minimum of a maximum delay for at least one link, where a link is channel from between one antenna of said N antennas of said first terminal and one said M antennas of said second terminal.

7. The system of claim 1 where said measure of goodness is based on a maximum of a minimum data rate for each link, where a link is channel from between one antenna of said N antennas of said first terminal and one said M antennas of said second terminal.

8. The system of claim 1 further comprising said second terminal, where M=N, and said first and second terminals employ orthogonal frequency division multiplexing (OFDM).

9. The system of claim 1 further comprising said second terminal, where:

(1) at transmission onset, the second terminal transmits one data stream in a downlink frame to said first terminal using a modulation method, a coding scheme, and a coding rate that are chosen based on A or B, or on A and B, where A is average SINR for communication from said second terminal to said first terminal, and B is a default system configuration, said one data stream including a training sequence of known symbols;

(2) after receiving said one data stream, said first terminal computes a weight for each of said N antennas and generates a composite signal that is the weighted summation of the signals received by said N antennas that minimizes mean-squared error (MSE) of decoded version of the training sequence contained in said one data stream;

(3) based on the composite signal, said first terminal decodes payload data, a CRC sequence, and a control sequence that are contained in said one data stream;

(4) if the decoded CRC sequence matches a CRC sequence computed from the decoded payload sequence, an ARQ flag in a control sequence in said instruction is set to indicate “

transmit next downlink frame” and

, otherwise the ARQ flag is set to request a retransmission of said one data stream;

(5) said first terminal formulates said attributes, include said attributes in said instruction and sends said instruction to said second terminal;

(6) after receiving said instruction, said second terminal sends a frame of one or more data streams in conformance of said instruction;

(7) after receiving said frame of one or more data streams, said first terminal station computes a best weight for each of said N antennas and generates a composite signal that is the weighted summation of the signals received by said N antennas that minimizes mean-squared error (MSE) of a decoded version of a training sequence contained in said frame of one or more data streams;

(8) based on the composite signal, said first terminal decodes payload data, a CRC sequence, and a control sequence that are contained in said frame of one or more data streams;

(9) based on the composite signal, said first terminal decodes payload data, determines number of streams, the coding scheme and coding rate that ought to be employed by said second terminal, constructs a new instruction, and sends the new instruction to said second terminal; and

(10) return to step (6).