Abstract: A random acoustic phase scrambler device is installed in-line with a telecommunications fiber link to prevent voice detection via fiber links. The device includes a transducer to produce vibrations; a length of optical fiber positioned to receive the vibration from the transducer; and a random acoustic phase driver configured to control the intensity and frequency of the vibrations. The transducer produces randomized vibrations within an acoustic bandwidth. The device is configured to introduce device-induced phase changes to signals within the telecommunications fiber link. The bandwidth of the device-induced phase changes is greater than the bandwidth of voice-induced phase changes, and the device-induced phase changes are greater in intensity than the voice-induced phase changes. The device-induced phase changes mask voice-induced phase changes through the telecommunications fiber link that are otherwise detectable by voice detection equipment tapped to the telecommunications fiber link.

Abstract: A method for allocating a point-to-point channel to a user module of an optical communication network. The network includes user modules and optical terminations, and supports point-to-multipoint channels and a plurality of point-to-point channels, one same point-to-point channel being assigned to one single optical termination. The method is implemented for a user module called a requester user module, and includes: detecting a predetermined availability signal conveyed by a point-to-point channel of the plurality of point-to-point channels; and allocating the point-to-point channel over which the predetermined availability signal is conveyed, called available point-to-point channel, to the requester user module.

Abstract: Example packet processing methods and devices are described. One example method includes that a first device identifies a received first packet through a first FlexE shim layer disposed in the first device. When identifying that the first packet is a flexible Ethernet (FlexE) packet, the first device performs timeslot mapping on the first packet, then encapsulates the first packet into a first gigabit passive optical network encapsulation mode (GEM) frame. One first identifier is selected by the first device from at least one identifier reserved for a FlexE service, and is allocated to the first GEM frame, where the first identifier is used to indicate that the first GEM frame is a GEM frame corresponding to the FlexE packet. The first device sends the first GEM frame that carries the first identifier.

Abstract: A differential pressure sensor includes a containment body including internally a wall creating first and second cavities, a piston slidingly housed in the first cavity and including a magnet mounted on a first axial end thereof, proximal to the wall and a magnetic sensor housed in the second cavity, near the wall for measuring the axial distance of the magnet from the wall and generating a signal representing such distance. The pressure sensor further includes a lighting element for emitting light radiation, a control circuit operatively interposed between the magnetic sensor and the lighting element and configured for varying the light radiation emitted by the lighting element as a function of a variation in the representative signal generated by the magnetic sensor. An interface element includes a radiant surface facing outwards from the body and an optical guide, extending between the lighting element and the radiant surface.

Abstract: There is provided an optical transmission system in which a plurality of optical transmission and reception apparatuses perform 1-to-N transmission and reception of optical signals (N is an integer equal to or greater than 1), the optical transmission system being configured to select a communication condition that includes at least a modulation scheme or a baud rate and is a communication condition when each of the optical transmission and reception apparatuses performs transmission and reception in accordance with a transmission line condition that is between any one first optical transmission and reception apparatus and each of second optical transmission and reception apparatuses, which are N grounds, other than the first optical transmission and reception apparatus.

Abstract: Techniques for dynamically identifying an optical path to utilize in an optical network in response to a bandwidth request are disclosed herein. In embodiments, router port information, IP address information, and optical transponder information may be obtained by a network controller system from a router controller. An optical network path and a particular wavelength may be obtained from a CDC node controller. The network controller system may instruct an optical transponder controller to configure an optical transponder in the optical network path to utilize the particular wavelength based on obtaining the optical network path. The network controller system may instruct the router controller to configure router ports for one or more routers to utilize the IP address information and the router port information based at least in part on the instructing of the optical transponder controller to configure the optical transponder.

Abstract: Provided are an apparatus and a method for resetting a transimpedance amplifier for low-power passive optical network equipment for improving the synchronization performance of an uplink burst signal by resetting the transimpedance amplifier for amplifying a received signal of an optical transceiver at a time point at which a frame of the uplink burst signal ends. There is an effect of improving the burst-mode clock and data reconstruction performance through simple analysis of a bit pattern and thus reducing a guard time or a number of repetitions of preambles by accurately identifying the time point at which the frame of the uplink burst signal ends without using a frame data analysis scheme to reset the transimpedance amplifier.

