Abstract: A method for processing data in an optical network element. A multi-carrier signal is linear pre-coded and the linear pre-coded signal is modulated. A corresponding optical network element is also described.

Abstract: We describe and demonstrate a novel and simple scheme to generate flattened optical subcarriers using only phase modulators driven by single frequency fundamental sinusoidal sources. 160.8 Gb/s PM-QPSK experiment over a single subcarrier has been demonstrated.

Abstract: Techniques for optical communications using optical orthogonal frequency division multiplexing (OFDM) include operating a signal transmitter to modulate laser light to produce modulated light that carries, in optical domain, OFDM subcarriers for carrying communication information, without a frequency guard band between the OFDM subcarriers, and pilot subcarriers for channel estimation at a signal receiver, each pilot subcarrier being free of communication information, and controlling optical power of the pilot subcarriers to vary with optical frequencies of the pilot subcarriers so that optical power of a pilot subcarrier at a high optical frequency is different from optical power of another pilot subcarrier at a low optical frequency.

Abstract: A method of generating a multi-subcarrier optical signal is disclosed. A local oscillator oscillates one or more data signals to generate one or more oscillating data signals. A series of modulators phase modulate a lightwave to generate a phase modulated lightwave, wherein the series of modulators are driven by the one or more oscillating data signals. The intensity modulator modulates the phase modulated lightwave, the intensity modulator being driven by one of the oscillating data signals, to generate the multi-subcarrier optical signal.

Abstract: An energy efficient OFDM transceiver includes a transmitter using a decision processor to control first internal elements that can be operated in parallel and can be selectively powered off or hibernated, and a receiver using a processing decision element to control second internal elements that can be operated in parallel and can be selectively powered off or hibernated, wherein control of the first and second internal elements enables tracking status of network traffic, adjustment of OFDM bandwidth based on a traffic decision and selectively powering off or hibernating parallel ones of the first and second internal elements.

Abstract: An optical signal processing apparatus includes a mixer and a first optical modulator. The mixer modulates a carrier signal of a first specific frequency received from a first oscillator with an information signal to generate a subcarrier modulated signal. The first optical modulator optically modulates, with the subcarrier modulated signal received from the mixer, carrier light optically modulated by a second optical modulator at a second specific frequency received from a second oscillator to generate and output modulated carrier light.

Abstract: In order to provide a transmission device which can resolve the deterioration in transmission characteristics due to lack of the resolution of a D/A converter in a high speed and large capacity digital communication, a transmission device according to an exemplary aspect of the present invention includes an encoding unit encoding input data; an unequal-interval quantization unit quantizing an output signal from the encoding unit by a quantization level number based on a resolution of a subsequent digital-to-analog conversion unit by using an unequally spaced quantization level interval based on the output signal; the digital-to-analog conversion unit converting an output signal from the unequal-interval quantization unit into an analog signal; an output level adjustment unit adjusting an output level of the digital-to-analog conversion unit so as to compensate a difference between a predetermined initial transfer function and a transfer function of the unequal-interval quantization unit; and a modulation unit

Abstract: A wireless transmit/receive unit (WTRU) that may receive an asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) signal is disclosed. The ACO-OFDM signal may include an ACO-OFDM symbol and the ACO-OFDM signal may be generated with or without a pilot or training data. Where the ACO-OFDM signal may not include a pilot or training data, the WTRU may determine a correlation minimum between a first part of N samples of the ACO-OFDM symbol and a second part of N samples of the ACO-OFDM symbol. The correlation minimum may indicate an estimated boundary of the ACO-OFDM symbol which may provide the WTRU with timing synchronization information. Where the ACO-OFDM signal may include one or more ACO-OFDM pilot symbols on one or more pilot subcarriers, the WTRU may interpret an amount of training data included in the one or more ACO-OFDM pilot symbols that may provide information for channel estimation.

Abstract: A method of allocating upstream bandwidth on a network comprising mapping an integer portion of a value obtained from a grant start time into a symbol number of a data frame on a coaxial segment of the network, wherein the value comprises the grant start time in units of a length of a data frame in the coaxial segment of a network, and wherein the length of the data frame comprises a preselected number of units of time defined in an optical segment of a network; mapping a fractional portion of the value obtained from the grant start time into a subcarrier number of the data frame; and mapping a grant length into a number subcarriers of the data frame.

