3419 results about "Optical network unit" patented technology

One embodiment provides a system for power saving in an Ethernet Passive Optic Network (EPON). The system includes an optical line terminal (OLT), an optical network unit (ONU), a traffic-detection module configured to detect status of traffic to and from the ONU, and a power-management module configured to place the ONU in sleep mode based on the detected traffic status. The ONU includes an optical transceiver that includes an optical transmitter configured to transmit optical signals to the OLT and an optical receiver configured to receive optical signals from the OLT.

The present invention relates to an optical fiber access network, and more particularly, to a multi-purpose optical fiber access network capable of accepting all services provided by hybrid wireline/wireless access network.

According to the present invention, in an optical fiber access network of double star structure where a central office/headend and several optical network units are connected through a splitting/combining device, a multi-purpose optical fiber access network capable of accepting not only wired telephone service, wired CATV and wired data service but also various kinds of wireless services including LMDS, WLL, PCS and so forth, in which LMDS local wireless base station is located in a place adjacent to the splitting/combining device, WLL local wireless base station is located in a place adjacent to the splitting/combining device, optical network unit connects the conventional wired network composed of said optical fiber access network, twisted pair and coaxial cable, telephone service, data service and CATV service are provided through the optical network unit and PCS local wireless base station is located in a place adjacent to the optical network unit, is provided.

The invention is a novel method and apparatus for controlling the flow of traffic between a host digital terminal (HDT) and a plurality of optical network units (ONUs). Each ONU is connected to the HDT by optical fiber and to a plurality of subscribers by a respective plurality of subscriber drops (typically pre-existing copper twisted pairs). The bandwidth on the fiber, although large, is usually inferior to the total bandwidth that can be transmitted across the subscriber drops. Therefore, both upstream and downstream traffic may become congested at various "choke points" under certain circumstances of usage. Ordinarily, the data is buffered at the choke points, leading to the installation of large queues within each ONU. This solution is not only expensive, but is inadequate since the required queue size is dependent on the maximum transaction size, which has no hard upper bound. In contrast, the present invention provides a traffic shaper located in the HDT, which gives centralized control of the traffic flowing to and from the ONUs. Consideration of the priority and destination of each traffic cell is taken into account by the traffic shaper to ensure that the capacity of the fiber and of the individual drops is never exceeded, irrespective of the transaction sizes, thereby eliminating the need for costly buffers in the outside plant. Any maintenance or repairs of the traffic shaper can be easily effected without field visits, due to its centralized location.

Methods and systems for processing communication signals in an Orthogonal Frequency Division Multiple Access (OFDMA)-Passive Optical Network (PON) are disclosed. An optical carrier at a wavelength generated at an optical line terminal (OLT) may be reused by optical network units (ONUs) in the network for upstream transmission of data signals to the OLT. In addition, each ONU may perform carrier suppression to avoid broadband beating noise resulting from the simultaneous transmission of upstream data signals on the same wavelength. Further, the optical source at the OLT used to generate the optical carrier may be reused as a local oscillator for coherent detection of received upstream signals to minimize any frequency offsets.

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.

An apparatus and method for providing a security function of frames transmitted between optical network terminals (OLTs) and optical network units (ONUs) in an Ethernet passive optical network (EPON) providing media access control (MAC) services are provided. The apparatus includes: a frame classifier distinguishing the type of a frame, and based on the logical link identifier (LLID) of the distinguished frame, determining whether or not the frame is a security link to which a security function is to be applied; a bypass unit delaying a no-security-function frame so that a processing time for converting the security-function-applied frame classified in the frame classifier into an encrypted frame is the same as a time for processing the no-security-function frame; and a parameter generation unit transmitting in relation to each of the LLIDs, a parameter set value including a security-function-application setting signal used in the encryption, decryption and authentication of the frame, a frame decryption signal, an encryption mode selection signal, and an authentication intensity adjustment signal.

Methods and apparatuses consistent with the present invention facilitate the transition from a legacy network to an upgraded network by providing a converter that communicates between the legacy network and the upgraded network. The converter is provisioned such that legacy devices, such as Optical Network Units (ONUs), appear as upgraded devices to the upgraded network, while the upgraded network looks like a legacy network to the legacy devices.

