Abstract: The present disclosure generally discloses capabilities for supporting new network zones and associated services. The network zones and associated services may include a near-real-time (NRT) zone and associated NRT services, a real-time (RT) zone and associated RT services, or the like. The resilient network zones and associated resilient and non-resilient services may be configured to provide bounded latency guarantees for reliably supporting various types of applications (e.g., mobile fronthaul, cloud computing, Internet-of-Things (IoT), or the like). The network zones and associated services may be provided using a distance-constrained fiber and wavelength switching fabric design comprised of various network devices and using associated controllers, which may be configured to support service provisioning functions, service testing functions, wavelength switching functions, and so forth.

Abstract: The present disclosure generally discloses capabilities for supporting new network zones and associated services. The network zones and associated services may include a near-real-time (NRT) zone and associated NRT services, a real-time (RT) zone and associated RT services, or the like. The resilient network zones and associated resilient and non-resilient services may be configured to provide bounded latency guarantees for reliably supporting various types of applications (e.g., mobile fronthaul, cloud computing, Internet-of-Things (IoT), or the like). The network zones and associated services may be provided using a distance-constrained fiber and wavelength switching fabric design comprised of various network devices and using associated controllers, which may be configured to support service provisioning functions, service testing functions, wavelength switching functions, and so forth.

Abstract: The present disclosure generally discloses capabilities for supporting new network zones and associated services. The network zones and associated services may include a near-real-time (NRT) zone and associated NRT services, a real-time (RT) zone and associated RT services, or the like. The resilient network zones and associated resilient and non-resilient services may be configured to provide bounded latency guarantees for reliably supporting various types of applications (e.g., mobile fronthaul, cloud computing, Internet-of-Things (IoT), or the like). The network zones and associated services may be provided using a distance-constrained fiber and wavelength switching fabric design comprised of various network devices and using associated controllers, which may be configured to support service provisioning functions, service testing functions, wavelength switching functions, and so forth.

Abstract: The present disclosure generally discloses capabilities for supporting new network zones and associated services. The network zones and associated services may include a near-real-time (NRT) zone and associated NRT services, a real-time (RT) zone and associated RT services, or the like. The resilient network zones and associated resilient and non-resilient services may be configured to provide bounded latency guarantees for reliably supporting various types of applications (e.g., mobile fronthaul, cloud computing, Internet-of-Things (IoT), or the like). The network zones and associated services may be provided using a distance-constrained fiber and wavelength switching fabric design comprised of various network devices and using associated controllers, which may be configured to support service provisioning functions, service testing functions, wavelength switching functions, and so forth.

Abstract: Various embodiments relate to an in-band measurement of the optical signal-to-noise ratio (OSNR) of an optical signal in an optically-amplified transmission system. A demodulation device may tap a transmission fiber to receive an optical signal containing a low-frequency signal. A filter may implement first and second passbands to filter portions of an optical channel in the optical signal. Once the filtered channel is converted to first and second target electrical signals, a measurement circuit may take measurements of DC and AC components for each of the target electrical signals. Based on measurements of the two target electrical signals, the demodulation device may calculate the OSNR as a function of the DC and AC components, or as a function of the adjustment factors between first and second passbands of the optical channel represented by the first and second target electrical signals.

Abstract: Various embodiments relate to an in-band measurement of the optical signal-to-noise ratio (OSNR) of an optical signal in an optically-amplified transmission system. A demodulation device may tap a transmission fiber to receive an optical signal containing a low-frequency signal. A filter may implement first and second passbands to filter portions of an optical channel in the optical signal. Once the filtered channel is converted to first and second target electrical signals, a measurement circuit may take measurements of DC and AC components for each of the target electrical signals. Based on measurements of the two target electrical signals, the demodulation device may calculate the OSNR as a function of the DC and AC components, or as a function of the adjustment factors between first and second passbands of the optical channel represented by the first and second target electrical signals.

