EFFICIENT LINEAR DETECTION IMPLEMENTATION FOR MASSIVE MIMO

• US 20200021348A1
• Filed: 06/07/2019
• Published: 01/16/2020
• Est. Priority Date: 07/13/2018
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Technologies Oy (Nokia Corporation)
• Inventors: Shental, Ori
• Granted Patent: US 10,644,778 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0473 taking constraints in layer or codeword to antenna mapping into account
• CPC Class Codes: H04B 7/0478 Special codebook structures directed to feedback optimisation
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178

Abstract

Per given time instance, K samples b are acquired from a signal r, which is based at least on K transmitted symbols x and a transfer matrix H of a communication channel, and a linear detection matrix A of a size K×K is acquired, which is based at least on the transfer matrix H (S101). For the K samples b and the linear detection matrix A, at most K(K−1) tentative parameters b^˜ and at most K(K−1) tentative parameters A^˜ are iteratively calculated (S102).

It is checked whether or not the tentative parameters b^˜ and A^˜ have converged (S103). If b^˜ and A^˜ have converged, K estimation values x{circumflex over ( )} are decided for the K transmitted symbols x based on b^˜ and A^˜ (S104). If b^˜ and A^˜ have not converged, it is returned to the iteratively calculating b^˜ and A^˜ for the K samples b.

Claims

1. A method comprising:

per given time instance, acquiring K samples b from a signal r, which is based at least on K transmitted symbols x and a transfer matrix H of a communication channel, and a linear detection matrix A of a size K×

K, which is based at least on the transfer matrix H;

iteratively calculating at most K(K−

1) tentative parameters b^˜

and at most K(K−

1) tentative parameters A^˜

for the K samples b and the linear detection matrix A;

checking whether or not the tentative parameters b^˜

and A^˜

have converged;

if b^˜

and A^˜

have converged, deciding K estimation values x{circumflex over ( 

)} for the K transmitted symbols x based on b^˜

and A^˜

; and

if b^˜

and A^˜

have not converged, returning to the iteratively calculating b^˜

and A^˜

for the K samples b.

2. The method of claim 1, the iteratively calculating b^˜

and A^˜

comprising approximating a matrix inversion of the linear transfer matrix A.

3. The method of claim 1, the iteratively calculating b^˜

and A^˜

comprising calculating approximate values of the K transmitted symbols x.

4. The method of claim 1, comprising:

initializing the iteratively calculating b^˜

and A^˜

by using the K samples b and the K×

K matrix A as inputs.

5. The method of claim 1, comprising:

initializing the iteratively calculating b^˜

and A^˜

by replacing the K samples b with b−

Ax{circumflex over ( 

)}_t=0,

wherein the deciding comprises adding the K estimation values x{circumflex over ( 

)} to x{circumflex over ( 

)}_t=0, with x{circumflex over ( 

)}_t=0=(D<sup>−

1</sup>−

D<sup>−

1</sup>ED<sup>−

1</sup>)b,

where D and E are the diagonal and complementary off-diagonal matrices of the linear transfer matrix, respectively.

6. The method of claim 1, wherein the linear detection matrix A comprises a linear minimum mean-square-error detection matrix and zero forcing detection matrix.

7. The method of claim 1, comprising:

receiving the signal r from K transmitting units.

8. The method of claim 1, comprising:

receiving the K samples b from a preceding matched filter module.

9. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following:

per given time instance, acquiring K samples b from a signal r, which is based at least on K transmitted symbols x and a transfer matrix H of a communication channel, and a linear detection matrix A of a size K×

K, which is based at least on the transfer matrix H;

iteratively calculating at most K(K−

1) tentative parameters b^˜

and at most K(K−

1) tentative parameters A^˜

for the K samples b and the linear detection matrix A;

checking whether or not the tentative parameters b^˜

and A^˜

have converged;

if b^˜

and A^˜

have converged, deciding K estimation values x{circumflex over ( 

)} for the K transmitted symbols x based on b^˜

and A^˜

; and

if b^˜

and A^˜

have not converged, returning to the iteratively calculating b^˜

and A^˜

for the K samples b.

10. The non-transitory computer readable medium of claim 9, the iteratively calculating b^˜

and A^˜

comprising approximating a matrix inversion of the linear transfer matrix A.

11. The non-transitory computer readable medium of claim 9, the iteratively calculating b^˜

and A^˜

comprising calculating approximate values of the K transmitted symbols x.

12. The non-transitory computer readable medium of claim 9, comprising program instructions for causing the apparatus to further perform the following:

initializing the iteratively calculating b^˜

and A^˜

by using the K samples b and the K×

K matrix A as inputs.

13. The non-transitory computer readable medium of claim 9, comprising program instructions for causing the apparatus to further perform the following:

initializing the iteratively calculating b^˜

and A^˜

by replacing the K samples b with b−

Ax{circumflex over ( 

)}_t=0,

wherein the deciding comprises adding the K estimation values x{circumflex over ( 

)} to x{circumflex over ( 

)}_t=0, with x{circumflex over ( 

)}_t=0=(D<sup>−

1</sup>−

D<sup>−

1</sup>ED<sup>−

1</sup>)b,

where D and E are the diagonal and complementary off-diagonal matrices of the linear transfer matrix, respectively.

14. An apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following:

per given time instance, acquiring K samples b from a signal r, which is based at least on K transmitted symbols x and a transfer matrix H of a communication channel, and a linear detection matrix A of a size K×

K, which is based at least on the transfer matrix H;

iteratively calculating at most K(K−

1) tentative parameters b^˜

and at most K(K−

1) tentative parameters A^˜

for the K samples b and the linear detection matrix A;

checking whether or not the tentative parameters b^˜

and A^˜

have converged;

if b^˜

and A^˜

have converged, deciding K estimation values x{circumflex over ( 

)} for the K transmitted symbols x based on b^˜

and A^˜

; and

if b^˜

and A^˜

have not converged, returning to the iteratively calculating b^˜

and A^˜

for the K samples b.

15. The apparatus of claim 14, wherein the calculating is configured to

approximate a matrix inversion of the linear transfer matrix A, and/or

calculate approximate values of the K transmitted symbols x.

16. The apparatus of claim 14, wherein the calculating is configured to initialize the iterative calculation of b^˜

and A^˜

by using the K samples b and the K×

K matrix A as inputs.

17. The apparatus of claim 14, wherein

the calculating is configured to initialize the iterative calculation of b^˜

and A^˜

by replacing the K samples b with b−

Ax{circumflex over ( 

)}_t=0; and

the deciding is configured to add the K estimation values x{circumflex over ( 

)} to x{circumflex over ( 

)}_t=0, with x{circumflex over ( 

)}_t=0=(D<sup>−

1</sup>−

D<sup>−

1</sup>ED<sup>−

1</sup>)b,

where D and E are the diagonal and complementary off-diagonal matrices of the linear transfer matrix, respectively.

18. The apparatus of claim 14, wherein the linear detection matrix A comprises a linear minimum mean-square-error detection matrix and zero forcing detection matrix.

19. The apparatus of claim 14, wherein the acquiring is configured to

receive the signal r from K transmitting units, and/or

receive the K samples b from a preceding matched filter module.

20. The apparatus of claim 14, wherein the apparatus is implemented in a base station of a communication system, and/or is used for baseband processing, and/or is implemented in access points or handsets, and/or is used for wireless communication.