Abstract: A forward optical intensity modulation signal, generated by optical intensity-modulating a laser signal using a forward microwave phase modulation signal, is transmitted from a base to a remote station. A backward microwave phase modulation signal, in which frequency of the forward microwave phase modulation signal is changed by demodulating the forward optical intensity modulation signal, is generated, and a backward optical intensity modulation signal, generated by optical intensity-modulating the laser signal using the backward microwave phase modulation signal, is transmitted from the remote station to the base. The backward microwave phase modulation signal is extracted by photoelectric converting the backward optical intensity modulation signal, a round trip timing is extracted by demodulating the backward microwave phase modulation signal, and transmission delay is determined from a difference between the timing and the round trip timing.

Abstract: A quantum communication system comprising: an transmitter and a receiver, the transmitter comprising transmitter components the transmitter components comprising a source of pulsed radiation and a modulation unit, the modulation unit being configured to randomly encode pulses of radiation; and a receiver comprising receiver components, the receiver components comprising a demodulator and detector configured to decode and detect said randomly encoded pulses, the system further comprising a control unit and an optimisation unit, the control unit being configured to apply a plurality of control signals defined by a set of control parameters to at least one of said transmitter components and receiver components, the optimization unit being configured to tune the set of control parameters, wherein the optimisation unit sets the control parameters by: obtaining a score indicating the quality of the system corresponding to a first set of control parameters; and estimating a further set of control parameters suita

Abstract: A photoelectric conversion apparatus includes a pixel including a photoelectric conversion circuit configured to output a signal corresponding to photon incidence. The photoelectric conversion apparatus further includes a first measurement circuit, a second measurement circuit, a selection circuit, and an output circuit. The first measurement circuit is configured to measure the signal output from the pixel. The second measurement circuit is configured to measure a time from when the first measurement circuit starts measuring the signal to when a measured value of the first measurement circuit reaches a first threshold value. The selection circuit is configured to switch a first measurement circuit to be connected to the second measurement circuit among a plurality of the first measurement circuits. The output circuit is configured to output a value of the measured time of the second measurement circuit.

Abstract: A system, comprising an optical transmitter including a memory and one or more processors, wherein the one or more processors are in communication with the memory and configured to perform creating a first signal and a second signal, wherein the first signal and the second signal are each polarized; rotating a polarization of the first signal and the second signal by ? degrees; adding a differential group delay (DGD) to the second optical signal; generating a first optical signal from the first signal; and generating a second optical signal from the second signal.

Abstract: The disclosure provides a binary iterative clock synchronization system based on polarization entanglement GHZ state comprising a first synchronization party, a second synchronization party and an emitting party; the first synchronization party is connected with the second synchronization party through a classical channel, the emitting party is connected with the first synchronization party through a quantum channel, and the emitting party is connected with the second synchronization party through a quantum channel and a classical channel; the emitting party realizes the preparation of three-photon polarization entangled GHZ states and measures one of the photon polarization states; the first synchronization party and the second synchronization party perform measurement on the polarization states of the other two photons, and the second synchronization party and the emitting party compare the measurement results to obtain the measurement sequence information between the first synchronization party and the sec

Abstract: Techniques to secure a time sensitive network are described. An apparatus may establish a data stream between a first device and a second device in a network domain, the network domain includes a plurality of switching nodes, receive messages from the first device by the second device in the network domain, the messages to comprise time information to synchronize a first clock for the first device and a second clock for the second device to a network time for the network domain, update a correction field for a received message with a residence time and time delay value by the second device, determine whether the updated message is benign or malicious, update the correction field for the updated message with an inference time when the updated message is benign, and prevent relay of the updated message to other devices in the network domain when the updated message is malicious.

Abstract: Provided are a state transition method and apparatus, a device, and a storage medium. The method comprises: an optical network unit verifies a received physical synchronization sequence field, and transitions the current state according to a verification result. As such, the probability of downstream synchronization detection can be effectively improved, and the probability of missed downstream synchronization detection can be reduced, thereby ensuring the normal operation of a PON system.