Abstract: This disclosure is directed to an optical transmitter arrangement 100 and a method therein producing a first RF-signal UA1 comprising a first set of data A1 carried by a subcarrier fC1, and a second RF-signal UB1 comprising a second set of data B1 carried by the subcarrier fC1. Further producing a first transform signal H(UA1) being a Hilbert Transform of the first RF-signal UA1, and a second transform signal ?H(UB1) being a Hilbert Transform of the second RF-signal UB1. In addition, modulating the optical carrier fopt with the first RF-signal UA1 and the first transform signal H(UA1), and forming a first sideband SB1 comprising the first set of data A1 at one side of the frequency f0 of the optical carrier fopt. In addition, modulating the optical carrier fopt with the second RF-signal UB1 and the second transform signal ?H(UB1), and forming a second sideband SB2 comprising the second set of data B1 at the other side of the frequency f0 of the optical carrier fopt.

Abstract: Methods and systems for secure communication include assigning data streams to respective orthogonal sub-carriers according to random number information at a transmitter. The data streams are modulated onto the respective orthogonal sub-carriers before the orthogonal sub-carriers are transmitted. The random number information is transmitted on a second medium, separate from the transmission medium. The orthogonal sub-carriers are received from the transmission medium at a receiver, while the random number information is received from the second medium at the receiver. The orthogonal sub-carriers are associated with data streams using the random number information and demodulated to produce data for the associated data stream.

Abstract: A method for data processing in an optical network includes providing at least one main wavelength and processing a subcarrier modulation for the at least one main wavelength, wherein a portion of the subcarrier modulated signal is suppressed. An optical network component and a communication system having such an optical network component are also provided.

Abstract: Methods and apparatus for generating and processing a signal are disclosed. The signal may comprise a plurality of mutually orthogonal subcarriers constituting a plurality of bands. The signal may be either an optical or a radio frequency signal.

Abstract: An optical receiver comprising a frontend configured to receive an optical signal and convert the optical signal into a plurality of digital electrical signals comprising a plurality of spectrally shaped subcarrier signals carrying symbol mapped data information, and a digital signal processor (DSP) unit coupled to the frontend and configured to receive the digital signals from the frontend, demulitplex the digital signals into the subcarrier signals, and compensate chromatic dispersion (CD) for each of the subcarrier signals by applying an equalizer, wherein each of the subcarrier signals is associated with a unique tone frequency and a unique spectral shape. Also disclosed is an optical transmitter comprising a digital signal processor (DSP) unit configured to map data symbols onto a plurality of electrical subcarrier signals that are non-overlapping and spectrally shaped in a frequency domain.

Abstract: A transmitting apparatus is used in an electrical frequency division multiplex transmission system including nodes that are on an optical transmission path and that respectively frequency-multiplex a sub-carrier of a unique frequency and a carrier wave to transmit information to a receiving apparatus on the optical transmission path. The transmitting apparatus is disposed in each node and includes a determining unit that receives an input of information concerning unused sub-carriers of a transmission signal in the optical transmission path and determines transmission of the information to the receiving apparatus using an unused sub-carrier; an electrical frequency division multiplex transmission unit that using a frequency of the unused sub-carrier determined by the determining unit, modulates the input information to be transmitted to the receiving apparatus; and a coupling unit that adds to the transmission signal in the optical transmission path, a modulated modulation signal.

Abstract: Disclosed is a subcarrier multiplexing type optical communication method including the steps of receiving a first optical signal composed of a plurality of subcarrier channels having different frequencies, creating a second optical signal having a wavelength different from a wavelength of a received signal; and detecting the subcarrier channels from a third optical signal obtained by subjecting the first optical signal to wavelength shift by means of the second optical signal.

