Frequency division multiple access optical subcarriers
A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.
1. A transmitter, comprising:
a laser that outputs an optical signal;
a digital signal processor operable to receive data and provide a first plurality of electrical signals based on the data;
a plurality of digital-to-analog conversion circuits operable to provide a second plurality of electrical signals based on the first plurality of electrical signals;
a plurality of driver circuits operable to provide a third plurality of electrical signals based on the second plurality of electrical signals; and
a modulator operable to modulate the optical signal to provide a plurality of optical subcarriers based on the third plurality of electrical signals, such that each of the plurality of optical signals is associated with the laser, each of the plurality of optical subcarriers including an in-phase component and a quadrature component, wherein the plurality of optical subcarriers is supplied to an optical communication path including an optical fiber, a first one of the plurality of optical subcarriers carries first control information associated with a first node remote from the transmitter and a second one of the plurality of optical subcarriers carries second control information associated with a second node remote from the transmitter,
wherein a modulation of a third one of the plurality of optical subcarriers is indicative of a characteristic of a node remote from the transmitter.
2. The transmitter in accordance with claim 1 , wherein the first control information is indicative of a capacity of the first node and the second control information is indicative of a capacity of the second node.
3. The transmitter in accordance with claim 1 , wherein the first control information is indicative of operation, administration, or maintenance information associated with the first node.
4. The transmitter in accordance with claim 1 , wherein each of the plurality of subcarriers is a Nyquist subcarrier.
5. The transmitter in accordance with claim 1 , wherein the digital signal processor includes a programmable gate array (PGA).
6. The transmitter in accordance with claim 5 , wherein the programmable gate array includes a field programmable gate array (FPGA).