Method and apparatus for detecting frame delimiters in Ethernet passive optical networks with forward error correction

摘要

Embodiments of the present invention provide a system that identifies an even delimiter in a forward error correction (FEC)-coded Ethernet frame. The system receives an FEC-coded Ethernet frame that includes the even delimiter, which is a predetermined sequence that separates a conventional Ethernet frame and FEC parity bits in the FEC-coded Ethernet frame. Next, the system scans a bit stream of the FEC-coded Ethernet frame. Then, the system determines a first Hamming distance between a first consecutive set of frame bits in the bit stream and the even delimiter. The system also determines a second Hamming distance between a second consecutive set of frame bits in the bit stream and the even delimiter. Both the first and second Hamming distances are shorter than a predefined value. The system subsequently selects one of the first and second sets of frame bits having the shorter Hamming distance as the even delimiter.

主权项

1. A method for identifying an even delimiter in a forward error correction (FEC)-coded Ethernet frame, comprising:
receiving an FEC-coded Ethernet frame that includes an even delimiter used to separate a conventional Ethernet frame and FEC parity bits in the FEC-coded Ethernet frame, wherein the even delimiter is a predetermined bit sequence; scanning a bit stream of the FEC-coded Ethernet frame; determining a first Hamming distance between a first consecutive set of frame bits in the bit stream and the even delimiter, wherein the first Hamming distance is shorter than a predefined value; determining a second Hamming distance between a subsequent second consecutive set of frame bits in the bit stream and the even delimiter, wherein the second Hamming distance is shorter than the predefined value; selecting one of the first and second consecutive sets of frame bits having the shorter Hamming distance as the even delimiter.