In this disclosure, methods for antenna combining to meet the pilot requirement of the massive MIMO system, and apparatuses for the same are provided. In a user equipment (UE) perspective of view, the UE transmits first pilot signals via each of multiple antennas of the UE, and receives antenna combining information from a base station. Here, the antenna combining information combines the multiple antennas into one or more antenna groups based on the first pilot signals, and each of orthogonal sequences is allocated to each of the antenna groups. The UE transmits second pilot signals using the allocated orthogonal sequences for each of the antenna groups. The second pilot signals can be used for estimating downlink channel from the base station to the UE.
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