Iterative covariance inversion based on linear receiver designs

• US 9,007,942 B2
• Filed: 08/02/2012
• Issued: 04/14/2015
• Est. Priority Date: 08/02/2012
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhao, Wanlun, Ling, Fuyun, Fan, Mingxi, Chen, Jinghu
• Primary Examiner(s): Lai, Andrew
• Assistant Examiner(s): HENSON, JAMAAL R
• Application Number:
  US13/565,316
• Publication Number:
  US 20140036698A1
• Time in Patent Office: 985 Days
• Field of Search: 370/252
• US Class Current: 370/252
• CPC Class Codes: H04L 25/03133 with a non-recursive structure H04L25/03127 takes precedence
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

A method of wireless communication includes receiving a wireless signal at a linear receiver, and iteratively computing an inverted covariance matrix in frequency domain, one channel code at a time. The method also includes computing receiver demodulation coefficients based on the inverted covariance matrix and the frequency domain channel estimate or time domain channel estimate. The method further includes deriving a transmitter symbol based on a received signal vector and the coefficients.

Claims

1. A method of wireless communication, comprising:

receiving a wireless signal at a linear receiver;

computing a time domain channel estimate of the wireless signal;

computing a frequency domain channel estimate based on the time domain channel estimate;

iteratively computing an inverted covariance matrix in frequency domain, one channel code at a time;

computing receiver demodulation coefficients based on the inverted covariance matrix and the frequency domain channel estimate or time domain channel estimate;

deriving a transmitter symbol based on a received signal vector and the receiver demodulation coefficients; and

initializing a signal decoding process after deriving the transmitter symbols.

2. The method of claim 1, in which the time domain channel estimate is for a time division synchronous code division multiple access (TD-SCDMA) network.

3. The method of claim 1, in which the iterative computing comprises:

initializing the inverted covariance matrix;

computing an intermediate vector based on the frequency domain channel estimate, associated with a first channel code and the initialized inverted covariance matrix;

updating the inverted covariance matrix based on the intermediate vector;

repeatedly computing an updated intermediate vector based on the frequency domain channel estimate, associated with another channel code and a previous updated inverted covariance matrix; and

updating the inverted covariance matrix based on the updated intermediate vector.

4. The method of claim 3, in which the intermediate vector is calculated as t=R_i⁻

1d_i,k,

in which R_i<sup>−

1</sup> is a previous inverted covariance matrix, d_i,k is the frequency domain channel estimate, d is a vector, i is a beam index, and k is the k^th block of the vector.

5. The method of claim 4, in which the updating the inverted covariance matrix is calculated as R_i+1⁻

1=R_i<sup>−

1</sup>−

t(1+d_i,k^Ht)<sup>−

1</sup>t^H.

6. An apparatus for wireless communication, comprising:

means for receiving a wireless signal at a linear receiver;

means for computing a time domain channel estimate of the wireless signal;

means for computing a frequency domain channel estimate based on the time domain channel estimate;

means for iteratively computing an inverted covariance matrix in frequency domain, one channel code at a time;

means for computing receiver demodulation coefficients based on the inverted covariance matrix and the frequency domain channel estimate or time domain channel estimate;

means for deriving a transmitter symbol based on a received signal vector and the receiver demodulation coefficients; and

means for initializing a signal decoding process after deriving the transmitter symbols.

7. The apparatus of claim 6, in which the time domain channel estimate is for a time division synchronous code division multiple access (TD-SCDMA) network.

8. The apparatus of claim 6, in which the means for iterative computing comprises:

means for initializing the inverted covariance matrix;

means for computing an intermediate vector based on the frequency domain channel estimate, associated with a first channel code and the initialized inverted covariance matrix;

means for updating the inverted covariance matrix based on the intermediate vector;

means for repeatedly computing an updated intermediate vector based on the frequency domain channel estimate, associated with another channel code and a previous updated inverted covariance matrix; and

means for updating the inverted covariance matrix based on the updated intermediate vector.

