Out-of-band communication channels for subcarrier-based optical communication systems

Abstract

A network or system in which a hub or primary node may communicate with multiple leaf or secondary nodes. The hub node may operate at or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed that receive data carrying optical signals from the hub node and provide 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, for example, one or more spans or segments of optical fiber, optical amplifiers, optical splitters / combiners, and optical add / drop multiplexers. Optical subcarriers may be transmitted across such connections, each carrying a data stream. The subcarriers may be generated by a combination of lasers and modulators, eliminating the need for and reducing costs of multiple lasers and modulators. Furthermore, as the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and therefore the amount of data provided to each node, may change accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control 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.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 813,151, filed March 4, 2019, which is incorporated by reference in its entirety. [Background technology]

[0002] In some optical communication systems, multiple optical signals, each with a corresponding wavelength and each modulated to carry a different data stream, are multiplexed onto an optical fiber. In such systems, lasers and modulators may be provided to generate each optical signal. Accordingly, to increase the capacity of such systems, additional lasers, modulators and associated circuitry are employed. Hence, the costs associated with such systems may increase as capacity increases. Thus, there is a need for a more cost-effective network that requires fewer components, such as those described above.

[0003] Additionally, conventional optical communication systems may include high speed circuits and components for generating high speed optical signals at the transmitting end of the system. At the receiving end, corresponding high speed circuits may be provided to detect incoming data and forward or distribute such data to lower capacity nodes. Thus, the receiving end of the system Intermediate High Speed ​​Circuits and Components Put There is a need to further reduce costs by providing high-capacity signals to affordable lower-capacity nodes without the need for high-capacity 10GbE (10GbE) signals.

[0004] Furthermore, in some conventional optical communication systems, data may be transmitted as a series of frames, each of which includes a payload portion containing customer or user data and a header or overhead portion containing operations, administration and maintenance ("OAM") information associated with the system. As networks become more complex, the amount of such control or OAM information is increasing, potentially limiting the amount of customer data transmitted. Therefore, there is also a need to transmit OAM information more efficiently so that more customer data can be transmitted. Summary of the Invention

[0005] In accordance with the present disclosure, a network or system is provided in which a hub or primary node may communicate with multiple remote nodes, such as leaf nodes or secondary nodes. The hub node may operate at or have a capacity that may be greater than that of the leaf nodes. Thus, relatively inexpensive leaf nodes may be deployed that receive data carrying optical signals from the hub node and provide 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, for example, one or more spans or segments of optical fiber, optical amplifiers, optical splitters / combiners, and optical add / drop multiplexers. In accordance with an aspect of the present disclosure, So Across connections such as Each carries a data stream An optical subcarrier may be transmitted. The subcarrier may be may be generated by a combination of a laser and a modulator, eliminating the need for multiple lasers and multiple modulators; In addition, the subcarriers may be employed using a multiple access technique, such as frequency division multiple access (FDMA), whereby a given group of subcarriers is detected at a corresponding leaf node. Also, the bandwidth or capacity requirements of the leaf node may be reduced. of change Along with , the number of subcarriers and thus the amount of data provided to each node. But this In a further example, Special For Subcarrier Group Each inThe subcarriers may carry OAM or control channel information to corresponding leaf nodes, and such information may be used by the leaf nodes to configure them to have a desired bandwidth or capacity.

[0006] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

[0007] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments and, together with the description, serve to explain the principles of the invention.

[0008] Other aspects, features, and advantages will become apparent from the following detailed description, the accompanying drawings, and the claims. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram illustrating an example of a network in accordance with an aspect of the present disclosure. [Diagram 2] FIG. 1 is a block diagram illustrating an example of a network in accordance with an aspect of the present disclosure.

[0010] [Diagram 3] 1A and 1B are block diagrams illustrating examples of a primary node and a secondary node according to an additional aspect of the present disclosure.

[0011] [Figure 4] 1 is an example of a spectral plot showing an optical subcarrier in accordance with an aspect of the present disclosure.

[0012] [Diagram 5] FIG. 2 is a block diagram illustrating an example of a network in accordance with a further aspect of the present disclosure.

[0013] [Figure 6] 1 is an example of a spectral plot showing an optical subcarrier in accordance with an additional aspect of the present disclosure.

[0014] [Figure 7] FIG. 2 is a block diagram illustrating an example network in accordance with an additional aspect of the present disclosure.

[0015] [Figure 8] 1 is an example of a spectral plot illustrating an optical subcarrier in accordance with a further aspect of the present disclosure.

[0016] [Figure 9] 1 illustrates an example of a primary node transmitter consistent with the present disclosure.

[0017] [Figure 10a] FIG. 13 is a block diagram illustrating an example of a primary node transmitter digital signal processor (DSP) in accordance with further aspects of the disclosure.

[0018] [Figure 10b] 1 illustrates a more detailed diagram of a portion of a primary node transmitter DSP in accordance with an aspect of the present disclosure.

[0019] [Figure 10c] 1 illustrates a more detailed view of a portion of a primary node transmitter DSP in accordance with another aspect of the disclosure.

[0020] [Figure 11a] 1 illustrates an example of a secondary node receiver consistent with the present disclosure. [Figure 11b] 1 illustrates an example of bandwidth associated with a secondary node consistent with the present disclosure.

[0021] [Figure 12] 1 illustrates an example of a secondary node receiver DSP consistent with the present disclosure.

[0022] [Figure 13a] 1 illustrates an example of a secondary node transmitter consistent with aspects of the present disclosure.

[0023] [Figure 13b] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13c] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13d] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13e] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13f] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13g] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13h] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13i] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure. [Figure 13j] 11 is an example of a spectral plot of a subcarrier output from a secondary node in accordance with an additional aspect of the present disclosure.

[0024] [Figure 13k] 1 is an example of a spectral plot showing combined subcarriers provided to a primary node receiver.

[0025] [Figure 14] 1 illustrates an example of a primary node receiver according to an aspect of the present disclosure.

[0026] [Figure 15] 1 illustrates an example of a guard band in accordance with an additional aspect of the present disclosure.

[0027] [Figure 16] 1 illustrates an example mesh network configuration in accordance with a further aspect of the present disclosure.

[0028] [Figure 17] FIG. 13 illustrates that subcarrier data allocations can change over time in accordance with an additional aspect of the present disclosure. [Figure 18a] FIG. 13 illustrates that subcarrier data allocations can change over time in accordance with an additional aspect of the present disclosure. [Figure 18b] FIG. 13 illustrates that subcarrier data allocations can change over time in accordance with an additional aspect of the present disclosure. [Figure 18c] FIG. 13 illustrates that subcarrier data allocations can change over time in accordance with an additional aspect of the present disclosure. [Figure 19] FIG. 13 illustrates that subcarrier data allocations can change over time in accordance with an additional aspect of the present disclosure.

[0029] [Figure 20] 1 is a flowchart of a method for determining time of flight and data transmission timing in accordance with an aspect of the present disclosure.

[0030] [Figure 21] 4 is a flow chart of a method for scheduling time slots to avoid collisions. [Figure 22] 1 is a plot showing an example of time hub request and leaf response times and corresponding TOF times. [Figure 23] 11 is a table showing example TOF data associated with a second node. [Figure 24] An example of a timing chart is shown. [Diagram 25] 1 illustrates an example of a transceiver consistent with the present disclosure that includes a common laser shared between a transmitter and a receiver. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Generally, the same reference numbers are used throughout the drawings to refer to the same or similar parts. The terms "hub," "hub node," and "primary node" are used interchangeably herein. Additionally, the terms "leaf," "leaf node," and "secondary node" are used interchangeably herein.

[0032] 1 illustrates an example aggregation network 100 consistent with the present disclosure, in which a primary node 110 may communicate with a number of secondary nodes 112-j through 112-m, which may be individually or collectively referred to as secondary nodes 112. The secondary nodes 112 are remote from the primary node 110, in one example. The primary node 110 may transmit optical subcarriers, described in more detail below, in a downstream direction on optical paths 111, which may include one or more segments of optical fiber, as well as one or more optical amplifiers, reconfigurable add-drop multiplexers (ROADMs), or other optical fiber communication equipment, such as each of the optical paths 113-j through 113-m. A splitter 114 may be coupled to an end of the optical path 111 to receive the optical subcarriers and provide a power-split portion of each subcarrier to a corresponding one of the secondary nodes 112-j through 112-m via a respective one of the optical paths 113-j through 113-m.

[0033] 1, primary node 110 has a data capacity to receive n Gbit / s of data (e.g., data streams) for transmission to secondary nodes 112. Each secondary node 112 may include: P To primary node 110 Receives part of the data to be entered and sends it to the user or customerIn this example, secondary nodes 112-j, 112-k, 112-l, and 112-m may output j Gbit / s, k Gbit / s, l Gbit / s, and m Gbit / s of data (data streams), respectively, such that the sum of j, k, l, and m may be equal to n (when j, k, l, m, and n are positive numbers).

[0034] 2 illustrates the transmission of additional subcarriers in the upstream direction from secondary nodes 112-j through 112-m to primary node 110. As further illustrated in FIG. 2, each of secondary nodes 112-j through 112-m may transmit a corresponding group of subcarriers or one subcarrier over a respective one of optical paths 115-1 through 115-m to optical combiner 116. Optical combiner 116 may then combine the optical subcarriers received from secondary nodes 112-j through 112-m into optical path 117. Optical paths 115-1 through 115-m and 117 may have a similar structure to optical paths 111 and 112-1 through 112-m.

[0035] 2, each of secondary nodes 112-j through 112-m receives a respective data stream having a corresponding data rate of j Gbit / s, k Gbit / s, l Gbit / s, and m Gbit / s. At primary node 110, the data contained in these streams may be output such that the aggregate data provided by primary node 110 may be equal to the sum of j, k, l, and m, as described above.

[0036] In another example, subcarriers may be transmitted in both upstream and downstream directions over the same optical path. In particular, selected subcarriers may be transmitted in the downstream direction from the primary node 110 to the secondary node 112, and other subcarriers may be transmitted in the upstream direction from the secondary node 112 to the primary node 110.

[0037] In some implementations, network 100 may include additional primary and / or secondary nodes and optical paths, may include fewer primary and / or secondary nodes and optical paths, or may have a different configuration than described above. For example, network 100 may have a mesh configuration or a point-to-point configuration.

[0038] 3 illustrates in more detail the primary node 110. The primary node 110 may include a transmitter 202 that provides a downstream modulated optical signal, such as a subcarrier, and a receiver 204 that may receive upstream subcarriers carrying data coming from secondary nodes, such as nodes 112-j through 112-m.

[0039] FIG. 3 further illustrates a block diagram of one of the secondary nodes 112, which may include receiver circuitry 302 that receives one or more downstream transmitted subcarriers and transmitter circuitry 304 that transmits one or more subcarriers in the upstream direction.

[0040] 4 illustrates an example transmission spectrum that can accommodate 20 subcarriers (SC0 through SC19) that may be output from primary node transmitter 202. Each of subcarriers SC0 through SC19 has a corresponding one of frequencies f0 through f19. In one example, subcarriers SC0 through SC19 are Nyquist subcarriers, each of which is a group of data-carrying optical signals, where (i) the spectrum of each such optical signal in the group is sufficiently non-overlapping such that the optical signals are distinguishable from one another in the frequency domain, and (ii) such group of optical signals is generated by modulation of a beam from a single laser. In general, each subcarrier may have an optical spectral bandwidth at least equal to the Nyquist frequency, as determined by the baud rate of such subcarrier.

[0041] As noted above, each of the secondary nodes 112 may include less expensive components than those included in the primary node 110. Thus, the bandwidth or data capacity of the secondary nodes 112 may be less than that associated with the primary node 110, and the capacity associated with each secondary node 112 may be less than the capacity of the primary node 110.

[0042] 4, primary node 110 may have a bandwidth BW-P such that data carried by each of subcarriers SC1 through SC20 may be processed and regenerated to be either output from transmitter 202 or received from receiver 204. Meanwhile, each of secondary nodes 112-j through 112-m may have a respective one of bandwidths BWj through BWm such that each secondary node has the data processing capacity or is capable of processing and outputting data carried by up to nine subcarriers, in this example.

[0043] As noted above, to reduce network costs, in some particular examples, less expensive components, such as optical and certain electrical components, may be capable of processing signals over a limited frequency range or bandwidth that is smaller than the range of signal frequencies that may be accommodated by the optical and electrical components in primary node 110. For example, On secondary node 112 Electrical components such as digital-to-analog converters (DACs), analog-to-digital converters (ADCs), and digital signal processors (DSPs), as well as optical components such as modulators Bandwidth associated with is the primary node 110 versus Respond Associated with more expensive components Narrower than bandwidth It is good .

[0044] Examples of the bandwidths of each of the secondary nodes 112 are further illustrated in Fig. 4. That is, the bandwidth BWj associated with the secondary node 112-j extends or encompasses the range including frequencies f0 to f8 of the subcarriers SC0 to SC8, respectively, the bandwidth BWk associated with the secondary node 112-k extends or encompasses the range including frequencies f5 to f13 of the subcarriers SC5 to SC13, respectively, the bandwidth BWl associated with the secondary node 112-l extends or encompasses the range including frequencies f10 to f18 of the subcarriers SC10 to SC18, respectively, and the bandwidth BWm associated with the secondary node 112-m extends or encompasses the range including frequencies f11 to f19 of the subcarriers SC11 to SC19, respectively. Meanwhile, the bandwidth BW-P of the primary node 110 encompasses the entire range including frequencies f0 to f19 of the subcarriers SC0 to SC19.

[0045] As further shown in FIG. 4, certain subcarriers have frequencies that fall within multiple bandwidths. For example, subcarriers SC5 and SC6 have frequencies that fall within bandwidths BWj and BWk. Thus, data carried by such subcarriers may be detected and selectively output from either secondary node 112-j or 112-k. For example, if a customer requires more data to be received and output from secondary node 112-k and less data to be output from secondary node 112-j, nodes 112-j and 112-k may be controlled or dynamically configured such that data carried by subcarriers SC5 and SC6 may be assigned to and output from secondary node 112-k rather than secondary node 112-j. Thus, as described in more detail below, data output from each node may be adapted to changing customer demands over time.

[0046] 4, certain subcarriers, such as subcarriers SC2, SC7, SC12 and SC17, may be designated or dedicated to carry information related to parameters or characteristics associated with one or more of the secondary nodes 112. For example, such parameters may include: It should be output by one or more secondary nodes. The amount of data, the data rate, or capacity In particular, such subcarriers may carry information to configure or adjust the data amount, capacity, or data rate of data output from secondary nodes 112-j through 112-m, respectively, e.g., as described above. In yet another example, each of these subcarriers may carry user or customer data (also referred to as client data) in addition to control information. In the example shown in FIG. 4, only subcarriers SC2, SC7, SC12, and SC17 are transmitted.

