Method and apparatus for codebook subset restriction for CSI reporting in advanced wireless communication systems

1. A user equipment (UE) for channel state information (CSI) reporting in a wireless communication system, the UE comprising:

a transceiver configured to receive, from a base station (BS), a higher layer signaling including codebook subset restriction (CBSR) information; and

a processor operably connected to the transceiver, the processor configured to:

determine a bitmap sequence B based on the CBSR information, wherein the bitmap sequence B includes a first bitmap sequence B 1 and a second bitmap sequence B 2 ,

determine the first bitmap sequence B 1 and the second bitmap sequence B 2 based on the bitmap sequence B,

identify, based on the first bitmap sequence B 1 and the second bitmap sequence B 2 , a restriction on P beam groups out of Q beam groups G(r 1 ,r 2 ) for the CSI reporting, wherein:

P is a positive integer and is less than or equal to Q,

Q is a total number of beam groups G(r 1 ,r 2 ), and

an index pair (r 1 ,r 2 ) indicates a beam group of the Q beam groups G(r 1 ,r 2 ), and

generate a CSI report based on the P beam groups with the identified restriction for the CSI reporting and remaining Q minus P beam groups without any restrictions for the CSI reporting, wherein the remaining beam groups are determined as the Q beam groups G(r 1 ,r 2 ) minus the P beam groups,

wherein the transceiver is further configured to transmit the CSI report to the BS.

2. The UE of claim 1 , wherein each beam group G(r 1 ,r 2 ) corresponds to a vector group comprising N 1 N 2 discrete Fourier transform (DFT) vectors, where N 1 and N 2 are indicated by the higher layer signaling are a number of antenna ports with a given polarization in a first and second dimension of an antenna port layout at the BS, respectively.

3. The UE of claim 2 , wherein Q=O 1 O 2 and the Q vector groups are given by

G ( r 1 ,r 2 )={ v N 1 r 1 +x 1 ,N 2 r 2 +x 2 :x 1 =0,1, . . . , N 1 −1; x 2 =0,1, . . . , N 2 −1},

where:

r

1

∈

{

0

,

1

,

…

⁢

,

O

1

-

1

}

r

2

∈

{

0

,

1

,

…

⁢

,

O

2

-

1

}

,

v l,m is a DFT vector:

v

l

,

m

=

[

u

m

e

j

⁢

2

⁢

π

⁢

⁢

l

O

1

⁢

N

1

⁢

u

m

…

e

j

⁢

2

⁢

π

⁢

⁢

l

⁡

(

N

1

-

1

)

O

1

⁢

N

1

⁢

u

m

]

T

with

⁢

⁢

u

m

=

{

[

1

e

j

⁢

2

⁢

π

⁢

⁢

m

O

2

⁢

N

2

…

e

j

⁢

2

⁢

π

⁢

⁢

m

⁡

(

N

2

-

1

)

O

2

⁢

N

2

]

N

2

>

1

1

N

2

=

1

;

 and

O 1 and O 2 are oversampling factors in the first and second dimension, respectively.

4. The UE of claim 1 , wherein P is four.

5. The UE of claim 1 , wherein:

the bitmap sequence B=B 1 B 2 is a concatenation of the first bitmap sequence B 1 and the second bitmap sequence B 2 ,

the first bitmap sequence B 1 indicates index pairs (r 1 ,r 2 ) of the P beam groups G(r 1 ,r 2 ),

the second bitmap sequence B 2 =B (1) B (2) . . . B (P) is a concatenation of P bitmaps B 2 (k) for k−0, 1, . . . , P−1,

the restriction on a k-th beam group of the P beam groups is indicated via a k-th bitmap B 2 (k) of the P bitmaps, and

the k-th bitmap B 2 (k) =b 2 (k,2N 1 N 2 −1) . . . b 2 (k,0) is of length 2N 1 N 2 , where a bit pair b 2 (k,2(N 1 x 2 x 1 )+1) . . . b 2 (k,2(N 1 x 2 x 1 )) indicates the restriction on a maximum allowed amplitude coefficient for a beam indexed by (x 1 , x 2 ) in the k-th beam group of the P beam groups.

6. The UE of claim 5 , wherein a mapping of the bit pair to the maximum allowed amplitude coefficient is determined based on a table given by:

bit-pair

maximum amplitude coefficient

00

0

01

{square root over (1/4)} = {square root over (0.25)}

10

{square root over (1/2)} = {square root over (0.5)}

11

1.

