39 results about "Subcarrier multiplexing" patented technology

Implementations of the present principles include methods, systems and apparatuses for transmitting data through a sub-carrier multiplexing and orthogonal frequency-division multiple access passive optical network. In accordance with aspects of the present principles, a plurality of optical network units are assigned electrical carrier frequency bandwidths that are narrower than a system capacity bandwidth. Modulation of optical waves transmitted between an optical line terminal and each optical network unit is conducted on different orthogonal sub-carrier frequencies within the assigned bandwidths such that sampling of said orthogonal sub-carrier frequencies is limited to the assigned electrical carrier frequency bandwidths. The waves are thereafter received and demodulated for the extraction of data.

A suite of optical performance monitoring (OPM) methods, based on optical subcarrier multiplexing, are described by the invention. The strength of this approach lies in the simplicity of double sideband subcarrier signals and the fact that these signals travel the complete optical path with the baseband signal of interest. The subcarrier signals can be recovered using techniques described in the application and are immune to fiber dispersion induced fading.

Digital compensation of chromatic dispersion (CD) effect experienced by optical orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission is provided in the frequency domain using a Fast Fourier Transform / Inverse Fast Fourier Transform (FFT / IFFT) pair with equal length of digital samples prior to OFDM receiver signal processing, wherein the equal length is larger than the length of a FFT used for OFDM subcarrier demultiplexing of the received signal. The OFDM signal processing is independent of fiber CD, so small guard-interval (GI) can still be used to achieve high spectral efficiency even under the experience of large CD. The GI need only to be large enough to accommodate other effects such as polarization-mode dispersion. The length of an IFFT used for OFDM subcarrier multiplexing, as well as the FFT for OFDM demultiplexing can be sufficiently small so subcarrier spacing is sufficiently large to tolerate typical frequency offsets between the transmitter laser and the optical local oscillator.

A free space laser communication system uses subcarrier multiplexing to prepare multiple data communication channels for impressing onto a laser carrier. Sending and receiving terminals mutually track to insure acquisition of the transmitted data signals.

Provided are a fault localization apparatus based on an optical communication network and a method thereof. In the fault localization apparatus according to the present invention, a downstream light source is used as a monitoring optical signal instead of using an additional monitoring light source and a subcarrier multiplexing (SCM) monitoring pulse signal of a certain frequency band having no interference with a frequency band of a downstream data signal is used and thus a fault position may be detected at low cost.

An optical transceiver for transmitting light source control information, which is applied to a Subcarrier Multiplexing optical network, is disclosed. The optical transceiver includes a controller, an SCM frame generation / restoring unit, a modulator / demodulator, and an EO / OE converter. The controller controls transmission of light source control information or collects received light source control information. The SCM frame generation / restoring unit generates an SCM frame containing light source control information received from the controller. The modulator / demodulator modulates an SCM frame generated by the SCM frame generation / restoring unit into a signal suitable for transmission. The EO / OE converter converts a transmission signal modulated by the modulator / demodulator into an optical signal and transmits the optical signal through an optical fiber. An optical network having a telephone office OLT and subscriber ONTs, each having the optical transceiver, is also disclosed.

The invention relates to an optical single-side band modulating device in the technical field of optical communication, which comprises an optical splitter, a DDMZM (dual-drive Mach-Zehnder modulator), an MZM (Mach-Zehnder modulator), a coupling, a frequency-selecting amplifier and a strength phase control unit, wherein one branch end of the optical splitter is connected with the DDMZM, and the other branch end of the optical splitter is connected with the strength phase control unit; the DDMZM is connected with the frequency-selecting amplifier; the strength phase control unit is connected with the MZM; the frequency-selecting amplifier is connected with one branch end of the coupling, and the MZM is connected with the other branch end of the coupling; the strength phase control unit comprises an attenuator and an FDL (Fiber-optic Delay Line); and the frequency-selecting amplifier comprises an optical circulator, an IL-FPLD (Injection Locked-Fabry-Perot Laser Diode) and an optical filter. The invention can generate an optical single-side band signal with better side band and high-order harmonic inhibition, has the advantages of simple structure, easy integration and good dynamic configuration and stability and is suitable for a broadcasting scheme based on an SCM (Subcarrier Multiplexing) mode in an OSSB (Optical Single-side Band) transmission system and a WDM-PON (Wave Division Multiplexing-Passive Optical Network) and a high-speed and high-capacity transmission system based on a plurality of subcarrier modes.

