MIMO equalizer method and apparatus

• US 8,077,805 B1
• Filed: 04/28/2008
• Issued: 12/13/2011
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Sarrigeorgidis, Konstantinos
• Primary Examiner(s): Ahn, Sam K
• Application Number:
  US12/111,029
• Time in Patent Office: 1,324 Days
• Field of Search: 375/142, 375/143, 375/144, 375/148, 375/150, 375/152, 375/267, 375/299, 375/316, 375/343, 375/346, 375/347, 375/349, 455/63.1, 455/114.2, 455/278.1, 455/296, 455/101, 455132-141, 700/53
• US Class Current: 375/316
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry

Abstract

A training signal is received, and a channel estimate matrix is determined based on the received training signal. The channel estimate matrix is partitioned into a plurality of block matrices, wherein at least one of the block matrices has at least one dimension greater than one. Additionally, a multiple input, multiple output (MIMO) equalizer is calculated based on a block matrix inverse or pseudo-inverse of the partitioned channel estimate matrix, and the MIMO equalizer is applied to data signals.

Claims

1. A method, comprising:

receiving a training signal;

determining a channel estimate matrix based on the received training signal;

partitioning the channel estimate matrix into a matrix [A B], wherein A is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of block matrix A, and wherein B is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of the block matrix B, and wherein at least one of the block matrices A and B contains elements corresponding to more than one receive and/or more than one transmit antenna;

calculating a multiple input, multiple output (MIMO) equalizer based on a block matrix inverse or pseudo-inverse of the partitioned channel estimate matrix, wherein calculating the MIMO equalizer comprises;

calculating P_A^⊥

=I−

A(A^TA)<sup>−

1</sup>A^T,

calculating P_B^⊥

=I−

B(B^TB)<sup>−

1</sup>B^T,

calculating P_A^⊥

B,

calculating P_B^⊥

A,

calculating (P_A^⊥

B)⁺, and

calculating (P_B^⊥

A)⁺,

wherein I is an identity matrix, and

P_A^⊥

and P_B^⊥

are orthogonal projection matrices; and

applying the MIMO equalizer to data signals.

2. The method of claim 1, wherein partitioning the channel estimate matrix into the matrix [A B] comprises partitioning the channel estimate matrix into a matrix [a b], wherein a is a vector having three rows, and wherein b is a vector having three rows.

3. The method of claim 2, wherein calculating the MIMO equalizer comprises:

calculating

4. The method of claim 1, further comprising adjusting the MIMO equalizer during reception of a packet, and wherein applying the MIMO equalizer to data signals comprises:

applying the MIMO equalizer to one or more symbols in the packet prior to adjusting the MIMO equalizer; and

applying the MIMO equalizer to one or more additional symbols in the packet after adjusting the MIMO equalizer.

5. A method, comprising:

receiving a training signal;

determining a channel estimate matrix based on the received training signal;

partitioning the channel estimate matrix into a matrix

6. The method of claim 5, wherein A is a 2×

2 matrix, B is 2×

1 vector, C is 1×

2 vector, D is a scalar;

wherein calculating the MIMO equalizer comprises calculating A<sup>−

1</sup> prior to receiving a third high throughput long training field (HT-LTF).

7. The method of claim 6, wherein calculating the MIMO equalizer comprises calculating and storing a matrix

8. The method of claim 5, further comprising adjusting the MIMO equalizer during reception of a packet, and wherein applying the MIMO equalizer to data signals comprises:

applying the MIMO equalizer to one or more symbols in the packet prior to adjusting the MIMO equalizer; and

applying the MIMO equalizer to one or more additional symbols in the packet after adjusting the MIMO equalizer.

9. An apparatus for a multiple input, multiple output (MIMO) receiver, comprising:

a matrix equalizer configured to;

determine a channel estimate matrix based on a training signal;

partition the channel estimate matrix into a matrix [A B], wherein A is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of block matrix A, and wherein B is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of the block matrix B, wherein at least one of the block matrices A and B contains elements corresponding to more than one receive and/or more than one transmit antenna;

calculate a MIMO equalizer based on a block matrix inverse or pseudo-inverse of the partitioned channel estimate matrix, wherein calculating the MIMO equalized comprises;

calculating P_A^⊥

=I−

A(A^TA)<sup>−

1</sup>A^T,

calculating P_B^⊥

=I−

B(B^TB)<sup>−

1</sup>B^T,

calculating P_A^⊥

B,

calculating P_B^⊥

A,

calculating (P_A^⊥

B)⁺, and

calculating (P_B^⊥

A)⁺,

wherein I is an identity matrix, and

P_A^⊥

and P_B^⊥

are orthogonal projection matrices; and

apply the MIMO equalizer to data signals.

10. The apparatus of claim 9, wherein partitioning the channel estimate matrix into the matrix [A B] comprises partitioning the channel estimate matrix into a matrix [a b], wherein a is a vector having three rows, and wherein b is a vector having three rows.