A point-to-multipoint passive optical network transmits downstream data from an optical line terminal (OLT) to multiple optical network units (ONUs) in variable-length packets and upstream data from the ONUs to the OLT in variable-length packets utilizing time division multiplexing to avoid transmission collisions. In an embodiment, the variable-length downstream packets and the variable-length upstream packets are formatted according to IEEE 802.3. In an embodiment, the length of the variable-length downstream and upstream packets is related to the length of Internet protocol (IP) datagrams carried within the packets.

Provided is a hybrid passive optical network (PON) system. The hybrid PON system of wavelength division multiplexing (WDM)/time division multiplexing (TDM) may include an optical line terminal (OLT) and an optical network unit (ONU). The OLT and the ONU may transmit a signal based on wavelength reuse using a seed light source and a reflective modulator. The light source may include a seed light source having a single wavelength, two seed light sources having different wavelength bands, and a light source having a wavelength tunable characteristic.

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.

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.

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

A communication recovering system for a wavelength division multiplexed passive optical network (WDM PON). The communication recovering system can recover fault of optical fibers between the central office and the remote nodes without additional optical fibers by grouping two remote nodes and employing an AWG having periodic transmission characteristics, and can also simply and rapidly recover such a fault with minimal optical loss using an AWG of 2×N structure and an On-Off optical switch, although protection optical fibers are additionally installed therein. The system can rapidly recover fault of optical fibers between a local office and optical network units, 1:N manner, using 2×2 optical switches, which are installed to each of the optical network units, a reserved transmitter and receiver, and a transceiver. The communication recovering system has advantages in that it can simplify network structure, be cost-effectively implemented, reduce optical loss, and rapidly perform protection of optical fiber fault.

An apparatus, system, computer program, and method for providing a Multimedia over Coax Alliance (MoCA) (or other multimedia-over-coaxial cable technology) network in conjunction with an optical network. In example embodiments, MoCA data is communicated between network nodes in an optical signal. In other example embodiments, MoCA data, or other data, is transmitted in optical frequencies above 860 MHz.

The invention provides a unified optical network architecture for metro and access communication networks, wherein a metro ring network interfaces access PONs through one or more reconfigurable Optical Add/Drop Multiplexers to provide wavelength-reconfigurable all-optical transmission of communication signals from the metro ring network to designated optical network units associated with the end-users, and wherein one metro hub located in the metro ring network is utilized to set transmission wavelengths and timing for both downstream and upstream signal transmission for multiple access PONs.

A system includes an optical network unit and a head-end or central office connected to a multi-drop optical network. The optical network unit transmits dim optical pulses via the multi-drop optical network using quantum cryptographic mechanisms to distribute encryption key symbols, where the dim optical pulses include one of single-photon optical pulses or weak attenuated optical pulses. The head-end or central office detects the dim optical pulses from the optical network unit, derives the encryption key symbols from the detected dim optical pulses, and encrypts data transmitted to the optical network unit using the encryption key symbols.

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.

An optical network unit for managing digital subscriber line (×DSL) connections to a passive optical network. According to one embodiment, the optical network unit comprises data structures in the form of managed entities that are issued by the optical network unit for managing each of the ×DSL connections. Each managed entity is associated with one or more network features and comprises one or more elements further comprising relationships to other managed entities, attributes, actions, and notifications. The passive optical network provides a data connection between the individual ×DSL subscriber connections and external networks, such as the Internet and a switched telephone network.

A data communications system which provides multiple logical channels on a passive optical network (PON) using subcarrier multiple access (SCMA). The PON includes multiple optical network units (ONU) which each communicate with a head-end over a logical channel. Collisions among upstream transmissions are thereby avoided and high speed Ethernet service over large distances is made possible.

Various types of passive optical networks operate simultaneously in one passive optical network system comprising an optical line terminal, a passive remote node, and multiple optical network units. Downstream data is orthogonal frequency division multiplexed onto a single wavelength optical carrier transmitted on a primary downstream optical beam from the optical line terminal to a splitter in the passive remote node. The primary downstream optical beam is split into multiple secondary downstream optical beams; each is transmitted to a specific optical network unit. Upstream data is orthogonal frequency division multiplexed onto a single wavelength optical carrier transmitted on a secondary upstream optical beam from each optical network unit to a coupler in the passive remote node. The upstream wavelength for each optical network unit is different. The wavelength division multiplexed optical beam is transmitted from the passive remote node to a parallel signal detector in the optical line terminal.