[0047] In yet another example, subcarriers SC2, SC7, SC12, and SC17 are modulated to carry control or OAM information and associated data corresponding to their associated parameters, such as the capacity and status of node 112. In an additional example, subcarrier SC2 is modulated to carry control and parameter information associated with node 112-j, subcarrier SC7 is modulated to carry control and parameter information associated with node 112-k, subcarrier SC12 is modulated to carry control and parameter information associated with node 112-l, and subcarrier SC17 is modulated to carry control and parameter information associated with node 112-m. As described in more detail below with respect to FIGS. Such SCs are from node 112 To primary node 110 information about parameters associated with the timing and scheduling of data transmissions luck The signal is modulated in a way that

[0048] FIG. 5 shows an example in which each of secondary nodes 112-j through 112-m outputs an equal amount of user data coming from primary node 110, and FIG. 6 shows how subcarriers SC0 through SC19 may be allocated or associated with each secondary node 112 to satisfy the data allocation shown in FIG. 5. Furthermore, in the example shown in FIGS. 5 and 6, the total data input to primary node 110 may be 20 Gbit / s (n=20), and each of secondary nodes 112 outputs an equal portion of such data, i.e., for 5 Gbit / s, j=k=m=5. In other words, based on the control information received by node 112-j, e.g., the associated data

[0049] Here, subcarriers SC0, SC1, SC3 and SC4 may be assigned to secondary node 112-j (subcarrier SC2 is further assigned to and carries control channel information for secondary node 112-j), subcarriers SC5, SC6, SC8 and SC9 may be assigned to secondary node 112-k (subcarrier SC7 is further assigned to and carries control channel information for secondary node 112-k), subcarriers SC10, SC11, SC13 and SC14 may be assigned to secondary node 112-l (subcarrier SC12 is further assigned to and carries control channel information for secondary node 112-l), and subcarriers SC15, SC16, SC18 and SC19 may be assigned to secondary node 112-m (subcarrier SC17 is further assigned to and carries control channel information for secondary node 112-m). Each subcarrier may have an associated data rate of 1 Gbit / s in this example.

[0050] In other words, based on the control information received by node 112-j, carried by subcarrier SC2, e.g. See below Input to DSP902 R Associated with subcarriers SC0, SC1, SC3 and SC4 The first partData but , together with any user data carried by subcarrier SC2. Node 112-j mosquito Further, based on the control information received by the node 112-k and carried by the subcarrier SC7, for example, R Associated with subcarriers SC5, SC6, SC8 and SC9 The second part Data but , along with any user data carried by subcarrier SC7. Node 112-k mosquito It is output from

[0051] 7 illustrates another example in which the allocation of data to secondary nodes 112-j through 112-m may be altered, for example, based on changing capacity requirements, e.g., at a time later than the time associated with the subcarrier allocations shown in FIG. pointIn FIG. 7, for example, node 112-j may require more data than node 112-k, here control information carried by subcarriers SC2, SC7, SC12, and SC17. FIG. 8 illustrates how subcarriers SC0 through SC19 may be assigned or associated with each secondary node 112 to satisfy the data allocation shown in FIG. In this example, secondary node 112-j may be assigned the maximum data capacity, i.e., data carried by seven subcarriers (SC0, SC1 through SC3-SC6, and SC8), and any customer data that may be carried by subcarrier SC2; secondary node 112-k may be assigned one-third (i.e., three-ninths) of the maximum data capacity, i.e., data carried by three subcarriers (SC9-SC11), and any customer data that may be carried by subcarrier SC7; secondary node 112-l may be assigned five-ninths of the maximum data capacity, i.e., data carried by four subcarriers (SC13-SC16), and any customer data that may be carried by subcarrier SC12; and secondary node 112-m may be assigned one-third (i.e., three-ninths) of the maximum data capacity, i.e., data carried by two subcarriers (SC18 and SC19), and any customer data that may be carried by subcarrier SC17.

[0052] In other words, In the example described above with respect to FIG. Based on the additional (third) control information received by node 112-j, carried by subcarrier SC2, example For example, Input to DSP902 Associated with subcarriers SC0, SC1, SC3-SC6, and SC8 The third part Data teeth , together with any user data carried by subcarrier SC2. Node 112-j mosquitoAlso, based on (fourth) control information received by node 112-k carried by subcarrier SC7, for example, a fourth portion of the data input to DSP 902 and associated with subcarriers SC9-SC11 is output from node 112-k, as well as any user data carried by subcarrier SC7.

[0053] Thus, by communicating control information to the secondary nodes, the amount of assigned data, e.g., data rate, for output from each secondary node 112 may be controlled or varied over time based on such control information. In the example discussed above, the control information may identify subcarriers associated with each node, and therefore the amount of data or data rate assigned to each node based on the number of subcarriers carrying data output from such node. As noted above, such assignments may change dynamically, e.g., in response to changing data traffic demands in network 100, and such assignment information may be carried by selected or dedicated subcarriers, such as subcarriers SC2, SC7, SC12, and SC17, as noted above.

[0054] Data allocation and subcarrier transmission will now be described with reference to Figure 9 and Figures 10a to 10c.

[0055] FIG. 9 illustrates the transmitter 202 of the primary node 110 in more detail. The transmitter 202 includes a number of circuits or switches SW, as well as a transmitter DSP (TX DSP) 902 and a D / A and optical block 901. In this example, 20 switches (SW-0 through SW-19) are shown, although more or less switches than those shown in FIG. 9 may be provided. Each switch may have two inputs in some examples. The first input may receive user data and the second input may receive control information or signals (CNT). Each switch SW-0 through SW-19 may receive a respective one of control signals SWC-0 through SWC-19 output from a control circuit 971, which may include a microprocessor, a field programmable gate array (FPGA), or other processor circuit. Based on the received control signal, each switch SW-0 through SW19 selectively outputs any one of the data streams D-0 through D-19 or the control signals CNT-0 through CNT-19. The control signal CNT may be any combination of configuration bits for control and / or monitoring purposes. For example, the control signal CNT may include instructions to one or more of such secondary nodes 112 to modify data output from such secondary nodes 112, such as by identifying the subcarrier associated with the data. In another example, the control signal may include a series of such known bits used in the secondary nodes 112 to "train" the receiver to detect and process bits so that the receiver can further process subsequent bits. In a further example, the control channel CNT includes information that may be used by the polarization mode dispersion (PMD) equalizer circuit 1125 discussed below to correct errors resulting from polarization rotation of the X and Y components of one or more subcarriers (SC). In a further example, the control information CNT is used to repair or correct a phase difference between the laser transmitter laser 908 and the local oscillator laser 1110 in each of the secondary nodes 112. Such a detected phase difference may be referred to as a cycle slip.In a further example, the control information CNT may be used to recover, synchronize, or correct timing differences between clocks provided at the primary node 110 and the secondary node 112 .

[0056] In another example, one or more of the switches SW may be omitted and the control signal CNT may be provided directly to the DSP 902. Furthermore, each input to the DSP 902, such as the input to the FEC encoder 1002 (see FIG. 10a) described below, receives a combination of control information and user data as described above in another example.

[0057] In a further example, the control signal CNT includes information related to the number of subcarriers that may be output from each of the secondary nodes 112. Such selective transmission of subcarriers is described with reference to Figures 10a-10c. Although such description is with respect to the primary node DSP 902, similar circuitry may be included in the secondary node TX DSP 1302 (Figure 13) to adjust or control the number of subcarriers output from the secondary node TX DSP 1302.

[0058] Based on the outputs of switches SW-0 through SW-19, DSP 902 may provide multiple outputs to D / A and optical block 901, which includes digital-to-analog conversion (DAC) circuits 904-1 through 904-4 that convert the digital signals received from DSP 902 to corresponding analog signals. D / A and optical block 901 includes DAC 904-1 through 904-4. ~ 904-4 mosquito Receives analog signal from and adjusts the voltage or other characteristics of the analog signal to provide a drive signal to a corresponding one of modulators 910-1 through 910-4. Driver circuit 906-1 ~ 906-2 too include 。

[0059] D / A and optics block 901 further includes modulators 910-1 through 910-4, each of which may be, for example, a Mach-Zehnder Modulator (MZM), that modulates the phase and / or amplitude of the light beam output from laser 908. As further shown in FIG. 9, the light beam output from laser 908, also included in block 901, is split such that a first portion of the light beam is provided to a first MZM pairing including MZMs 910-1 through 910-2 and a second portion of the light beam is provided to a second MZM pairing including MZMs 910-3 through 910-4. The first portion of the beam is further split into a third portion and a fourth portion, the third portion being modulated by MZM 910-1 to provide an in-phase (I) component of the X (or TE) polarization component of the modulated optical signal, and the fourth portion being modulated by MZM 910-2 and sent to phase shifter 912-1 to shift the phase of such beam by 90 degrees to provide a quadrature (Q) component of the X polarization component of the modulated optical signal. Similarly, the second portion of the beam is further split into a fifth portion and a sixth portion, the fifth portion being modulated by MZM 910-3 to provide an I component of the Y (or TM) polarization component of the modulated optical signal, and the sixth portion being modulated by MZM 910-4 to phase shifter 912-2 to shift the phase of such beam by 90 degrees to provide a Q component of the Y polarization component of the modulated optical signal.

[0060] The optical outputs of MZMs 910-1 and 910-2 are combined to provide an X-polarized optical signal including an I component and a Q component, which is sent to a polarization beam combiner (PBC) 914 provided in block 901. Furthermore, the outputs of MZMs 910-3 and 910-4 are combined to provide an optical signal which is sent to a polarization rotator 913 further provided in block 901. Said polarization rotator 913 rotates the polarization of such optical signal to provide a modulated optical signal having Y (or TM) polarization. The Y-polarized modulated optical signal is also provided to PBC 914, which combines the X-polarized modulated optical signal and the Y-polarized modulated optical signal to provide a polarization multiplexed ("dual-pol") modulated optical signal onto optical fiber 916, which may be included, for example, as a segment of optical fiber in optical path 111.

[0061] The polarization multiplexed optical signal output from the D / A and optical block 401 includes the above-mentioned subcarriers SC0 to SC19, each subcarrier having an X-polarization component and a Y-polarization component, and an I component and a Q component. Furthermore, each subcarrier SC0 to SC19 may be associated with or correspond to a respective one of the outputs of the switches SW-0 to SW-19. In one example, the switches SW2, SW7, SW12, and SW17 may provide control information carried by a respective one of the control signals CNT-2, CNT-7, CNT-12, and CNT-17 to the DSP 902. Based on such control signals, the DSP 902 provides resulting outputs on the optical subcarriers SC2, SC7, SC12, and SC17 carrying data representing the control information carried by the CNT-2, CNT-7, CNT-12, and CNT-17, respectively, as shown in FIGS. 4, 6, and 8. Furthermore, the remaining subcarriers SC0, SC1, SC3 to SC6, SC8 to SC11, SC13 to SC16, and SC18 to SC20 carry information representing a respective one of the outputs of data streams D-0, D-1, D-3 to D-6, D-8 to D-11, D-13 to D-16, and D-18 to D-20 from a corresponding one of the switches SW0, SW1, SW3 to SW6, SW8 to SW11, SW13 to SW16, and SW18 to SW20, as shown in Figures 4, 6 and 8.

[0062] FIG. 10a illustrates an example of the TX DSP 902 in more detail. The TX DSP 902 may include FEC encoders 1002-0 through 1002-19, each of which may receive a respective one of a number of outputs from switches SW0 through SW19. The FEC encoders 1002-0 through 1002-19 perform forward error correction coding on a corresponding one of the switch outputs, such as by adding parity bits to the received data. The FEC encoders 1002-0 through 1002-19 may provide timing skew between subcarriers to compensate for skew caused by links between the nodes 110 and 112-j through 112-m. Additionally, the FEC encoders 1002-0 through 1002-19 may interleave the received data.

[0063] Each of the FEC encoders 1002-0 through 1002-19 provides an output to a corresponding one of a number of bit-to-symbol circuits 1004-0 through 1004-19 (collectively referred to herein as "1004"). Each of the bit-to-symbol circuits 1004 outputs the encoded bits to Complex Plane above Symbol For example, the bit-to-symbol circuit 1004 may map a dual polarization QPSK constellation above 4 bits in 1 Each of the bit-to-symbol circuits 1004 may map to a symbol, such as D-0. To DSP section 1003 The first symbol having complex representation XI+j*XQ associated with each one of the switch outputs is proposal The data representing such first symbol is carried by the X-polarized component of each subcarrier SC0-SC19.

[0064] Each of the bit-to-symbol circuits 1004 may further provide a second symbol having complex representation YI+j*YQ that is also associated with a corresponding output of a switch SW0-SW19, but with data representing such second symbol being carried by the Y polarization components of each of the subcarriers SC-0 through SC-19.

[0065] Such mapping, as carried by circuits 1004-0 through 1004-19 or thereabout, defines a particular modulation format for each subcarrier in one example. That is, such circuitry may define a mapping for all optical subcarriers that represents a binary phase shift keying (BPSK) modulation format, a quadrature phase shift keying (QPSK) modulation format, or an m-quadrature amplitude modulation (QAM, where m is a positive integer, e.g., 4, 8, 16, or 64) format. In another example, one or more of the optical subcarriers may have a modulation format that is different from the modulation format of the other optical subcarriers. That is, one of the optical subcarriers has a QPSK modulation format and another optical subcarrier has a different modulation format, such as 8-QAM or 16-QAM. In another example, one of the optical subcarriers has an 8-QAM modulation format and another optical subcarrier has a 16-QAM modulation format. Thus, while all optical subcarriers may carry data at the same data rate or baud rate in accordance with aspects of the present disclosure, one or more of the optical subcarriers may carry data at a different data rate or baud rate than one or more of the other optical subcarriers. Also, the modulation format, baud rate, and data rate may change over time, for example, depending on capacity requirements. Adjustment of such parameters may include, for example, Books The control information or data described herein and the control information or data further disclosed herein Between hub nodes and leaf nodes This may be accomplished by applying an appropriate signal to mapper 1004 based on the communication of such data.

