RATE ADAPTIVE TRANSMISSION SCHEME FOR MIMO SYSTEMS

• US 20100119005A1
• Filed: 01/20/2010
• Published: 05/13/2010
• Est. Priority Date: 10/16/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Vijayan, Rajiv, Agrawal, Avneesh, Kadous, Tamer
• Granted Patent: US 8,619,717 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• 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 method of processing data for transmission in a multiple-input multiple-output (MIMO) communication system, comprising:

receiving at least one data symbol stream, each of the at least one data symbol stream being scaled with a respective weight corresponding to an amount of transmit power allocated to the data symbol stream, wherein a 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 at least one transmit symbol stream for transmission via a plurality of antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of antennas and each of the at least one transmit symbol stream is transmitted via a corresponding antenna.

2. The method of claim 1, wherein the transmit basis matrix is a Walsh-Hadamard matrix.

3. The method of claim 1, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

4. The method of claim 1, further comprising:

allocating the total amount of 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.

5. The method of claim 4, wherein the amount of transmit power allocated to each of the at least one data symbol stream is determined based on channel condition.

6. The method of claim 1, 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.

7. The method of claim 6, wherein the single data symbol stream is transmitted on a spatial channel associated with a highest received signal quality.

8. The method of claim 1, 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.

9. The method of claim 1, 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.

10. The method of claim 1, wherein a variable number of data symbol streams is transmitted based on channel condition.

11. The method of claim 1, 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.

12. The method of claim 1, further comprising:

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

13. An apparatus used in a multiple-input multiple-output (MIMO) communication system, comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured to receive at least one data symbol stream, each of the at least one data symbol stream being scaled with a respective weight corresponding to an amount of transmit power allocated to the data symbol stream, wherein a 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

wherein the at least one processor is further configured to process the at least one data symbol stream with a transmit basis matrix to provide at least one transmit symbol stream for transmission via a plurality of antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of antennas and each of the at least one transmit symbol stream is transmitted via a corresponding antenna.

14. The apparatus of claim 13, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

15. An apparatus used in a multiple-input multiple-output (MIMO) communication system, comprising:

means for receiving at least one data symbol stream, each of the at least one data symbol stream being scaled with a respective weight corresponding to an amount of transmit power allocated to the data symbol stream, wherein a 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

means for processing the at least one data symbol stream with a transmit basis matrix to provide at least one transmit symbol stream for transmission via a plurality of antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of antennas and each of the at least one transmit symbol stream is transmitted via a corresponding antenna.

16. The apparatus of claim 15, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

17. A computer readable medium having program code recorded thereon, said program code comprising:

program code to cause at least one processor to receive at least one data symbol stream, each of the at least one data symbol stream being scaled with a respective weight corresponding to an amount of transmit power allocated to the data symbol stream, wherein a 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

program code to cause the at least one processor to process the at least one data symbol stream with a transmit basis matrix to provide at least one transmit symbol stream for transmission via a plurality of antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of antennas and each of the at least one transmit symbol stream is transmitted via a corresponding antenna.

18. The computer readable medium of claim 17, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

19. A method of processing symbols in a multiple-input multiple-output (MIMO) communication system, comprising:

receiving a plurality of transmit symbol streams via a plurality of receive antennas, wherein the plurality of received transmit symbol streams are obtained by processing at least one data symbol stream with a transmit basis matrix before transmission from a plurality of transmit antennas to the plurality of receive antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of transmit antennas and each of the plurality of transmit symbol stream is transmitted via a corresponding transmit antenna; and

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

20. The method of claim 19, wherein the processing the plurality of received transmit symbol streams comprises:

equalizing the plurality of received transmit 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.

21. The method of claim 20, wherein the equalizing is performed based on a matched filter matrix that comprises the transmit basis matrix.

22. The method of claim 19, further comprising:

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.

23. An apparatus used in a multiple-input multiple-output (MIMO) communication system, comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured to receive a plurality of transmit symbol streams via a plurality of receive antennas, wherein the plurality of received transmit symbol streams are obtained by processing at least one data symbol stream with a transmit basis matrix before transmission from a plurality of transmit antennas to the plurality of receive antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of transmit antennas and each of the plurality of transmit symbol stream is transmitted via a corresponding transmit antenna; and

wherein the at least one processor is further configured to process the plurality of received transmit symbol streams to recover the at least one data symbol stream.

24. The apparatus of claim 23, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

25. An apparatus used in a multiple-input multiple-output (MIMO) communication system, comprising:

means for receiving a plurality of transmit symbol streams via a plurality of receive antennas, wherein the plurality of received transmit symbol streams are obtained by processing at least one data symbol stream with a transmit basis matrix before transmission from a plurality of transmit antennas to the plurality of receive antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of transmit antennas and each of the plurality of transmit symbol stream is transmitted via a corresponding transmit antenna; and

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

26. The apparatus of claim 25, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.

27. A computer readable medium having program code recorded thereon, said program code comprising:

program code to cause at least one processor to receive a plurality of transmit symbol streams from a plurality of receive antennas, wherein the plurality of received transmit symbol streams are obtained by processing at least one data symbol stream with a transmit basis matrix before transmission from a plurality of transmit antennas to the plurality of receive antennas, wherein the transmit basis matrix is defined such that each of the at least one data symbol stream is transmitted via the plurality of transmit antennas and each of the plurality of transmit symbol stream is transmitted via a corresponding transmit antenna; and

program code to cause the at least one processor to process the plurality of received transmit symbol streams to recover the at least one data symbol stream.

28. The computer readable medium of claim 27, wherein the transmit basis matrix is a discrete Fourier transform (DFT) matrix.