969 results about "Optical line termination" patented technology

An optical line terminal, a passive optical network and a radio frequency signal transmission method in the communication technical field are provided. The passive optical network comprises: an OLT, an ODN and at least one ONU. The OLT comprises: at least one transmitting unit, which provides one dedicated downstream optical carrier and two dedicated upstream optical carriers for ONU; the two dedicated optical carriers for ONU are configured to carry ONU upstream radio frequency signals; a multiplexing / demultiplexing unit; and at least one receiving unit which obtains the upstream signal from the demultiplexed upstream optical signal. The bandwidth of wireless access network is enhanced, and the design of ONU is simple.

An optical network termination (ONT) apparatus can determine its own geographic location information automatically, thereby permitting the ONT to report its geographic location to a management entity in a passive optical network (PON) automatically, without manual intervention.

Systems and techniques for multiple bit rate optical data transmission. A passive optical network includes an optical line termination unit (OLT) connected to one or more optical network units (ONUs) by optical elements. The OLT is capable of performing downstream transmission to the ONUs at each of a variety of different bit rates, and each ONU performs upstream transmission at one or more bit rates. The OLT can sense a bit rate of a received transmission and change its operation so as to receive and process the transmission exhibiting the sensed bit rate. Each of the ONUs receives and processes downstream transmissions at one or more bit rates, but each ONU is capable of maintaining a phase and frequency lock to downstream transmissions at all bit rates supported by the OLT. One or more of the ONUs may also receive and process downstream transmissions exhibiting different or changed bit rates.

A point-to-multipoint communications network includes an optical line terminal (OLT) and a number of optical network terminals (ONTS) which each detect and remove rogue ONTs from the network. The OLT monitors transmission errors to detect the presence of a rogue ONT, and can determine the identity of the rogue. Each ONT monitors its own upstream data packets to detect the presence of a rogue, and turns itself off when a rogue is detected.

One embodiment provides a system for performance monitoring in a passive optic network (PON). The system includes an optical line terminal (OLT) and an optical network unit (ONU). The OLT includes an optical transceiver configured to transmit optical signals to and receive optical signals from the ONU, and a performance monitoring mechanism configured to monitor performance of the PON based on received optical signals.

A system and method for managing link status in Gigabit Ethernet passive optical network (GE-PON) units (ONUs) is disclosed. The GE-PON comprises one or more ONUs allocated data transmission periods, respectively. Each of the ONUs sends a report signal and a data signal in a corresponding one of the allocated data transmission periods. The report signal contains a signal to request allocation of a bandwidth for data signal transmission in a next window period. The GE-PON further comprises an optical splitter having its one side connected with the ONUs and its other side connected with at least one optical communication channel. The optical splitter switches an input signal to a desired destination. The GE-PON further comprises an optical line terminal (OLT) for determining whether the report signal is received, identifying a specific one of the ONUs having sent the report signal when the report signal is received, determining whether the data signal is received from the specific ONU in a specific one of the data transmission periods allocated to the specific ONU, and discriminating and managing a link status of the specific ONU in accordance with the determination made.

Provided are an apparatus and method for monitoring optical fibers of a passive optical network system including an optical line termination located in a central office, a remote node that is a local office, and optical network units on the subscriber side. The apparatus respectively allocates monitoring light wavelengths to optical network units such that optical fibers of the respective optical network units can be identified and monitored using the monitoring light wavelengths, combines a monitoring light having various wavelengths and a downward optical signal using the WDM coupler, and analyzes signal waveforms of the monitoring light having various wavelengths reflected from the optical network units, to detect the position of a defect generated on an optical line. Accordingly, it is possible to transmit optical signals and monitor the physical states of the optical fibers of the optical network units.

The embodiment of the invention discloses a passive optical network system and a downlink transmission method thereof. The passive optical network system comprises an optical line terminal, an optical distribution network and a plurality of optical network units. The optical line terminal is used to send a downlink multi-wavelength optical signal composed of a plurality of downlink optical signal wavelength division multiplexing having different wavelengths, and the optical distribution network comprises a first-stage optical splitter, a plurality of second-stage optical splitters and a plurality of filter modules. The first-stage optical splitter is used to divide a downlink multi-wavelength signal sent by the optical line terminal into a plurality of downlink multi-wavelength signals, the plurality of filter modules are used to carry out filter processing on the plurality of downlink multi-wavelength signals to obtain a downlink single wavelength optical signal of which the wavelength corresponds to a channel central wavelength; wherein, the channel central wavelengths of the plurality of filter modules respectively correspond to the plurality of downlink optical signals having different wavelengths, the second-stage optical splitters are used to carry out spectral processing on the downlink single wavelength signal and then provide the downlink single wavelength signal to the optical network unit.