The invention discloses a WiFi (Wireless Fidelity) optical fiber radio central control system which comprises a controller, n radio-frequency signal distribution units and n radio-frequency branches, wherein each radio-frequency branch comprises a second combiner / shunt, a circulator, an electro-optical conversion module and an optical-electro conversion module; each radio-frequency signal distribution unit comprises a first combiner / shunt, n radio-frequency switches and a radio-frequency interface connected with the first combiner / shunt, and one ends of the n radio-frequency switches are connected to the first combiner / shunt, while the other ends are respectively connected to the n second combiners / shunts; and all the radio-frequency switches are independently controlled by a controller. The invention combines a radio-frequency switching technology, an optical fiber subcarrier multiplexing (SCM) technology and an optical fiber radio technology, and realizes the distribution, the switching and the optical fiber distribution of WiFi radio-frequency signals.

The present invention discloses a method, system and optical line terminal of WDM-PON for realizing multicast service. The method comprises the following steps: the optical line terminal copies a multicast group data according to demand massage of the multicast group from each optical network unit, and conducts subcarrier multiplexing to the multicast group data and downlink unicast data which are then modulated to optical signals with different wavelength, and then compounds the optical signals with different wavelength into a downlink mixed optical signals; an optical fiber distributive network routes respectively the optical signals with different wavelength in the downlink mixed optical signals to optical network units with relevant wavelength, and the multicast group data and / downlink unicast data in the downlink optical signals with relevant wavelength is restored by each optical network unit. The invention provides a method that the multicast group data and the unicast data are mixed to be transported to ONU, which improves the bandwidth utilization rate of single wavelength, ensures QoS of the multicast and unicast in a better manner, which is good for the popularization of IPTV.

The invention relates to a method and apparatus for performing unlink and downlink data transmission on an optical line terminal (OLT) and a remote radio unit (RRU) in a front backhaul network. The method for transmitting downlink data on the OLT comprises steps of: A, receiving multiple sets of baseband vector signals transmitted from a baseband unit pool; B, modulating the sets of baseband vector signals to intermediate frequency subcarrier sets, and acquiring intermediate frequency signal sets corresponding to the RRU by means of subcarrier multiplexing; C, modulating the intermediate frequency signal sets onto carriers with various wave lengths on an optical wave by means of wavelength division multiplexing in order to acquire an optical wave carrying signals with various wave lengths; and D, guiding the optical wave to a transmission link. The method solves a bandwidth bottleneck in a MFH transmission process based on a CPRI protocol in the prior art, and contributes to multi-antenna MFH transmission in a conventional 4G LTE network or a B4G / 5G network in the future.

A multiplexing technique for optical communications used to create a pseudo-random communications signal in the optical domain such that only the sender and / or receiver can decode the signal. The multiplexing technique may include one or more information-bearing optical signals combined with one or more dynamic pseudo-randomly-generated optical signals to create a combined dynamic subcarrier multiplexed privacy-protected output signal. The information-bearing signal is protocol-independent and can be of mixed type, such as RF, analog, and / or digital. Only the receiver of the privacy-protected signal may decode the pseudo-random signal so as to disclose the information-bearing signal. The present invention may use dynamic subcarrier multiplexing selection based on standard digital encryption and the use of optical range time to ensure synchronization.

Systems and methods for reducing variance in reach of wavelength division multiplexed (WDM) channels in optical transport networks may include selecting, for each channel assigned to a respective wavelength, an initial modulation format and an initial distribution of constellation points in the complex plane, determining a target reach for all WDM channels that is achievable by higher wavelength channels but not by shorter wavelength channels, and applying one or more reach extension techniques to at least one shorter wavelength channel but not to the higher wavelength channels. The reach extension techniques may include probabilistic constellation shaping, symbol rate optimized subcarrier multiplexing, or a combination of the two. Transponders may be configurable to transmit or receive traffic over the WDM channels with or without implementing the reach extension techniques, as applicable.

The invention provides an optical signal-to-noise ratio (OSNR) test method. The method includes: determining the number of subcarriers in multi-subcarrier multiplexing super channels and measuring central wavelength and effective bandwidth of the subcarriers; subjecting each subcarrier to OSNR measurement which includes that the OSNR of the subcarrier is measured in the effective bandwidth at the central wavelength location, and the effective bandwidth is the effective bandwidth acquired during performing the effective bandwidth measurement on the subcarrier; acquiring the multi-subcarrier multiplexing super channels according to the OSNRs of the subcarriers and the number of the subcarriers acquired in measurement. On the basis of the method, the invention further provides an OSNR test device. By the method and the device, the reliable OSNRs of the multi-subcarrier multiplexing super channels can be acquired.

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.

Provided are a fault localization apparatus based on an optical communication network and a method thereof. In the fault localization apparatus according to the present invention, a downstream light source is used as a monitoring optical signal instead of using an additional monitoring light source and a subcarrier multiplexing (SCM) monitoring pulse signal of a certain frequency band having no interference with a frequency band of a downstream data signal is used and thus a fault position may be detected at low cost.