Abstract: Embodiments include, but are not limited to, systems and methods for enabling Orthogonal Frequency Division Multiple Access (OFDMA) in the upstream in an Ethernet Passive Optical Network over Coax (EPoC) network. Embodiments include systems and methods for translating Ethernet Passive Optical Network (EPON) upstream time grants to OFDMA resources represented by individual subcarriers of an upstream OFDMA frame. In an embodiment, the translation of EPON upstream time grants to OFDMA resources ensures that Coaxial Network Units (CNUs) sharing an OFDMA frame do not use overlapping subcarriers within the frame. Embodiments further include systems and methods for timing upstream transmissions by the CNUs in order for the transmissions to be received within the same upstream OFDMA frame at a Fiber Coax Unit (FCU). Embodiments further include systems and methods for re-generating a data burst from OFDMA resources for transmission from the FCU to an Optical Line Terminal (OLT).

Abstract: A subcarrier system generates a phase comparison signal in a transmitter and transmits the phase comparison signal together with an optical subcarrier multiplex signal in the same transmission channel of an optical network. A receiver measures a phase distortion between a phase reference signal and the received phase comparison signal for each modulation section of the received subcarrier symbols, calculating at least one correction value and correcting time jitters or phase impairments of all parallel received or regained subcarrier symbols as a function of the phase distortion of the received phase comparison signal. Time jitter/phase jitter can be compensated without high hardware expenses.

Abstract: Methods and apparatuses are provided to digitize an analog multi-channel RF narrowcast signal in an overlay system by dividing the signal into a plurality of subband signals and digitizing each subband signal using practical A/D converters.

Abstract: An optical signal receiving apparatus includes: a chromatic dispersion medium having an amount of chromatic dispersion which is determined according to a frequency of the sub-carrier modulation signals so as to receive the sub-carrier modulation signals, a photodetector configured to convert the carrier optical signal that has passed through the chromatic dispersion medium, into electrical signals, and a signal receiving unit configured to receive an electrical signal selected from the electrical signals obtained by the photodetector.

Abstract: An optical network terminal (ONT) for use in an optical access network and comprising: an optical transceiver arranged to communicate with an optical line terminal using a wavelength which is modulated to carry sub-channels; a second transceiver arranged to communicate with a number of subscriber equipment using respective subscriber equipment channels; the ONT arranged to automatically map each subscriber equipment channel to a respective sub-channel of the wavelength without using an address associated with the respective subscriber equipment.

Abstract: Embodiments provide systems and methods for enabling the support of multiple Ethernet Passive Optical Network over Coax (EPoC) channels, which can be bonded together into a single high-speed channel. The multiple EPoC channels can be configured according to available spectrum, such that they occupy one or more, frequency contiguous or separated, segments of the available spectrum. The size (number of sub-carriers) of each of the channels can be configured according to embodiments based on the available spectrum and/or other requirements (e.g., EPoC emission requirements, existing services, etc.). Further, within each channel, individual sub-carriers can be configured independently, including turning each sub-carrier on/off and/or specifying the symbol bit loading for the sub-carrier independently of other sub-carriers in the channel.

Abstract: The present disclosure provides a transmission system, apparatus and method to provide for variable channel spacing in multiplexed or combined optical signals for transmission over a network infrastructure. The channel spacing may be monitored and maintained at desired values in order to maximize the channel density under various conditions related to the network infrastructure. The individual carrier frequencies associated with each signal channel of the transmission system may be individually controlled to define the desired channel. The channel spacing may be altered to provide for higher channel densities increasing system capacity, or to provide for lower channel densities improving the overall reach of the transmission system. The channel spacing may be continuously monitored and maintained at desired values allowing for rapid and automated reconfiguration of the transmission system, which may result in maximized capacity and reduced costs.

Abstract: A system for transporting a plurality of analog and/or digital signals over an optical fiber can include one or more master modems for modulating digital signals and/or RF inserters modulating video signals. The RF signals from the modem(s)/RF inserters are up-converted resulting in frequency bands that are non-overlapping and are spaced apart within a single sub-octave. The sub-octave signal is then converted into an optical signal and directed onto an end of an optical fiber. At the downstream end of the optical fiber, the received optical signal is converted to an RF signal at an optical receiver. The RF signal is then filtered, down-converted and directed to a selected coaxial distribution unit. From the coaxial distribution unit, the RF signal is demodulated, e.g. at a slave modem, to recover the initial analog and/or digital signal.