It is necessary to completely remove overlapping of signals between plural PONs in order to make the PONs coexist. Accordingly, it is required to share or intensively manage bandwidth use conditions over an optical fiber that serves as a common band between plural systems. Therefore, transmission clocks should be synchronized with high accuracy between plural systems. A reference clock is provided from an external device or a representative OLT to the entire systems to perform clock synchronization between plural systems, so that the overall systems are synchronized by synchronizing each OLT with the reference clock. A hierarchical management method is selected that manages ONUs under the control of each OLT by managing band use information arranged for each OLT with respect to an external device or a representative OLT for sharing of bandwidth use conditions between plural systems.

A passive optical network. The optical network has an optical fiber ring with ends terminating at an optical line terminal. The optical line terminal transmits signals through the fiber ring to optical network units passively connected to the fiber ring. The optical network units receive signals from the optical line terminal through the fiber ring. In one embodiment, the optical line terminal transmits redundant signals in opposite directions through the fiber ring and the optical network units receive the redundant signals from opposite directions through the fiber ring. In another embodiment, the optical network units receive TDM signals from and transmit TDMA signals to the optical line terminal through a fiber line. A first WDM coupler passively connected to the fiber line multiplexes an overlay signal with at least one of the TDM signals and the TDMA signals for transmission through the fiber line. The overlay signal has a wavelength different than the signals with which it is multiplexed.

Provided is an apparatus for providing a broadcasting service through an overlay structure in a WDM-PON. The apparatus comprises: a first grating section receiving a multiplexed signal of N data communication optical wavelength signals and a broadcasting optical wavelength signal, which have separate wavelengths, transmitted from an optical line terminal (OLT) and wavelength-demultiplexing the multiplexed signal; a mirror reflecting the broadcasting optical wavelength signal wavelength-demultiplexed by the first grating section; and a second grating section receiving the reflected broadcasting optical wavelength signal and splitting it to all subscriber ports.

There is provided a method for supporting a multicast service in an Ethernet passive optical network system. Since an Optical Network Unit (ONU) system monitors an IGMP (Internet Group Management Protocol) message and informs the monitored result of an Optical Line Terminal (OLT) system so that the OLT system creates L2 multicast forwarding table using a multicast address and ONU ID information in a PON port, the ONU system transmits the multicast packet only to a corresponding subscriber on the basis of the L2 multicast forwarding table when receiving a multicast packet. Therefore, it is possible to transfer a multicast packet only to a specific ONU system belonging to a corresponding multicast address group among a plurality of ONU systems.

Optical Time-Domain Reflectometer (OTDR) troubleshooting of a passive optical network (PON) can be enhanced by deploying cascaded splitters, at least some of which have multiple inputs. That is, at least some of the splitters in the PON have not only a first input coupleable to the optical line terminator (OLT) or output of another splitter but also a second input directly coupleable to an Optical Time-Domain Reflectometer (OTDR). Optical time-delay reflectometry can be performed upon a selected portion or segment of the PON by selecting a splitter and transmitting an optical test signal from the OTDR directly to the input of the selected splitter and analyzing the reflected signal.

A gigabit passive optical network (GPON) residential gateway comprising a microprocessor for at least processing packets including voice data and packets including video data; dual packet processors for performing GPON and residential gateway processing tasks; a plurality of Ethernet media access control (MAC) adapters for interfacing with a plurality of subscriber devices; a GPON MAC adapter for interfacing with an optical line terminal (OLT) of the GPON; and a digital signal processor (DSP) for processing voice signals.

An optical termination system is provided. The optical termination system includes a working Optical Line Terminal (OLT) that communicates with a plurality of Optical Network Units (ONUs) near end users through an optical transmission line. The OLT includes a control information storage to store control information of the plurality of ONUs. In addition, the optical termination system includes a standby OLT, which includes a storage to store the control information to be transmitted from the working OLT. Furthermore, the optical termination system includes a controller that controls switching from the working OLT to the standby OLT.

A fiber to the home (FTTH) system based on a passive optical network (PON) includes an optical line terminal (OLT) block, an optical network terminal (ONT) block, and an optical distribution network (ODN). The ONT block includes a video-optical line terminal (V-OLT) and an optical line terminal (OLT) in order to output optical signals of the video-optical line terminal (V-OLT) and the optical line terminal (OLT) by multiplexing the optical signals. The VOLT receives cable TV, master antenna TV, and satellite broadcasting optical signals inputted from a broadcasting service network so as to output received signals as a first optical signal having a predetermined wavelength band. The OLT includes a first downstream data optical transmitter and a first upstream data optical receiver and outputs a data communication signal inputted from a data service network as a second optical signal having different wavelength from the video-optical line terminal. The ONT block includes a video-optical network terminal (V-ONT) and an optical network terminal (ONT) in order to split multiplexed data communication signals, and cable TV broadcasting, master antenna TV broadcasting, and satellite broadcasting optical signals. The V-ONT processes the split cable TV broadcasting, master antenna TV and satellite broadcasting optical signals so as to provide subscribers with the split cable TV broadcasting, master antenna TV and satellite broadcasting optical signals. The optical network terminal (ONT) has an upstream data optical transmitter and a downstream data optical receiver so as to process split data communication signals. The optical distribution network (ODN) connects the optical line terminal block to the optical network terminal as an optical transmission medium.

