Method, device, and system for transmitting signals in unlicensed band

1. A user equipment used in a cellular wireless communication system, the user equipment comprising:

a wireless communication module; and

a processor,

wherein the processor is configured to:

receive Channel State Information Reference Signal (CSI-RS) configuration information indicating one of plurality of CSI-RS configuration information included in a CSI-RS configuration information set for a downlink cell from a base station, and

receive CSI-RS in the downlink cell according to the CSI-RS configuration information from the base station,

wherein when the downlink cell operates in a licensed band, the CSI-RS configuration information set is a first CSI-RS configuration information set including one or more first CSI-RS configuration information related to Orthogonal Frequency Division Multiplexing (OFDM) symbols #5/#6, one or more second CSI-RS configuration information related to OFDM symbols #9/#10, and one or more third CSI-RS configuration information related to OFDM symbols #12/#13,

wherein when the downlink cell operates in an unlicensed band, the CSI-RS configuration information set is a second CSI-RS configuration information set,

wherein the second CSI-RS configuration information set is part of the first CSI-RS configuration set and does not comprise the one or more third CSI-RS configuration information.

2. The user equipment of claim 1 , wherein the second CSI-RS configuration information set does not comprise the one or more first CSI-RS configuration information.

3. The user equipment of claim 1 , wherein the first CSI-RS configuration information set is a CSI-RS configuration {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19} and the second CSI-RS configuration information set is a CSI-RS configuration {1, 2, 3, 6, 7, 8, 12, 13, 14, 15, 16, 17}.

4. The user equipment of claim 3 , wherein the OFDM symbols for CSI-RS according to a CSI-RS configuration information is given by the following Table

Number of CSI reference signals configured

1 or 2

4

8

CSI-RS

OFDM symbol

OFDM symbol

OFDM symbol

configuration

index

index

index

0

5, 6 

5, 6 

5, 6 

1

9, 10

9, 10

9, 10

2

9, 10

9, 10

9, 10

3

9, 10

9, 10

9, 10

4

12, 13 

12, 13 

12, 13 

5

5, 6 

5, 6 

6

9, 10

9, 10

7

9, 10

9, 10

8

9, 10

9, 10

9

12, 13 

12, 13 

10

5, 6 

11

5, 6 

12

9, 10

13

9, 10

14

9, 10

15

9, 10

16

9, 10

17

9, 10

18

12, 13 

19

12, 13.

5. The user equipment of claim 1 , wherein when the downlink cell operates in the unlicensed band and the CSI-RS is configured to Discovery Reference Signal (DRS), the processor is further configured to perform a Radio Resource Management (RRM) measurement using the CSI-RS.

6. The user equipment of claim 5 , wherein an index of a time unit #n is not used for an initialization value of a CSI-RS sequence of the CSI-RS used for the DRS.

7. The user equipment of claim 6 , wherein the time unit #n is a subframe #n or a slot #n.

8. The user equipment of claim 7 , wherein the initialization value of the CSI-RS sequence is given by the following Equation,

c init =2 10 ·(7·( n s +1)+ l+ 1)·(2· N ID CSI +1)+2· N ID CSI +N CP

Here, l represents the OFDM symbol within a slot,

N ID CSI represents a value configured by higher layers or a physical cell identifier,

N CP has 0 or 1 depending on a Cyclic Prefix (CP) type, and

n s has the index of the time unit #n or has another predetermined value according to the use of the CSI-RS.

9. A method of a base station to transmit a downlink signal in a cellular communication system, the method comprising:

selecting Channel State Information Reference Signal (CSI-RS) configuration information for a downlink cell from a CSI-RS configuration information set;

transmitting the selected CSI-RS configuration information to a user equipment; and

transmitting CSI-RS to the user equipment in the downlink cell according to the selected CSI-RS configuration information,

wherein each CSI-RS configuration information represents Orthogonal Frequency Division Multiplexing (OFDM) symbols for CSI-RS in a subframe including OFDM symbols #0 to #13,

wherein when the downlink cell operates in a licensed band, the CSI-RS configuration information set is a first CSI-RS configuration information set including one or more first CSI-RS configuration information related to OFDM symbols #5/#6, one or more second CSI-RS configuration information related to OFDM symbols #9/#10, and one or more third CSI-RS configuration information related to OFDM symbols #12/#13,

wherein when the downlink cell operates in an unlicensed band, the CSI-RS configuration information set is a second CSI-RS configuration information set,

wherein the second CSI-RS configuration information set is part of the first CSI-RS configuration set and does not comprise the one or more third CSI-RS configuration information.

10. The method of claim 9 , wherein the second CSI-RS configuration information set does not comprise the one or more first CSI-RS configuration information.