Abstract: A switched wireless system is used to increase the range of peer-to-peer communications. The optically-switched fiber optic communication system includes a head-end unit (HEU) having a switch bank. Cables couple the HEU to one or more remote access points in different coverage areas. The switch bank in the HEU provides a link between the remote access points in the different coverage areas such that devices in the different cellular coverage areas communicate with each other. By using the switched communication system, the range and coverage of communication between devices may be extended such that devices in different coverage areas and devices using different communication protocols can communicate.

Abstract: Techniques and configurations are provided to generate multiple coherent optical subcarriers. A laser source generates as output a light beam at a carrier frequency. A multicarrier generator is provided that is coupled to the laser source and comprises one or more dual carrier generators each configured to modulate the light beam at the same modulation frequency or different modulation frequencies so as to output a plurality of light beams each at a different subcarrier frequency that is offset from the carrier frequency. The multicarrier generator generates the plurality of light beams on individual outputs, e.g., fibers, without the need for an optical demultiplexing filter.

Abstract: Systems and methods for enabling different network nodes of a network access system to share a backhaul communication link are disclosed. In one embodiment, the method includes: connecting a first modem to a first node of the network access system; connecting a second modem to a second node of the network access system; connecting the first modem to a first port of a splitter filter; connecting the second modem to a second port of the splitter filter; and connecting a backhaul communication link to a third port of the splitter filter, which is configured to multiplex signals transmitted by the modems onto the backhaul communication link, wherein the frequency spectrum of the signal transmitted by the first modem does not overlap substantially with the frequency spectrum of the signal transmitted by the second modem.

Abstract: The invention relates to improvements in or relating to modulation in an Optical Network, and to an apparatus, a method and a communications network for modulation in an Optical Network. An apparatus is arranged to receive a modulated optical signal comprising a carrier wavelength and first data. The apparatus is arranged to substantially erase the first data from the optical signal by performing an inversion operation on the modulated optical signal. The apparatus is arranged to receive second data and to modulate the carrier wavelength with the second data for onward transmission of the second data. The inversion operation comprises applying a signal comprising an inverse of the first data to at least a portion of the modulated optical signal. The signal may further comprise the second data such that the modulation of the carrier wavelength and erasure of the first data is performed in a single operation.

Abstract: The present disclosure provides a system, apparatus and method to provide for monitoring of characteristics of optical signals, as part of wavelength division multiplexed signals for example, transmitted over a network infrastructure. The characteristics of each optical signal may be monitored and maintained at desired values in order to optimize system performance. A system including a coherent detector, as part of a coherent receiver for example, may be employed to associate each transmitted optical signal with a modulated source. Control signals generated by the system can then be provided to elements of the modulated source to control characteristics, such as optical power, optical frequency, and optical phase, for example, of the transmitted optical signal.

Abstract: Methods and systems for optical signal grooming that include providing one or more input signals, each having one or more modulated subcarriers, to a grooming processor; and grooming the input signals at a subcarrier level with the grooming processor to produce one or more output signals by arranging the modulated subcarriers in the output signals according to a grooming operation such that the modulated subcarriers are not demodulated or decoded prior to grooming.

Abstract: A broadband receiving apparatus includes an antenna to receive a radio signal having a plurality of modulation frequencies. An amplifier drives a laser source from the broadband radio signal to produce an optical signal having a plurality of spectral components. A diffraction grating transforms the optical signal into its spectral components. An array of photo-detectors converts the spectral components into electronic signals corresponding to the plurality of modulation frequencies. A transmitting apparatus includes an array of coherent laser emitters driven by electronic signals corresponding to a plurality of modulation frequencies to produce optical signals corresponding to a plurality of spectral components. A diffraction grating inverse transforms the spectral components into a composite optical signal. A photo-detector converts the composite optical signal into a composite electronic signal including the plurality of modulation frequencies.

Abstract: A technique for reducing a necessary bandwidth of an optical receiver in an optical OFDM communication system is disclosed. Optical OFDM signals of different spectra are alternately transmitted for each OFDM symbol time, and; after this light is transmitted via an optical fiber, the light undergoes photoelectric conversion by a delay interferometer having a delay time equal to one symbol time and a balanced direct detection receiver and is received.