Abstract: A system includes a first photonic integrated circuit. The circuit includes a qubit encoder configured to receive a spatial-mode qubit and convert the spatial-mode qubit to a temporal-mode qubit and an optical interconnect configured to receive and transmit the temporal-mode qubit. The system further includes a second photonic integrated circuit, itself including a qubit decoder configured to receive the temporal-mode qubit and convert the temporal-mode qubit back into the spatial-mode qubit.

Abstract: A data processing method and a device, the method including determining, by an optical network unit, in a received data stream, after the optical network unit enters a pre-synchronization state, a position of a forward error correction (FEC) codeword boundary in the data stream based on a position of a physical synchronization sequence (Psync) field, performing an FEC codeword decoding check, where the Psync field is a field that matches a preset Psync, in the data stream, and entering, by the optical network unit, a synchronization state in response to an FEC codeword among N consecutive FEC codewords in the data stream passing the decoding check, where N is an integer greater than or equal to 1.

Abstract: A method includes: determining a first material and a second material of a photonic waveguide for propagating light, the photonic waveguide having a first section and a second section arranged in a first layer and a second layer, respectively, of the photonic waveguide; determining a spacing between the first layer and the second layer; determining a parameter set of a crosstalk reduction structure, according to the spacing, the first material and a wavelength of the light, to cause insertion losses of the first section and the second section to be lower than a predetermined threshold; and forming the first and second sections with the first and second materials, respectively, the first section having the crosstalk reduction structure overlapping the second section.

Abstract: A method for estimating a chromatic dispersion of an optical-fiber channel is disclosed includes receiving, via the optical-fiber channel, a chromatically-dispersed signal having a symbol rate 1/T. The method also includes, for each chromatic-dispersion value of a plurality of chromatic-dispersion values, determining a respective clock-tone magnitude by: (i) applying, to the chromatically-dispersed signal or a signal derived therefrom, a chromatic dispersion equal to the chromatic-dispersion value to generate a dispersion-compensated signal, and (ii) extracting the clock-tone magnitude from at least one of a positive-frequency clock-tone and a negative-frequency clock-tone of the dispersion-compensated signal, the positive-frequency clock-tone and the negative-frequency clock-tone being spectral components of the dispersion-compensated signal at temporal frequencies 1/T or ?1/T respectively. The method also includes determining a maximum of the extracted clock-tone magnitudes.

Abstract: Optical circuits support reconfigurable spatial rearrangement (also referred to as “spatial multiplexing”) for a group of photons propagating in waveguides. According to some embodiments, a set of 2×2 muxes can be used to rearrange a pattern of photons on a first set of waveguides into a usable input pattern for a downstream optical circuit.

Abstract: An isolation amplifier of an embodiment includes: a primary circuit including an encoder configured to encode an input signal and output the encoded input signal and an anomaly detection circuit configured to detect anomaly having occurred to the input signal and generate a detection signal; an isolation unit configured to insulate the primary circuit from a secondary circuit; an output circuit configured to generate an output signal corresponding to the input signal; and an anomaly-input sensing-output circuit configured to generate an output signal from the secondary circuit by changing the output signal from the output circuit based on the detection signal.

Abstract: A time synchronization device focuses on a possibility of multiplexing a plurality of PTP domains on a transmission line with the same PTP and derives one time based on time information from a plurality of PTP domains. The time synchronization device includes PTP slave units belonging to corresponding PTP domains different from each other and configured to synchronize with times of the corresponding PTP domains, and a time integration unit 12 configured to use time information that is a time after the PTP slave unit synchronizes with the time of a master device belonging to the corresponding PTP domain and synchronization accuracy information that is an accuracy of synchronization of the PTP slave unit with the time of the master device to generate one integrated time.

Abstract: A tunable multi-mode laser is configured to generate a multi-mode optical signal at a tuned wavelength. The laser includes a semiconductor optical gain region, a feedback region, and a phase modulation region between the gain and feedback regions. Each of the regions may be monolithically integrated. A feedback loop is coupled to the tunable laser to receive the optical signal and includes at least one delay line. The delay line may also be monolithically integrated. An output of the delay line is fed back to the tunable multi-mode laser in order to provide at least one of self-injection locking and self-phase locked looping for the multi-mode tunable laser. Each of the optical gain region and phase modulation region of the laser is biased by the output of the delay line in order to reduce phase drift of the optical signal.

