US Patent RE50112 Distributed digital antenna system

An optical medium, such as fiber, is tapped to provide an antenna port wherever radio service coverage is desired. Each antenna port is a bi-directional remote unit that receives a digital optical signal from a host unit and transforms the signal to a radio frequency signal for transmission by the remote unit. The remote unit receives radio frequency signals that are converted to digital signals and summed with signals from other remote units and converted to an optical signal for transmission to the host unit.