[0066] As further shown in Figure 10a, each of the first symbols output from each of the bit-to-symbol circuits 1004 is provided to a respective one of the first overlap and save buffers 1005-0 through 1005-19 (collectively referred to herein as overlap and save buffers 1005), which may, for example, buffer 256 symbols. B from a corresponding one of the bit-symbol circuits 1004 128 first symbols at a time or another number of such symbols Thus, overlap and save buffer 1005 may combine 128 new symbols from bit-to-symbol circuit 1004 with the previous 128 symbols received from bit-to-symbol circuit 1004.

[0067] Each overlap and save buffer 1005 provides an output in the time domain to a corresponding one of fast Fourier transform (FFT) circuits 1006-0 through 1006-19 (collectively "FFTs 1006"). In one example, the output includes 256 symbols or another number of symbols. Each of the FFTs 1006 transforms the received symbols to the frequency domain, for example, using or based on a fast Fourier transform. Each of the FFTs 1006 may provide frequency domain data to a bin and switch block 1021-0 through 1021-19. As discussed in more detail below, the bin and switch block 1021 includes a memory or register that stores frequency components associated with each subcarrier SC, also referred to as a frequency bin (FB) or frequency point.

[0068] Selected frequency bins FB are shown in Fig. 10b. Such a group of frequency bins FB is associated with a given subcarrier. Thus, for example, a first group of frequency bins FB0-0 to FB0-n is associated with SC0, and a second group of frequency bins FB19-0 to FB19-n is associated with SC19 (where n is a positive integer). As further shown in Fig. 10b, each of the frequency bins FB is further coupled to a respective one of the switches SW. For example, each of the frequency bins FB0-0 to FB0-n is coupled to a respective one of the switches SW0-0 to SW0-n, and each of the FB19-0 to FB19-n is coupled to a respective one of the switches or switch circuits SW19-0 to SW19-n.

[0069] Each switch SW selectively provides the frequency domain data output from one of the FFT circuits 1006-0 through 1006-19, or a predetermined value, such as zero. To block or erase the transmission of a particular subcarrier, the switch SW associated with the group of frequency bins FB associated with that subcarrier is configured to provide a zero value to the corresponding frequency bin. Thus, for example, to block subcarrier SC0, switches SW0-0' through SW0-n' provide a zero (0) value to each one of the frequency bins FB0-0 through FB0-n. Further processing of the zero (0) values ​​by replicator component 1007, as well as other components and circuits in DSP 902, as described below, results in a drive signal provided to modulator 910, with subcarrier SC0 being omitted from the optical output from the modulator.

[0070] Meanwhile, switch SW′ may be configured to provide the output of FFT 1006, i.e., frequency domain data FD, to the corresponding frequency bin FB. Further processing of the contents of frequency bin FB by replicator component 1007 and other circuitry in DSP 902 results in a drive signal provided to modulator 910, which generates an optical subcarrier corresponding to the grouping of frequency bins associated with that optical subcarrier based on such drive signal.

[0071] In the example discussed above, switches SW0-0' through SW0-n' provide frequency domain data FD0-0 through FD0-n from FFT 1006-0 to respective ones of switches SW0-0 through SW0-n, which then provide the frequency domain data to respective ones of frequency bins FB0-0 through FB0-n for further processing, as described in more detail below.

[0072] Each of the replicator components or circuits 1007-0 through 1007-19 may replicate the contents of the frequency bin FB and store such contents in a respective one of the multiple replicator components (e.g., for T / 2-based filtering of the subcarriers). Such replication may increase the sample rate. Additionally, the replicator components or circuits 1007-0 through 1007-19 may position or align the contents of the frequency bins to fall within bandwidths associated with the pulse shaping filter circuits 1008-0 through 1008-19 described below.

[0073] Each of the pulse shaping filter circuits 1008-0 through 1008-19 may apply a pulse shaping filter to the data stored in the 512 frequency bins of each of the multiple replicator components or circuits 1007-0 through 1007-19 to provide a respective one of a plurality of filtered outputs that are multiplexed and subjected to an inverse FFT, as described below. The pulse shaping filter circuits 1008-1 through 1008-19 calculate the transition between the symbol and the desired subcarrier spectrum so that the subcarriers may be spectrally packed together for transmission, e.g., with close frequency separation. The pulse shaping filter circuits 1008-0 through 1008-19 may also be used to introduce timing skew between the subcarriers, e.g., to correct timing skews caused by links between the nodes shown in FIG. 1. A multiplexer component 1009, which may include a multiplexer circuit or a memory, may receive the filtered outputs from the pulse shaping filter circuits 1008-0 through 1008-19 and may multiplex or combine such outputs together to form an element vector.

[0074] An IFFT circuit or component 1010-1 may then receive the element vector and provide a corresponding time domain signal or data based on an inverse fast Fourier transform (IFFT). In one example, the time domain signal may have a rate of 64 Gsamples / sec. A final buffer or memory circuit 1011-1 may, for example, select the last 1024 samples or another number of samples from the output of the IFFT component or circuit 1010-1 and provide the samples to DACs 904-1 and 904-2 (see FIG. 9 ) at, for example, 64 Gsamples / sec. As described above, DAC 904-1 is associated with the in-phase (I) component of the Xpol signal, and DAC 904-2 is associated with the quadrature (Q) component of the Ypol signal. Thus, along with the complex representation XI+jXQ, DAC 904-1 receives a value associated with XI, and DAC 904-2 receives a value associated with jXQ. Based on these inputs, as indicated in FIG. 9, DACs 904-1 and 904-2 provide analog outputs to MZMD 906-1 and MZMD 906-2, respectively, as discussed above.

[0075] 10a, each of bit-to-symbol circuits 1004-0 through 1004-19 outputs a corresponding one of the symbols representing the data carried by the Y polarization component of the output polarization multiplexed modulated optical signal output onto fiber 916. As further noted above, these symbols may have a complex representation YI+j*YQ. Each such symbol may be processed by a respective one of the duplication and saving buffers 1015-0 through 1015-19, a respective one of the FFT circuits 1016-0 through 1016-19, a respective one of the replicator components or circuits 1017-0 through 1017-19, a respective one of the pulse shaping filter circuits 1018-0 through 1018-19, a multiplexer or memory 1019, an IFFT 1010-2, and a final buffer or memory circuit 1011-2 to provide a processed symbol having representation YI+j*YQ in a similar or same manner as discussed above in generating the processed representation XI+j*XQ output from the final circuit 1011-1. Further, the symbol components YI and YQ are provided to DACs 904-3 and 904-4, respectively (FIG. 9). Based on these inputs, DACs 904-3 and 904-4 provide analog outputs to MZMD 906-3 and MZMD 906-4, respectively, as discussed above.

[0076] 10a illustrates a DSP 902 including a particular number and arrangement of functional components in some implementations, although the DSP 902 may include additional, fewer, different, or different arrangements of functional components. Additionally, a typical number of duplication and save buffer circuits, FFT circuits, replicator circuits, and pulse shaping filters associated with the X component may be equal to the number of switch outputs, and the number of such circuits associated with the Y component may also be equal to the number of switch outputs. However, in other examples, the number of switch outputs may differ from the number of these circuits.

[0077] As described above, based on the output of MZMDs 906-1 through 906-4, a plurality of optical subcarriers SC0 through SC19 may be output onto an optical fiber 916 (FIG. 9) that is coupled to primary node 110.

[0078] In accordance with aspects of the disclosure, the number of subcarriers transmitted from the primary node 110 to the secondary node 112 may vary over time based on, for example, capacity requirements at the primary and secondary nodes. For example, if less downstream capacity is initially required at one or more of the secondary nodes, the transmitter 202 of the primary node 110 may be configured to output fewer optical subcarriers. On the other hand, if more capacity is later required, the transmitter 202 may provide more optical subcarriers.

[0079] Additionally, based on changing capacity demands, adjustments to particular secondary nodes 112 may be necessary; for example, the output capacity of such secondary nodes may correspondingly increase or decrease by increasing or decreasing the number of optical subcarriers output from the secondary nodes.

[0080] As noted above, a given subcarrier SC may be removed or erased by storing a zero (0) or other predetermined value in the frequency bin FB grouping associated with that subcarrier SC and then processing. To add or restore such a subcarrier, the frequency domain data output from the FFT 1006 may be stored in the frequency bin FB and then processed to provide the corresponding subcarrier. In this manner, subcarriers may be selectively added or removed from the optical outputs of the primary node transmitter 202 and the secondary node transmitter 304 to alter the number of subcarriers output from such transmitters as desired.

[0081] In the above example, zeros (0) or other predetermined values ​​are stored in selected frequency bins FB to prevent transmission of particular subcarriers SC. Such zeros or values ​​may instead be provided at the output of a corresponding replicator component 1007, e.g., in a manner similar to that described above, or stored in a corresponding location in memory or multiplexer 1009. Alternatively, the zeros or values ​​may be provided at the corresponding output of a pulse shaping filter 1008, e.g., in a manner similar to that described above.

[0082] In yet another example, a corresponding one of the pulse-shaping filters 1008-1 through 1008-19 may selectively generate zero or a predetermined value that, if further processing occurs, also causes one or more subcarriers SC to be omitted from the output of either the primary node transmitter 202 or the secondary node transmitter 304. Notably, as shown in FIG. 10c, the pulse-shaping filters 1008-0 through 1008-19 are shown as including a group of multiplier circuits M0-0 through M0-n, M19-0 through M19-n (also referred to individually or collectively as M). Each multiplier circuit M forms part of a corresponding butterfly filter. Furthermore, each grouping of multiplier circuits is associated with a corresponding one of the corresponding subcarriers SC.

[0083] Each multiplier circuit M receives a corresponding one of output groupings RD0-0 through RD0-n, RD19-0 through RD19-n from the replicator component 1007. To remove or eliminate one of the subcarriers SC, the multiplier circuit M receiving the output in the particular grouping associated with that subcarrier multiplies such output by zero (0) such that each multiplier M in that group produces a solution equal to zero (0). The zero solution then undergoes further processing similar to that described above to provide a drive signal to the modulator 910 resulting in the corresponding subcarrier SC being omitted from the output of the transmitter (either transmitter 202 or 304).

[0084] Meanwhile, to provide the subcarrier SC, each of the multiplier circuits M in a particular grouping multiplies a corresponding one of the replicator outputs RD by a respective one of the coefficients C0-0 through C0-n...C19-0 through C19-n, resulting in at least some non-zero solution being output. Based on the solution output from the corresponding multiplier grouping, a drive signal is provided to the modulator 910 to output the desired subcarrier SC from the transmitter (either transmitter 202 or 304).

[0085] Thus, for example, to block or erase subcarrier SC0, each of multiplier circuits M0-0 through M0-n (associated with subcarrier SC0) multiplies a respective one of replicator outputs RD0-0 through RD0-n by zero (0). Each such multiplier circuit therefore provides a solution equal to zero, which is further processed as described above such that the resulting drive signal causes modulator 910 to provide an optical output without SC0. To recover SC0, multiplier circuits M0-0 through M0-n multiply a respective one of replicator outputs RD0-0 through RD0-n by a corresponding one of appropriate coefficients C0-0 through C0-n to provide solutions, at least some of which are non-zero. Based on these solutions, as described above, modulator drive signals are generated, which result in output subcarrier SC0.

[0086] The above examples are described in relation to generating or removing the X component of a subcarrier SC. The processes and circuits described above may be employed or included in the DSP 902 and the optical circuitry used to generate the Y components of the subcarriers to be blocked. For example, the switch and bin circuit blocks 1022-0 through 1022-19 may have a similar structure and operate in a similar manner to the switch and bin circuit block 1021 described above to provide zeros or frequency domain data to selectively block the Y components of one or more subcarriers SC, as the case may be. Alternatively, a multiplier circuit may be provided to provide a solution of zeros output from a selected pulse shaping filter 1018 to block the Y components of a particular subcarrier, similar to that described above in relation to FIG. 10c, or to generate a subcarrier if a non-zero coefficient is instead provided to the multiplier circuit.

[0087] Thus, the above example illustrates a mechanism by which subcarriers SC may be selectively blocked from or added to the output of transmitter 202. As discussed below, the DSP and optical circuitry provided in the secondary node transmitter 304 is similar to that of the primary node transmitter 202, so that the processes and circuitry described above may be provided in the secondary node transmitter 304, for example, to selectively add and remove subcarriers SC′ from the output of the secondary node transmitter, as described in connection with FIGS. 13b through 13k. Further, consistent with the present disclosure, the circuitry described above in connection with FIGS. 10b and / or 10c may be configured such that a first number of optical subcarriers are output from a transmitter (at either the primary node 110 or the secondary node 112) based on an initial capacity request during a first period of time. Thereafter, a second number of optical subcarriers may be output from a hub and / or leaf transmitter based on a capacity request that differs from the first capacity request during a second period of time.

[0088] Optical subcarriers SC0 through SC19 may be provided to the secondary nodes 112 of Figure 1. An example of a receiver circuit 302 in one of the secondary nodes 112 will now be described with reference to Figure 11a.

[0089] As shown in FIG. 11a, the optical receiver 302 may include an Rx optics and A / D block 1100 that may perform coherent detection in conjunction with a DSP 1150. Block 1100 may include a polarization splitter (PBS) 1105 with a first output (1105-1) and a second output (1105-2), a local oscillator (LO) laser 1110, 90 degree optical hybrids or mixers 1120-1 and 1120-2 (collectively referred to as multiple hybrid mixers 1120 and individually as hybrid mixers 1120), detectors 1130-1 and 1130-2 (collectively referred to as multiple detectors 1130 and individually as detectors 1130, each including either a single photodiode or a balanced photodiode), AC coupling capacitors 1132-1 and 1132-2, transimpedance amplifier / automatic gain control circuits TIA / AGC 1134-1 and 1134-2, and ADCs 1140-1 and 1140-2 (collectively referred to as multiple ADCs 1140 and individually as ADCs 1140).

[0090] Polarizing beam splitter (PBS) 1105 may comprise a polarization splitter that receives an input polarization multiplexed optical signal including optical subcarriers SC0 to SC19 provided by optical fiber link 1101. Optical fiber link 1101 may be, for example, an optical fiber segment as part of one of optical paths 113-k to 113-m mentioned above. PBS 1105 may split the incoming optical signal into two X and Y orthogonal polarization components. The Y component may be provided to polarization rotator 1106 that rotates the polarization of the Y component to obtain X polarization. Hybrid mixer 1120 may include: Bureau Light from the external oscillator laser 1110 and, X-polarized component and rotated Y-polarized component and Let's combine In one example, the hybrid mixer 1120 is a tunable laser.For example, hybrid mixer 1120-1 may combine a first polarization signal (e.g., the component of the incoming optical signal having a first or X(TE) polarization output from the first PBS port) with the light from the local oscillator 1110, and hybrid mixer 1120-2 may combine the rotated polarization signal with the light from the local oscillator 1110. In one example, a polarization rotator 1190 may be provided at the PBS output to rotate the Y component polarization to obtain X polarization.

