An apparatus comprising an optical line terminal (OLT) configured to couple to a plurality of optical network units (ONUs) and transmit a plurality of downstream frames to the ONUs, wherein each of the downstream frames comprises a plurality of forward error correction (FEC) codewords and a plurality of additional non-FEC encoded bytes that comprise synchronization information that is protected by Header Error Control (HEC) code. An apparatus comprising a processing unit configured to arrange control data, user data, or both into a plurality of FEC codewords in a downstream frame and arrange a physical synchronization sequence (PSync), a superframe structure, and a Passive Optical Network-identifier (PON-ID) structure in a plurality of additional non-FEC encoded bytes in the downstream frame, and a transmission unit configured to transmit the FEC codewords and the additional non-FEC encoded bytes in the downstream frame within a 125 microsecond window.