Abstract: A system for delivering multiple passive optical network services is disclosed. The system includes a first optical transmission service comprising a common wavelength pair routed from a source to each of a plurality of subscribers. The system further includes a second optical transmission service comprising a plurality of unique wavelength pairs, where each of the unique wavelength pairs is routed from the source to a subscriber among the plurality of subscribers. The system delivers the first optical transmission service and the second optical transmission service to the subscriber on a single optical fiber.

Abstract: The techniques described herein may be used to deploy a digital kiosk, within a fiber optic network, in a manner that is efficient and that minimizes the risk of damaging the kiosk during the installation process. This may include manufacturing the kiosk with a Fiber Distributed Panel (FDP) that functions as an interface between a fiber optic stub (that connects the kiosk to a fiber optic network backbone) and individual, internal components of the kiosk. A technician therefore may install the kiosk without having to physically open the kiosk and/or configure the fiber cabling and internal components inside the kiosk.

Abstract: Embodiments of the present invention provide a link switching method, device, and system. The method comprises: an optical network unit (ONU) transmits a monitoring packet through a first Maintenance association End Point on a first link connected to the ONU and an aggregation side switch device, so as to monitor the first link; the ONU performs switching from a first sub-link of the first link to a first sub-link of a second link if it is detected that a link fault occurs on the first link; the ONU sends a notification message to a second optical line terminal (OLT), so that the second OLT enables a transmission port; and the ONU sends an automatic protection switching message to the aggregation side switch device through a second Maintenance association End Point on the second link.

Abstract: The present invention discloses a system for full-duplex data transmission using polarization multiplexing comprises a central station having a first means for processing downlink signals and a second means for processing uplink signals, and a remote antenna unit connected to the central station via a transmission medium, having a third means for processing downlink signals and a fourth means for processing uplink signals, characterised in that the remote antenna unit is configured to receive downlink signals from the central station, and then to split a portion of the downlink signals to be used as uplink data transmission simultaneously with transmission of the downlink.

Abstract: A system for delivering multiple passive optical network services is disclosed. The system includes a first optical transmission service comprising a common wavelength pair routed from a source to each of a plurality of subscribers. The system further includes a second optical transmission service comprising a plurality of unique wavelength pairs, where each of the unique wavelength pairs is routed from the source to a subscriber among the plurality of subscribers. The system delivers the first optical transmission service and the second optical transmission service to the subscriber on a single optical fiber.

Abstract: RFID (radio frequency identification) systems are provided in which tag and interrogator devices implement a hybrid framework for signaling including an optical transmitter/receiver system and an RF transmitter/receiver system. For instance, an RFID tag device includes: optical receiver circuitry configured to receive an optical signal having an embedded clock signal from an interrogator device, and convert the optical signal into an electrical signal comprising the embedded clock signal; clock extraction circuitry configured to extract the embedded clock signal from the electrical signal, and output the extracted clock signal as a clock signal for controlling clocking functions of the tag device; voltage regulator circuitry configured to generate a regulated supply voltage from the electrical signal, wherein the regulated supply voltage is utilized as a bias voltage for components of the tag device; and data transmitter circuitry configured to wirelessly transmit tag data to the interrogator device.

Abstract: Embodiments are directed to decomposing an all-to-all interconnection network topology into a plurality of smaller all-to-all interconnection network elements, replicating the interconnection network elements in a modular fashion, wherein the modular interconnection network elements construct the all-to-all interconnection network topology. Embodiments are directed to an apparatus comprising a shuffle cable assembly comprising a plurality of shuffle cables, where each of the plurality of shuffle cables comprises a plurality of optical fibers and a plurality of connectors, a block configured to organize, align, and maintain a position of the plurality of connectors, and at least one handle coupled to the block and configured to actuate the plurality of connectors.

Abstract: An access network includes an access device having an optical interface module that outputs a plurality of pairs of optical communication signals, each of the pairs of optical communication signals comprising a modulated optical transmit signal and an unmodulated optical receive signal, each of the pairs of optical communication signals having a different wavelength. A customer premise equipment (CPE) comprises an optical interface module to receive the modulated optical transmit signal and the unmodulated optical receive signal for any of the plurality of pairs of optical communication signals. The optical interface module includes a receive module to demodulate the modulated optical transmit signal into inbound symbols and a transmit module having an optical modulator and reflective optics to modulate the unmodulated optical receive signal in accordance with a data signal and reflect a modulated optical receive signal to communicate outbound data symbols to the access device.