Mechanisms for providing a subscriber-side interface with a passive optical network are described herein. An optical network termination (ONT) having an integrated broadband passive optical network processor is utilized to receive downstream data from an optical line termination (OLT) via a passive optical network and provide the contents of the downstream data to one or more subscriber devices via one or more data interfaces. Similarly, the ONT is adapted to receive and transmit upstream data from the one or more subscriber devices to the OLT via the passive optical network. The ONT preferably implements one or burst buffers for buffering upstream and / or downstream data. The ONT can be adapted to notify the OLT of the status of the burst buffer, thereby allowing the OLT to modify the bandwidth allocations.

The present invention discloses a network architecture for upgrading a legacy time division multiplexing-passive optical network (TDM-PON) to a wavelength division multiplexing-passive optical network (WDM-PON) based next-generation passive optical network (next-generation PON), wherein the legacy TDM-PON comprises: a central office (CO) having a first optical line termination (OLT); a remote node (RN) having a splitter; a single mode fiber (SMF) connecting the first OLT and the splitter; and a first group of one or more optical network terminations (ONTs) being connected to the splitter by a first group of one or more distribution fibers, and wherein the network architecture further comprises: in case that the next-generation PON is a WDM-PON, a first apparatus for combining and splitting wavelength bands being positioned between the SMF and the first OLT, in order to add a second OLT to be used for the WDM-PON within the CO or within another CO which is located in a position different from the CO, while sharing the SMF; a second apparatus for combining and splitting wavelength bands being positioned at a front terminal of the splitter; and an arrayed waveguide grating (AWG) being connected to the second apparatus for combining and splitting wavelength bands within the RN, and being connected to a second group of one or more ONTs by a second group of one or more distribution fibers within the RN or within another RN which is located in a position different from the RN.

Locating a fault of an optical transmission line in a system which performs bidirectional optical communication between a wire center Optical Line Terminal (OLT) and plural subscriber devices, Optical Network Terminal (ONT). In this ITU defined topology, a feeder extending from the OLT is branched by a passive (non powered) splitter / coupler device into plural legs each connected to the ONT devices. The present invention encompasses a novel test apparatus and technique for fault location on Passive Optical Networks (PON) and / or Fiber of the premise Networks (FTTP), encompassing APON, BPON and EPON allowing non-service interruptive test, without damage to the ONT or OLT transceivers. The invention provides service providers the ability to locate a fault occurring on an optical transmission line while the system is actively performing bidirectional optical communication between a OLT / head-end device and plurality of ONT / subscriber devices.

Disclosed are a wavelength division multiplexing-passive optical network (WDM-PON) system using self-injection locking, an optical line terminal thereof, and a data transmission method. A wavelength division multiplexing-passive optical network (WDM-PON) system according to an aspect of the invention includes an optical line terminal. The optical line terminal includes a reflector that is installed at the input side of a multiplexer and reflects an optical signal having a predetermined wavelength, and a light source that generates a multimode optical signal to transmit the generated multimode optical signal to the multiplexer through the reflector, receives reflected light by the reflector, and oscillates at a wavelength of the received reflected light. According to the aspect of the invention, it is not necessary to separately control the temperature of a light source for a downstream signal, and stable communication can be performed by collectively controlling wavelengths of downstream channel optical signals for downstream channels through temperature control of the multiplexer.

An Ethernet passive optical network provides a subscriber with a high speed and large capacity data service and a real time digital broadcast / video service. The network includes an optical line terminal for frame-multiplexing broadcast / video signals, which are obtained by performing a switching operation and a time-slot multiplexing with respect to a plurality of digital broadcast / video data delivered from external broadcasting vendors according to broadcast / video selection information delivered from each user, and communication data delivered through an Internet protocol network.