[0091] The detector 1130 may detect the mixed products output from the optical hybrid and form a corresponding voltage signal, which is subject to AC coupling by the capacitors 1132-1 and 1132-2, and amplification and gain control by the TIA / AGCs 1134-1 and 1134-2. The outputs of the TIA / AGCs 1134-1 to 1134-2 and the ADC 1140 may convert the voltage signals into digital samples. For example, two detectors (e.g., photodiodes) 1130-1 may detect the X-polarized signal and form a corresponding voltage signal, and after amplification, gain control and AC coupling, the corresponding two ADCs 1140-1 may convert the voltage signals into digital samples for the first polarization signal. Similarly, two detectors 1130-2 may detect the rotated Y-polarized signal and form a corresponding voltage signal, and after amplification, gain control and AC coupling, the corresponding two ADCs 1140-2 may convert the voltage signals into digital samples for the second polarization signal. The RX DSP 1150 may process digital samples associated with the X-polarized and Y-polarized components to output data associated with one or more subcarriers within a group of subcarriers SC0 through SC19 encompassed by a bandwidth (one of BWj, BWk, BWl, and BWm) associated with a secondary node that houses the particular DSP 1150. For example, as shown in FIG. 6, subcarriers SC0 through SC8 are within bandwidth BSj, and such subcarriers may be processed by a receiver at secondary node 112-j. However, as noted above, subcarriers SC5 through SC13 are within bandwidth BWk, and therefore may be processed by a receiver at secondary node 112-k. That is, bandwidths BWj and BWk overlap such that subcarriers within overlapping portions of these bandwidths, i.e., subcarriers SC5 through SC8, are processed by receivers at both secondary nodes 112-j and 112-k.If data associated with these subcarriers is intended to be output from secondary node 112-k, then, for example, switch circuitry may be provided to selectively output such data at node 112-k but not at node 112-j, as discussed in more detail below.

[0092] 11a illustrates an optical receiver 302 including a particular number and arrangement of components in some implementations, which may include additional, fewer, or different components, and may include a different arrangement of components. The number of detectors 1130 and / or ADCs 1140 may be selected to implement an optical receiver 302 that can receive polarization multiplexed signals. In some examples, one of the components shown in FIG. 11a may perform a function described herein as being performed by another one of the components shown in FIG. 11a.

[0093] In accordance with the present disclosure, to select a particular subcarrier or group of subcarriers at a secondary node 112, the local oscillator 1110 may be tuned to output a beam having a wavelength or frequency relatively close to that of the selected subcarriers, such that beating occurs between the local oscillator beam and the selected subcarriers. Such beating either does not occur or is significantly buffered by the other, unselected subcarriers so that data carried by the selected subcarriers can be detected and processed by the DSP 1150.

[0094] As described above, each secondary node 112 may have a bandwidth smaller than the bandwidth associated with the primary node 110. The subcarriers encompassed by each secondary node may be determined by the frequency of the local oscillator laser 1110 in the secondary node receiver 302. For example, as shown in FIG. 11b, the bandwidth BWj associated with the secondary node 112-j may be centered on the local oscillator frequency fLOj, the bandwidth BWk associated with the secondary node 112-k may be centered on the local oscillator frequency fLOk, the bandwidth BWl associated with the secondary node 112-l may be centered on the local oscillator frequency fLOl, and the bandwidth BWm associated with the secondary node 112-m may be centered on the local oscillator frequency fLOm. Thus, each bandwidth BWj to BWm may shift depending on the frequency of the local oscillator laser 1110 of each secondary node. Tuning the local oscillator frequency, for example by changing the temperature of the local oscillator laser 1110, can result in a corresponding shift in bandwidth to include a different group of subcarriers than were detected prior to such bandwidth shift. The temperature of the local oscillator laser 1110 can be controlled, for example, with a thin film heater provided on the local oscillator laser or adjacent to a portion of the local oscillator laser, such as a mirror. Alternatively, the local oscillator laser can be frequency tuned by controlling the current supplied to the laser. The local oscillator laser 1110 can be a semiconductor laser, such as a distributed feedback laser or a distributed Bragg reflector laser.

[0095] However, the maximum bandwidth or number of subcarriers that can be received, detected, and processed by the secondary node receiver 302 may be limited based on the hardware limitations of the various circuit components in the receiver 302, as described above, and therefore may be fixed in this example. Thus, as described above, the bandwidth associated with each secondary node 112 may be narrower than the bandwidth BW-P associated with the primary node 110. Furthermore, consistent with the present disclosure, the number of secondary nodes may be greater than the number of subcarriers output from the primary node 110. Also, the number of upstream subcarriers received by the primary node 110 may be equal to the number of subcarriers transmitted by the primary node 110 in the upstream direction. Alternatively, the number of subcarriers transmitted by the secondary nodes 112 collectively in the upstream direction may be less than or greater than the number of downstream subcarriers output from the primary node. Furthermore, in another example, one or more of the secondary nodes 112 may output a single subcarrier.

[0096] 11b and discussed above, the bandwidths associated with the secondary nodes 112 may also overlap, such that a particular subcarrier SC may be detected by multiple secondary nodes 112, as described above. If the data associated with such a subcarrier SC is intended for one of the secondary nodes but not the other secondary nodes, then switch circuitry as described above may be provided to selectively output the data at the intended secondary node but not at the other secondary nodes.

[0097] For example, as further shown in FIG. 11a, switches or circuits SW-0 through SW-8 may be provided at the output of DSP 1150 to selectively output data detected from the received subcarriers based on respective ones of control signals CNT-0 through CNT-8 output from control circuit 1171, which may include a microprocessor, FPGA or other processor circuitry, such as control circuit 971 described above. The control signals may specify the output of each respective switch. Thus, for example, if data carried by a given subcarrier is intended to be output at a particular secondary node 112, then switch SW at that secondary node may be configured to supply the desired data but block data not intended for that node, based on the received control signal CNT.

[0098] FIG. 12 illustrates exemplary components of the receiver digital signal processor (DSP) 1150. As described above, the analog-to-digital (A / D) circuits 1140-1 and 1140-2 (FIG. 11a) output digital samples corresponding to analog inputs provided thereto. In one example, the samples may be provided by the respective A / D circuits at a rate of 64 Gsamples / sec. The digital samples correspond to symbols carried by the X polarization of the optical subcarrier and may be represented by the complex numbers XI+jXQ. The digital samples may be provided to an overlap and save buffer 1205-1 as shown in FIG. 12. An FFT component or circuit 1210-1 may receive, for example, 2048 vector elements from the overlap and save buffer 1205-1 and convert the vector elements to the frequency domain using, for example, a fast Fourier transform (FFT). The FFT component 1210-1 may convert the 2048 vector elements into 2048 frequency components, each of which may be stored in a register or "bin" or other memory as a result of performing the FFT.

[0099] The frequency components may then be demultiplexed by demultiplexer 1211-1, and groups of such components may be provided to a respective one of chromatic dispersion equalizer circuits CDEQ 1212-1-0 through 1212-1-8, each of which may include a finite impulse response (FIR) filter that corrects, cancels or reduces the effects of or errors associated with chromatic dispersion of the transmitted optical subcarriers. Each of CDEQ circuits 1212-1-0 through 1212-1-8 provides an output to a corresponding polarization mode dispersion (PMD) equalizer circuit 1225-0 through 1225-8 (which may be referred to individually or collectively as 1225).

[0100] The digital samples output from A / D circuit 640-2 associated with the Y-polarization component of subcarrier SC1 may be processed in a manner similar to the processing of the digital samples output from A / D circuit 1240-1 to associate with the X-polarization component of the respective subcarrier. That is, overlap and save buffer 1205-2, FFT 1210-2, demultiplexer 1211-2, and CDEQ circuits 1212-2-0 through 1212-2-8 may have a similar structure and operate in a similar manner to buffer 1205-1, FFT 1210-1, demultiplexer 1211-1, and CDEQ circuits 1212-1-0 through 1212-1-8, respectively. For example, each of CDEQ circuits 1212-2-0 through 1212-8 may include an FIR filter that compensates, cancels, or reduces the effects of chromatic dispersion or errors associated with chromatic dispersion of the transmitted optical subcarriers. Additionally, each of the CDEQ circuits 1212-2-0 through 1212-2-8 provides an output to a corresponding one of the PMDEQs 1225-0 through 1225-8.

[0101] 12, the output of one of the CDEQ circuits, such as CDEQ 1212-1-0, may be provided to a clock phase detector circuit 1213 to determine the clock phase or clock timing associated with the received subcarriers. Such phase or timing information or data may be provided to ADCs 1140-1 and 1140-2 to adjust or control the timing of the digital samples output from ADCs 1140-1 and 1140-2.

[0102] Each of the PMDEQ circuits 1225 may include another FIR filter that compensates, cancels, or reduces the effects of or errors associated with PMD in the transmitted optical subcarriers. Each of the PMDEQ circuits 1225 may provide a first output to a respective one of IFFT components or circuits 1230-0-1 through 1230-8-1 and a second output to a respective one of IFFT components or circuits 1230-0-2 through 1230-8-2, each of which may transform the 256-element vector back to the time domain, for example as 256 samples in accordance with an inverse fast Fourier transform (IFFT), in this example.

[0103] The time domain signals or data output from IFFT 1230-0-1 through 1230-8-1 may be provided to a corresponding one of Xpol carrier phase correction circuits 1240-1-1 through 1240-8-1 to apply carrier regeneration techniques to compensate for the X-polarization transmitter (e.g., laser 908) and receiver (e.g., local oscillator laser 1110) linewidths. In some implementations, each carrier phase correction circuit 1240-0-1 through 1240-8-1 may compensate or correct the frequency and / or phase difference between the X-polarization of the transmitted signal and the X-polarization of the light from local oscillator 1100 based on the output of Xpol carrier regeneration circuit 1240-0-1, which performs carrier regeneration in relation to one of the subcarriers based on the output of IFFT 1230-01. After such X-polarization carrier phase correction, data associated with the X-polarization components may be represented as symbols having complex representation xi+j*xq in a constellation, such as a QPSK constellation or a constellation associated with another modulation format, such as m-quadrature amplitude modulation (QAM), where m is an integer. In some implementations, taps of an FIR filter included in one or more of the PMDEQ circuits 1225 may be updated based on the output of at least one of the carrier phase correction circuits 1240-0-1 through 1240-8-01.

[0104] Similarly, the time domain signals or data output from IFFT 1230-0-2 through 1230-8-2 may be provided to a corresponding one of Ypol carrier phase correction circuits 1240-0-2 through 1240-8-2 to compensate or correct Y-polarization transmitter (e.g., laser 908) and receiver (e.g., local oscillator laser 1110) linewidths. In some implementations, each carrier phase correction circuit 1240-0-2 through 1240-8-2 may also correct or compensate for frequency and / or phase differences between the Y polarization of the transmitted signal and the Y polarization of the light from local oscillator 1110. After such Y-polarization carrier phase correction, data associated with the Y-polarization component may be represented as symbols having complex representation yi+j*yq in a constellation, such as a QPSK constellation, or a constellation associated with another modulation format, such as m-quadrature amplitude modulation (QAM), where m is an integer. In some implementations, an output of one of circuits 1240-0-2 through 1240-8-2 may be used instead of, or in addition to, an output of at least one of carrier recovery circuits 1240-0-1 through 1240-8-1 to update taps of an FIR filter included in one or more of PMDEQ circuits 1225. As further shown in FIG. 12, the output of a carrier recovery circuit, e.g., carrier recovery circuit 1240-0-1, may also be provided to carrier phase correction circuits 1240-1-1 through 1240-8-1 and 1240-0-2 through 1240-8-2, such that the phase correction circuits may determine or calculate a corrected carrier phase associated with each of the received subcarriers based on one of the recovered carriers instead of providing multiple carrier recovery circuits, each associated with a corresponding subcarrier. The equalizer, carrier recovery, and clock recovery can be further enhanced by utilizing known (training) bits that can be included in the control signal CNT, for example by providing an absolute phase reference between the transmitted laser and the local oscillator laser.

[0105] Each of the symbol-to-bit circuits or components 1245-0-1 through 1245-8-1 may receive the symbols output from a corresponding one of the circuits 1240-0-1 through 1240-8-1 and map the symbols back to bits. For example, each of the symbol-to-bit components 1245-0-1 through 1245-8-1 may map one X-polarized symbol in a QPSK or m-QAM constellation to Z bits, where Z is an integer. For a dual-polarized QPSK modulated subcarrier, Z is 4. The bits output from each of the components 1245-0-1 through 1245-8-1 are provided to a corresponding one of the FEC decoder circuits 1260-0 through 1260-8.

[0106] The Y-polarized symbols are output from a respective one of circuits 1240-0-2 through 1240-8-2, each of which has a complex representation yi+j*yq associated with the data carried by the Y-polarized component. Each Y-polarized symbol may be provided to a corresponding one of bit-to-symbol circuits or components 1245-0-2 through 1245-8-2, each of which has a similar structure and operates in a similar manner as the symbol-to-bit components 1245-0-1 through 1245-8-1, as with the X-polarized symbol described above. Each of circuits 1245-0-2 through 1245-8-2 may provide an output to a corresponding one of FEC decoder circuits 1260-0 through 1260-8.

[0107] Each of the FEC decoder circuits 1260 may remove errors at the output of the symbol-to-bit circuit 1245, for example using forward error correction. Such error-corrected bits, which may comprise user data for output from the secondary node 112, may be provided to a corresponding one of the switch circuits SW-0 through SW-8. As described above, the switch circuits SW-0 through SW-8 of each secondary node 112 may selectively provide or block data based on whether such data is intended to be output from the secondary node. Furthermore, if there is one of the control information (CNT) of the received subcarrier, such as an information identification switch SW that outputs the data and another switch SW that blocks the data, the control information may be output from one of the switches to cause the control circuit 1171 of the secondary node to generate a control signal CNT based on such control information.

