1. An apparatus for adaptively allocating transmission power for beamforming combined with orthogonal space-time block codes (OSTBC) in a distributed wireless communication system, the apparatus comprising: a plurality of geographically distributed sub-arrays for beamforming, each sub-array of said plurality comprising a plurality of distributed antennas placed in random groups; and a central processing unit for identification of a performance of each subset of the sub-arrays by applying a predetermined power allocation scheme thereto, each said subset being obtained by combining the sub-arrays using a Nakagami fading parameter and information about large-scale fading of each sub-array of the sub-arrays fed back from a receiving party, determination of a subset having a best identified performance as an optimal subset according to the identified performances thereof, and performance of power allocation based on the subset determined as the optimal subset.