The invention discloses a resource allocation method of a multi-carrier NOMA systemmulti-carrier NOMA (Non-Orthogonal Multiple Access) system. Under the condition of ensuring the minimum data rate under the constraint of the service quality of users accessed by all systems and the limitation of the total transmitting power of a base station, a mathematical optimization problem taking maximization of the system sum rate as a target is constructed, and an original non-convex problem is split into two main convex sub-problems to be solved respectively. On one hand, a two-step bilateral matching algorithm is provided for scheduling of the users and the subcarriers, and scheduling and matching of the users and the subcarriers in the system can be quickly and effectively completed under the condition that the system performance is guaranteed. on the other hand, for the power distribution problem in the system, on the premise of ensuring that a receiving end can successfully execute a continuous serial interference cancellation (SIC) technology, a closed-form solution of power distribution between subcarrier multiplexing users is deduced, and water injection distribution of residual increment power between subcarriers is completed on the basis of the closed-form solution. According to the method provided by the invention, the throughput performance of the system is remarkably improved.

The invention discloses a method for processing a signal, a junction station, a base station and a network system thereof. The method comprises the following steps: a subcarrier signal carrying communication data is subject to multiplexing processing; and the multiplexed subcarrier signal is transmitted, wherein the multiplexing processing comprises single subcarrier multiplexing, combination of subcarrier multiplexing and optical wavelength-division multiplexing, and combination of subcarrier multiplexing and optical add drop multiplexing. Only down link carrier wave is multiplexed during optical wavelength-division multiplexing; or, down link carrier wave and up link carrier wave can be simultaneously multiplexed. Through the embodiment of the invention, optical fiber wireless system capacity can be improved.

A method and structure for compensation techniques in coherent optical receivers. The present invention provides a coherent optical receiver with an improved 8×8 adaptive MIMO (Multiple Input, Multiple Output) equalizer configured within a digital signal processor (DSP) to compensate the effects of transmitter I / Q skew in subcarrier multiplexing (SCM) schemes. The 8×8 MIMO equalizer can be configured such that each of the 8 outputs is electrically coupled to 3 of 8 inputs, wherein each of the input-output couplings is configured as a filter. The method includes compensating for impairments to the digital conversion of an optical input signal via the 8×8 MIMO equalizer following other signal processing steps, such as chromatic dispersion (CD) / polarization-mode dispersion (PMD) compensation, carrier recovery, timing synchronization, and cycle slip correction.

The invention relates to a device and a system for simultaneously generating wired and wireless signals by adopting a dual-polarization MZM modulator, the device is used for generating mixed optical signals containing QPSK (Quadrature Phase Shift Keying) signal I-path data, QPSK signal Q-path data and OOK (On-Off Keying) data signals, and comprises a millimeter wave carrier generation module; an I / Q mixer which is used for generating a QPSK millimeter wave signal; a dual-polarization MZM modulator which generates a wireless millimeter wave signal in a QPSK modulation format and a wired baseband signal in an OOK modulation format at the same time by adopting an optical subcarrier multiplexing technology to form a double-sideband optical signal; an optical amplifier which is used for amplifying the double-sideband optical signal; and an optical filter which is used for converting the amplified double-sideband optical signal into a finally output mixed optical signal. Compared with the prior art, the device has the advantages of high reliability, high stability, low cost, simple structure, easiness in implementation and the like.

The invention discloses a system and method for fast realizing 400G subcarrier multiplexing, and relates to the field of subcarrier multiplexing in optical communication. The system comprises an OTU (optical transform unit), an OSA (optical spectrum analyzer) and an FWSS, wherein when the system realizes 400G subcarrier multiplexing, firstly, the wavelength frequency of the 100Gbit / s speed PM-QPSK (polarization-multiplexed quadrature phase shift keying) subcarriers on four output ports are respectively set on the OUT, and the wavelength intervals of the adjacent subcarriers are set according to the wavelength frequency; then, the wave channel intervals identical to the wavelength intervals of the subcarriers are set on the FWSS, the subcarriers on the four output ports are respectively configured to the corresponding frequency input ports, the FWSS carries out optical filtering on the four subcarriers, and four-carrier PM-QPSK 400Gbit / s speed optical signals are obtained through wave combining multiplexing. The system and the method have the advantages that the realization is more convenient, the performance is better, in addition, the crosstalk between the adjacent subcarriers can be reduced, and the frequency spectrum efficiency is improved.