Abstract: A system for delivering multiple passive optical network services is disclosed. The system includes a first optical transmission service comprising a common wavelength pair routed from a source to each of a plurality of subscribers. The system further includes a second optical transmission service comprising a plurality of unique wavelength pairs, where each of the unique wavelength pairs is routed from the source to a subscriber among the plurality of subscribers. The system delivers the first optical transmission service and the second optical transmission service to the subscriber on a single optical fiber.

Abstract: A method of analyzing the characteristics of a power source includes receiving a power source having at least one phase and sensing voltage signals of each phase of the at least one phase. The method includes detecting a zero crossing event of a selected phase of the at least one phase based on the sensed voltage signals of the selected phase. The method also includes determining, using a processor, voltage information for each phase of the at least one phase based on the corresponding sensed voltage signals. The method further includes outputting a series of pulses via a galvanic isolator in response to the zero crossing event. Respective lengths of some or all of the pulses in the series are based on the corresponding voltage information for each of the at least one phase.

Abstract: Optical apparatus and methods utilizing sensors operating in the reflection mode are provided. The apparatus includes at least one optical bus. The at least one optical bus is configured to be optically coupled to at least one source of input optical signals, to at least one optical detector, and to a plurality of reflective sensing elements. The at least one optical bus transmits an input optical signal from the at least one source to the plurality of reflective sensing elements. At least one reflective sensing element of the plurality of reflective sensing elements receives a portion of the input optical signal and reflects at least a portion of the received portion. The at least one optical bus transmits the reflected portion to the at least one optical detector.

Abstract: Devices and systems to perform optical alignment by using one or more liquid crystal layers to actively steer a light beam from an optical fiber to an optical waveguide integrated on a chip. An on-chip feedback mechanism can steer the beam between the fiber and a grating based waveguide to minimize the insertion loss of the system.

Abstract: An optical communication system may include a light transmission unit transmitting a light beam having a first polarization, a quarter waveplate to receive the light beam and to modify the light beam to have a second polarization, and a retroreflector to receive the light beam from the quarter waveplate and reflect the light beam to the quarter waveplate, which modifies the light beam to have a third polarization. The optical communication system may also include a half waveplate to modify the first polarization such that the first polarization is about 90 degrees rotated compared to the third polarization, and a polarizer to pass the light beam having the third polarization and to block most of the light beam having the first polarization.

Abstract: The present invention provides a method, a network device, and a user equipment for switching a MAC address. The network device provides a first port and a second port, each port being connected to at least one user equipment. After switching from the first port to the second port, the network device sends a first packet to the user equipment. The first packet carries a second MAC address, so that the user equipment switches a first MAC address to the second MAC address according to the first packet; receiving a second packet returned by the user equipment. After determining, according to the second packet, that the user equipment switches to the second MAC address, the locally used first MAC address is switched to the second MAC address.

Abstract: An optical fiber transmission system adapted to provide a remote passive identification of components deployed in said transmission system, wherein each component comprises an associated passive optical identification unit adapted to provide identification of a component type of the respective component on the basis of a received optical identification signature carried in an optical identification signal to said component.

Abstract: The embodiments herein relate to a method in an optical network unit (103), referred to as an ONU, for providing wireless connectivity capability to the ONU (103). The ONU (103) is comprised in a communications network (100). The ONU (103) is interconnected to an optical line terminal (101), referred to as an OLT, via a wireline communications link (104) and a wireless communications link (113). The ONU (103) is configured to support a sleep mode. The ONU (103) obtains information about entry into the sleep mode. The ONU (103) identifies whether the wireless communications link (113) is activated or deactivated, and activates the wireless communications link (113) if the wireless communications link (113) is identified as deactivated. The ONU (103) enters sleep mode, and provides wireless connectivity capability to the ONU (103) by means of the wireless communications link during the sleep mode.

Abstract: An optical subscriber network for power reduction is provided. The optical subscriber network may include an Optical Line Terminal (OLT) and an Optical Network Terminal (ONT). The OLT may manage a plurality of ONTs by classifying the plurality of ONTs into a sleep group, and may multicast a sleep allowance message only to ONTs included in a predetermined sleep group.

Abstract: Systems and methods are disclosed to provide an upstream rate between 1 Gbps and 10 Gbps in a cost effective manner in a 10 GEPON. In an embodiment, an optical network unit (ONU) transmitter includes a burst transceiver and a physical layer (PHY) including a high performance digital to analog converter (DAC), a pulse amplitude modulation (PAM) module configured to encode end user data using a modulation scheme having more than two levels, and a laser. The ONU transmitter transmits the encoded end user data to an optical line terminal (OLT) receiver, which demodulates the data using a PAM demodulator and sends it to a service provider.