Abstract: For wavelength division multiplexing (WDM) communications, apparatus and methods are provided for performing tone-based optical channel monitoring that is less sensitive to stimulated Raman scattering (SRS). In tone-based optical channel monitoring, in which WDM channels are modulated with one or more tones, detecting and measuring the tone power is commonly used as a measure of signal power in each channel. In WDM systems with long fiber spans and high signal powers, however, SRS tends to transfer energy from shorter wavelengths to longer wavelengths, whereby the tones are no longer accurately indicative of the signal power of the individual wavelength channels. Apparatus and methods are provided which reduce the effect of SRS by filtering the monitored WDM signals into sub-bands and detecting each sub-band independently.

Abstract: A method and apparatus for distributed measurement of chromatic dispersion in an optical network is disclosed. The network comprises optical switching nodes interconnected by optical links. An optical link may comprise multiple spans, each span ending in a transport module which comprises signal-processing components. At least one optical switching node has a probing signal generator transmitting an optical probing signal along a selected path in the network. Probing-signal detectors placed at selected transport modules determine chromatic-dispersion values and send results to a processing unit which determines appropriate placement of compensators or appropriate adjustments of compensators placed along the path. A preferred probing signal has the form of wavelength modulated optical carrier which is further intensity modulated by a periodic, preferably sinusoidal, probing tone.

Abstract: Signals in an optical communications network, such as optical channels in an optical WDM network for example, are each identified by at least two low frequency dither tones with which the signal is modulated. The dither tones alternate with a predetermined periodicity to produce a cyclically repeated sequence of dither tones. A network parameter, such as a channel identifier for example, is obtained by the detection of the particular combination of dither tones in the sequence. To detect a number of network parameters a signal is modulated with a number of cyclically repeated sequences of dither tones each uniquely identifying a respective network parameter. In some implementations each dither tone in a cyclically repeated sequence of dither tones is repeated with substantially the same phase and coherent averaging is performed over a number of periods to detect dither tones on low power signals.

Abstract: A method and apparatus for distributed measurement of chromatic dispersion in an optical network is disclosed. The network comprises optical switching nodes interconnected by optical links. An optical link may comprise multiple spans, each span ending in a transport module which comprises signal-processing components. At least one optical switching node has a probing signal generator transmitting an optical probing signal along a selected path in the network. Probing-signal detectors placed at selected transport modules determine chromatic-dispersion values and send results to a processing unit which determines appropriate placement of compensators or appropriate adjustments of compensators placed along the path. A preferred probing signal has the form of wavelength modulated optical carrier which is further intensity modulated by a periodic, preferably sinusoidal, probing tone.

Abstract: Identification of optical channels in wavelength division multiplex (WDM) optical networks may be confounded by unwanted noise tones interfering with pilot/dither tones used for identifying optical channels. The invention describes a method of selecting pilot/dither tones that are selectively restricted to avoid allocating dither/pilot tone frequencies that appear as noise tones along the path of an optical channel in the optical network.

Abstract: Methods and apparatus for optical-power control in an optical network employing wavelength-division multiplexed (WDM) optical-fiber links are devised to circumvent the effect of crosstalk caused by optical-power scattering. Each carrier signal is amplitude-modulated by an identifying tone, with the power of an identifying tone having a predetermined ratio to the power of its carrier signal. A fiber span within an optical-fiber link is tapped at a preferred monitoring point, and the power spectrum of the envelope of the tapped optical signal is measured. To estimate an individual carrier power, a temporary gain is applied and the power of a corresponding tone is measured. To control optical power of each wavelength carrier in several spans in the network, a network controller selects an order of processing the spans of interest, and selects the order of processing of each channel within each span.

Abstract: This invention provides a method for commissioning and upgrading an optical ring network using its internal amplifiers as Automatic Spontaneous Emission sources of light that are used in making measurements. A modular segmented approach is adopted and the network is commissioned segment by segment. A flexible method is used for upgrading a commissioned network by adding or deleting a node or changing the internal configuration of a node. The method uses techniques for the correction of the Optical Signal to Noise Ratio induced error as well as the Spectral Filtering Error during the loss computation required for adjusting the gains of the amplifiers at each network node to an appropriate value. Since the method does not require an external laser source that needs to be moved manually from node to node it greatly reduces the commissioning time. Since it uses only the components of the network itself and does not deploy any additional device it also leads to a significant saving in cost.