[0108] In accordance with another aspect of the disclosure, data may be blocked from the output from DSP 1150 without using switches SW-0 through SW-8. In one example similar to the example described above, zeros (0) or other predefined values ​​may be stored in the blocked data as well as in the frequency bins associated with the subcarriers corresponding to the blocked data. Further processing by the circuitry of DSP 1150 as described above on such zeros or predefined data may result in, for example, a null output or zero data output from the corresponding one of FEC decoders 1260. Switch circuits provided at the outputs of FFTs 1210-1 and 1210-2, such as switch circuitry SW of FIG. 10b as described above, may be provided to selectively insert zeros or predefined values ​​to selectively block corresponding output data from DSP 1150. Such switches may also be provided at or within the outputs of demultiplexers 1211-1 and 1211-2 to selectively provide zeros or predefined values.

[0109] In another example, zeros (0) may be inserted into chromatic dispersion equalizer (CDEQ) circuits 1212 associated with both the X-polarization and Y-polarization components of each subcarrier. In particular, a multiplier circuit, such as the multiplier circuit M described above (provided in a corresponding butterfly filter circuit), may multiply the input to the CDEQ circuit 1212 by either zero or a desired coefficient. As discussed above in connection with FIG. 10c, multiplication by zero produces a zero solution. If such a zero solution is further processed by a corresponding circuit in the DSP 1150, such as a corresponding IFFT 1230, carrier phase correction component 1240, symbol-to-bit component 1245, and FEC decoder, the corresponding output in the DSP 1150 will also be zero. Thus, data associated with a subcarrier SC received by the secondary node receiver 112 but not intended for output from that receiver may be blocked.

[0110] On the other hand, if capacity requirements change such that previously blocked data is now output from a given secondary node receiver DSP 1150, appropriate coefficients may be provided to the multiplier circuitry such that at least some of the inputs thereto are not multiplied by zero. After further processing as described above, data associated with the inputs to the multiplier circuitry and corresponding to a particular subcarrier SC is output from the secondary node receiver DSP 1150.

[0111] While FIG. 12 illustrates DSP 1150 as including a particular number and arrangement of functional components in some implementations, DSP 650 may include additional functional components, fewer functional components, different functional components, or a different arrangement of functional components.

[0112] Upstream transmission from the secondary node 112 to the primary node 110 will now be described with reference to FIGS. 13a-13k and 14. FIG.

[0113] FIG. 13a illustrates the secondary node transmitter 304 in more detail. The transmitter 304 includes a number of circuits or switches SW. In this example, nine switches (SW-0 to SW-8) are shown, although more or less switches than those shown in FIG. 13a may be provided. Each switch may have two inputs, in one example. The first input may receive user data and the second input may receive control information or signals (CNT). Each switch SW-0 to SW-8 further receives a respective one of control signals SWC-0 to SWC-8 output from the control circuit. Based on the received control signal, each switch SW-0 to SW-8 selectively outputs one of the respective one of the data streams D-0 to D-8 and one of the respective one of the control signals CNT-0 to CNT-8 to the DSP 1302.

[0114] Alternatively, in a manner similar to that described above, if a user desires that a particular subcarrier be omitted so that fewer subcarriers are transmitted, the transmitted subcarrier may be removed by inserting zero amplitudes at the input or output of the FFT or by programming zero coefficients into selected multiplier inputs of the pulse shaping filters 1008 and 1016.

[0115] The DSP 1302 may have a similar structure to the DSP 902 described above with reference to Figures 9 and 10a. However, in some examples, the DSP 1302 may have less capacity than the DSP 902, so that the number of circuits, such as FEC encoders, bit-to-symbol mappers, duplication and saving buffers, FFT circuits, replicator circuits, and pulse shaping filters, may be reduced depending on, for example, the number of inputs to the DSP 1302. Thus, fewer subcarriers may be output from each of the secondary nodes 112 compared to the number of subcarriers output from the primary node 110.

[0116] Based on the outputs of switches SW-0 through SW-8, DSP 1302 may provide multiple outputs to D / A and optics block 1301, which may have a similar structure to D / A and optics block 901 described above, to provide X-polarized and Y-polarized optical signals, where the X-polarized and Y-polarized optical signals each include I and Q components that are combined by a PBC and output to an optical fiber segment 1316 included in one of the optical paths 115 shown in FIG.

[0117] Alternatively, subcarriers may be blocked or added based on zeros (0) stored or generated by the DSP 1302 in a manner similar to that described above.

[0118] Figures 13b through 13e respectively show subcarriers (SC') output from each of secondary nodes 112-j through 112-m in the upstream direction, for example when subcarriers SC0-SC19 shown in Figure 6 are transmitted in the downstream direction. That is, Figure 13b may show a first group of subcarriers SC0' through SC4' that may be output from secondary node 112-j, Figure 13c may show a second group of subcarriers SC5' through SC9' that may be output from secondary node 112-k, Figure 13d may show a third group of subcarriers SC10' through SC14' that may be output from secondary node 112-l, and Figure 13e may show a fourth group of subcarriers SC15' through SC19' that may be output from secondary node 112-m. As shown in Figure 2, each group subcarrier may be combined, for example at combiner 116, and provided to a receiver (e.g., receiver 204 shown in Figure 3) of primary node 110 over optical path 117. Figure 13f shows such combined optical subcarriers SC0' through SC19', each having a corresponding one of frequencies f0 through f19.

[0119] 13g through 13j respectively show subcarriers (SC'') output from each of secondary nodes 112-j through 112-m in the upstream direction, for example when subcarriers SC0-SC19 shown in FIG. 8 are transmitted in the downstream direction. In particular, FIG. 13g shows a first group of subcarriers SC0'' through SC6'' and SC8'' that may be output from secondary node 112-j, FIG. 13h shows a second group of subcarriers SC7'' and SC9''-SC11'' that may be output from secondary node 112-k, FIG. 13i shows a third group of subcarriers SC12'' through SC16'' that may be output from secondary node 112-l, and FIG. 13j shows a fourth group of subcarriers SC17'' through SC19'' that may be output from secondary node 112-m. In this manner, each group subcarrier output from the secondary node may be combined, for example at combiner 116, and provided over optical path 117 to receiver 204 of primary node 110. Figure 13k shows such combined optical subcarriers SC0'' through SC19'', each having a corresponding one of frequencies f0 through f19.

[0120] FIG. 14 illustrates an example of a primary node receiver 204 in more detail. The primary node receiver 204 includes an Rx optics and A / D block 1400 having a structure similar to the Rx optics and receiver block 1100 described above in connection with FIG. 11a. For example, the block 1400 may include a polarizing beam splitter receiving an upstream polarization multiplexed optical signal including optical subcarriers SC0′ through SC19′ or SC0″ through SC19″ provided by an optical fiber link 1401, which may be configured in a manner similar to that described above, including, for example, an optical fiber segment as part of one of the optical paths 115-k through 115-m described above, a local oscillator laser, an optical hybrid, a photodiode, a capacitive coupler, a TIA / AGC circuit, and analog-to-digital (A / D) conversion circuitry similar to that described above. Thus, the block 1400 provides outputs XI, XQ, YI, and YQ similar to the corresponding outputs provided by the block 1100. However, the bandwidth associated with each of the components and circuits in block 1400 may have a wider bandwidth than the corresponding components in the secondary node 112 so that the primary node receiver 204 can detect and process each of the subcarriers output from the secondary node 112.

[0121] As further shown in Figure 14, the primary node receiver 204 may also include a DSP 1450 that receives signals XI, XQ, YI, and YQ from block 1400. The DSP 1450 may have a similar structure to the DSP 1150 shown in Figure 11a. However, since the DSP 1450 may have a larger capacity than the DSP 1150, the number of circuits such as FEC decoders, symbol-to-bit mappers, duplication and saving buffers, CDEQ circuits, and PMDEQ circuits may be more or less than those shown in Figure 11a depending on the number of outputs from the DSP 1450.

[0122] The output from the DSP1450 is next may be supplied to switches SW-0 through SW-19, which Control of control signals similar to those described above underSo, data streams D-0 to D-19 home handle thing and the corresponding control signals CNT-0 to CNT-19 Things Selectively output one of 。 The control information is, for example, Monitoring information associated with or scheduling information, such as time of flight (TOF) or delta time TOF information, as described below with reference to Figures 20-24. of It may include.

[0123] Alternatively, based on zeros generated or stored in DSP 1450, data may be selectively provided from each DSP output in a manner similar to that described above.

[0124] In further examples consistent with the present disclosure, guard bands or frequency gaps may be provided between adjacent subcarriers SC. As shown in FIG. 15, guard band GB1 may be provided between subcarriers SC4 and SC5, and guard band GB2 may be provided between subcarriers SC5 and SC6. Additional guard bands may be provided between remaining pairs of adjacent subcarriers. Such guard bands may be provided to more accurately detect and process each subcarrier by reducing crosstalk or other interference between the subcarriers.

[0125] As noted above, network configurations other than the aggregated network configurations discussed above in connection with Figures 1 and 2 are contemplated herein, such as mesh networks, an example of which (network 1800) is shown in Figure 16. Network 1800 may include multiple nodes 1802, 1804, 1806, 1808, 1810, and 1812 connected to have multiple paths between each other. For example, node 1802 may communicate with node 1812 via a path that includes nodes 1806 and 1808 or a path that includes nodes 1804 and 1810. Nodes 1802, 1804, 1806, 1808, 1810, and 1812 may include at least one primary node similar to node 110 and at least one secondary node 112 similar to that described above. Additionally, in a manner similar to that described above, the amount or rate of data output from each of the nodes shown in FIG. 16 may be controlled or dynamically adapted based on control information exchanged between the respective nodes.

[0126] Subcarrier SC0 ~ SC19 To It is carried by secondary node 112-j ~ 112-m mosquito Allocation of data output from 、 Reassignment of such data coming out of secondary nodes Examples of , then Figs. 19 and 20a ~ 20c of 19 is a timing diagram illustrating the transmission of control information on the dedicated subcarriers SC2, SC7, SC12, and SC17 further shown in FIG. 4. As shown in the example illustrated in FIG. 17, each of these subcarriers is transmitted continuously from the primary node 110, meanwhile The remaining subcarriers SC1, SC3-SC6, SC8-SC11, SC13-SC16, SC18, and SC19 are not transmitted. The control information carried by subcarriers SC2, SC7, SC12, and SC17 is associated with nodes 112-j, 112-k, 112-l, and 112-m, respectively. Additionally, In another example, Subcarriers SC2, SC7, SC12, and SC17 teeth Also, It takes node each Associated with R It can also carry user data.

[0127] FIG 18a is a timing diagram corresponding to the subcarrier transmission shown in FIG 6, where data associated with node 112-j is transmitted on subcarrier SC0. ~ SC4 above The data associated with node 112-k is continuously transmitted on subcarrier SC5. ~ SC9 above The data associated with node 112-l is continuously transmitted on subcarrier SC10. ~ SC14 above The data associated with node 112-m is continuously transmitted on subcarrier SC15. ~ SC19 above is sent continuously.

[0128] As mentioned above, the data associated with the secondary node 112 is transmitted on subcarrier SC0 ~ SC19 between In accordance with the present disclosure, such reallocation may occur on a per-time slot basis. An example of such reallocation is shown in FIG. 18b. That is, as shown in FIG. 18b, during time slot TS1, subcarrier SC8 carries data associated with node 112-k, but during time slot TS2, subcarrier S8 carries data associated with node 112-j, and so on until time slot TS6. At that point, Subcarrier SC8 teeth Carrying data associated with node 112-k until time slot TS9 Do it like that Similarly, other time slots may be switched to carry data associated with different nodes. Well , or as further shown in FIG. 18b, subcarrier SC0 ~ SC4 etc.The subcarrier of carries data associated with only node 112-j. Continuously Such reallocation may be based on capacity demands in the system. Further, as noted above, the data associated with a particular secondary node 112 may be determined based on control information received by the second node and the configuration of the second node, as described above with reference to Figures 10b and 10c. S This is the data output from the candidacy node.

[0129] Figure 18c shows identification During the time slot 、 A further example shows that no data is transmitted in the absence of a specific capacity need, i.e., during time slot TS5, subcarriers SC11, SC8 and SC4 carry nothing, as shown in Fig. 18c. These subcarriers are shown in Figs. 10b to 10c. above It is blocked during time slot TS5 by the circuitry described below.

[0130] The above example is from primary node 110 to secondary node 112. D Transmitted in the downstream direction D Data To sub-carriers In the upstream direction, one or more subcarriers may be transmitted from one or more secondary nodes 112 to the primary node 110, as described above. Multiple If the secondary nodes 112 are located at different distances away from the primary node 110, the arrival time of data from one secondary node 112 to the primary node 110 may be different from the arrival time of data from another secondary node 112. As a result, data input from the secondary nodes 112 to the primary node 110 may not be synchronized. There is a possibility , the result, 1 time slot Medium To 、 From the first secondary node identification Sub-carrier On Data submitted but , Primary node 110 but Receiving data from another secondary node It may arrive in between , Primary node 110 In This can lead to errors or loss of data.

[0131] For example, referring to FIG. 19, if node 112-l is farther away from primary node 110 than node 112-m, 、 for example of From 112-l On subcarrier SC4 The output data is delayed t d Encountered Such data will not reach the primary node 110 until time t5+td, as shown in FIG. 19, and will be sent during the time slot, i.e., until time t6+td. Receiving However, at time t6, primary node 110 may be receiving data from node 112-m, and due to the delayed data transmission from node 112-l, primary node 110 receives data from both nodes 112-l and 112-m on subcarrier SC4 in this example, so that both the data provided by node 112-l and the data provided by node 112-m are not received during the interval from t6 to t6+td. teeth It may not be reliably detected.

[0132] According to aspects of the disclosure, the circuitry in the primary node 110 may include a “time of flight” delay, That is The primary node sends a request to the secondary node. the law of nature , and The primary node receives a response from the secondary node. of Determine the amount of time required to obtain Based on such time-of-flight information, the primary node 110 may schedule or coordinate transmissions over various time slots to avoid collisions such as those shown in FIG.