Abstract: A system comprises an internal optical switch, couplable to a plurality of fibers, configured to automatically select fibers in succession from the plurality of fibers for testing. An optical test module, coupled to the internal optical switch, is configured to generate or receive one or more wavelengths of light on each selected fiber of the plurality of fibers. A communications interface, coupled to the internal optical switch and the optical test module, is configured to establish a communications link between the system and a second system to test each selected fiber.

Abstract: Methods and apparatus for detecting alignment markers in received data streams received via a plurality of data lanes are disclosed. Corresponding data streams may be received via respective data lanes in the plurality of data lanes, where each data stream includes alignment markers delineating data frames, and each alignment marker has a predefined bit pattern. For each respective data lane, a determination is made whether a specified portion of the received data stream has at least a threshold degree of similarity with a portion of the predefined bit pattern. In response to determining, for one of the plurality of data lanes, that the specified portion has at least the threshold degree of similarity, a frame boundary may be determined based on the specified portion, and a verification may be performed, that the specified portion of the received data stream corresponds to an alignment marker.

Abstract: An optical frequency transfer device based on passive phase compensation and a transfer method are provided, where the device comprises a local side, a transfer link and a user side. Optical frequency transfer based on passive phase compensation is achieved by simple optical frequency mixing, microwave filtration, and frequency division processing in a passive phase compensation manner, and the device has simple system structure and high reliability.

Abstract: A method for processing low-rate service data, an apparatus, and a system, where the method includes: mapping low-rate service data into a newly defined low-rate data frame, where a rate of the low-rate data frame matches a rate of the low-rate service data, the data frame includes an overhead area and a payload area, the payload area is used to carry the low-rate service data, a rate of the payload area in the low-rate data frame is not less than the rate of the low-rate service data, and the rate of the low-rate service data is less than 1 Gbps; mapping the low-rate data frame into one or more slots in another data frame, where a rate of the slot is not greater than 100 Mbps; mapping the other data frame into an optical transport unit (OTU) frame; and sending the OTU frame.

Abstract: A system comprises a transmitter that generates a combined signal including a first group of optical signals and a second group of optical signals, the first group of optical signals comprising M+X number of optical signals in a first polarization mode, the second group of optical signals comprising N number of optical signals in a second polarization mode, wherein the number of N and M optical signals comprise payload signals, where the X number of optical signals comprises at least one first pilot signal. The system may further include a receiver comprising a polarization recovery device that receives the combined signal and that recovers, from the combined signal, the first group of optical signals with the first polarization mode and the second group optical signals with the second polarization mode based on feedback indicative of at least one signal characteristic of the at least one first pilot signal.

Abstract: An optical network receiver (ONU) circuit associated with a passive optical network (PON) is disclosed. The ONU circuit comprises one or more processors is configured to operate in a hunt state, wherein the one or more processors is configured to detect frame boundaries associated with an incoming data signal based on a detecting a predefined synchronization (psync) pattern associated with the incoming data signal and transition to a pre-sync state, when the predefined psync pattern is detected correctly. The one or more processors is further configured to operate in the pre-sync state, wherein the one or more processors is configured to perform forward error correction (FEC) decoding for the incoming data signal, in order to determine signal statistics associated with the incoming data signal.

Abstract: Processing signals is disclosed. A method includes receiving a signal transmission with a nb/mb encoding scheme that maps n-bit words to m-bit symbols. In this scheme, m>n. The method further includes, for a first payload data word in the transmission, determining that the first payload data word corresponds to a valid payload data word, and as a result, assigning a first reliability metric to bits in the first payload data word. The method further includes for a second payload data word in the transmission, determining that the second payload data word does not correspond to a valid payload data word, and as a result, assigning a second reliability metric to bits in the second payload data word. The method further includes performing signal decoding using the assigned reliability metrics.