Abstract: Provided is an optical OFDM receiver. The optical OFDM receiver receives an optical signal dependent on the nonlinearity of a transmitter. The optical OFDM receives includes an optical down converter, a nonlinearity compensator, and an OFDM demodulator. The optical down converter converts the optical signal into an electrical signal. The nonlinearity compensator filters the electrical signal, for compensating distortion which is added to the optical signal when the transmitter performs optical modulation. The OFDM demodulator demodulates the distortion-compensated electrical signal in an OFDM scheme.

Abstract: A method and system for generating multi-subcarriers is disclosed. Re-circulating frequency shifters—based on the frequency shifting in two cascading phase modulators—are used to generate 112 subcarriers with stable architecture since there is no direct current bias in phase modulators.

Abstract: In accordance with some embodiments of the present disclosure a method for receiving and processing an optical orthogonal frequency-division multiplexed signal containing a plurality of traffics comprises receiving the optical orthogonal frequency-division multiplexed signal.

Abstract: A receiver receiving a phase-modulated optical frequency division multiplexed signal is provided. The receiver includes a light spectrum shaper configured to extract a carrier wave and a modulated light component contained in either one of a short-wavelength-side waveband or a long-wavelength-side waveband with respect to the carrier wave, to output a spectrum-shaped light signal; and an optical-to-electric converter configured to convert the spectrum-shaped light signal into an electric signal.

Abstract: An optical signal transmitting device includes direct modulators configured to be driven using electric signals of channels to generate directly-modulated optical signals of channels, a beat light source configured to generate beat light at a specific frequency spacing, subcarrier converters configured to modulate, using the beat light from the beat light source, the directly-modulated optical signals of the channels from the direct modulators to generate optical subcarrier modulation signals of channels, probe light sources configured to generate probe light of channels having frequencies that are different from frequencies of the directly-modulated optical signals of the channels, multiplexers configured to multiplex, for individual channels, the optical subcarrier modulation signals of the channels with the probe light of the channels, and nonlinear optical media configured to perform, for individual channels, optical cross modulation for the optical subcarrier modulation signals and the probe light, which

Abstract: Communication apparatus and techniques, such as for optical communication, can include providing a reference frequency derived from an atomic energy level transition or a molecular energy level transition, generating at least two specified optical carrier signals at least in part using the reference frequency, coherently modulating the specified optical carrier signals using respective baseband information signals to provide respective coherently-modulated optical subcarriers. A combined optical information signal comprising the optical subcarriers can be transmitted to a receiver, such as via a fiber optic cable. In an example, a received optical information signal can be optically Fourier transformed to provide respective coherent outputs, which can be coherently downconverted.

Abstract: Each of a plurality of data flows is classified as having a respective data flow type, and each data flow is assigned to one of a plurality of subcarrier groups, based on the data flow's type, wherein each subcarrier group comprises a respective plurality of subcarriers. First data flows assigned to a first subcarrier group are transmitted exclusively on respective subcarriers in the first subcarrier group, and second data flows assigned to a second subcarrier group are transmitted together on all of the subcarriers in the second subcarrier group.

Abstract: Optical safety functions are incorporated into protection switching modules which maintain redundant pathways to avoid interruptions in optical network connections. The optical safety functions which lower optical power levels upon interruptions of optical connections are effectively combined with protection switching procedures which are also triggered by interruptions in optical network connections. The interoperation of protection and safety processes keep optical power levels below hazardous levels at system points which might be accessible to human operators.

Abstract: In accordance with some embodiments of the present disclosure, a method for spectrally spacing carrier waves comprises determining a frequency offset between a first frequency of a first optical carrier wave and a second frequency of a second optical carrier wave. The method further comprises adjusting the second frequency of the second optical carrier wave according to the frequency offset. The method additionally comprises combining a first optical signal associated with the first carrier wave and a second optical signal associated with he second carrier wave into a multi-frequency signal.

Abstract: The present invention is directed towards a frequency modulated (FM) burst mode optical system that allows optical signals having a common wavelength provided by a plurality of FM burst mode optical transmitters to be passively combined onto a single optical fiber. A single FM optical receiver receives the combined signals and processes them accordingly. Each FM burst mode optical transmitter includes an FM modulator, is carrier detect circuit and a laser. The FM modulator modulates a carrier signal, such as a 1.21 GHz signal, with received reverse electrical signals. When a subcarrier signal is detected o the carrier detect circuit, the laser is turned and the frequency modulated carrier signal is used to intensity modulate a laser to provide an optical signal. Due to the burst-mode transmission of optical signals, the optical signals can be passively combined and transmitted to a single optical receiver.

