Patent ID: 8817589

Claim:
A method in a communications network for line coding, the method comprising: receiving a plurality of downstream communications traffic bits; mapping the downstream communications traffic bits into a plurality of downstream bit positions of a transmission structure and providing a pre-selected bit in each of a plurality of upstream bit positions of the transmission structure to form a downstream transmission structure, wherein the plurality of upstream bit positions is in positions different from the plurality of downstream bit positions of the downstream transmission structure, and wherein each downstream communications traffic bit has a first bit period, and each downstream bit position and each upstream bit position has a second bit period which is less than the first bit period, the total of the second bit periods of the downstream bit positions and the upstream bit positions being equal to the total of the first bit periods of the communications traffic bits; generating and transmitting a downstream optical signal carrying the downstream transmission structure; receiving a plurality of upstream communications traffic bits; mapping the upstream communications traffic bits into the upstream bit positions of the transmission structure to form an upstream transmission structure; and generating and transmitting an upstream optical signal carrying the upstream transmission structure.