The invention discloses a terahertz wireless communication system which comprises a transmitting device and a receiving device. The transmitting device comprises a transmitting baseband processing module which is used for processing received multi-channel user data so as to generate a subcarrier multiplexing signal; a central station module which is used for modulating the subcarrier multiplexing signal on a first optical carrier with a first frequency to generate an optical signal; and a base station module which is used for performing beat frequency processing on the optical signal to generate a photon terahertz signal with a preset frequency. The receiving device comprises a terminal receiving module which is used for receiving the terahertz signal and carrying out frequency mixing processing and power compensation on the terahertz signal to obtain an intermediate frequency signal with a third frequency; and a receiving baseband processing module which is used for performing down-conversion processing on the intermediate frequency signal in a digital frequency domain to obtain a baseband signal, and then de-multiplexing the baseband signal into each path of independent and parallel user signal. The terahertz wireless communication system has a relatively high communication transmission rate.

The invention discloses a frequency offset processing method and system for a digital subcarrier multiplexing signal, and relates to the technical field of optical fiber communication. The method comprises the following steps: setting a frequency offset estimation range, selecting a plurality of test frequencies in the frequency offset estimation range, and carrying out the test frequency offset compensation of an initial SCM signal through each test frequency, independently calculating the signal average power of the low-frequency SCM signal in each frequency offset compensation SCM signal, obtaining a frequency offset estimation value according to the signal average power, and outputting the frequency offset compensation SCM signal corresponding to the frequency offset estimation value; according to the invention, the frequency offset compensation can be estimated before the dispersion compensation, the transmission performance of the system and the complexity of the dispersion compensation are not influenced, the spectrum efficiency of the SCM system is not sacrificed, and the modulation format is transparent.

The present invention discloses a method, system and optical line terminal of WDM-PON for realizing multicast service. The method comprises the following steps: the optical line terminal copies a multicast group data according to demand massage of the multicast group from each optical network unit, and conducts subcarrier multiplexing to the multicast group data and downlink unicast data which are then modulated to optical signals with different wavelength, and then compounds the optical signals with different wavelength into a downlink mixed optical signals; an optical fiber distributive network routes respectively the optical signals with different wavelength in the downlink mixed optical signals to optical network units with relevant wavelength, and the multicast group data and / downlink unicast data in the downlink optical signals with relevant wavelength is restored by each optical network unit. The invention provides a method that the multicast group data and the unicast data are mixed to be transported to ONU, which improves the bandwidth utilization rate of single wavelength, ensures QoS of the multicast and unicast in a better manner, which is good for the popularization of IPTV.

The present invention provides a subcarrier multiplexing optical network uplink transmission system based on filter multi-carrier modulation, which includes a sequentially connected access control module, a filter-based multi-carrier modulation module, a subcarrier modulation module, a multiplexing module, and a feeder Type optical fiber, optical amplifier, demultiplexing module, photodetector, subcarrier demodulation module, uplink data receiving module. In the present invention, the data generated by the access control module is modulated by a filter-based multi-carrier modulation method, and the modulated user data is modulated to different optical sub-carriers by using the radio frequency sub-carrier modulation of the optical carrier for transmission. The data of the unit is multiplexed to the upstream fiber channel. The present invention utilizes filter-based multi-carrier modulation technology combined with sub-carrier multiplexing technology to make efficient use of uplink spectrum resources, and at the same time has good performance against inter-symbol interference and inter-subcarrier interference between uplink users, thereby supporting Higher transmission rate and spectral efficiency.

The invention discloses a passive optical network architecture and an inter-ONU communication method based on the architecture, in the architecture, an OLT is connected with a plurality of ODNs, the communication method supports mutual communication between different ONUs under the control of the same CO without passing through the CO, in the communication method, the ONUs generate an uplink data frame containing uplink user data and target ODN address signaling, and the uplink data frame is used for sending the uplink user data and the target ODN address signaling to the OLT. The method comprises the following steps of: receiving uplink data by an OLT (Optical Line Terminal), modulating the uplink data to a pre-allocated subcarrier of a system by adopting a frequency division multiplexing technology based on subcarrier multiplexing, distributing downlink wavelength for the data according to address signaling information in the uplink data after the OLT receives the uplink data, and issuing the downlink wavelength to a target ODN (Optical Distribution Network) connected with the OLT, so that the data transmission of each user is only performed between the OLT and an ONU (Optical Network Unit), and the data transmission efficiency is improved. According to the invention, the CO is only responsible for sending the communication authority control instruction and controlling the downlink communication of the OLT, and does not process the uplink ONU data, thereby reducing the occupation of the storage space of the CO caused by the data between the ONUs under the control of the same CO entering the CO, and enabling the CO to meet the requirements of more cross-CO ONU communication.

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.