1. Field of the Invention
The present invention relates to a method and an apparatus for channel state information transmission/reception. More particularly, the present invention relates to a method and an apparatus for transmitting/receiving channel state information in multi-antenna system.
2. Description of the Related Art
A Reference Signal (RS) is a signal used for measuring the channel state (or quality) between the base station and users by taking notice of a signal strength or distortion, an interference strength, and Gaussian noise to help demodulating and decoding the data symbol at the receiver. Another use of the reference signal is to measure the radio channel state. The receiver measures the received signal strength of the reference signal transmitted at the negotiated transmission power level on the radio channel. The radio channel state determined in this way is used in order for the receiver to determine the data rate to be requested to the transmitter.
The next generation wireless mobile communication system standards, such as the 3rd Generation Partnership Project (3GPP), the Long Term Evolution Advanced (LTE-A) and the Institute of Electrical and Electronics Engineers (IEEE) 802.16m adopt a multicarrier-based multiple access technique, such as Orthogonal Frequency Division Multiplexing/Orthogonal Frequency Division Multiple Access (OFDM/OFDMA). In the case of the wireless mobile communication system adopting multicarrier-based multiple access, the channel estimation and measurement performance varies depending on the positions and number of symbols and subcarriers in time and frequency domains. Furthermore, the channel estimation and measurement performance are influenced by the power level allocated for the reference signal. Accordingly, as the resource amount (i.e., time, frequency, and transmission power) allocated for the reference signal increases, the channel estimation and measurement performance are improved, resulting in improvement of demodulation and decoding performance of the received data symbol and channel state measurement accuracy.
In the typical mobile communication system operating with a limited radio resource (i.e., time, frequency, and transmission power), however, if a large amount of radio resource is allocated for reference signal transmission, the radio resource amount for data transmission decreases. For this reason, the radio resource allocation for reference signal transmission has to be determined in consideration of the system throughput. More particularly, in a Multiple Input Multiple Output (MIMO) system for multi-antenna transmission, the resource allocation for reference signal and measurement of resource signal are very important technical factors.
Therefore, a need exists for a method and an apparatus for transmitting channel state information efficiently.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.
USPTO Backgrounds
USPTO Backgrounds