a method of communicating between a base band unit and a plurality of remote radio heads includes the steps of receiving a first signal through an antenna in a first remote radio head , transmitting the first signal to a second remote radio head through a digital radio interface , receiving a second signal through an antenna in the second remote radio head , compensating for a delay accrued in the first signal , adding the first signal and the second signal to obtain a resulting signal , and transmitting the resulting signal to a base band unit through a digital radio interface .