The inventive concept relates to a distributed antenna system (DAS), and more particularly, to an uplink signal transmission operation of each of node units constituting a DAS. A node unit of a DAS includes a signal input/output unit configured to receive m uplink signals from m lower node units and output the m uplink signals, and a multiplexer configured to generate a single uplink signal by selectively outputting any one of the m uplink signals at an interval of a predetermined output time. Accordingly, it is possible to provide a DAS capable of processing and outputting, as one signal, uplink signals received from a plurality of remote units, without any error.