Abstract: A main-remote radio base station system includes plural remote radio units each having a remote digital interface unit and a main unit having a main digital interface unit. Different length links couple different remote radio units to the main unit. The digital interfaces in the main and remote units include a digital data channel and a digital timing channel. A delay associated with each link is determined without interrupting transmission of data over the digital data channel. The delays, reported continuously, periodically, or upon request, are compensated for and equalized by advancing a time when the timing and data signals are sent over their respective digital channels. In a preferred embodiment, the interface is a digital optical interface. A hybrid base station includes synchronized “near” and “remote” radio units.