11. The method of claim 9 , wherein the first CSI-RS configuration information set is a CSI-RS configuration {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19} and the second CSI-RS configuration information set is a CSI-RS configuration {1, 2, 3, 6, 7, 8, 12, 13, 14, 15, 16, 17}.

12. The method of claim 11 , wherein the OFDM symbols for the CSI-RS according to the CSI-RS configuration information is given by the following Table

Number of CSI reference signals configured

1 or 2

4

8

CSI-RS

OFDM symbol

OFDM symbol

OFDM symbol

configuration

index

index

index

0

5, 6 

5, 6 

5, 6 

1

9, 10

9, 10

9, 10

2

9, 10

9, 10

9, 10

3

9, 10

9, 10

9, 10

4

12, 13 

12, 13 

12, 13 

5

5, 6 

5, 6 

6

9, 10

9, 10

7

9, 10

9, 10

8

9, 10

9, 10

9

12, 13 

12, 13 

10

5, 6 

11

5, 6 

12

9, 10

13

9, 10

14

9, 10

15

9, 10

16

9, 10

17

9, 10

18

12, 13 

19

12, 13.

13. The method of claim 9 , wherein when the downlink cell operates in the unlicensed band and the CSI-RS is configured to DRS, the transmitting the CSI-RS comprises transmitting the CSI-RS to the user equipment so that the user equipment performs a Radio Resource Management (RRM) measurement using the CSI-RS.

14. The method of claim 13 , wherein the transmitting the CSI-RS comprises transmitting the CSI-RS using an initialization value of a CSI-RS sequence for the CSI-RS on the unlicensed band, and

wherein an index of a time unit #n is not used for the initialization value of a CSI-RS sequence of the CSI-RS used for the DRS.

15. The method of claim 14 , wherein the time unit #n is a subframe #n or a slot #n.

16. The method of claim 15 , wherein the initialization value of the CSI-RS sequence is given by the following Equation.

c init =2 10 ·(7·( n s +1)+ l+ 1)·(2· N ID CSI +1)+2· N ID CSI +N CP

Here, l represents the OFDM symbol within a slot,

N ID CSI represents a value configured by higher layers or a physical cell identifier,

N CP has 0 or 1 depending on a Cyclic Prefix (CP) type, and

n s has the index of the time unit #n or has another predetermined value according to the use of the CSI-RS.

17. A base station used in a cellular wireless communication system, the base station comprising:

a wireless communication module; and

a processor,

wherein the processor is configured to select Channel State Information Reference Signal (CSI-RS) configuration information for a downlink cell from a CSI-RS configuration information set,

transmit the selected CSI-RS configuration information to a user equipment, and

transmit CSI-RS to the user equipment in the downlink cell according to the selected CSI-RS configuration information,

wherein each CSI-RS configuration information represents Orthogonal Frequency Division Multiplexing (OFDM) symbols for CSI-RS in a subframe including OFDM symbols #0 to #13,

wherein when the downlink cell operates in a licensed band, the CSI-RS configuration information set is a first CSI-RS configuration information set including one or more first CSI-RS configuration information related to OFDM symbols #5/#6, one or more second CSI-RS configuration information related to OFDM symbols #9/#10, and one or more third CSI-RS configuration information related to OFDM symbols #12/#13,

wherein when the downlink cell operates in an unlicensed band, the CSI-RS configuration information set is a second CSI-RS configuration information set,

wherein the second CSI-RS configuration information set is part of the first CSI-RS configuration set and does not comprise the one or more third CSI-RS configuration information.

18. The base station of claim 17 , wherein the second CSI-RS configuration information set does not comprise the one or more first CSI-RS configuration information.

19. The base station of claim 17 , wherein the first CSI-RS configuration information set is a CSI-RS configuration {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19} and the second CSI-RS configuration information set is a CSI-RS configuration {1, 2, 3, 6, 7, 8, 12, 13, 14, 15, 16, 17}.

20. The base station of claim 19 , wherein the OFDM symbols for the CSI-RS according to the CSI-RS configuration information is given by the following Table

Number of CSI reference signals configured

1 or 2

4

8

CSI-RS

OFDM symbol

OFDM symbol

OFDM symbol

configuration

index

index

index

0

5, 6 

5, 6 

5, 6 

1

9, 10

9, 10

9, 10

2

9, 10

9, 10

9, 10

3

9, 10

9, 10

9, 10

4

12, 13 

12, 13 

12, 13 

5

5, 6 

5, 6 

6

9, 10

9, 10

7

9, 10

9, 10

8

9, 10

9, 10

9

12, 13 

12, 13 

10

5, 6 

11

5, 6 

12

9, 10

13

9, 10

14

9, 10

15

9, 10

16

9, 10

17

9, 10

18

12, 13 

19

12, 13.