There are disclosed systems and methods for detecting and controlling congestion in an Optical Line Terminal (OLT). The OLT has a plurality of ports. Each port of the plurality of ports communicates with at least one Optical Network Unit (ONU), and each port of the plurality of ports has a respective enforced maximum upstream bandwidth. For example, the maximum upstream bandwidth may be enforced by a Dynamic Bandwidth Allocation (DBA) algorithm. The OLT further includes an uplink port through which data received from each of the plurality of ports are transmitted. In one embodiment, if there is congestion of the data at the uplink port, then the enforced maximum upstream bandwidth for at least one port of the plurality of ports is modified.

An instrument for measuring bidirectional optical signals propagating in an optical transmission path between elements one of which will not transmit if continuity of the transmission path is not maintained, for example a branch path between a central offices optical line terminal (OLT) and an end-user's optical network terminal (ONT), comprises first and second connector receptacles for connecting the instrument into the path, a 2×2 coupler (32) having first and second ports (28, 30) connected to the first and second connectors (22, 24), respectively, for completing the optical transmission path, a third port (36) for, outputting a portion of each optical signal received via the first port (28) and a fourth port (34) for outputting a portion of each optical signal received via the second port (30) Detectors (38, 42, 44) coupled to the third and fourth ports convert the optical signal portions into corresponding electrical signals, which are processed to provide the desired measurements. The measurement results may be displayed by a suitable display unit (60) Where the ÖLT transmits signals at two different wavelengths, the instrument may separate parts of the corresponding optical signal portion according to wavelength and process them separately.

A PON (Passive Optical Network) system, which is installed in an access network for connecting a user terminal to a network and can improve the utilization efficiency of the network, is provided. The PON system comprises an OLT (Optical Line Terminal) and at least one ONU (Optical Network Unit), and the OLT connects with the network and the ONU accommodates a user terminal and connected to the OLT via an optical fiber. A logical link generation or deletion condition table and a logical link identifier management table are provided for allocating logical links to be used between the OLT and the ONU. The logical link generation or deletion condition table defines generation or deletion conditions of logical link depending on the traffic (or service) class indicated by contents of a packet passing through the PON system. The logical link identifier management table contains logical link information to be allocated, and a content of this table is added or deleted by the control with referring to the logical link generation or deletion condition table. Whenever the packet is received, the PON system peeps in the contents of the packet, and allocates an appropriate logical link in accordance with the contents.

The invention provides a method and an optical line terminal for performing fiber fault diagnosis in a passive optical network. The method comprises that: a receiving module of the optical line terminal triggers a test module after receiving a fiber fault diagnosis message; the test module performs an optical time-domain reflection test to obtain test data information after being triggered by the receiving module; and a fault diagnosis module analyzes the data information and performs the fiber fault diagnosis. In the method, OTDR technology is applied to the design of the PON OLT, so that the network equipment of the PON has fiber fault diagnosis capacity and the networking structure of a system is simplified.

A photonic integrated circuit (PIC) for a PON transceiver comprises a single monolithic chip having a modulated transmitter laser diode of a first wavelength, λ1, for generating a first communication signal outgoing from the chip via an input / output port and a receiving photodetector for receiving a second communication signal of a second wavelength, λ2, onto chip incoming from the input / output port and a monitoring photodetector for receiving a portion of the first communication signal to monitor the laser diode output power. In one embodiment, the chip is provided with multimode (MM) coupler set to direct a substantial portion of the incoming communication signal to the receiving photodetector and to direct a substantial portion of the outgoing communication signal to the input / output port. A filter may be inserted before the receiving photodetector and / or the laser diode to extract any remaining and undesired signal to either such electro-optic elements. In another embodiment, the laser diode, power monitoring photodetector and the receiving photodetector are collinear in the same chip having a common waveguide where the power monitoring photodetector is capable of both monitoring power and insuring no backward reflecting light of the laser diode reaches the receiving photodiode through it absorption of such light. The active region of the power monitoring photodetector can be set to be absorptive of incoming of backward reflected polarized light of both the TE and TM polarization modes respectively from the chip input or the on-chip laser diode.

The invention discloses an optical line terminal (OLT) optical module, which comprises an optical device, a passive optical network (PON) data signal driver, a PON data signal amplitude limiting amplifier and an optical time domain reflectometer (OTDR) data processing module, wherein the optical device comprises a wavelength division multiplexer (WDM). The OLT optical module can simplify a network wiring structure, and compared with the prior art, reduces OTDR equipment and the WDM as well as the wiring difficulties and network cost of a PON system.

Provided are a wavelength division multiplexing-passive optical network (WDM-PON) in which a reflective semi-conductor optical amplifier (RSOA) is used as each optical transmitter of an optical line termination (OLT) and an optical network unit (ONU) and additional spectrum-sliced light is injected into RSOAs of each of the OLT and the ONU, and a WDM-PON that is combined with time division multiple access (TDMA) technology, by which the number of included ONUs increases and conventional TDMA ONUs can be used.