Patent ID: 8224135

Claim:
An office side line terminal apparatus (OLT) for communicating with a plurality of subscriber connection apparatuses (ONUs) through an optical network including a trunk optical fiber connected to the OLT and a plurality of branch optical fibers each connected to one of said ONUs, said branch optical fibers branching from said trunk optical fiber, and each of said ONUs being provided with a plurality of spread-spectrum spreaders having different spreading codes to each other and a plurality of spread-spectrum despreaders having different spreading codes to each other, the office side line terminal apparatus (OLT) comprising: an OLT upstream interface and an OLT downstream interface which are connected to said trunk optical fiber; and an OLT controller connected to said OLT upstream interface and said OLT downstream interface, said OLT upstream interface including an optical signal receiver for receiving a wavelength-division multiplexed optical CDMA signal through said trunk optical fiber, and a plurality of spread-spectrum despreaders connected to said optical signal receiver and having different spreading codes from each other, and said OLT downstream interface including a plurality of spread-spectrum spreaders having different spreading codes from each other, and at least one optical signal transmitter for transmitting CDMA signals outputted from said spread-spectrum spreaders to said trunk optical fiber as an optical CDMA signal, wherein said OLT controller is configured so as to periodically broadcast a channel resource information block specifying a carrier wavelength and a spreading code to a first downstream channel to which a spread-spectrum spreader having a first spreading code is applied, receive a connection request from one of said ONUs by using a spread-spectrum despreader having the spreading code specified in said channel resource information block, and transmit to said first channel a new channel resource information block, which is addressed to the ONU having made the connection request and specifies a carrier wavelength and a spreading code to be used in an upstream data channel, so that the ONU transmits upstream data as an optical CDMA signal by using the carrier wavelength and the spreading code specified in the new channel resource information block and the OLT receives the upstream data by using a spread-spectrum despreader having the specified spreading code.