Disclosed herein are a method for simultaneously transmitting/receiving upstream and downstream signals using a remote PHY architecture and an apparatus for the same. The method determines whether to divide frequencies depending on whether signal interference occurs among multiple cable modems connected to a cable network, if it is determined to divide the frequencies, categorize the multiple cable modems into multiple groups so that signal interference occurs in each group, but signal interference does not occur between groups, set transmission bands for the multiple groups so that an upstream band and a downstream band of one group alternate with upstream bands and downstream bands of remaining groups by dividing the frequencies in accordance with a number of groups, and cancels, by a remote physical layer (PHY) device located at an optical network terminal of the cable network, self-interference signals for respective groups based on the transmission bands.