Embodiments enable a half-duplex Time Division Duplex (TDD) mode for Ethernet Passive Optical Network (EPON) or EPON over Coax (EPoC) networks. Specifically, embodiments provide systems and methods for enabling an Optical Line Terminal (OLT)/Coaxial Line Terminal (CLT) to share a physical medium spectrum in time with the Optical Network Units (ONUs)/Coaxial Network Units (CNUs) that it services. In an embodiment, the OLT/CLT includes an EPON scheduler that can schedule downstream and upstream transmissions over the same physical medium spectrum. In another embodiment, the OLT/CLT is equipped with a burst mode transmit physical layer (PHY) module, which can be controlled by an EPON Medium Access Control (MAC) module, to transmit in burst mode over the physical medium. In a further embodiment, there is provided an ONU/CNU with a burst mode receive PHY module. The burst mode receive PHY module can maintain clock timing even with non-continuous reception from the OLT/CLT.