Rate adaptive transmission scheme for MIMO systems

• US 7,675,886 B2
• Filed: 08/16/2004
• Issued: 03/09/2010
• Est. Priority Date: 10/16/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Agrawal, Avneesh, Vijayan, Rajiv, Kadous, Tamer
• Primary Examiner(s): Ton; Dang T
• Assistant Examiner(s): O CONNOR, BRIAN T
• Application Number:
  US10/919,698
• Publication Number:
  US 20050013239A1
• Time in Patent Office: 2,031 Days
• Field of Search: 370/203, 370/208, 370/209, 370/210, 370/334, 370/310, 375/267, 375/299, 375/347
• US Class Current: 370/334
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0443 utilizing "waterfilling" technique
• CPC Class Codes: H04B 7/0465 taking power constraints at power amplifier or emission constraints, e.g. constant modulus, into account
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

A rate adaptive transmission scheme for MIMO systems, which can transmit a variable number of data symbol streams, provide transmit diversity for each data symbol stream, and fully utilize the total transmit power of the system and the full power of each antenna. In one method, at least one data symbol stream is received for transmission from a plurality of antennas. Each data symbol stream is scaled with a respective weight corresponding to the amount of transmit power allocated to that stream. The scaled data symbol stream(s) are multiplied with a transmit basis matrix to provide a plurality of transmit symbol streams for the plurality of antennas. The transmit basis matrix (e.g., a Walsh-Hadamard matrix or a DFT matrix) is defined such that each data symbol stream is transmitted from all antennas and each transmit symbol stream is transmitted at (or near) the full power for the associated antenna.

Claims

1. A receiver apparatus in a multiple-input multiple-output (MIMO) communication system, comprising:

means for obtaining a plurality of streams of received symbols for a plurality of receive antennas, wherein the plurality of received symbol streams comprise at least one stream of data symbols having been processed with a transmit basis matrix to form a plurality of streams of transmit symbols for a plurality of transmit antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted from the plurality of transmit antennas and each transmit symbol stream is transmitted at or near full power available for the associated transmit antenna; and

means for processing the plurality of received symbol streams to recover the at least one data symbol stream.

2. The receiver apparatus of claim 1, wherein the means for processing includes

means for equalizing the plurality of received symbol streams to obtain an estimate of the at least one data symbol stream, and

means for decoding the estimate of the at least one data symbol stream.

3. The receiver apparatus of claim 1, further comprising:

means for estimating a received signal quality for each of the at least one data symbol stream; and

means for determining a rate for each of the at least one data symbol stream based on the estimated received signal quality.

4. A processor-readable memory having instructions thereon, the instructions being executable for:

receiving at least one stream of data symbols for transmission from a plurality of antennas;

scaling each of the at least one data symbol stream with a respective weight corresponding to an amount of transmit power allocated to the data symbol stream, wherein total amount of transmit power allocated to the at least one data symbol stream is less than or equal to total transmit power available for the system; and

processing the at least one data symbol stream with a transmit basis matrix to provide a plurality of streams of transmit symbols, one transmit symbol stream for each of the plurality of antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted from the plurality of antennas and each transmit symbol stream is transmitted at or near full power available for the associated antenna.

5. The processor-readable memory of claim 4, wherein the transmit basis matrix is a Walsh-Hadamard matrix.

6. The processor-readable memory of claim 4, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

7. The processor-readable memory of claim 4, wherein the instructions are further executable for:

allocating the total transmit power to the at least one data symbol stream, and wherein the weight for each data symbol stream is determined based on the amount of transmit power allocated to the data symbol stream.

8. The processor-readable memory of claim 7, wherein the amount of transmit power allocated to each of the at least one data symbol stream is determined based on channel condition.

9. The processor-readable memory of claim 4, wherein a single data symbol stream is transmitted from the plurality of antennas at or near full power available for each of the plurality of antennas.

10. The processor-readable memory of claim 9, wherein the single data symbol stream is transmitted on a spatial channel associated with a highest received signal quality.

11. The processor-readable memory of claim 4, wherein N_T data symbol streams are transmitted from N_T antennas at or near full power available for each of the N_T antennas, where N_T is an integer greater than one.

12. The processor-readable memory of claim 4, wherein N_D data symbol streams are transmitted from N_T antennas at or near full power available for each of the N_T antennas, where N_T is an integer greater than one and N_D is an integer less than or equal to N_T.

13. The processor-readable memory of claim 4, wherein a variable number of data symbol streams is transmitted based on channel condition.

14. The processor-readable memory of claim 4, wherein each of the at least one data symbol stream is associated with a particular rate determined based at least in part on a received signal quality for the data symbol stream.

15. The processor-readable memory of claim 4, wherein the instructions are further executable for:

multiplexing pilot symbols in each of the plurality of transmit symbol streams.

16. A processor-readable memory having instructions thereon, the instructions being executable for:

obtaining a plurality of streams of received symbols for a plurality of receive antennas, wherein the plurality of received symbol streams comprise at least one stream of data symbols having been processed with a transmit basis matrix to form a plurality of streams of transmit symbols for a plurality of transmit antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted from the plurality of transmit antennas and each transmit symbol stream is transmitted at or near full power available for the associated transmit antenna; and

processing the plurality of received symbol streams to recover the at least one data symbol stream.

17. The processor-readable memory of claim 16, wherein the processing includes

equalizing the plurality of received symbol streams to obtain an estimate of the at least one data symbol stream, and

decoding the estimate of the at least one data symbol stream.

18. The processor-readable memory of claim 17, wherein the equalizing is performed based on a matched filter matrix that comprises the transmit basis matrix.

19. The processor-readable memory of claim 16, wherein the instructions are further executable for:

estimating a received signal quality for each of the at least one data symbol stream; and

determining a rate for each of the at least one data symbol stream based on the estimated received signal quality.