7. The UE of claim 1 , wherein:

if N 2 =1, the first bitmap B 1 is empty, and

if N 2 >1, a length of the first bitmap sequence B 1 is 11 bits that indicate P=4 beam groups out of Q=O 1 O 2 =16 total beam groups.

8. A base station (BS) for channel state information (CSI) reporting in a wireless communication system, the BS comprising:

a transceiver configured to:

transmit, to a user equipment (UE), a higher layer signaling including codebook subset restriction (CBSR) information, and

receive, from the UE, a CSI report that is generated based on P beam groups with a restriction for the CSI reporting and remaining Q minus P beam groups without any restrictions for the CSI reporting, wherein the remaining beam groups are the Q beam groups G(r 1 ,r 2 ) minus the P beam groups,

wherein:

the CBSR information includes a bitmap sequence B that further includes a first bitmap sequence B 1 and a second bitmap sequence B 2 , and

the first bitmap sequence B 1 and the second bitmap sequence B 2 indicate the restriction on P beam groups out of Q beam groups G(r 1 ,r 2 ) for the CSI reporting, wherein:

P is a positive integer and is less than or equal to Q,

Q is a total number of beam groups G(r 1 ,r 2 ), and

an index pair (r 1 ,r 2 ) indicates a beam group of the Q beam groups G(r 1 ,r 2 ).

9. The BS of claim 8 , wherein each beam group G(r 1 ,r 2 ) corresponds to a vector group comprising N 1 N 2 discrete Fourier transform (DFT) vectors, where N 1 and N 2 are indicated by the higher layer signaling are a number of antenna ports with a given polarization in a first and second dimension of an antenna port layout at the BS, respectively.

10. The BS of claim 9 , wherein Q=O 1 O 2 and the Q vector groups are given by

G ( r 1 ,r 2 )={ v N 1 r 1 +x 1 ,N 2 r 2 +x 2 :x 1 =0,1, . . . , N 1 −1; x 2 =0,1, . . . , N 2 −1},

where:

r

1

∈

{

0

,

1

,

…

⁢

,

O

1

-

1

}

r

2

∈

{

0

,

1

,

…

⁢

,

O

2

-

1

}

,

v l,m is a DFT vector:

v

l

,

m

=

[

u

m

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

l

O

1

⁢

N

1

⁢

u

m

…

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

l

⁡

(

N

1

-

1

)

O

1

⁢

N

1

⁢

u

m

]

T

⁢

⁢

with

⁢

⁢

u

m

=

{

[

1

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

m

O

2

⁢

N

2

…

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

m

⁡

(

N

2

-

1

)

O

2

⁢

N

2

]

N

2

>

1

1

N

2

=

1

⁢

;

 and

O 1 and O 2 are oversampling factors in the first and second dimension, respectively.

11. The BS of claim 8 , wherein:

P is four,

the bitmap sequence B=B 1 B 2 is a concatenation of the first bitmap sequence B 1 and the second bitmap sequence B 2 ,

the first bitmap sequence B 1 indicates index pairs (r 1 ,r 2 ) of the P beam groups G(r 1 ,r 2 ),

the second bitmap sequence B 2 =B (1) B (2) . . . B (P) is a concatenation of P bitmaps B 2 (k) for k−0, 1, . . . , P−1,

the restriction on a k-th beam group of the P beam groups is indicated via a k-th bitmap B 2 (k) of the P bitmaps, and

the k-th bitmap B 2 (k) =b 2 (k,2N 1 N 2 −1) . . . b 2 (k,0) is of length 2N 1 N 2 , where a bit pair b 2 (k,2(N 1 x 2 x 1 )+1) . . . b 2 (k,2(N 1 x 2 x 1 )) indicates the restriction on a maximum allowed amplitude coefficient for a beam indexed by (x 1 , x 2 ) in the k-th beam group of the P beam groups.

12. The BS of claim 11 , wherein a mapping of the bit pair to the maximum allowed amplitude coefficient is determined based on a table given by:

bit-pair

maximum amplitude coefficient

00

0

01

{square root over (1/4)} = {square root over (0.25)}

10

{square root over (1/2)} = {square root over (0.5)}

11

1.

13. The BS of claim 8 , wherein:

if N 2 =1, the first bitmap B 1 is empty, and

if N 2 >1, a length of the first bitmap sequence B 1 is 11 bits that indicate P=4 beam groups out of Q=O 1 O 2 =16 total beam groups.

