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

1. A method of a user equipment to receive a downlink signal in a cellular communication system, the method comprising:

detecting a Channel State Information Reference Signal (CSI-RS) in a time unit #n on an unlicensed band cell;

verifying whether the CSI-RS is used for Discovery RS (DRS) using an initialization value of a CSI-RS sequence of the CSI-RS; and

performing at least one of a Radio Resource Management (RRM) measurement or a Channel State Information (CSI) measurement using the CSI-RS based on whether the CSI-RS is used for the DRS,

wherein when the CSI-RS is used for the DRS, the user equipment performs the RRM measurement using the CSI-RS, and when the CSI-RS is not used for the DRS, the user equipment performs the CSI measurement, wherein the time unit #n is not a subframe # 0 or # 5 , and

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

2. The method of claim 1 , wherein the time unit #n is a subframe #n or a slot #n.

3. The method of claim 1 , wherein when a slot index of the subframe # 0 or # 5 is used for the initialization value of the CSI-RS sequence, the CSI-RS is used for the DRS.

4. The method of claim 1 , 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 an OFDM symbol index within a slot,

N ID CS: 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.

5. The method of claim 4 , wherein OFDM symbol indexes according to a CSI-RS configuration for the CSI-RS 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.

6. The method of claim 5 , wherein when the CSI-RS is used for the DRS, the CSI-RS configuration for the CSI-RS is one of the CSI-RS configuration {1, 2, 3, 6, 7, 8, 12, 13, 14, 15, 16, 17} in the Table.

7. The method of claim 1 , wherein the cellular communication system is a 3rd Generation Partnership Project (3GPP) Long-term Evolution (LTE)-based communication system.

8. 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:

detect a Channel State Information Reference Signal (CSI-RS) in a time unit #n on an unlicensed band cell,

verify whether the CSI-RS is used for Discovery RS (DRS) using an initialization value of a CSI-RS sequence of the CSI-RS,

perform a Radio Resource Management (RRM) measurement using the CSI-RS when the CSI-RS is used for the DRS, and

perform a Channel State Information (CSI) measurement when the CSI-RS is not used for the DRS,

wherein the time unit #n is not a subframe # 0 or # 5 , and

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

9. The user equipment of claim 8 , wherein the time unit #n is a subframe #n or a slot #n.

10. The user equipment of claim 8 , wherein when a slot index of the subframe # 0 or # 5 is used for the initialization value of the CSI-RS sequence, the CSI-RS is used for the DRS.

11. The user equipment of claim 8 , 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 an OFDM symbol index within a slot,

N ID CS: 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.

12. The user equipment of claim 11 , wherein OFDM symbols indexes according to a CSI-RS configuration for the CSI-RS 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 user equipment of claim 12 , wherein when the CSI-RS is used for the DRS, the CSI-RS configuration for the CSI-RS is one of the CSI-RS configuration { 1 , 2 , 3 , 6 , 7 , 8 , 12 , 13 , 14 , 15 , 16 , 17 } in the Table.

14. The user equipment of claim 8 , wherein the cellular communication system is a 3rd Generation Partnership Project (3GPP) Long-term Evolution (LTE)-based communication system.

15. 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 transmit a Channel State Information Reference Signal (CSI-RS) to a user equipment using an initialization value of a CSI-RS sequence of the CSI-RS on an unlicensed band cell,

wherein a time unit #n is not a subframe # 0 or # 5 ,

wherein the initialization value of the CSI-RS sequence is not generated according to an index of the time unit #n when the CSI-RS is used for the Discovery RS (DRS), and the initialization value of the CSI-RS sequence is generated according to the index of the time unit #n when the CSI-RS is not used for the DRS, and

wherein when the CSI-RS is used for the DRS, the CSI-RS is used for performing a Radio Resource Management (RRM) measurement on the user equipment, and when the CSI-RS is not used for the DRS, the CSI-RS is used for performing a Channel State Information (CSI) measurement on the user equipment.

16. The base station of claim 15 , wherein the time unit #n is a subframe #n or a slot #n.

17. The base station of claim 15 , wherein when a slot index of the subframe # 0 or # 5 is used for the initialization value of the CSI-RS sequence, the CSI-RS is used for the DRS.

18. The base station 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 an OFDM symbol index within a slot,

N ID CS: 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.

19. The base station of claim 18 , wherein OFDM symbols indexes according to a CSI-RS configuration for the CSI-RS 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.

20. The base station of claim 19 , wherein when the CSI-RS is used for the DRS, the CSI-RS configuration for the CSI-RS is one of the CSI-RS configuration { 1 , 2 , 3 , 6 , 7 , 8 , 12 , 13 , 14 , 15 , 16 , 17 } in the Table.