Abstract: Signals in an optical communications network, such as optical channels in an optical WDM network for example, are each identified by at least two low frequency dither tones with which the signal is modulated. The dither tones alternate with a predetermined periodicity to produce a cyclically repeated sequence of dither tones. A network parameter, such as a channel identifier for example, is obtained by the detection of the particular combination of dither tones in the sequence. To detect a number of network parameters a signal is modulated with a number of cyclically repeated sequences of dither tones each uniquely identifying a respective network parameter. In some implementations each dither tone in a cyclically repeated sequence of dither tones is repeated with substantially the same phase and coherent averaging is performed over a number of periods to detect dither tones on low power signals.

Abstract: Signals in an optical communications network, such as optical channels in an optical WDM network for example, are each identified by at least two low frequency dither tones with which the signal is modulated. The dither tones alternate with a predetermined periodicity to produce a cyclically repeated sequence of dither tones. A network parameter, such as a channel identifier for example, is obtained by the detection of the particular combination of dither tones in the sequence. To detect a number of network parameters a signal is modulated with a number of cyclically repeated sequences of dither tones each uniquely identifying a respective network parameter. In some implementations each dither tone in a cyclically repeated sequence of dither tones is repeated with substantially the same phase and coherent averaging is performed over a number of periods to detect dither tones on low power signals.

Abstract: Ethernet packets are transmitted in full duplex mode over a single coaxial cable, such as RG6 and RG59. Symmetrical full duplex operation is achieved by separating the upstream and downstream signals in the frequency domain whereby a 100BaseT signal is transmitted unmodified in one direction while the other is modulated upon a high frequency carrier to be transmitted in the other direction. In a second embodiment, the separation is in the time domain whereby the signals are sampled in blocks, each block compressed in time and transmitted at a higher rate, thus allowing for the interleaving of upstream and downstream blocks on the same coaxial cable. In a third embodiment, different rate upstream and downstream signals are separated in the frequency domain, but without modulation. The resulting asymmetrical 1000/100 Mb/s Ethernet over coax link is valuable in network architectures where asymmetry in the up and down traffic loads is expected.

Abstract: This invention provides a method for commissioning an optical network using internal Automatic Spontaneous Emission (ASE) light inherently present in the optical network as a light source (the ASE light source) for measuring losses inside and between nodes in the network. A modular segmented approach is adopted and the network is commissioned segment by segment. The method uses techniques for the correction of the Optical Signal to Noise Ratio induced error as well as the Spectral Filtering Error during the loss computation required for adjusting the gains of the amplifiers at each network node to an appropriate value. Since the method does not require an external laser source that needs to be moved manually from node to node, it greatly reduces the commissioning time. Since it uses only the existing components of the network nodes it also leads to a significant saving in cost.

Abstract: Methods and apparatus for optical-power control in an optical network employing wavelength-division multiplexed (WDM) optical-fiber links are devised to circumvent the effect of crosstalk caused by optical-power scattering. Each carrier signal is amplitude-modulated by an identifying tone, with the power of an identifying tone having a predetermined ratio to the power of its carrier signal. A fiber span within an optical-fiber link is tapped at a preferred monitoring point, and the power spectrum of the envelope of the tapped optical signal is measured. To estimate an individual carrier power, a temporary gain is applied and the power of a corresponding tone is measured. To control optical power of each wavelength carrier in several spans in the network, a network controller selects an order of processing the spans of interest, and selects the order of processing of each channel within each span.

Abstract: Identification of optical channels in wavelength division multiplex (WDM) optical networks may be confounded by unwanted noise tones interfering with pilot/dither tones used for identifying optical channels. The invention describes a method of selecting pilot/dither tones that are selectively restricted to avoid allocating dither/pilot tone frequencies that appear as noise tones along the path of an optical channel in the optical network.

Abstract: A method and system for identification of a channel in an optical network is provided. The channel is identified by the use of unique combinations of two or more low frequencies, or tones, modulated onto the channel and optionally, a network parameter associated with the channel.