Method for transmitting feedback information in multi input multi out put system based on codebook and a method for transmitting precoding information in multi input multi output system using codebook-bases precoding scheme
A method for transmitting feedback information in a codebook-based multiple-input multiple-output (MIMO) system is disclosed. To transmit the feedback information, a signal is received to discern channel characteristics of the received signal, and a codebook is updated using an extended matrix including a plurality of vector components and using previous feedback information. Feedback information is selected for transmission from the updated codebook in consideration of the channel characteristics of the received signal.
1. A feedback method in a multiple-input multiple-output (MIMO) system using a codebook, comprising:
estimating a reception channel by receiving a signal; and
feeding back a codeword selected based on the estimated channel from a codebook which is updated using a phase shift matrix having phase values as parameters and previous feedback information,
wherein each of the phase values is reset to 0° at a preset repetition period.
2. The method according to claim 1 , the method is repeatedly performed a predetermined number of times.
3. A method for transmitting precoding information in a multiple-input multiple-output (MIMO) system using a codebook-based precoding scheme, comprising:
determining to operate in a codebook updating mode;
feeding back first precoding information selected from a first codebook;
receiving a signal; and
feeding back second precoding information selected from a second codebook based on channel characteristics of the received signal,
wherein the second codebook is configured by a phase shift matrix having phase values as parameters and using the first precoding information,
wherein the second codebook determines a plurality of phase shift matrices by determining a plurality of phase values and determines codebook codewords by multiplying each of the determined phase shift matrices by a vector component according to the first precoding information to include the determined codebook codewords.
4. The method according to claim 3 , wherein the phase values are determined by adding or subtracting integral times of a phase interval to or from the first precoding information.
5. The method according to claim 4 , wherein the phase interval is generated by equally dividing a predetermined phase range into a number corresponding to the number of feedback bits.