9. The apparatus of claim 8, in which the means for computing the intermediate vector calculates:

t=R_i<sup>−

1</sup>d_i,k,

in which R_i<sup>−

1</sup> is a previous inverted covariance matrix, d_i,k is the frequency domain channel estimate, d is a vector, i is a beam index, and k is the k^th block of the vector.

10. The method of claim 9, in which the means for updating the inverted covariance matrix calculates:

R_i+1⁻

R_i⁻

t(1+d_i,k^Ht)<sup>−

1</sup>t^H.

11. A computer program product for wireless communication in a wireless network, comprising:

a non-transitory computer-readable medium having non-transitory program code recorded thereon, the program code comprising;

program code to receive a wireless signal at a linear receiver;

program code to compute a time domain channel estimate of the wireless signal;

program code to compute a frequency domain channel estimate based on the time domain channel estimate;

program code to iteratively compute an inverted covariance matrix in frequency domain, one channel code at a time;

program code to compute receiver demodulation coefficients based on the inverted covariance matrix and the frequency domain channel estimate or time domain channel estimate;

program code to derive a transmitter symbol based on a received signal vector and the receiver demodulation coefficients; and

program code to initialize a signal decoding process after deriving the transmitter symbols.

12. The computer program product of claim 11, in which the time domain channel estimate is for a time division synchronous code division multiple access (TD-SCDMA) network.

13. The computer program product of claim 11, in which the program code to iteratively compute comprises:

program code to initialize the inverted covariance matrix;

program code to compute an intermediate vector based on the frequency domain channel estimate, associated with a first channel code and the initialized inverted covariance matrix;

program code to update the inverted covariance matrix based on the intermediate vector;

program code to repeatedly compute an updated intermediate vector based on the frequency domain channel estimate, associated with another channel code and a previous updated inverted covariance matrix; and

program code to update the inverted covariance matrix based on the updated intermediate vector.

14. The computer program product of claim 13, in which the program code to compute the intermediate vector calculates:

t=R_i<sup>−

1</sup>d_i,k,

in which R_i<sup>−

1</sup> is a previous inverted covariance matrix, d_i,k is the frequency domain channel estimate, d is a vector, i is a beam index, and k is the k^th block of the vector.

15. The computer program product of claim 14, in which the program code to update the inverted covariance matrix calculates R_i+1⁻

1=R_i<sup>−

1</sup>−

t(1+d_i,k^Ht)⁻

t^H.

16. An apparatus for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory, the at least one processor being configured;

to receive a wireless signal at a linear receiver;

to compute a time domain channel estimate of the wireless signal;

to compute a frequency domain channel estimate based on the time domain channel estimate;

to iteratively compute an inverted covariance matrix in frequency domain, one channel code at a time;

to compute receiver demodulation coefficients based on the inverted covariance matrix and the frequency domain channel estimate or time domain channel estimate;

to derive a transmitter symbol based on a received signal vector and the receiver demodulation coefficients; and

to initialize a signal decoding process after deriving the transmitter symbols.

17. The apparatus of claim 16, in which the time domain channel estimate is for a time division synchronous code division multiple access (TD-SCDMA) network.

18. The apparatus of claim 16, in which the at least one processor is further configured:

to initialize the inverted covariance matrix;

to compute an intermediate vector based on the frequency domain channel estimate, associated with a first channel code and the initialized inverted covariance matrix;

to update the inverted covariance matrix based on the intermediate vector;

to repeatedly compute an updated intermediate vector based on the frequency domain channel estimate, associated with another channel code and a previous updated inverted covariance matrix; and

to update the inverted covariance matrix based on the updated intermediate vector.

19. The apparatus of claim 18, in which the at least one processor calculates the intermediate vector as t=R_i⁻

1d_i,k,

in which R_i<sup>−

1</sup> is a previous inverted covariance matrix, d_i,k is the frequency domain channel estimate, d is a vector, i is a beam index, and k is the k^th block of the vector.

20. The apparatus of claim 19, in which the at least one processor updates the inverted covariance matrix as R_i+1⁻

1=R_i<sup>−

1</sup>−

t(1+d_i,k^Ht)<sup>−

1</sup>t^H.