11. The apparatus of claim 10, wherein the matrix equalizer is configured to:

calculate

12. The apparatus of claim 9, further comprising a matrix equalizer update block coupled to the matrix equalizer;

wherein matrix equalizer update block is configured to generate a plurality of adjustments to the MIMO equalizer during reception of a packet; and

wherein the matrix equalizer is configured to;

apply the MIMO equalizer to one or more symbols in the packet after each adjustment to the MIMO equalizer.

13. An apparatus for a multiple input, multiple output (MIMO) receiver, comprising:

a matrix equalizer configured to;

determine a channel estimate matrix based on a training signal;

partition the channel estimate matrix

14. The apparatus of claim 13, wherein A is a 2×

2 matrix, B is 2×

1 vector, C is 1×

2 vector, D is a scalar;

wherein the matrix equalizer is configured to calculate A<sup>−

1</sup> prior to receiving a third high throughput long training field (HT-LTF).

15. The apparatus of claim 14, wherein the matrix equalizer comprises a memory;

wherein the matrix equalizer is configured to calculate and store in the memory a matrix

16. The apparatus of claim 13, further comprising a matrix equalizer update block coupled to the matrix equalizer;

wherein matrix equalizer update block is configured to generate a plurality of adjustments to the MIMO equalizer during reception of a packet; and

wherein the matrix equalizer is configured to;

apply the MIMO equalizer to one or more symbols in the packet after each adjustment to the MIMO equalizer.

17. A method of wirelessly receiving signals in a multiple input, multiple output (MIMO) communication system having a receiver with a plurality of receive antennas and a transmitter with a plurality of transmit antennas, the method comprising:

receiving a training signal;

demodulating the training signal to produce a demodulated training signal;

determining a channel estimate matrix based on the demodulated training signal;

partitioning the channel estimate matrix into a matrix [A B], wherein A is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of block matrix A, and wherein B is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of the block matrix B, and wherein at least one of the block matrices A and B contains elements corresponding to more than one receive and/or more than one transmit antenna;

calculating a multiple input, multiple output (MIMO) equalizer based on a block matrix inverse or pseudo-inverse of the partitioned channel estimate matrix, wherein calculating the MIMO equalizer comprises;

calculating P_A^⊥

=I−

A(A^TA)<sup>−

1</sup>A^T,

calculating P_B^⊥

=I−

B(B^TB)<sup>−

1</sup>B^T,

calculating P_A^⊥

B,

calculating P_B^⊥

A,

calculating (P_A^⊥

B)⁺, and

calculating (P_B^⊥

A)⁺,

wherein I is an identity matrix, and

P_A^⊥

and P_B^⊥

are orthogonal projection matrices;

receiving a data signal;

demodulating the data signal to produce a demodulated data signal;

applying the MIMO equalizer to the demodulated data signal to produce an equalized data signal; and

decoding the equalized data signal.

18. The method of claim 17, further comprising adjusting the MIMO equalizer during reception of a packet, and wherein applying the MIMO equalizer to the demodulated data signal comprises:

applying the MIMO equalizer to one or more symbols in the packet prior to adjusting the MIMO equalizer; and

applying the MIMO equalizer to one or more additional symbols in the packet after adjusting the MIMO equalizer.

19. A wireless receiver for receiving signals in a multiple input, multiple output (MIMO) communication system, the wireless receiver comprising:

a plurality of receive antennas;

a signal demodulator coupled to the plurality of receive antennas and adapted to demodulate signals received via the plurality of receive antennas to produce a demodulated signal;

a matrix equalizer coupled to the signal demodulator to generate an equalized signal; and

a decoder coupled to the matrix equalizer and adapted to decode the equalized signal;

where the matrix equalizer is configured to;

determine a channel estimate matrix based on a demodulated training signal;

partition the channel estimate matrix into a matrix [A B], wherein A is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of block matrix A, and wherein B is a block matrix having a row dimension of at least three and a column dimension less than the row dimension of the block matrix B, wherein at least one of the block matrices A and B contains elements corresponding to more than one receive and/or more than one transmit antenna;

calculate a MIMO equalizer based on a block matrix inverse or pseudo-inverse of the partitioned channel estimate matrix, wherein calculating the MIMO equalized comprises;

calculating P_A^⊥

=I−

A(A^TA)<sup>−

1</sup>A^T,

calculating P_B^⊥

=I−

B(B^TB)<sup>−

1</sup>B^T,

calculating P_A^⊥

B,

calculating P_B^⊥

A,

calculating (P_A^⊥

B)⁺, and

calculating (P_B^⊥

A)⁺,

wherein I is an identity matrix, and

P_A^⊥

and P_B^⊥

are orthogonal projection matrices.

20. The wireless receiver of claim 19, further comprising a matrix equalizer update block coupled to the matrix equalizer and coupled to the decoder;

wherein matrix equalizer update block is configured to generate a plurality of adjustments to the MIMO equalizer during reception of a packet based on output of the decoder; and

wherein the matrix equalizer is configured to apply the MIMO equalizer to one or more symbols in the packet after each adjustment to the MIMO equalizer.