Frequency division multiple access optical subcarriers

Abstract

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.

What is claimed is: 
     
         1 . A transmitter, comprising:
 a laser operable to output light;   a processor operable to receive data and provide a plurality of electrical signals based on the data;   a modulator operable to modulate the light to provide a plurality of optical subcarriers, a first one of the plurality of subcarriers carrying first control information, and a second one of the plurality of subcarriers carrying second control information, the first control information being indicative of a first parameter associated with a first node remote from the transmitter and the second control information being indicative of a second parameter associated with a second node remote from the transmitter.   
     
     
         2 . A transmitter in accordance with  claim 1 , wherein the first parameter is a first amount of data output from the first node, and the second parameter is a second amount of data output from the second node. 
     
     
         3 . A transmitter in accordance with  claim 1 , wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. 
     
     
         4 . A transmitter in accordance with  claim 1 , wherein each of the plurality of optical subcarriers does not spectrally overlap with another of the plurality of optical subcarriers. 
     
     
         5 . A transmitter in accordance with  claim 1 , wherein the processor is a digital signal processor. 
     
     
         6 . A transmitter in accordance with  claim 1 , wherein the processor has a plurality of inputs, the transmitter further including:
 switch circuitry coupled to at least one of the plurality of inputs.   
     
     
         7 . A transmitter in accordance with  claim 1 , wherein the processor has a plurality of inputs, the transmitter further including:
 a plurality of switches, each of which is coupled to a respective one of the plurality of inputs.   
     
     
         8 . A transmitter in accordance with  claim 7 , wherein each of the plurality of switches selectively supplies one of a data and control information to a respective one of the plurality of inputs. 
     
     
         9 . A transmitter in accordance with  claim 1 , wherein the modulator includes a Mach-Zehnder modulator. 
     
     
         10 . A transmitter in accordance with  claim 1 , wherein the processor has an output, the transmitter further including digital-to-analog converter circuitry coupled to the output, the digital-to-analog converter circuitry operable to supply an analog output. 
     
     
         11 . A transmitter in accordance with  claim 10 , further including a driver circuitry that receives the analog output and supplies a drive signal to the modulator. 
     
     
         12 . A transmitter in accordance with  claim 1 , wherein at least one of the plurality of optical subcarriers is modulated in accordance with a modulation format, the modulation format being one of an m-quadrature amplitude modulation (m-QAM) modulation, where m is a positive integer, a quadrature phase shift keying (QPSK) modulation format, and a binary phase shift keying (BPSK) modulation format. 
     
     
         13 . A transmitter in accordance with  claim 1 , wherein the processor has a plurality of inputs, a number of the plurality of subcarriers is based on a number of the plurality of inputs receiving one of data or control information. 
     
     
         14 . A transmitter in accordance with  1 , wherein a spectral gap is present between spectra associated with at least first and second adjacent ones of the plurality of optical subcarriers. 
     
     
         15 . A receiver, comprising:
 a local oscillator laser operable to supply light;   optical hybrid circuits operable to mix the light and optical subcarriers to provide mixing products;   photodiodes operable to convert the mixing products to electrical signals;   analog to digital conversion circuitry operable to provide digital signals based on the electrical signals;   a processor operable to receive the digital signals and provide information indicative of data carried by at least a group of the subcarriers based on the digital signals,   wherein the receiver is operable to selectively output the data.   
     
     
         16 . A receiver in accordance with  claim 14 , wherein one of the plurality of subcarriers carries control information associated with the receiver. 
     
     
         17 . A receiver in accordance with  claim 16 , wherein the control information identifies an amount of data output from the receiver. 
     
     
         18 . A receiver in accordance with  claim 15 , wherein the control information identifies a number of subcarriers carrying information indicative of data output from the receiver. 
     
     
         19 . A receiver in accordance with  claim 15 , wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. 
     
     
         20 . A receiver in accordance with  claim 15 , wherein each of the plurality of optical subcarriers does not spectrally overlap with another of the plurality of optical subcarriers. 
     
     
         21 . A receiver in accordance with  claim 15 , wherein the processor is a digital signal processor. 
     
     
         22 . A receiver in accordance with  claim 15 , wherein the processor has a plurality of outputs, the receiver further including:
 switch circuitry coupled to at least one of the plurality of inputs.   
     
     
         23 . A receiver in accordance with  claim 15 , wherein the processor has a plurality of outputs, the transmitter further including:
 a plurality of switches, each of which is coupled to a respective one of the plurality of outputs.   
     
     
         24 . A receiver in accordance with  claim 21  wherein each of the plurality of switches is operable to selectively supply one of a data or control information from a respective one of the plurality of outputs. 
     
     
         25 . A receiver in accordance with  15 , wherein a spectral gap is present between spectra associated with at least first and second adjacent ones of the plurality of optical subcarriers. 
     
     
         26 . A receiver in accordance with  claim 15 , wherein at least one of the plurality of optical subcarriers is modulated in accordance with a modulation format, the modulation format being one of an m-quadrature amplitude modulation (m-QAM) modulation, where m is a positive integer, a quadrature phase shift keying (QPSK) modulation format, or a binary phase shift keying (BPSK) modulation format.