Field
The present invention relates to wireless communication, and more particularly, to an apparatus and a method for transmitting a reference signal in a multiple antenna system.
Discussion of the Background
An existing mobile communication system may support 8 transmission antennas for a beamforming operation. Particularly, in a multi-user Multiple Input Multiple Output (MIMO) operation, the same physical resource block (PRB) may be scheduled or assigned to maximum 4 user equipment (UE). Associated with a configuration of an antenna in a next generation mobile communication system, for example, a closely-spaced X-polarized antenna of 0.5λ to 0.7λ is considered.
Meanwhile, a next generation mobile communication system is aimed at supporting maximum 64 transmission antennas as a two-dimensional antenna arrangement associated with a closed loop (CL) MIMO. However, if 64 transmission antennas are stably supported, overhead of a control signal is increased. An important consideration is to design for minimizing a channel state information-reference signal (CSI-RS) being a reference signal for estimating a channel state in a wireless communication system supporting 64 transmission antennas, a precoding matrix indicator (PMI) feedback, a demodulation reference signal (DMRS) being a reference signal for data demodulation. However, there is no methods for minimizing overhead of a control in addition to increase in the number of transmission antennas.