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 UE-specific reference signal overhead, wherein the UE-specific reference signal overhead is determined according to a rank value; and

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

wherein the channel quality information index is determined further based on an assumption of no resource element allocated for a Channel Status Information-Reference Signal (CSI-RS).

2. The method of claim 1 , 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 user equipment comprising:

a receiving module configured to receive a downlink signal from a base station;

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

a processor configured to be connected to the receiving module and the transmitting module and control operations of the user equipment,

wherein the processor is further configured to:

receive, through the receiving module, configuration information on periodic channel state information (CSI) reporting by higher layer signaling,

determine a channel quality information index at least based on a UE-specific reference signal overhead, wherein the UE-specific reference signal overhead is determined according to a rank value, and

transmit the determined channel quality information index through the transmitting module, and

wherein the channel quality information index is determined further based on an assumption of no resource element allocated for a Channel Status Information-Reference Signal (CSI-RS).

7. The user equipment of claim 6 , 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 user equipment 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 user equipment 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 user equipment 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 UE-specific reference signal overhead,

wherein the UE-specific reference signal overhead is determined according to a rank value, and

wherein the channel quality information index is determined further based on an assumption of no resource element allocated for a Channel Status Information-Reference Signal (CSI-RS).

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

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

a transmitting module configured to transmit a downlink signal to the UE; and

a processor configured to be connected to the receiving module and the transmitting module and control operations of the base station,

wherein the processor is further configured to:

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

receive, through the receiving module, a channel quality information index,

wherein the channel quality information index is determined by the UE at least based on a UE-specific reference signal overhead, wherein the UE-specific reference signal overhead is determined according to a rank value, and

wherein the channel quality information index is determined further based on an assumption of no resource element allocated for a Channel Status Information-Reference Signal (CSI-RS).