Abstract: An optical switching and delay system for optical encryption and/or optical decryption may comprise a switch bank, a set of optical delay lines, a combiner, and a processor. The switch bank may be configured to receive an optical signal in a first arrangement and route the optical signal to the set of optical delay lines according to a switching arrangement key. The set of optical delay lines may be configured to provide delays to the optical signal. The combiner may be configured to receive the optical signal with delays from the set of optical delay lines and combine the optical signal into a second arrangement. The processor may be configured to receive the switching arrangement key and control the switch bank according to the switching arrangement key. The switching arrangement key may comprise a set of instructions for routing the optical signal.

Abstract: A high-performance optical OFDM receiver is realized. A subcarrier separation circuit receives an optical OFDM signal consisting of two subcarriers A and B and separates a subcarrier component, signal light and first local oscillator light are input to the subcarrier separation circuit, the subcarrier separation circuit converts the signal light and the first local oscillator into a baseband electrical signal, the subcarrier separation circuit converts the baseband electrical signal into a digital signal, the subcarrier separation circuit shifts the frequency of the converted digital signal so that a center frequency of the subcarrier A becomes zero, and the subcarrier separation circuit adds a frequency shifted signal to a signal obtained by delaying the frequency shifted signal by ½ of a symbol time to separate a component of the subcarrier A.

Abstract: A system and communication method for the system interconnecting the optical network with the radio communication network is provided. The solution mainly applies to an optical access network employing fiber for transmission and the radio communication network connected to the optical access network, wherein a base station of the radio communication network is connected to the optical access network and communicates to an entity in the optical access network to achieve interconnection between the optical network and the radio communication network. After the interconnection is established, a user equipment can enjoy communication services through the interconnected radio communication network and the optical network.

Abstract: Methods and apparatuses are provided to modify existing overlay system architectures in a cost effective manner to meet the growing demand for narrowcast services and to position the existing overlay systems for additional future modifications. The implementations of the improved overlay system of this disclosure re-digitize narrowcast analog signals after they have been QAM modulated and upconverted to RF frequencies and replace the analog narrowcast transmitters with digital narrowcast transmitters. In the fiber nodes, the received narrowcast signals are converted back to analog signals and combined with analog broadcast signals for transmission to the service groups.

Abstract: Methods and systems for secure communication include assigning data streams to respective orthogonal sub-carriers according to random number information at a transmitter. The data streams are modulated onto the respective orthogonal sub-carriers before the orthogonal sub-carriers are transmitted. The random number information is transmitted on a second medium, separate from the transmission medium. The orthogonal sub-carriers are received from the transmission medium at a receiver, while the random number information is received from the second medium at the receiver. The orthogonal sub-carriers are associated with data streams using the random number information and demodulated to produce data for the associated data stream.

Abstract: Optical superchannel methods and systems that couple two or more local oscillators into a single coherent receiver front end to receive multiple optical subcarriers are shown and described. With multiple local oscillators coupled into a single coherent receiver and appropriate optical selective filtering of the superchannel signal, non-neighboring subcarriers may be received by the single coherent optical receiver.

Abstract: The present invention provides a method and system for transmitting data over an optical channel using OFDM with a variable transmission rate. Such method and system feeds an essentially constant transmission power over a predetermined OFDM bandwidth into the optical channel. In an embodiment, at least two OFDM subcarriers may be modulated with signal information derived from a single word of an OFDM symbol. Further thereto, the frequency spacing between the transmitted OFDM subcarriers may be changed.

Abstract: Disclosed is an apparatus and a method for transmitting data by using visible light. The transmission apparatus includes: a Serial-to-Parallel (S/P) converter for performing a Serial-to-Parallel conversion on transmission data, and generating multiple parallel data; a modulation means for modulating the multiple parallel data generated by the S/P converter, and generating multiple modulation signals; an Inverse Fast Fourier Transform (IFFT) means for performing an IFFT on the multiple modulation signals so that the multiple modulation signals are orthogonal to one another, and generating an IFFT signal; and a light-emitting means for causing a light source to emit light based on the IFFT signal generated by the IFFT means.