14. A method of user equipment (UE) for channel state information (CSI) reporting in a wireless communication system, the method comprising:

receiving, from a base station (BS), a higher layer signaling including codebook subset restriction (CBSR) information;

determining a bitmap sequence B based on the CBSR information, wherein the bitmap sequence B includes a first bitmap sequence B 1 and a second bitmap sequence B 2 ;

determining the first bitmap sequence B 1 and the second bitmap sequence B 2 based on the bitmap sequence B;

identifying, based on the first bitmap sequence B 1 and the second bitmap sequence B 2 , a restriction on P beam groups out of Q beam groups G(r 1 ,r 2 ) for the CSI reporting, wherein:

P is a positive integer and is less than or equal to Q,

Q is a total number of beam groups G(r 1 ,r 2 ), and

an index pair (r 1 ,r 2 ) indicates a beam group of the Q beam groups G(r 1 ,r 2 );

generating a CSI report based on the P beam groups with the identified restriction for the CSI reporting and remaining Q minus P beam groups without any restrictions for the CSI reporting, wherein the remaining beam groups are determined as the Q beam groups G (r 1 ,r 2 ) minus the P beam groups; and

transmitting the CSI report to the BS.

15. The method of claim 14 , wherein each beam group G(r 1 ,r 2 ) corresponds to a vector group comprising N 1 N 2 discrete Fourier transform (DFT) vectors, where N 1 and N 2 are indicated by the higher layer signaling are a number of antenna ports with a given polarization in a first and second dimension of an antenna port layout at the BS, respectively.

16. The method of claim 15 , wherein Q=O 1 O 2 and the Q vector groups are given by

G ( r 1 ,r 2 )={ v N 1 r 1 +x 1 ,N 2 r 2 +x 2 :x 1 =0,1, . . . , N 1 −1; x 2 =0,1, . . . , N 2 −1},

where:

r

1

∈

{

0

,

1

,

…

⁢

,

O

1

-

1

}

r

2

∈

{

0

,

1

,

…

⁢

,

O

2

-

1

}

,

v l,m is a DFT vector:

v

l

,

m

=

[

u

m

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

l

O

1

⁢

N

1

⁢

u

m

…

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

l

⁡

(

N

1

-

1

)

O

1

⁢

N

1

⁢

u

m

]

T

⁢

⁢

with

⁢

⁢

u

m

=

{

[

1

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

m

O

2

⁢

N

2

…

e

j

⁢

⁢

2

⁢

⁢

π

⁢

⁢

m

⁡

(

N

2

-

1

)

O

2

⁢

N

2

]

N

2

>

1

1

N

2

=

1

⁢

;

 and

O 1 and O 2 are oversampling factors in the first and second dimension, respectively.

17. The method of claim 14 , wherein P is four.

18. The method of claim 14 , wherein:

the bitmap sequence B=B 1 B 2 is a concatenation of the first bitmap sequence B 1 and the second bitmap sequence B 2 ,

the first bitmap sequence B 1 indicates index pairs (r 1 ,r 2 ) of the P beam groups G(r 1 ,r 2 ),

the second bitmap sequence B 2 =B (1) B (2) . . . B (P) is a concatenation of P bitmaps B 2 (k) for k−0, 1, . . . , P−1,

the restriction on a k-th beam group of the P beam groups is indicated via a k-th bitmap B 2 (k) of the P bitmaps, and

the k-th bitmap B 2 (k) =b 2 (k,2N 1 N 2 −1) . . . b 2 (k,0) is of length 2N 1 N 2 , where a bit pair b 2 (k,2(N 1 x 2 x 1 )+1) . . . b 2 (k,2(N 1 x 2 x 1 )) indicates the restriction on a maximum allowed amplitude coefficient for a beam indexed by (x 1 , x 2 ) in the k-th beam group of the P beam groups.

19. The method of claim 18 , wherein a mapping of the bit pair to the maximum allowed amplitude coefficient is determined based on a table given by

bit-pair

maximum amplitude coefficient

00

0

01

{square root over (1/4)} = {square root over (0.25)}

10

{square root over (1/2)} = {square root over (0.5)}

11

1.

20. The method of claim 14 , wherein:

if N 2 =1, the first bitmap B 1 is empty, and

if N 2 >1, a length of the first bitmap sequence B 1 is 11 bits that indicate P=4 beam groups out of Q=O 1 O 2 =16 total beam groups.