Abstract: Power saving is achieved in an optical wireless communication (VLC/LiFi) system by using a polling-based medium access control (MAC) scheme, wherein an access point can use a silent period when no one is polled (and EPs can thus sleep). When transmission queues are empty, the access point may apply the silent period which may be based on a minimum polling interval announced by broadcast.

Abstract: Methods and apparatuses for mapping processing and de-mapping processing in an optical transport network are provided. A Low Order Optical Channel Data Unit (LO ODU) signal is mapped into a payload area of an Optical Channel Data Tributary (ODTU) signal in units of M bytes. M is equal to the number of time slots of a High Order Optical Channel Payload Unit (HO OPU) that are to be occupied by the ODTU signal, and M is an integer larger than 1. Overhead information is encapsulated to an overhead area of the ODTU signal. Thereafter, the ODTU signal is multiplexed into the HO OPU. According to the application, an efficient and universal mode for mapping the LO ODU to the HO OPU is provided.

Abstract: A transceiver circuit includes a counter device, a compensation circuit and an adjusting circuit. The counter device is configured to count an execution time of a reception operation and accordingly generate a counting result. The compensation circuit is coupled to the counter device and configured to receive the counting result, determine a plurality of compensation values according to the counting result and sequentially output the compensation values in a transmission operation. The transmission operation follows the reception operation. The adjusting circuit is coupled to the compensation circuit, and configured to receive the compensation values and sequentially adjust amplitude of a signal according to the compensation values in the transmission operation. The compensation values are respectively applied to different portions of the signal.

Abstract: A coordination node can be configured to control communications between Visible Light Communication, VLC, Access Points, APs, and user equipments, UEs. The coordination node can: identify occurrence of an event relating to operation of a first VLC AP; determine that a second VLC AP and a third VLC AP each have communication coverage areas that are at least partially within a communication coverage area of the first VLC AP; control the second VLC AP to avoid it interfering with communications between the first VLC AP and a UE while it is within a common communication coverage area of the first VLC AP and the second VLC AP; and control the third VLC AP to avoid it interfering with communications between the first VLC AP and the UE while it is within a common communication coverage area of the first VLC AP and the second VLC AP.

Abstract: A device determines a first latency value of a first data flow from a first physical port of the device to a second physical port of the device and a second latency value of a second data flow from the second physical port to the first physical port, where the first latency value is less than the second latency value. The device determines a first target latency value based on the first latency value and the second latency value. The device adjusts a latency value of the first data flow to the first target latency value.

Abstract: Systems and methods for providing dispersion compensation to optical systems. In some embodiments, the disclosed dispersion compensation system may be capable of adjusting the amount of dispersion compensation. The disclosed dispersion compensation system may include a cascade of varactor circuit elements, each with separate bias control, and optionally may include one or more switches to enable or disable selective ones of the cascaded varactor circuit elements.

Abstract: A flight direction indication system for an aerial vehicle having a plurality of rotors includes: for each of the plurality of rotors, at least one rotor blade having a plurality of light sources arranged along a radial extension of the rotor blade; and a control unit, coupled to the plurality of light sources of the rotor blades of the plurality of rotors. The control unit is configured to effect a coordinated control of the plurality of light sources of the rotor blades of the plurality of rotors, with the coordinated control yielding an image or a sequence of images across the plurality of rotors to an observer of the aerial vehicle and to to control the plurality of light sources of the rotor blades of the plurality of rotors on the basis of a momentary flight direction of the aerial vehicle.

Abstract: A time synchronization system includes a master station (100) and slave stations (200) communicably connected to the master station (100). The master station (100) includes a contention determiner (114) and a time synchronization frame processing unit (113). The contention determiner (114) determines, based on receipt timings of a plurality of first time synchronization frames transmitted from the respective slave stations (200), whether the plurality of first time synchronization frames have a possibility of contention over relay processing. The time synchronization frame processing unit (113) discards, when the contention determiner (114) determines that the plurality of first time synchronization frames have the possibility of the contention, out of first time synchronization frames that have a possibility of mutual contention, a first time synchronization frame received later.