Abstract: Example modular optical network terminals (ONTs) and methods to implement the same are disclosed. A disclosed example ONT includes a base unit having an integral optical interface to optically couple the ONT to an optical network, and to convert an optical signal received from the optical network to form an electrical signal, a plug-in service module to distribute the electrical signal within a customer premises, and a modular interface connector configured to receive the plug-in service module and to couple the electrical signal from the base unit to the plug-in service module.

Abstract: An Optical Network Unit (ONU) in a Passive Optical Network (PON), the ONU comprising: a receiver module configured to receive a first rate selection signal from an optical line terminal (OLT) that indicates a reduced rate mode, and a component comprised within the receiver module, the component configured to transition from a normal operation mode to the reduced rate mode in response to the receiver module receiving the first rate selection signal, wherein operating in the normal operation mode comprises receiving a downstream signal from the OLT at a nominal data rate, and wherein operating in the reduced rate mode comprises receiving the downstream signal from the OLT at a reduced data rate that is less than the nominal data rate but greater than zero.

Abstract: An apparatus comprising a wavelength division multiplexer (WDM), an optical network unit (ONU) coupled to the WDM, a passive optical network (PON) data over cable service interface specification (DOCSIS) upstream proxy (PDUP) coupled to the ONU and configured to couple to a coaxial cable, and a downstream (DS) optical/electrical (O/E) converter coupled to the WDM and configured to couple to the coaxial cable. An apparatus comprising a WDM, an optical line terminal (OLT) coupled to the WDM, a cable model termination system (CMTS) coupled to the OLT via an upstream external physical (PHY) interface (UEPI), and a DOCSIS and a Quadrature Amplitude Modulation (QAM) unit coupled to the WDM and the CMTS.

Abstract: Embodiments of the invention include a system for registering an optical network unit (ONU) installed in a passive optical network (PON), including a mobile terminal, a registration server, and an optical line terminal (OLT). The mobile terminal is configured to collect an ONU identification from the ONU, collect a subscriber identification, and transmit the ONU identification and the subscriber identification to a registration server via a communication system. The registration server is configured to receive the ONU identification and subscriber identification from the mobile terminal via the communication system, retrieve subscriber information from a subscriber database based on the subscriber identification, associate the ONU with the subscriber information, and transmit, to an optical line terminal, an association between the ONU and the subscriber information. The optical line terminal (OLT) is configured to serve as an endpoint for the ONU in the PON.

Abstract: A network comprising a first optical line terminal (OLT), and a second OLT in communication with the first OLT, at least one first-type optical network unit (ONU), and at least one second-type ONU. Included is an OLT configured to implement a method comprising forwarding a first downstream data from a first-type OLT to at least one first-type ONU, and transmitting a second downstream data to at least one second-type ONU. Also included is a method comprising adding at least one second-type ONU to a passive optical network (PON) comprising a first-type OLT and at least one first-type ONU without removing the first-type OLT from the PON.

Abstract: A method includes detecting wavelength collision including identifying a pair or pairs of ONTs that transmit the colliding wavelengths and recovering from collision wherein wavelengths of the pair or pairs of ONTs that cause collisions are re-adjusted to eliminate the collision.

Abstract: A passive optical network is provided which uses existing GPON OAM functionality and standard routing protocol messages to solve the downstream routing problem between an access service provider and one or more other communication provider networks.

Abstract: A bi-directional optical transceiver includes multiple single mode optical ports and a multi-mode optical port. A multi-mode optical combiner combines single mode optical signals received at the single mode optical ports into a multi-mode optical signal at the multi-mode optical port. Each single mode optical signal having a distinct optical mode that does not interfere with the optical mode of the other single mode optical signals. A photo detector coupled to the multi-mode optical combiner detects a total optical power of the single mode optical signals in the multi-mode optical signal.

Abstract: OSUs 1 to N are connected to a plurality of PON lines respectively. A control unit performs processing for registering a plurality of subscriber devices connected to the plurality of PON lines respectively and processing for allocating a bandwidth. In addition, the control unit switches an OSU while a state of registration of the plurality of subscriber devices is maintained, by changing a communication path between the plurality of PON lines and a plurality of OSUs 1 to N.

