Synchronized DMT for multipoint-to-point communications on HFC networks

This paper presents a method for synchronizing a large number of discrete-multitone-based modems for multipoint-to-point communications on hybrid fiber-coax (HFC) networks. Each newly-installed remote unit is first loop-timed to the central modem master clock. Ranging is then performed to determine the sample delay required to align at the central unit receiver the symbols transmitted by the remote with those transmitted by remote units already operating. Upon completing the synchronization procedure, the remote unit transmits a signal to train the central unit receiver so that the available upstream bandwidth can be used as efficiently as possible during steady-state operation