Abstract: A function of detecting an unused path through which actual data is not transmitted in a long-distance redundant network is realized at low cost. In an optical transmission system 20, each of the optical transceivers 21a and 21b that are connected to each other by an optical fiber cable 22 and disposed separately includes a protocol IC unit 35. The protocol IC unit 35 transmits an idle signal A1 with empty data using an optical signal P1 to an unused path of the optical fiber cable 22. At the time of this transmission, the protocol IC unit 35 outputs, to the transmission unit 33, a control signal C1 for performing, at a fixed modulation period, ON/OFF modulation on the optical signal P1 on which the idle signal A1 is superimposed. Also, the protocol IC unit 35 transmits an OAM signal O1 at an OAM period that is a period different from a modulation period, and performs control to turn ON the control signal C1 at the time of this transmission.

Abstract: An optical transmission device includes: a first receiver circuit, a second receiver circuit, a switch circuit, a terminator circuit, a packet buffer, a clock generator, and a signal generator. The first receiver circuit converts an optical signal received via a first route into a first electric signal. The second receiver circuit converts an optical signal received via a second route into a second electric signal. The switch circuit selects the first electric signal or the second electric signal. The terminator circuit extracts a packet from an electric signal selected by the switch circuit. The packet buffer stores the packet extracted by the terminator circuit. The clock generator generates a clock signal. The signal generator generates a continuous signal that includes the packet stored in the packet buffer by using the clock signal.

Abstract: Devices, systems and methods for encoding information using optical components are described. Information associated with a first optical signal (e.g., an optical pump) is encoded onto the phase of a second optical signal (e.g., an optical probe) using cross phase modulation (XPM) in a non-linear optical medium. The optical signals are multiplexed together into the nonlinear optical medium. The probe experiences a modified index of refraction as it propagates through the medium and thus accumulates a phase change proportional to the intensity of the pump. The disclosed devices can be incorporated into larger components and systems for various applications such as scientific diagnostics, radar, remote sensing, wireless communications, and quantum computing that can benefit from encoding and generation of low noise, high resolution signals.

Abstract: Aspects of the technology include establishing a primary communication link between a communication system of a first balloon and a communication system of a second balloon, detecting a movement of the second balloon relative to the first balloon that is expected to cause the primary communication link to become unavailable at a given time during the movement, establishing an RF communication link between an RF communication system of the first balloon and an RF communication system of the second balloon, detecting that the movement of the second balloon relative to the first balloon is such that the primary communication link between the communication system of the first balloon and the optical communication system of the second balloon can be re-established, and re-establishing the primary communication link between the communication system of the first balloon and the communication system of the second balloon.

Abstract: A method of correcting gravity-induced error in quantum cryptography system, which is capable of improving accuracy when an optical cable is not installed and photons are transmitted through an artificial satellite, is disclosed. The method performed by an electronic device, comprises receiving a distance (r) to a satellite that receives polarized photon from a sender and transmits the polarized photon to a receiver, receiving an angular momentum per unit mass of the satellite (lobs), and calculating a rotation amount of the polarized photon, which is induced by a warp of space due to gravity by using the distance to the satellite and the angular momentum per unit mass of the satellite (lobs). The rotation 2? of the polarized photon is calculated by the following equation, sin ? ? ? ? ( r ) ? - l obs rr s ? 1 - r s r , wherein ‘rs’ is the Schwarzschild radius of the Earth.

Abstract: A configurable wide area distributed antenna system is provided. At least one remote master unit of the system is in communication with at least one base station. The remote master unit includes a remote switch function that provides at least multiplexing in a downlink direction, demultiplexing in an uplink direction and routing of digital samples. The local master unit is located remote from the remote master unit. The local master unit is in communication with at least one remote antenna unit used to provide communication coverage in a select coverage area. The local master unit includes a local switch function providing at least demultiplexing in a downlink direction, multiplexing in an uplink direction and routing of digital samples. At least one communication link communicatively couples the remote master unit to the local communication unit with transport media interfaces.