Abstract: The present invention discloses a multiple star wavelength division multiplexing passive optical network system using a wavelength assignment method. In a multiple star wavelength division multiplexing passive optical network system using a wavelength assignment method according to the present invention, only one WDM-PON system can provide services for a plurality of subscribers who is distributed in a wide range of area through multiple starring, by setting one or more band for transmitting up-stream signals as an up-stream basic band and one or more band for transmitting down-stream signals as a down stream basic band, respectively, and by dividing each of the up-stream basic band and the down stream basic band into a plurality of wavelength sub-bands and assigning the divided sub-bands to different areas using a wavelength division multiplexer/de-multiplexer which splits a band into two or more sub-bands.

Abstract: This concerns a protected long-reach PON having a plurality of terminals connected to a distribution network that is fed by both a main and back up feed, each feed including a head end and a repeater. The back up head end had access to a ranging table with data previously obtained by the main head end, thereby speeding up the switch over in the event of a fault with the main feed. In one embodiment, the repeater has a virtual ONU therein, allowing the back up repeater to be ranged by the back up head end, thereby yet further speeding up the ranging procedure. The main and back up repeaters are sufficiently equidistant from the distribution network to allow the back up head to perform normal scheduling without performing a ranging operation on each of the terminals, even if the different terminals transmit at slightly different wavelengths. This is achieved using the ranging information obtained with regard to the back up repeater.

Abstract: According to one embodiment, there is provided a visible-light communications system in which bidirectional visible-light communication is performed between a visible-light communications device and a mobile terminal. The device has one light source. The mobile terminal has a retroflection unit. The mobile terminal further has first and second optical filters. The first optical filter extracts a visible light beam modulated with the data transmitted from the visible-light communications device. The second optical filter extracts a visible light beam that will be used as a retroflection light beam that is not modulated.

Abstract: A method and system for single laser bidirectional links are disclosed and may include communicating a high speed optical signal from a transmit CMOS photonics chip to a receive CMOS photonics chip and communicating a low-speed optical signal from the receive CMOS photonics chip to the transmit CMOS photonics chip via one or more optical fibers. The optical signals may be coupled to and from the CMOS photonics chips utilizing single-polarization grating couplers. The optical signals may be coupled to and from the CMOS photonics chips utilizing polarization-splitting grating couplers. The optical signals may be amplitude or phase modulated. The optical fibers may comprise single-mode or polarization-maintaining fibers. A polarization of the high-speed optical signal may be configured before communicating it over the single-mode fibers. The low-speed optical signal may be generated by modulating the received high-speed optical signal or from a portion of the received high-speed optical signal.

Abstract: The present invention discloses a low-cost light source for optical transmission systems and optical networks based on wavelength-division multiplexing (WDM) technology. A light source in accordance with the present invention is implemented by externally injecting a narrow-band incoherent light into a Fabry-Perot laser diode (F-P LD). After injection of narrow-band incoherent light, the output of F-P LD becomes wavelength-selective rather than multi-mode and the output wavelength of F-P LD coincide with the peak wavelength of the injected incoherent light. Multi-channel WDM light sources according to the present invention can be implemented using a single broadband incoherent light source and plurality of F-P LDs. An optical transmission system for upstream signal transmission in an passive optical network using the light source according the present invention is also disclosed.

Abstract: An apparatus comprising a plurality of optical line terminals (OLTs) corresponding to different providers that share an optical distribution network (ODN), a plurality of optical network units (ONUs) coupled to the OLTs via the same ODN and configured to communicate with the different OLTs using different corresponding pairs of upstream and downstream channels, wherein the upstream and downstream channels are interleaved across a plurality of wavelength bands and comprise a sequence of alternating and contiguous upstream and downstream channels, are aligned with a plurality of wavelength division multiplexing (WDM) channels, and satisfy a plurality of design requirements for the OLTs and ONUs.

Abstract: An optical communication device comprises an input/output configured to be coupled to an optical communications line, and a passive optical loopback module coupled to the input and configured to receive optical signals from the input/output, the loopback module being further configured to reflect incoming signals of a test wavelength to the input/output.

Abstract: The present invention discloses a multiple star wavelength division multiplexing passive optical network system using a wavelength assignment method. In a multiple star wavelength division multiplexing passive optical network system using a wavelength assignment method according to the present invention, only one WDM-PON system can provides services for a plurality of subscribers who is distributed in a wide range of area through multiple starring, by setting one or more band for transmitting up-stream signals as an up-stream basic band and one or more band for transmitting down-stream signals as a down-stream basic band, respectively, and by dividing each of the up-stream basic band and the down-stream basic band into a plurality of wavelength sub-bands and assigning the divided sub-bands to different areas using a wavelength division multiplexer/de-multiplexer which splits a band into two or more sub-bands.

