Methods and apparatuses for reducing feedback overhead

Patent metadata

Field	Value
Publication number	US-12438583-B2
Application number	US-202418676535-A
Country	US
Kind code	B2
Filing date	May 29, 2024
Priority date	Nov 13, 2018
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

The invention describes a method performed by a radio network node, a network node, a method performed by a UE and a UE for reducing s feedback overhead. The method performed by the UE is decomposing each entry corresponding to a combining coefficient of a precoder matrix into at least two coefficients and quantizing, separately, each of two coefficients with a least one bit, and reporting information related to a phase value or an amplitude value or at a phase value and an amplitude value of the quantized coefficient.

First claim

The invention claimed is:

1. A method comprising:
decomposing each (i,j)-th combining coefficient of a precoder matrix W 2 (r) into at least two coefficients,
wherein r denotes a r-th transmission layer,
wherein the (i,j)-th combining coefficient is associated with a i-th beam and a j-th delay,
wherein each combining coefficient is associated with an amplitude and a phase-information,
wherein the decomposed (i,j)-th combining-coefficient of the matrix W 2 (r) is given by:
[ W 2 (r) ] i,j a i b i ,

wherein b i,j is a complex-valued normalized combining coefficient associated with the i-th beam and j-th delay,
wherein a i is a real-valued coefficient representing a common amplitude for the combining coefficients for all delays associated with the i-th beam;
quantizing each of the at least two coefficients with at least one bit; and
reporting the amplitude and phase values of quantized non-zero coefficients b i,j .

2. The method according to claim 1 , further comprising reporting the indices of the quantized non-zero coefficients b i,j in a bitmap, wherein each bit of the bitmap is associated with one coefficient b i,j .

3. The method according to claim 1 , further comprising:
quantizing each of the a i with N a bits; and
quantizing each of the b i,j with N b,1 bits for the amplitude and N b,2 bits for the phase,
wherein N b,1 is less than N b,2 .

4. The method according to claim 3 , further comprising representing each amplitude value by two quantization levels “a” and “b”, wherein N b,1 =1.

5. The method according to claim 1 , further comprising:
quantizing the entries of matrix W 2 (r) with N a bits per amplitude and N a bits per phase; and
using 2UDN a bits for reporting the coefficients of W 2 (r) ,
wherein UD is the number of combining coefficients.

6. The method according to claim 5 wherein when N a =3, the amplitude set for quantizing a i is selected from the group consisting of

{

1
,

0.5

,

0.25

,

0.125

,

0.0625

,

0.0313

,

0.0156

,
0

}

.

7. The method according to claim 1 , further comprising applying different quantization levels for the phase values of the quantized non-zero coefficients b i,j .

8. The method according to claim 7 , further comprising using N b,2 ′ bits for the phase values associated with non-zero coefficients b i,j and the U′ strongest beams and N b,2 ″ bits for the phase values associated with the non-zero coefficients b i,j and the remaining beams, wherein N b,2 ′>N b,2 ″.

9. The method according to claim 1 , further comprising reporting indices of Discrete Fourier Transform/Discrete Cosine Transform, vectors associated with the complex combining coefficients of a matrix K F (r) .

10. The method according to claim 9 , further comprising selecting the Discrete Fourier Transform/Discrete Cosine Transform vectors from a group of predefined Discrete Fourier Transform/Discrete Cosine Transform basis vectors, wherein each Discrete Fourier Transform/Discrete Cosine Transform basis vector is associated with an index.

11. The method according to claim 10 , further comprising reporting a bitmap, wherein each bit in the bitmap is associated with an index “d” from the group of Discrete Fourier Transform/Discrete Cosine Transform basis vectors associated with the complex combining coefficients of matrix K F (r) .

12. The method according to claim 1 ,
wherein a number of leading beams is B,
wherein a number of spatial beams configured is L,
wherein the leading beams for which the amplitude values of b i,j shall be reported is given by B=2L or 2L−1,
wherein the reporting uses a Discrete Fourier Transform/Discrete Cosine Transform transformation.

13. The method according to claim 1 , wherein the amplitude set for quantization of b i,j is selected from the group consisting of {0, 1}.

14. The method according to claim 1 , wherein the phase set for quantizing b i,j is selected from the group consisting of 8PSK, Phase Shift Keying or constellation or a 16PSK constellation.

15. The method according claim 1 , further comprising:
reporting the phase and amplitude values associated with the coefficient b i,j when a bit in bitmap is set to one; and
reporting the bitmap, wherein each bit in the bitmap is associated with each of the b i,j .

16. The method according to claim 15 , wherein the bitmap comprises K or less than K “1”s.

17. The method according to claim 15 , further comprising reporting the amplitude and phase information with respect to the non-zero coefficients of the quantized matrix W 2 (r) when the number of non-zero amplitude values of the quantized matrix W 2 (r) is less than K.

18. A method comprising:
decomposing each (i,j)-th combining coefficient of a precoder matrix W 2 (r) into at least two coefficients,
wherein r denotes a r-th transmission layer,
wherein the (i, j)-th combining coefficient is associated with a i-th beam and a j-th delay,
wherein each combining coefficient is associated with an amplitude and a phase-information,
wherein the decomposed (i, j)-th combining-coefficient of the matrix W 2 (r) is given by:
[ W 2 (r) ] i,j =a i b i,j ,

wherein b i,j is a complex-valued normalized combining coefficient associated with the i-th beam and j-th delay,
wherein a i is a real-valued coefficient representing a common amplitude for the combining coefficients for all delays associated with the i-th beam;

quantizing each of the at least two coefficients with at least one bit; and
reporting information from the coefficients in W 2 (r) , wherein the information comprises only phase values or only amplitude values.

19. The method according to claim 18 , further comprising reporting the amplitude and phase values of K strongest coefficients of matrix W 2 (r) , wherein the value of the parameter K is configurable.

20. The method according to claim 19 , further comprising selecting K u strongest coefficients per row/beam out of matrix W 2 (r) , wherein the K u is configurable.

21. The method according to claim 19 , further comprising selecting K d strongest coefficients per column/delay out of matrix W 2 (r) , wherein the K d is configurable.

22. The method according to claim 18 , further comprising reporting indices of Discrete Fourier Transform/Discrete Cosine Transform, vectors associated with the complex combining coefficients of a matrix K F (r) .

23. The method according to claim 22 , further comprising selecting the Discrete Fourier Transform/Discrete Cosine Transform vectors from a group of predefined Discrete Fourier Transform/Discrete Cosine Transform basis vectors, wherein each Discrete Fourier Transform/Discrete Cosine Transform basis vector i

Assignees

• Koninklijke Philips Nv

Inventors

• Grossmann Marcus
• Venkatesh Ramireddy
• Landmann Markus

Classifications

• H04B7/0456

  Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting · CPC title

• H04B7/0626 Primary

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B7/0478 Primary

  Special codebook structures directed to feedback optimisation · CPC title