Transmission and reception of control information

1. A method of transmitting control information to user equipment through data regions of two or more physical resource-block (PRB) pairs in a subframe, in a transmission/reception point including at least one processor, the method comprising:

forming enhanced control channel elements (ECCEs), wherein (i) resource elements (REs) in each of the two or more PRB pairs are indexed by repetitively using 16 numbers according to a frequency-first scheme, (ii) resource elements (REs) having an identical index are included in an identical enhanced resource-element group (EREG), (iii) each of the ECCEs includes 4 or 8 EREGs corresponding to different EREG indices having an identical remainder when the different EREG indices are divided by one of 4 and 2, and (iv) the EREGs included in each of the ECCEs are located in the two or more PRB pairs; and

transmitting the control information to the user equipment through at least one of the formed ECCEs,

wherein the forming includes:

when the number of the EREGs forming each of the ECCEs is less than the number of the PRB pairs,

forming the ECCEs such that each of the ECCEs is mapped to EREGs included in at least two PRB pairs which are selected by hopping at a constant index interval.

2. The method of claim 1 , wherein the constant index interval is determined based on the number of the EREGs and the number of the PRB pairs.

3. The method of claim 1 , wherein the two or more PRB pairs are included in one enhanced physical downlink control channel (EPDCCH) set formed according to a distributed type scheme.

4. The method of claim 1 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 4, 8, 12}, {1, 5, 9, 13}, {2, 6, 10, 14}, and {3, 7, 11, 15}.

5. The method of claim 1 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 2, 4, 6, 8, 10, 12, 14} and {1, 3, 5, 7, 9, 11, 13, 15}.

6. A method of receiving control information from a transmission/reception point through data regions of two or more physical resource-block (PRB) pairs in a subframe, in user equipment including at least one processor, the method comprising:

receiving a wireless signal through at least one enhanced control channel element (ECCE), wherein (i) resource elements (REs) in each of the two or more PRB pairs are indexed by repetitively using 16 numbers according to a frequency-first scheme, (ii) resource elements (REs) having an identical index are included in an identical enhanced resource-element group (EREG), (iii) each of ECCEs includes 4 or 8 EREGs corresponding to different EREG indices having an identical remainder when the different EREG indices are divided by one of 4 and 2, and (iv) the EREGs included in each of the ECCEs are located in the two or more PRB pairs; and

obtaining the control information from the received wireless signal,

wherein when the number of the EREGs forming each of the ECCEs is less than the number of the PRB pairs,

each of the ECCEs associated with reception of the wireless signal is mapped to EREGs included in at least two PRB pairs which are selected by hopping at a constant index interval.

7. The method of claim 6 , wherein the constant index interval is determined based on the number of the EREGs and the number of the PRB pairs.

8. The method of claim 6 , wherein the two or more PRB pairs are included in one enhanced physical downlink control channel (EPDCCH) set formed according to a distributed type scheme.

9. The method of claim 6 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 4, 8, 12}, {1, 5, 9, 13}, {2, 6, 10, 14}, and {3, 7, 11, 15}.

10. The method of claim 6 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 2, 4, 6, 8, 10, 12, 14} and {1, 3, 5, 7, 9, 11, 13, 15}.

11. A transmission/reception point for transmitting control information to user equipment through data regions of two or more physical resource-block (PRB) pairs in a subframe, the transmission/reception point comprising:

a control processor configured to form enhanced control channel elements (ECCEs), wherein (i) resource elements (REs) in each of the two or more PRB pairs are indexed by repetitively using 16 numbers according to a frequency-first scheme, (ii) resource elements (REs) having an identical index are included in an identical enhanced resource-element group (EREG), (iii) each of the ECCEs includes 4 or 8 EREGs corresponding to different EREG indices having an identical remainder when the different EREG indices are divided by one of 4 and 2, and (iv) the EREGs included in each of the ECCEs are located in the two or more PRB pairs; and

a transmitter configured to transmit the control information to the user equipment through at least one of the formed ECCEs,

wherein the control processor is configured to:

when the number of the EREGs forming each of the ECCEs is less than the number of the PRB pairs,

form the ECCEs such that each of the ECCEs is mapped to EREGs included in at least two PRB pairs which are selected by hopping at a constant index interval.

12. The transmission/reception point of claim 11 , wherein the constant index interval is determined based on the number of the EREGs and the number of the PRB pairs.

13. The transmission/reception point of claim 11 , wherein the two or more PRB pairs are included in one enhanced physical downlink control channel (EPDCCH) set formed according to a distributed type scheme.

14. The transmission/reception point of claim 11 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 4, 8, 12}, {1, 5, 9, 13}, {2, 6, 10, 14}, and {3, 7, 11, 15}.

15. The transmission/reception point of claim 11 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 2, 4, 6, 8, 10, 12, 14} and {1, 3, 5, 7, 9, 11, 13, 15}.

16. A user equipment receiving control information from a transmission/reception point through data regions of two or more physical resource-block (PRB) pairs in a subframe, the user equipment comprising:

a receiver configured to receive a wireless signal through at least one enhanced control channel element (ECCE), wherein (i) resource elements (REs) in each of the two or more PRB pair are indexed by repetitively using 16 numbers according to a frequency-first scheme, (ii) resource elements (REs) having an identical index are included in an identical enhanced resource-element group (EREG), (iii) each of ECCEs includes 4 or 8 EREGs corresponding to different EREG indices having an identical remainder when the different EREG indices are divided by one of 4 and 2, and (iv) the EREGs included in each of the ECCEs are located in the two or more PRB pairs; and

a control processor configured to obtain the control information from the received wireless signal,

wherein when the number of the EREGs forming each of the ECCEs is less than the number of the PRB pairs,

each of the ECCEs associated with reception of the wireless signal is mapped to EREGs included in at least two PRB pairs which are selected by hopping at a constant index interval.

17. The user equipment of claim 16 , wherein the constant index interval is determined based on the number of the EREGs and the number of the PRB pairs.

18. The user equipment of claim 16 , wherein the two or more PRB pairs are included in one enhanced physical downlink control channel (EPDCCH) set formed according to a distributed type scheme.

19. The user equipment of claim 16 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 4, 8, 12}, {1, 5, 9, 13}, {2, 6, 10, 14}, and {3, 7, 11, 15}.

20. The user equipment of claim 16 , wherein an EREG index group corresponding to each of the ECCEs is selected as one of {0, 2, 4, 6, 8, 10, 12, 14} and {1, 3, 5, 7, 9, 11, 13, 15}.