Abstract: An access network includes an access device having an optical interface module that outputs a plurality of pairs of optical communication signals, each of the pairs of optical communication signals comprising a modulated optical transmit signal and an unmodulated optical receive signal, each of the pairs of optical communication signals having a different wavelength. A customer premise equipment (CPE) comprises an optical interface module to receive the modulated optical transmit signal and the unmodulated optical receive signal for any of the plurality of pairs of optical communication signals. The optical interface module includes a receive module to demodulate the modulated optical transmit signal into inbound symbols and a transmit module having an optical modulator and reflective optics to modulate the unmodulated optical receive signal in accordance with a data signal and reflect a modulated optical receive signal to communicate outbound data symbols to the access device.

Abstract: A data transmission network comprising: a base comprising: a base light source and a base light detector; a plurality of nodes, each node comprising a node light source and a node light detector; and a plurality of optical fibers arranged to form a optical fiber network. Each optical fiber is arranged to receive light from the base light source, transmit the light received from the base light source to one or more of the node light detectors via an air gap, receive light from one or more of the node light sources via an air gap, and transmit the light received from the node light source(s) towards the base light detector.

Abstract: In a passive optical network, upstream transmission frames from an ONU to an OLT can include additional delimiters that assist in overcoming high signal distortion at the beginning of the frame that can obscure an initial frame delimiter. The second delimiter can be inserted into the frame at various locations within the frame known to the OLT such that the OLT can active a delimiter detector at the beginning of a timing window for delimiter detection. The ONU can assist the OLT in synchronizing the frame by ensuring that a frame header immediately follows a second delimiter or appears at the start of a first FEC code block following the second delimiter. Depending on where the ONU inserts the second delimiter in the frame generation process, the second delimiter may be scrambled and/or may form part of the FEC.

Abstract: In a passive optical network, upstream transmission frames from an ONU to an OLT can include additional delimiters that assist in overcoming high signal distortion at the beginning of the frame that can obscure an initial frame delimiter. The second delimiter can be inserted into the frame at various locations within the frame known to the OLT such that the OLT can active a delimiter detector at the beginning of a timing window for delimiter detection. The ONU can assist the OLT in synchronizing the frame by ensuring that a frame header immediately follows a second delimiter or appears at the start of a first FEC code block following the second delimiter. Depending on where the ONU inserts the second delimiter in the frame generation process, the second delimiter may be scrambled and/or may form part of the FEC.

Abstract: A device may include a first module to capture information relating to network traffic passing through a first interface in a network device. A second module may capture information relating to network traffic passing through a second interface in the network device. A control module may be configured to transmit control commands to the first module and the second module, the control commands instructing the first module and the second module to capture information relating to network traffic passing through the first interface and the second interface, respectively. The control module may be further configured to receive the captured information from the first module and the second module, correlate the received information from the first module and the second module; and provide the correlated information to a user.

Abstract: A method is provided for managing connections in an optical access network. Also provided are a corresponding platform, exchange, network and computer software product. The method manages connections of a plurality of user modules to a plurality of transmission modules of an exchange in an optical access network. The management method includes a dynamic re-arrangement of the connection of at least one of the user modules to at least one of the transmission modules according to at least one predetermined optimization criterion.

Abstract: A method for synchronizing time by an optical network terminal (ONT) in a passive optical network system is provided. The method includes: receiving a ranging request message including a first current time of an optical line terminal (OLT); calculating a first compensation time when a transmission delay is compensated at a time that the ranging request message is received; transmitting a serial number response message to the OLT; calculating a second compensation time when the transmission delay is compensated at a time when the serial number response message is transmitted; receiving a ranging time message including a second current time when the serial number response message from the OLT is received; calculating an offset time from the first current time, the second current time, the first compensation time, and the second compensation time; and synchronizing a clock of the ONT and a clock of the OLT based on the offset time.

Abstract: In a PON system in which communication is performed at a plurality of types of transmission rate (L, M, and H) in an upstream direction from a plurality of terminals connected to a station apparatus through optical fibers, within a discovery period for allowing an unregistered terminal to be recognized by station apparatus, the terminal makes a discovery response at one type of transmission rate (L). With this configuration, station apparatus can wait for a discovery response with a receive function being allowed to support transmission rate (L).