Method and an apparatus for providing channel quality information in a wireless communication system

1. A method for transmitting channel quality information for a downlink channel, the method comprising:

receiving, by a user equipment (UE), configuration information on periodic channel state information (CSI) reporting by higher layer signaling;

determining, by the UE, a channel quality information index at least based on a number of a specific resource element; and

transmitting the determined channel quality information index to a base station,

wherein the number of the specific resource element is determined based on a UE-specific reference signal overhead, and

wherein a resource element allocated for a Channel Status Information-Reference Signal (CSI-RS) is regarded as the specific resource element regardless of transmitting the CSI-RS.

2. The method of claim 1 , wherein the UE-specific reference signal overhead is determined according to a rank value,

wherein the UE-specific reference signal overhead within one resource block for one subframe is 12 resource elements for the rank value of 1 or 2, and

wherein the UE-specific reference signal overhead within one resource block for one subframe is 24 resource elements for the rank value of 3, 4, 5, 6, 7 or 8.

3. The method of claim 1 , wherein the UE is configured for reporting at least one of a Precoding Matrix Indicator (PMI) or a Rank Indication (RI).

4. The method of claim 1 , wherein the configuration information on periodic CSI reporting includes a transmission period of channel information and an offset for the transmission period in subframe units.

5. The method of claim 1 , wherein the determined channel quality information index is transmitted to the base station on a Physical Uplink Control Channel (PUCCH).

6. A user equipment (UE) for transmitting channel quality information for a downlink channel, the UE comprising:

a receiver configured to receive a downlink signal from a base station;

a transmitter configured to transmit an uplink signal to the base station; and

a processor connected to the receiver and the transmitter and configured to control operations of the UE,

wherein the processor is further configured to:

control the receiver to receive configuration information on periodic channel state information (CSI) reporting by higher layer signaling,

determine a channel quality information index at least based on a number of a specific resource element, and

control the transmitter to transmit the determined channel quality information index,

wherein the number of the specific resource element is determined based on a UE-specific reference signal overhead, and

wherein a resource element allocated for a Channel Status Information-Reference Signal (CSI-RS) is regarded as the specific resource element regardless of transmitting the CSI-RS.

7. The UE of claim 6 , wherein the UE-specific reference signal overhead is determined according to a rank value,

wherein the UE-specific reference signal overhead within one resource block for one subframe is 12 resource elements for the rank value of 1 or 2, and

wherein the UE-specific reference signal overhead within one resource block for one subframe is 24 resource elements for the rank value of 3, 4, 5, 6, 7 or 8.

8. The UE of claim 6 , wherein the UE is configured for reporting at least one of a Precoding Matrix Indicator (PMI) or a Rank Indication (RI).

9. The UE of claim 6 , wherein the configuration information on periodic CSI reporting includes a transmission period of channel information and an offset for the transmission period in subframe units.

10. The UE of claim 6 , wherein the determined channel quality information index is transmitted to the base station on a Physical Uplink Control Channel (PUCCH).

11. A method for receiving channel quality information for a downlink channel, the method comprising:

transmitting, by a base station to a user equipment (UE), configuration information on periodic channel state information (CSI) reporting by higher layer signaling; and

receiving, by the base station, a channel quality information index,

wherein the channel quality information index is determined by the UE at least based on a number of a specific resource element,

wherein the number of the specific resource element is determined based on a UE-specific reference signal overhead, and

wherein a resource element allocated for a Channel Status Information-Reference Signal (CSI-RS) is regarded as the specific resource element regardless of transmitting the CSI-RS.

12. A base station for receiving channel quality information for a downlink channel, the base station comprising:

a receiver configured to receive an uplink signal from a user equipment (UE);

a transmitter configured to transmit a downlink signal to the UE; and

a processor connected to the receiver and the transmitter so as to control operations of the base station,

wherein the processor is further configured to:

control the transmitter to transmit, to the UE, configuration information on periodic channel state information (CSI) reporting by higher layer signaling, and

control the receiver to receive a channel quality information index, wherein the channel quality information index is determined by the UE at least based on a number of a specific resource element,

wherein the number of the specific resource element is determined based on a UE-specific reference signal overhead, and

wherein a resource element allocated for a Channel Status Information-Reference Signal (CSI-RS) is regarded as the specific resource element regardless of transmitting the CSI-RS.