Abstract: The disclosed system implements a bandwidth-reconfigurable optical interconnect, which couples optical signals between N interconnect inputs and N interconnect outputs. The system includes an arrayed waveguide grating router (AWGR), which provides cyclic, single-wavelength, all-to-all routing between N AWGR inputs and N AWGR outputs. The system also includes a wavelength-insensitive switch, which provides all-wavelength, all-to-all connectivity between N wavelength-insensitive inputs and N wavelength-insensitive outputs. The system additionally includes a wavelength-selective input switch, which selectively directs up to L wavelengths from each of the N interconnect inputs into a corresponding input of the wavelength-insensitive switch, wherein unselected wavelengths from each of the N interconnect inputs pass into a corresponding AWGR input.

Abstract: A node can include a clock; and mapper circuitry configured to determine a timestamp from the clock, and transmit the timestamp to a second node in a Radio over Ethernet (RoE) frame with the timestamp in a control subtype and with an operational code (opcode) that designates the timestamp is in the frame. The node can also include a demapper circuit configured to receive a second timestamp from the second node in a second RoE frame, and provide the second timestamp to a Differential Clock Recovery (DCR) circuit for adjustment of the clock to a second clock at the second node.

Abstract: A local device of a time synchronization system includes a path switching unit that connects respective remote devices using individual optical fibers and switches the respective optical fibers sequentially in a cyclic order, a counter unit, a phase difference memory unit, and a table unit. The counter unit counts a pulse signal P1d demodulated by a PPS demodulation unit to obtain a count value. The phase difference memory unit stores the count value as path information in association with a phase difference detected by a phase detection unit, and outputs the phase difference associated with this path information indicated by the count value to the variable delay unit. When the count value is input, the table unit outputs a path switching signal for switching to the next optical fiber in the cyclic order to the path switching unit and the path switching unit performs switching to the next optical fiber.

Abstract: In general, various aspects of the techniques described in this disclosure provide time synchronization for encrypted traffic in a computer network. In one example, the disclosure describes an apparatus, such as a network device, having a control unit for a network device in a computerized network having a topology of network devices; and a forwarding unit operative to determine a release time for sending a synchronization packet in accordance with a time synchronization protocol; modify the synchronization packet to include a release timestamp specifying the release time; sending a time value via sideband data associated with the synchronization packet, wherein the time value is based on the release time specified by the release timestamp; and schedule transmission of the synchronization packet for a time corresponding to the time value in the sideband data, the synchronization packet to be transmitted to a destination network device.

Abstract: Disclosed in some examples, are optical devices, systems, and machine-readable mediums that send and receive multiple streams of data across a same optical communication path (e.g., a same fiber optic fiber) with a same wavelength using different light sources transmitting at different power levels—thereby increasing the bandwidth of each optical communication path. Each light source corresponding to each stream transmits at a same frequency and on the same optical communication path using a different power level. The receiver differentiates the data for each stream by applying one or more detection models to the photon counts observed at the receiver to determine likely bit assignments for each stream.

Abstract: A method of combining optical signals from a plurality of optical fibers into a single optical signal includes receiving, at corresponding optical-signal receivers optically coupled to corresponding trunk fibers, respective optical signals. The method further includes determining, by the corresponding optical-signal receivers, when each respective optical signal is received. When the respective optical signal is received, the method includes performing the following steps: converting, by the corresponding optical-signal receiver, the respective optical signal to a corresponding electrical signal; transmitting, by the corresponding optical-signal receiver, the corresponding electrical signal to a corresponding input channel of an electrical-multiplexing device; and configuring the electrical-multiplexing device to select the corresponding input channel.

Abstract: A method of measuring lengths of optical fibers on forward and return paths is provided in order to synchronize clocks of optical nodes connected by asymmetrical optical fiber paths. The method includes calculating, by a first optical network device, a first propagation delay of a first optical signal transmitted at a first wavelength on a first optical fiber to the first optical network device from a second optical network device and a second propagation delay of a second optical signal transmitted at a second wavelength on the first optical fiber to the first optical network device from the second optical network device. The second wavelength is different from the first wavelength. The method further includes determining, by the first optical network device, a first length of the first optical fiber based on the first propagation delay and the second propagation delay.