[0133] FIG. 20 is a flow chart of a method for determining time-of-flight information for each second node 112. 、 Circuit in Primary Node 110 teeth , each About Leaf 112, Time of Flight (TOF) offset of Initialize to zero In step 2004, a test message or TOF offset but, each Leaf node 112 For multiple Subcarrier Our Carried by one , sent along with the data In-Band Channels etc. Responding on the control channel is sent to each leaf node 112 along with an instruction or request requesting that The circuitry in the primary node 110 then: each Leaf node 112 About The response time is measured (step 2006). The circuitry in the primary node 110 then: each Node T Determine the difference in OF time ("delta TOF"), each Delta TOF of, The leaf node 112 with the longest TOF is zero. delta The circuitry in the primary node 110 then adjusts the TOF to have the following: each The delta TOF response time of leaf node 112 is identification within the tolerance or margin of In some cases (step 2010). If not, steps 2004, 2006, 2008, and 2010 are repeated and continue to be repeated until the delta response time is within such margin. Once the delta response time is within the margin, the above method After a given period of X milliseconds Start again at step 2002, T Once the TOF and delta TOF information has been obtained by the method shown in FIG. 20, the primary node 110 may then reassess the OF information through a further method having an associated flow chart shown in FIG. 、The first step of the scheduling method, 2102, is for the hub 110 to determine the leaf node utilization of subcarriers and time slots via the control channel described above. of Based on the utilization so measured, circuitry in hub 110 determines whether the leaf node is within the TOF tolerance or margin (step 2104). If yes, one or more time slots are assigned to that leaf node (step 2106); if not, the hub node determines whether one or more subcarriers are assigned to such leaf node (step 2107). and gave the command to Such a leaf node Haso The data is transmitted to the hub node 110 on the assigned subcarriers as follows: It is okay And the leaf nodes are According to the received command, Only during the specified time slot 、 or 1 On one or more subcarriers Only continuously Configured to send Such subcarriers may, for example, be the subcarriers mentioned above dedicated for the transmission of control channel information. (Step 2110). In step 2112, the hub monitors leaf node utilization over a predetermined period of time, such as a time period of Y milliseconds. The process then proceeds to step 2102. return .

[0134] The above TOF-related calculations may be performed external to the primary node 110 or by internal circuitry of the primary node 110 as described above. Please note that .

[0135] Figure 22 shows Ha B of request time and Leaf of response time , and 22 is a plot showing an example of corresponding TOF times. As shown in FIG. 22, the farther away the secondary node is from the primary node, the longer or larger the TOF time. For example, if secondary node 112-m is located 100 km away from primary node 110, the law of nature , Therefore R but It is the secondary node furthest from primary node 110. Furthermore, in this example, secondary node 112-l is 60 km away from primary node 110, and secondary node 112-k is 50 km away. Furthermore, node 112-j is 30 km away from primary node 110, and is therefore the secondary node closest to the primary node.

[0136] The TOF value is The primary node TOF Request Response Later, Receive a response from the secondary node of Measure the time it takes to Within As shown in FIGS. 22 and 23, the TOF associated with the second node 112-j is 300 μs (or each Assuming the time slot is 200μs 、1.5 Time Slot (TS) ) The TOF associated with node 112-k is 500 μs (or 2.5 TS), the TOF associated with node 112-l is 600 μs (or 3.0 TS), and the TOF associated with node 112-m is 1000 μs (or 5.0 TS). After the respective TOFs are determined as described above, the primary node 110 Within circuit Each determining a TOF associated with the node; where The delta TOF is the longest TOF, here 1000 μs, and the remaining each Between the TOF of secondary node 112 of difference (i.e., the longest TOF minus the TOF of each remaining secondary node).Thus, as further shown in table 2302, the delta TOF associated with secondary node 112-j is 700 μs (1000 μs-300 μs=700 μs or 3.5TS), the delta TOF associated with secondary node 112-k is 500 μs (1000 μs-500 μs=500 μs or 2.5TS), the delta TOF associated with secondary node 112-l is 400 μs (1000 μs-600 μs=400 μs or 2.0TS), and the delta TOF associated with secondary node 112-m is 0.0 μs (1000 μs-1000 μs=0 μs or 0TS).

[0137] In scheduling transmissions from the secondary node 112 to the primary node 110, For each such transmission, to achieve the desired time, Both TOF and delta TOF are but An example of such scheduling will now be described with reference to FIG.

[0138] FIG. 24 shows example timing diagrams 2402 and 2404, where, for ease of explanation, only subcarrier SC1 ~ SC4 above The chart 2402 shows the transmission of figure 22 and 23 Shown in Has TOF and delta TOF Shows the launch time in absolute time for secondary nodes and leaf node utilization Chart 2404 is If the node leaves such a secondary node, there will be no collisions in absolute time. The data carried by the various subcarriers; P On the primary node Corresponding reach time In one example, as shown in FIG. teeth, Time slot TS6 To start On subcarriers SC1, SC2, and SC4, , from secondary nodes 112-j, 112-k, and 112-m, respectively.It is desirable to receive data from node 112-k. As mentioned above, secondary node 112-m is furthest from primary node 110, so secondary node 112-m has an associated delta TOF of zero (0). The data is then scheduled to be transmitted during time slot TS1, as shown in chart 2402, and such data arrives five time slots later during time slot TS6, as shown in chart 2404 (see Figures 22 and 23). Node 112-k, on the other hand, has a shorter time of flight of 2.5 TS, arriving at node 110 at approximately the same time as the data output from node 112-m. To , In chart 2402, The transmission from node 112-k is of Transmission of data from 112-m after a D-k time or delay (approximately equal to the delta TOF or 2.5 TS associated with node 112-k) from Node 112-k is scheduled for output or transmission to node 110 (see chart 2402). As a result, after such a delay, the data at node 112-k is of Further delay by the TOF (2.5TS) associated with code 112-k As a result, the 112-k data arrives at approximately the same time as the 112-m data. (See Chart 2404).

[0139] Furthermore, data sent from node 112-j arrives at node 110 at approximately the same time as data output from node 112-m. Bek , the transmission from node 112-j is of Transmission of data from 112-m After D-j time or delay (approximately equal to the delta TOF or 3.5TS associated with node 112-j) from Node 110 is scheduled to be sent (see chart 2402). rear The data of node 112-k is further divided into TOFs (1.5TS) associated with node 112-j. Delayed , the result, The 112-j data will arrive at approximately the same time as the 112-m data (see chart 2404).

[0140] Other examples of origination and arrival times and subcarrier utilization are further shown in FIG.

[0141] In another example, as shown in FIG. 19, for example, a free slot may be provided between a transmission by one node on a given subcarrier and a transmission by another node on that subcarrier to provide sufficient time between the slots to reduce the risk of collisions or data transmissions on a given subcarrier that have overlapping time slots.

[0142] Various modifications and other embodiments will be apparent to those skilled in the art upon review of this specification, and the above detailed implementation examples are provided as examples. For example, the digital signal processing disclosed above may be implemented as a programmable gate array circuit (PGA) or a field programmable gate array circuit (FPGA). Furthermore, although separate lasers 908 and 1110 are provided in the transmitter and receiver, respectively, as described above, a transceiver according to the present disclosure may have a common laser "shared" between the transmitter and receiver. For example, FIG. 25 illustrates an example of a transceiver 110 using a shared laser 2502 that provides an optical signal (as a local oscillator signal) for both transmission and reception, according to one or more implementations of the present disclosure. As shown, the laser 2502 generates an optical signal and provides the optical signal to a splitter 2504. The splitter 2504 splits the optical signal into two parts. One portion is provided to optical hybrids or mixers 1120-1 and 1120-2, and the other portion is provided to modulators 910-1 through 910-4.