Abstract: A method for removing static differential delays resulting from an independent transport of the client signals of a client signal bundle through an optical transport network, OTN, which comprises OTN mappers mapping received client signals to ODU signals transported to OTN demappers demapping received ODU signals to client signals, wherein a process slave, PS, at the OTN mapper end of said OTN network supplies continuously or in response to a received request information about timing relations between the client signals of said client signal bundle to a process master, PM, at the OTN demapper end of said OTN network used by the process master, PM, to remove the static differential delays between the client signals of the respective client signal bundle.

Abstract: A parallel-processing apparatus has information-processing apparatuses coupled mutually through an optical transmission line having channels. Each of the information-processing apparatuses has processors allocated to the channels of the optical transmission line, a controller and a display. When one of the processors detects a channel failure, the processor notifies a processor in the other information-processing apparatus of the channel failure, notifies the controller of the information-processing apparatus of the channel failure and notifies the controller of the information-processing apparatus of the notification of the channel failure from the other information-processing apparatus.

Abstract: Embodiments for accurately performing time of flight estimations are provided. These embodiments include using a first wireless device to monitor a wireless link and subsequently generate a wireless link estimation based on the monitoring. The embodiments also include deriving a correction metric based on the generated wireless link estimation and transmitting the correction metric from the first wireless device to a second wireless device. The second wireless device may then calculate a time of arrival of a first signal received from the first wireless communication device and correct any errors associated with the time of arrival calculation using the received correction metric. Further, the second wireless device may transmit the corrected time of arrival back to the first wireless device, such that the first wireless device can use the corrected time of arrival to estimate the time of flight of the first signal.

Abstract: According to an embodiment, a transmission device is for a second quantum communication system sharing a quantum communication channel with a first quantum communication system, and includes a generator, a modulator, a controller, and a changer. The generator is configured to generate a photon. The modulator is configured to transmit a quantum signal generated by modulating the photon to a reception device. The controller is configured to control the generator and the modulator. The changer is configured to input, to the controller, control signals for changing an operation timing of the generator and an operation timing of the modulator when an error rate of the quantum signal of the first quantum communication system and an error rate of the quantum signal of the second quantum communication system are equal to or higher than a predetermined threshold.

Abstract: A correlation processor derives a correlation value indicating correlation between each of a plurality of reference signals produced by extracting symbols from the synchronization signal of each pattern at a predetermined interval and a received signal. A controller compares the correlation value for each pattern and for each sample derived by the correlation processor with a threshold value and, when at least one correlation value is larger than the threshold value, changes symbols extracted to produce respective reference signals before causing the correlation processor to perform the same process, incorporating the received signal newly acquired. A first selector selects one of the plurality of patterns when all symbols of the synchronization signal have been extracted to produce the reference signals and at least one correlation value is larger than the threshold value.

Abstract: Provided are an optical transceiver, an optical transmitter IC, and an optical receiver IC, which can be applied to both a case of coding an optical signal and a case of decoding an optical signal, and can suppress an influence of waveform degradation with an inexpensive circuit. The optical transceiver includes an optical transmitter, an optical receiver, and at least any one of: a first delay circuit included in the optical transmitter and configured to delay an input first multi-level digital signal by a delay time corresponding to an amplitude level of the first multi-level digital signal; and a second delay circuit included in the optical receiver and configured to delay an input second multi-level digital signal by a delay time corresponding to an amplitude level of the second multi-level digital signal.

Abstract: An optical line terminal (OLT) coupled to a plurality of optical network units (ONUs) through a passive optical network (PON). The OLT includes a transceiver configured to communicate via a management channel of a communication network with a plurality of OLTs. The communication includes sending or receiving a notification, wherein the notification includes the following: a source OLT identifier associated with a source OLT sending the notification, wherein the source OLT is configured to communicate over a first channel at a first wavelength of the PON; a destination OLT identifier associated with a destination OLT receiving the notification, wherein the destination OLT is configured to communicate over a second channel at a second wavelength of the PON; and an ONU identifier associated with a first ONU associated with the notification.