[0143] Accordingly, other implementations are within the scope of the following claims. [Other possible items] (Item 1) A transceiver comprising: a laser operable to output an optical signal; a first digital signal processor operable to receive the first data and provide a first plurality of electrical signals based on the first 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; a modulator operable to modulate the optical signal to provide a first plurality of optical subcarriers based on the third plurality of electrical signals, each of the first plurality of subcarriers having an in-phase component and a quadrature component, at least one of the plurality of optical subcarriers carrying control information; a transmitter having a photodiode circuit having at least one photodiode operable to receive an optical mixing product based on a second plurality of optical subcarriers, the photodiode circuit providing a fourth electrical signal based on at least one of the plurality of optical subcarriers and a local oscillator optical signal; a plurality of analog-to-digital conversion circuits providing a plurality of fifth electrical signals based on the fourth electrical signal; a second processor circuit that outputs second data based on the fifth electrical signal; a receiver having a A transceiver comprising: (Item 2) 2. The transceiver of claim 1, wherein the number of the second plurality of optical subcarriers is less than the number of the first plurality of optical subcarriers. (Item 3) 2. The transceiver of claim 1, wherein the number of the second plurality of optical subcarriers is the same as the number of the first plurality of optical subcarriers. (Item 4) 2. The transceiver of claim 1, wherein the optical signal is a first optical signal and the laser further provides the local oscillator signal. (Item 5) 2. The transceiver of claim 1, wherein the receiver further comprises an optical hybrid circuit that receives the local oscillator optical signal and at least a portion of each of the second plurality of optical subcarriers, the optical hybrid circuit providing the optical mixing product. (Item 6) 2. The transceiver of claim 1, wherein a first guard band extends between a first frequency associated with a first one of the first plurality of subcarriers and a second frequency associated with a second one of the first plurality of subcarriers. (Item 7) Item 2. The transceiver of item 1, wherein the receiver has a local oscillator laser that provides a local oscillator beam to the optical hybrid circuit. (Item 8) 8. The transceiver of claim 7, wherein the local oscillator laser is a tunable laser. (Item 9) a receiver, comprising: an optical hybrid circuit that receives a local oscillator beam, a first polarization component of a plurality of optical subcarriers, and a second polarization component of a plurality of optical subcarriers, the plurality of optical subcarriers being spectrally non-overlapping with one another, each of the plurality of optical subcarriers being generated by modulation of an optical signal output from a laser, the optical hybrid circuit providing a plurality of mixing products; a photodiode circuit for providing a first electrical signal based on the plurality of mixing products; a digital signal processor circuit that receives a first control signal, outputs first data associated with a first subset of the plurality of subcarriers based on the first control signal and the first electrical signal, and outputs second data associated with a second subset of the plurality of subcarriers based on a second control signal; A receiver comprising: (Item 10) 10. The receiver of claim 9, wherein the first subset has a smaller number of subcarriers in the plurality of subcarriers than the second subset. (Item 11) 10. The receiver of claim 9, wherein the first subset comprises one of the plurality of subcarriers. (Item 12) Item 12. The receiver of item 11, further comprising a local oscillator laser providing the local oscillator beam. (Item 13) Item 13. The receiver of item 12, wherein the local oscillator laser is a tunable laser. (Item 14) 1. A system comprising: A laser that outputs an optical signal; a first digital signal processor circuit for receiving the first data and providing a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator that modulates the optical signal to provide a plurality of optical subcarriers based on the third plurality of electrical signals, each of the first plurality of subcarriers having an in-phase component and a quadrature component; a transmitter having a receiver optically coupled to the optical communication path, the receiver comprising: an optical hybrid circuit that receives a local oscillator beam, a first polarization component of a plurality of optical subcarriers, and a second polarization component of the plurality of optical subcarriers, each of the plurality of optical subcarriers being generated by modulation of an optical signal output from a laser, the optical hybrid circuit providing a plurality of mixing products; a photodiode circuit for providing a first electrical signal based on the plurality of mixing products; a second digital signal processor circuit configured to output a portion of the data associated with a subset of the plurality of subcarriers based on the first electrical signal; and a receiver having a A system comprising: (Item 15) 15. The system of claim 14, wherein the portion of the data is a first portion of the data and the subset of the plurality of optical subcarriers is a first subset of the plurality of subcarriers, and based on a control signal provided to the second processor, the second processor provides a second portion of the data associated with a second subset of the plurality of optical subcarriers. (Item 16) Item 15. The system of item 14, wherein the receiver comprises a local oscillator laser providing the local oscillator beam. (Item 17) Item 17. The system of item 16, wherein the local oscillator laser is a tunable laser. (Item 18) Item 15. The system of item 14, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 19) 10. The receiver of claim 9, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 20) 2. The transceiver of claim 1, wherein the first digital signal processor has a programmable gate array (PGA). (Item 21) 2. The transceiver of claim 1, wherein the first digital signal processor has a field programmable gate array (FPGA). (Item 22) A laser that outputs an optical signal; a digital signal processor that receives the data and provides a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator that modulates the optical signal to provide a plurality of optical subcarriers based on the third plurality of electrical signals, each of the plurality of optical subcarriers having an in-phase component and a quadrature component, the plurality of optical subcarriers being provided to an optical communication path having an optical fiber; and having A transmitter, where the modulation of one of the plurality of optical subcarriers represents a characteristic of a node remote from the transmitter. (Item 23) 23. The transmitter of claim 22, wherein the data received by the digital signal processor includes control information associated with characteristics of the node remote from the transmitter. (Item 24) A transmitter as described in Item 23, wherein the control information represents a capacity of the node remote from the transmitter. (Item 25) 23. The transmitter of claim 22, wherein the control data represents operational, management, or maintenance information associated with the remote node. (Item 26) 23. The transmitter of claim 22, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 27) 23. The transmitter of claim 22, wherein the feature is a first feature, the remote node is a first remote node from the transmitter, and the modulation of a second of the plurality of subcarriers represents a characteristic of a second node remote from the transmitter. (Item 28) 28. The transmitter of claim 27, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 29) A transceiver comprising: A laser that outputs an optical signal; a first digital signal processor circuit for receiving the data and providing a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator for modulating the optical signal to provide a plurality of optical subcarriers based on the third plurality of electrical signals, each of the plurality of optical subcarriers having an in-phase component and a quadrature component, the plurality of optical subcarriers being provided to an optical communication path having an optical fiber, a modulator for modulating the plurality of optical subcarriers characteristic of a node remote from the transmitter; a receiver for receiving a second plurality of optical subcarriers and control data from a second optical communication path, the control data indicative of a characteristic of the transceiver; A transceiver comprising: (Item 30) 30. The transceiver of claim 29, wherein the data received by the digital signal processor includes control information associated with characteristics of the node remote from the transmitter. (Item 31) 31. The transceiver of claim 30, wherein the control information represents a capacity of the node remote from the transmitter. (Item 32) 30. The transceiver of item 29, wherein the control data represents operational, management, or maintenance information associated with the remote node. (Item 33) 30. The transceiver of claim 29, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 34) 30. The transceiver of item 29, wherein the feature is a first feature, the remote node is a first remote node from the transmitter, and the modulation of a second of the plurality of subcarriers represents a characteristic of a second node remote from the transmitter. (Item 35) Item 35. The transceiver of item 34, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 36) 1. A system comprising: A laser that outputs an optical signal; a digital signal processor circuit for receiving the data and providing a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator that modulates the optical signal to provide a plurality of optical subcarriers based on the third plurality of electrical signals, each of the plurality of optical subcarriers having an in-phase component and a quadrature component, and the plurality of optical subcarriers are supplied to an optical communication path having an optical fiber; a modulator, wherein modulation of one of the plurality of optical subcarriers represents one of first control data and second control data; a transmitter having a receiver having an optical input, the receiver operable to receive the plurality of subcarriers at the optical input, such that when the modulation of the one of the plurality of optical subcarriers represents the first control data, the receiver outputs a first portion of the data associated with a first number of the first plurality of subcarriers, and when the modulation of the one of the plurality of optical subcarriers represents the second control data, the receiver outputs a second portion of the data associated with a second number of the plurality of subcarriers; A system comprising: (Item 37) Item 37. The system of item 36, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 38) 1. A system comprising: A laser that outputs an optical signal; a digital signal processor circuit for receiving the data and providing a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator for modulating the light beam to provide a plurality of optical subcarriers based on the third plurality of electrical signals, each of the first plurality of subcarriers having an in-phase component and a quadrature component, the plurality of optical subcarriers being provided to an optical output of the transmitter; a receiver having an optical input, the receiver receiving the plurality of optical subcarriers at the optical input, the receiver further receiving control information at the optical input such that the receiver selectively outputs portions of the data based on the control information, the portions of the data being associated with at least one of the plurality of optical subcarriers; A transmitter having A system comprising: (Item 39) Item 39. The system of item 38, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 40) A transceiver comprising: A laser that outputs a light beam; an electrical signal processor circuit for receiving the data and providing a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator that modulates the light beam to provide a first plurality of optical subcarriers based on the plurality of electrical signals, each of the first plurality of subcarriers having an in-phase component and a quadrature component, each of the first plurality of optical subcarriers being spectrally disjoint from one another; and a transmitter having a receiver for receiving at least a second optical subcarrier and control data at an optical input, the group of the first plurality of subcarriers being selected based on the control data; A transceiver comprising: (Item 41) Item 41. The system of item 40, wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers are Nyquist subcarriers. (Item 42) 23. The transmitter of claim 22, wherein the digital signal processor comprises a programmable gate array (PGA). (Item 43) Item 43. The transmitter of item 42, wherein the programmable gate array comprises a field programmable gate array (FPGA). (Item 44) A transceiver comprising: A laser that outputs a light beam; a first electrical signal processor circuit for receiving the data and providing a first plurality of electrical signals based on the data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits providing a third plurality of electrical signals based on the second plurality of electrical signals; a modulator for modulating the optical beam to provide a first plurality of optical subcarriers based on the plurality of electrical signals, each of the first plurality of subcarriers having an in-phase component and a quadrature component; a transmitter having a receiver receiving a second plurality of subcarriers at an optical input of the receiver, the transmitter providing a first number of the first plurality of optical subcarriers based on first control data received at the optical input of the receiver, and the transmitter providing a second number of the first plurality of optical subcarriers based on second control data received at the optical input of the receiver; A transceiver comprising: (Item 45) Item 45. The system of item 44, wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers are Nyquist subcarriers. (Item 46) a transmitter having a laser and a modulator, the modulator providing a plurality of optical subcarriers, the transmitter providing first control information and second control information; A first receiver; a second receiver, wherein based on the first control information, the first receiver outputs first data associated with at least a first of the plurality of subcarriers, and based on the second control information, the second receiver outputs second data associated with at least a second of the plurality of subcarriers; A system comprising: (Item 47) Item 47. The system of item 46, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 48) a transmitter having a laser and a modulator, the modulator providing a plurality of optical subcarriers, the transmitter providing first control information and second control information; A first receiver; a second receiver, wherein based on the first control information, the first receiver outputs first data associated with at least a first of the plurality of subcarriers and the second receiver outputs second data associated with at least a second of the plurality of subcarriers; a second receiver, wherein the first receiver outputs third data associated with at least a third one of the plurality of subcarriers based on the second control information, and the second receiver outputs fourth data associated with at least a fourth one of the plurality of subcarriers; A system comprising: (Item 49) Item 49. The system of item 48, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 50) a transmitter for receiving data, the transmitter having a laser and a modulator, the modulator providing a plurality of optical subcarriers based on the data at an output; a first receiver providing a first portion of the data based on first control information provided by an output of the transmitter, the first portion of the data being associated with a first plurality of the plurality of subcarriers; the second receiver providing a second portion of the data based on second control information provided by an output of the transmitter, the second portion of the data being associated with a second plurality of the plurality of subcarriers; the first receiver provides a third portion of the data based on third control information provided by an output of the transmitter after the first control information is provided by the optical transmitter, the third portion of the data being associated with a third plurality of the plurality of subcarriers; a second receiver providing a fourth portion of the data based on fourth control information provided by an output of the transmitter after the second control information is provided by the optical transmitter, the fourth portion of the data being associated with a third plurality of the plurality of subcarriers; and A system comprising: (Item 51) Item 51. The system of item 50, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 52) transmitting a plurality of optical subcarriers from a first node to a second node in the network; transmitting first control information from the first node to the second node; receiving at the second node the plurality of subcarriers and the first control information; outputting first data from the second node, the first data representing first information carried by at least a first of the plurality of optical subcarriers based on the first control information; transmitting second control information from the first node to the second node; outputting second data from the second node representing second information carried by at least a second of the plurality of optical subcarriers based on the second control information; A method for providing the above. (Item 53) Item 53. The method of item 52, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 54) Item 53. The method of item 52, wherein the control information is received over an optical communication path optically coupling the first node to the second node. (Item 55) 53. The method of claim 52, wherein at least one of the plurality of subcarriers carries the first control information. (Item 56) Item 53. The method of item 52, further comprising modulating at least some of the plurality of optical subcarriers to carry the first control information. (Item 57) transmitting a plurality of optical subcarriers from a first node, the plurality of subcarriers carrying information representative of data input to the first node, the data comprising first data and second data; transmitting first control information from the first node to the second node; receiving at a second node at least one of the plurality of subcarriers and the first control information; outputting the first data from the second node based on the first control information; transmitting second control information from the first node to the second node; outputting the second data from the second node based on the second control information; A method for providing the above. (Item 58) Item 58. The method of item 57, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 59) transmitting a first plurality of optical subcarriers from a first node to a second node in the network; transmitting first control information from the first node to the second node; receiving the first plurality of subcarriers; and receiving the first control information at the second node. outputting first data from the second node based on first information carried by the first plurality of optical subcarriers and the first control information; transmitting second control information from the first node to the second node; transmitting a second plurality of optical subcarriers from the first node to the second node; receiving the second plurality of subcarriers; receiving the second control information; outputting second data from the second node based on second information carried by the second plurality of optical subcarriers and the second control information; A method for providing the above. (Item 60) Item 60. The method of item 59, wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers are Nyquist subcarriers. (Item 61) Item 61. The method of item 60, wherein the number of the first plurality of optical subcarriers is different from the number of the second plurality of optical subcarriers. (Item 62) generating an optical signal; receiving data and generating a plurality of digital signals based on said data; generating a plurality of analog signals based on the digital signals; modulating the optical signal to provide the first plurality of optical subcarriers based on the analog signal; Item 59. The method of item 59, further comprising: (Item 63) receiving a first plurality of optical subcarriers at an optical input; receiving control data at said optical input; generating a second plurality of optical subcarriers, the number of the second plurality of subcarriers being based on the control data; transmitting the second plurality of subcarriers from an optical output; A method for providing the above. (Item 64) Item 64. The method of item 63, wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers are Nyquist subcarriers. (Item 65) Item 64. The method of item 63, wherein the number of the first plurality of optical subcarriers is different from the number of the second plurality of optical subcarriers. (Item 66) generating an optical signal; receiving data and generating a plurality of digital signals based on said data; generating a plurality of analog signals based on the digital signals; modulating the optical signal to provide the second plurality of optical subcarriers based on the analog signal; Item 64. The method of item 63, further comprising: (Item 67) a laser operable to output an optical signal; a digital signal processor circuit operable to receive first data and, after receiving the first data, to receive second data, the digital signal processor circuit providing a first plurality of electrical signals based on the first data and providing a second plurality of electrical signals based on the second data; a plurality of digital-to-analog conversion circuitry operable to provide a first plurality of analog signals based on the first plurality of electrical signals and a second plurality of analog signals based on the second plurality of electrical signals; a modulator operable to modulate the optical signal to provide a first plurality of optical subcarriers based on the first plurality of electrical signals and a second plurality of optical subcarriers based on the second plurality of electrical signals, each of the plurality of subcarriers and each of the second plurality of optical subcarriers having an in-phase component and a quadrature component, and a number of the first plurality of optical subcarriers differs from a number of the second plurality of optical subcarriers; A transmitter comprising: (Item 68) Item 68. The transmitter of item 67, wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers are Nyquist subcarriers. (Item 69) Item 68. The transmitter of item 67, further comprising a plurality of switches coupled to the digital signal processor, each of the plurality of switches selectively providing an input to the digital signal processor. (Item 70) 70. The transmitter of claim 69, wherein one of the plurality of switches is configured to provide control data to the digital signal processor, and one of the plurality of optical subcarriers carries information representing the control data. (Item 71) Item 68. The transmitter of item 67, wherein the digital signal processor comprises a programmable gate array (PGA). (Item 72) Item 68. The transmitter of item 67, wherein the digital signal processor comprises a field programmable gate array (FPGA). (Item 73) an optical hybrid circuit that receives a local oscillator beam, a first polarization component of a plurality of optical subcarriers, and a second polarization component of the optical subcarriers, each of the plurality of optical subcarriers being generated by modulation of an optical signal output from a laser, the optical hybrid circuit providing a plurality of mixing products; a photodiode circuit for providing a first electrical signal based on the plurality of mixing products; a digital signal processor that outputs data associated with the plurality of optical subcarriers based on the first electrical signal, the processor circuit having a plurality of outputs; a plurality of switch circuits coupled to the plurality of outputs for selectively providing a plurality of portions of the data; A receiver comprising: (Item 74) 74. The receiver of claim 73, wherein one of the plurality of switch circuits provides control data representative of information carried by one of the plurality of subcarriers. (Item 75) Item 74. The receiver of item 73, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 76) Item 74. The receiver of item 73, wherein the digital signal processor comprises a programmable gate array (PGA). (Item 77) Item 74. The receiver of item 73, wherein the digital signal processor comprises a field programmable gate array (FPGA). (Item 78) A laser that outputs an optical signal; 1. A digital signal processing circuit for receiving client data, comprising: a Fourier transform circuit that generates first frequency domain data based on the first information during a first time period and second frequency domain data during a second time period; a plurality of memories for storing first frequency domain data during the first time period and for storing the second frequency domain data during the second time period; an inverse Fourier transform circuit for generating first time domain data based on the first frequency domain data and second time domain data based on the second frequency domain data; a digital signal processor circuit having a plurality of digital-to-analog conversion circuits providing a first plurality of analog signals based on the first frequency domain data and a second plurality of analog signals based on the second frequency domain data; a modulator that modulates an optical signal to provide a first plurality of optical subcarriers based on the first plurality of analog signals and a second plurality of optical subcarriers based on the second plurality of analog signals, each of the first plurality of optical subcarriers and the second plurality of optical subcarriers having an in-phase component and a quadrature component, the plurality of optical subcarriers being supplied to an optical communication path including an optical fiber; the number of the first plurality of subcarriers is different from the number of the second plurality of optical subcarriers; A modulator; A transmitter comprising: (Item 79) Item 79. The transmitter of item 78, wherein each of the plurality of subcarriers is a Nyquist subcarrier. (Item 80) Item 79. The receiver of item 78, wherein the digital signal processing circuitry comprises a programmable gate array (PGA). (Item 81) Item 79. The receiver of item 78, wherein the digital signal processing circuitry comprises a field programmable gate array (FPGA). (Item 82) generating an optical signal; receiving first data and receiving second data after receiving the first data; providing a first plurality of digital signals based on the first data and providing a second plurality of digital signals based on the second data; providing a first plurality of analog signals based on the first plurality of electrical signals and providing a second plurality of analog signals based on the second plurality of electrical signals; modulating the optical signal to provide a first plurality of optical subcarriers based on the first plurality of electrical signals and a second plurality of optical subcarriers based on the second plurality of electrical signals, each of the plurality of subcarriers and each of the second plurality of optical subcarriers having an in-phase component and a quadrature component, and a number of the first plurality of optical subcarriers differs from a number of the second plurality of optical subcarriers; A method comprising: (Item 83) Item 83. The method of item 82, wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers are Nyquist subcarriers. (Item 84) Item 83. The method of item 82, further comprising selectively providing an input to a digital signal processor. (Item 85) 85. The method of claim 84, further comprising providing control data to the digital signal processor such that one of the plurality of optical subcarriers carries information representative of the control data. (Item 86) 86. The method of claim 85, wherein the digital signal processor comprises a programmable gate array (PGA). (Item 87) Item 86. The method of item 85, wherein the digital signal processor comprises a field programmable gate array (FPGA). (Item 88) a laser operable to output a beam of light; a processor operable to receive the data and provide a plurality of electrical signals based on the data; a modulator operable to modulate a light beam to provide a plurality of optical subcarriers, a first of the plurality of subcarriers carrying first control information and a second of the plurality of subcarriers carrying second control information, the first control information representing a first parameter associated with a first node remote from the transmitter, and the second control information representing a second parameter associated with a second node remote from the transmitter; A transmitter comprising: (Item 89) 89. The transmitter of claim 88, wherein the first parameter is an amount of first data output from the first node and the second parameter is an amount of second data output from the second node. (Item 90) Item 89. The transmitter of item 88, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 91) Item 89. The transmitter of item 88, wherein each of the plurality of optical subcarriers is spectrally non-overlapping with another of the plurality of optical subcarriers. (Item 92) Item 90. The transmitter of item 88, wherein the processor is a digital signal processor. (Item 93) The processor has a plurality of inputs, and the transmitter further comprises: a switch circuit coupled to at least one of the plurality of inputs; Item 89. The transmitter of item 88, having a (Item 94) The processor has a plurality of inputs, and the transmitter further comprises: a plurality of switches, each of which is coupled to a respective one of said plurality of inputs; Item 89. The transmitter of item 88, having a (Item 95) Item 95. The transmitter of item 94, wherein each of the plurality of switches selectively provides one of data and control information to a respective one of the plurality of inputs. (Item 96) Item 91. The transmitter of item 88, wherein the modulator comprises a Mach-Zehnder modulator. (Item 97) Item 90. The transmitter of item 88, wherein the processor has an output, the transmitter further comprising a digital-to-analog conversion circuit coupled to the output and operable to provide an analog output. (Item 98) Item 98. The transmitter of item 97, further comprising a driver circuit receiving the analog output and providing a drive signal to the modulator. (Item 99) Item 89. The transmitter of item 88, wherein at least one of the plurality of optical subcarriers is modulated according to a modulation format, the modulation format being one of m-quadrature amplitude modulation (m-QAM) modulation, a quadrature phase shift keying (QPSK) modulation format, and a binary phase shift keying (BPSK) modulation format, where m is a positive integer. (Item 100) 89. The transmitter of claim 88, wherein the processor has a plurality of inputs, and the number of the plurality of subcarriers is based on the number of the plurality of inputs that receive one of data or control information. (Item 101) Item 89. The transmitter of item 88, wherein a spectral gap exists between spectra associated with at least first adjacent and second adjacent ones of the plurality of optical subcarriers. (Item 102) a local oscillator laser operable to provide a light beam; an optical hybrid circuit operable to mix the optical beam with an optical subcarrier to provide a mixed product; a photodiode operable to convert the mixture product into an electrical signal; an analog-to-digital conversion circuit operable to provide a digital signal based on the electrical signal; a processor operable to receive said digital signal and provide information representative of data carried by at least said group of subcarriers based on said digital signal; said receiver being operable to selectively output said data. (Item 103) Item 103. The receiver of item 102, wherein one of the plurality of subcarriers carries control information associated with the receiver. (Item 104) Item 104. A receiver as described in item 103, wherein the control information identifies an amount of data output from the receiver. (Item 105) Item 103. The receiver of item 102, wherein the control information identifies a number of subcarriers carrying information representing data output from the receiver. (Item 106) Item 103. The receiver of item 102, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 107) Item 103. The receiver of item 102, wherein each of the plurality of optical subcarriers is spectrally non-overlapping with another of the plurality of optical subcarriers. (Item 108) Item 103. The receiver of item 102, wherein the processor is a digital signal processor. (Item 109) The processor has a plurality of outputs, and the receiver further comprises: a switch circuit coupled to at least one of the plurality of inputs; Item 103. The receiver of item 102, having a (Item 110) The processor has a plurality of outputs, and the transmitter further comprises: a plurality of switches, each of which is coupled to a respective one of said plurality of outputs; Item 103. The receiver of item 102, having a (Item 111) Item 109. The receiver of item 108, wherein each of the plurality of switches is operable to selectively provide one of data or control information from a respective one of the plurality of outputs. (Item 112) Item 103. The receiver of item 102, wherein a spectral gap exists between spectra associated with at least first adjacent and second adjacent ones of the plurality of optical subcarriers. (Item 113) Item 103. The receiver of item 102, wherein at least one of the plurality of optical subcarriers is modulated according to a modulation format, the modulation format being one of m-quadrature amplitude modulation (m-QAM) modulation, a quadrature phase shift keying (QPSK) modulation format, or a binary phase shift keying (BPSK) modulation format, where m is a positive integer. (Item 114) a transmitter operable to output a plurality of optical subcarriers and control information; a receiver operable to at least receive the group of the plurality of optical subcarriers and the control information, based on the control information, the receiver outputs data representative of information carried by at least one of the plurality of optical subcarriers in the group of the plurality of optical subcarriers; A communication system comprising: (Item 115) the control information is first control information, the group of the plurality of optical subcarriers is a first group of the plurality of subcarriers, the data is first data, and the information is first information; Item 115. The communication system of item 114, wherein based on second control information, the receiver outputs second data representing second information carried by at least one of the optical subcarriers in a second group of the optical subcarriers, and the amount of the first data is different from the amount of the second data. (Item 116) Item 115. The system of item 114, wherein the transmitter has an associated first bandwidth and the receiver has an associated second bandwidth that is narrower than the first bandwidth. (Item 117) Item 115. The system of item 114, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 118) Item 115. The system of item 114, wherein at least one of the plurality of optical subcarriers is modulated according to a modulation format, the modulation format being one of m-quadrature amplitude modulation (m-QAM) modulation, a quadrature phase shift keying (QPSK) modulation format, or a binary phase shift keying (BPSK) modulation format, where m is a positive integer. (Item 119) The receiver above is a local oscillator laser operable to provide a light beam; an optical hybrid circuit operable to mix the optical beam with the plurality of optical subcarriers; Item 115. The system of item 114, comprising: (Item 120) Item 115. The system of item 114, further comprising an optical splitter provided between the transmitter and the receiver. (Item 121) Item 115. The system of item 114, wherein the receiver is a first receiver and the system further comprises a second receiver that receives a power divided portion of each of the plurality of subcarriers. (Item 122) Item 115. The system according to item 114, wherein the receiver is a first receiver, and the system further comprises: a splitter operable to receive the plurality of optical subcarriers and provide a first power split portion for each of the plurality of optical subcarriers and a second power split portion for each of the plurality of optical subcarriers; a second receiver, wherein a first power split portion of each of the plurality of optical subcarriers is provided to the first receiver and a second power split portion of each of the plurality of optical subcarriers is provided to a second receiver; A system comprising: (Item 123) Item 115. The system of item 114, wherein the control information is carried by one of the plurality of optical subcarriers. (Item 124) Item 115. The system of item 114, wherein a spectral gap exists between spectra associated with at least first adjacent and second adjacent ones of the plurality of optical subcarriers. (Item 125) Item 115. The system of item 114, wherein the transmitter and receiver are provided at a first node and a second node, respectively, of an aggregation network. (Item 126) Item 115. The system of item 114, wherein the transmitter and receiver are provided at a first node and a second node, respectively, of a mesh network. (Item 127) a transmitter operable to output a first plurality of optical subcarriers and control information; a receiver operable to receive the first plurality of subcarriers and a second plurality of optical subcarriers comprising control information, a bandwidth associated with the receiver being greater than a bandwidth associated with the transmitter; and A communication system comprising: (Item 128) Item 128. The system of item 127, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier. (Item 129) Item 128. The system of item 127, wherein at least one of the plurality of optical subcarriers is modulated according to a modulation format, the modulation format being one of m-quadrature amplitude modulation (m-QAM) modulation, a quadrature phase shift keying (QPSK) modulation format, or a binary phase shift keying (BPSK) modulation format, where m is a positive integer. (Item 130) The receiver is a local oscillator laser operable to provide a light beam; an optical hybrid circuit operable to mix the optical beam with the plurality of optical subcarriers; Item 128. The system of item 127, comprising: (Item 131) Item 128. The system of item 127, further comprising an optical combiner between the transmitter and the receiver. (Item 132) Item 128. The system of item 127, wherein the transmitter is a first transmitter, and the system further comprises a second transmitter operable to provide a third plurality of optical subcarriers, the second plurality of optical subcarriers including the first plurality of subcarriers and the third plurality of subcarriers. (Item 133) Item 127. The system of item 127, wherein the transmitter is a first transmitter and the plurality of optical subcarriers is a first plurality of optical subcarriers, and the system further comprises: a second transmitter operable to provide a second plurality of optical subcarriers; a combiner operable to receive the first plurality of subcarriers and the second plurality of subcarriers and provide the first plurality of subcarriers and the second plurality of subcarriers to the receiver; A system comprising: (Item 134) Item 128. The system of item 127, wherein the control information is carried by one of the plurality of optical subcarriers. (Item 135) Item 128. The system of item 127, wherein a spectral gap exists between spectra associated with at least first adjacent and second adjacent ones of the plurality of optical subcarriers. (Item 136) Item 128. The system of item 127, wherein the transmitter and receiver are provided at a first node and a second node, respectively, of an aggregation network. (Item 137) Item 128. The system of item 127, wherein the transmitter and receiver are provided at a first node and a second node, respectively, of the mesh network. (Item 138) transmitting a plurality of optical subcarriers from a first node to a second node in the network; transmitting first control information from the first node to the second node; receiving the plurality of subcarriers and the first control information at the second node; outputting first data representative of first information carried by a first group of the plurality of optical subcarriers from the second node based on the first control information; transmitting second control information from the first node to the second node; outputting second data from the second node representing second information carried by a second group of the optical subcarriers based on the second control information; A method for providing the above.

Claims

1. A transceiver comprising: a laser operable to output an optical signal; a first digital signal processor circuit operable to receive first data and provide a first plurality of electrical signals based on the first 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; a modulator operable to modulate the optical signal to provide a first plurality of optical subcarriers based on the third plurality of electrical signals, each of the first plurality of optical subcarriers including an in-phase component and a quadrature component, at least one of the first plurality of optical subcarriers carrying control information, the control information including information regarding a number of the first plurality of optical subcarriers to be output from a node that received the control information; wherein the first plurality of optical subcarriers includes at least one set of optical subcarriers, and particular optical subcarriers within the at least one set of optical subcarriers carry the control information and user data; a photodiode circuit having at least one photodiode operable to receive a plurality of optical mixing products based on the second plurality of optical subcarriers and a local oscillator optical signal, the photodiode circuit providing a fourth plurality of electrical signals based on the plurality of optical mixing products; a plurality of analog-to-digital conversion circuits providing a fifth plurality of electrical signals based on the fourth plurality of electrical signals; a second digital signal processor circuit that outputs second data based on the fifth plurality of electrical signals; a receiver having a A transceiver comprising:

2. The transceiver of claim 1 , wherein the control information dynamically varies a number of the first plurality of optical subcarriers output from the node in response to traffic demand.

3. the modulator has a pair of first modulator sections and a pair of second modulator sections; The transmitter comprises: a first phase shifter that shifts the phase of an output from one of the pair of first modulator sections by 90 degrees; a second phase shifter that shifts the phase of an output from one of the pair of second modulator sections by 90 degrees; a polarization rotator that rotates the polarization of an optical signal obtained by combining an output from the other second modulator section of the pair of second modulator sections and an output from the second phase shifter; 3. The transceiver of claim 1, further comprising a polarization beam combiner that combines an optical signal obtained by combining an output from the other first modulator section of the pair of first modulator sections and an output from the first phase shifter with an optical signal from the polarization rotator.

4. 2. The transceiver of claim 1, wherein the number of said second plurality of optical subcarriers is less than the number of said first plurality of optical subcarriers.

5. 2. The transceiver of claim 1, wherein a number of said second plurality of optical subcarriers is the same as a number of said first plurality of optical subcarriers.

6. The transceiver of claim 1 , wherein the optical signal is a first optical signal, and the laser further provides the local oscillator optical signal.

7. 7. The transceiver of claim 1, wherein the receiver further comprises an optical hybrid circuit that receives the local oscillator optical signal and at least a portion of each of the second plurality of optical subcarriers, the optical hybrid circuit providing the plurality of optical mixing products.

8. 8. The transceiver of claim 1, wherein a first guard band extends between a first frequency associated with a first optical subcarrier of the first plurality of optical subcarriers and a second frequency associated with a second optical subcarrier of the first plurality of optical subcarriers.

9. 8. The transceiver of claim 7, wherein the receiver comprises a local oscillator laser that provides a local oscillator beam to the optical hybrid circuit.

10. 10. The transceiver of claim 9, wherein the local oscillator laser is a tunable laser.

11. A receiver, an optical hybrid circuit that receives a local oscillator beam, a first polarization component of a plurality of optical subcarriers, and a second polarization component of the plurality of optical subcarriers, the plurality of optical subcarriers being spectrally non-overlapping with one another, each of the plurality of optical subcarriers being generated by modulation of an optical signal output from a laser, the optical hybrid circuit providing a plurality of optical mixing products; a photodiode circuit for providing a first plurality of electrical signals based on the plurality of optical mixing products; a digital signal processor circuit that receives a first control signal, outputs first data associated with a first subset of the plurality of optical subcarriers based on the first control signal and the first plurality of electrical signals, and outputs second data associated with a second subset of the plurality of optical subcarriers based on a second control signal; the first control signal includes first information regarding the number of the plurality of optical subcarriers output from a first node that has received the first control signal, and the second control signal includes second information regarding the number of the plurality of optical subcarriers output from a second node that has received the second control signal; a first optical subcarrier in the first subset of the plurality of optical subcarriers carries the first information and first user data, and a second optical subcarrier in the second subset of the plurality of optical subcarriers carries the second information and second user data.

12. The receiver of claim 11 , wherein the first subset has fewer optical subcarriers of the plurality of optical subcarriers than the second subset.

13. 13. The receiver of claim 11 or 12, wherein the first subset comprises one of the plurality of optical subcarriers.

14. The receiver of claim 13 further comprising a local oscillator laser providing the local oscillator beam.

15. 15. The receiver of claim 14, wherein the local oscillator laser is a tunable laser.

16. 1. A system comprising: A laser that outputs an optical signal; a first digital signal processor circuit for receiving first data and providing a first plurality of electrical signals based on the first data; a plurality of digital-to-analog conversion circuits providing a second plurality of electrical signals based on the first plurality of electrical signals; a plurality of driver circuits that provide a third plurality of electrical signals based on the second plurality of electrical signals; a modulator that modulates the optical signal to provide a plurality of optical subcarriers based on the third plurality of electrical signals, each of the plurality of optical subcarriers including an in-phase component and a quadrature component, at least one of the plurality of optical subcarriers carrying control information, the control information including information regarding a number of the plurality of optical subcarriers that are output from a node that receives the control information; wherein the plurality of optical subcarriers includes at least one set of optical subcarriers, and particular subcarriers within the at least one set of optical subcarriers carry the control information and user data; 1. A receiver optically coupled to an optical communication path, the receiver comprising: an optical hybrid circuit that receives a local oscillator beam, a first polarization component of the plurality of optical subcarriers, and a second polarization component of the plurality of optical subcarriers, each of the plurality of optical subcarriers being generated by modulation of an optical signal output from a laser, the optical hybrid circuit providing a plurality of optical mixing products; a photodiode circuit for providing a fourth plurality of electrical signals based on the plurality of optical mixing products; a second digital signal processor circuit that outputs a portion of second data associated with a subset of the plurality of optical subcarriers based on the fourth plurality of electrical signals; a receiver having a A system comprising:

17. 17. The system of claim 16, wherein the portion of the second data is a first portion of the second data, the subset of the plurality of optical subcarriers is a first subset of the plurality of optical subcarriers, and based on a control signal provided to the second digital signal processor circuit, the second digital signal processor circuit provides a second portion of the second data associated with a second subset of the plurality of optical subcarriers.

18. 18. A system according to claim 16 or 17, wherein the receiver comprises a local oscillator laser providing the local oscillator beam.

19. 20. The system of claim 18, wherein the local oscillator laser is a tunable laser.

20. 20. The system of claim 16, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier.

21. 16. The receiver of claim 11, wherein each of the plurality of optical subcarriers is a Nyquist subcarrier.

22. 11. The transceiver of claim 1, wherein the first digital signal processor circuit comprises a programmable gate array (PGA) or a field programmable gate array (FPGA).

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