1314results about "Time-division optical multiplex systems" patented technology

A method and an apparatus measure blood oxygenation in a subject. A first signal source applies a first input signal during a first time interval. A second signal source applies a second input signal during a second time interval. A detector detects a first parametric signal responsive to the first input signal passing through a portion of the subject having blood therein. The detector also detects a second parametric signal responsive to the second input signal passing through the portion of the subject. The detector generates a detector output signal responsive to the first and second parametric signals. A signal processor receives the detector output signal and demodulates the detector output signal by applying a first demodulation signal to a signal responsive to the detector output signal to generate a first output signal responsive to the first parametric signal. The signal processor applies a second demodulation signal to the signal responsive to the detector output signal to generate a second output signal responsive to the second parametric signal. The first demodulation signal and the second demodulation signal both include at least a first component having a first frequency and a first amplitude and a second component having a second frequency and a second amplitude. The second frequency is a harmonic of the first frequency. The second amplitude is related to the first amplitude to minimize crosstalk from the first parametric signal to the second output signal and to minimize crosstalk from the second parametric signal to the first output signal.

An optical signaling header technique applicable to optical networks wherein packet routing information is embedded in the same channel or wavelength as the data payload so that both the header and data payload propagate through network elements with the same path and the associated delays. The header routing information has sufficiently different characteristics from the data payload so that the signaling header can be detected without being affected by the data payload, and that the signaling header can also be removed without affecting the data payload. The signal routing technique can be overlaid onto the conventional network elements in a modular manner using two types of applique modules. The first type effects header encoding and decoding at the entry and exit points of the data payload into and out of the network; the second type effects header detection at each of the network elements.

A wireless communication system comprises a base station controller and a base station interface connected to the base station controller by a central optical fiber. The base station interface may include a flexible wavelength router. At least one base station is connected to the base station interface, and the central optical fiber carries at least one communication channel associated with an optical signal having one of a plurality of wavelengths. The base station interface selectively provides a communication path between the base station controller and at least one base station using at least one communication channel.

A network system and method include a wireless base station integrated at a central office of a service provider. The wireless base station is configured to provide portable and fixed services to customers. A passive optical network is coupled to the wireless base station at the central office to provide a link to extend an antenna for wireless operations of the wireless base station to a remote site such that a wireless signal from the wireless base station is transmitted in parallel with a passive fiber network signal through the link.

Systems and methods for visible light communication are disclosed. In part, illumination devices and related systems and methods are disclosed that can be used for general illumination, lighting control systems, or other applications. The illumination devices synchronize preferentially to the AC mains to produce time division multiplexed channels in which control information can be communicated optically by the same light source that is producing illumination. Such illumination devices preferentially comprise LEDs for producing illumination, transmitting data, detecting ambient light, and receiving data, however, other light sources and detectors can be used. The physical layer can be used with a variety of protocols, such as ZigBee, from the Media ACcess (MAC) layer and higher.

A communication system is disclosed for providing dedicated bandwidth to at least one subscriber location for transmitting to a common point of distribution via an HFC network. In an embodiment of the invention, the communication system includes a channel interface module and at least one gateway coupled across the HFC network. The channel interface module is located at the point of distribution and includes a transmitter that transmits a windowing signal via the HFC network. The gateway is located at a subscriber location and includes a processor that encapsulates subscriber data into data cells suitable for burst transmission, receive logic that receives the windowing signal, timing logic that indicates burst transmission times only at programmed time slots within each of repeating transmission windows based on the windowing signal and a predetermined transmission timing offset, and a burst transmitter that burst transmits subscriber data cells in a predetermined upstream frequency channel when indicated by the timing logic.

A time-sharing Visible Light Communication (VLC) system is provided. Two or more light sources transmit data received from one or more VLC terminals located in its service area to a communication control device, and transmits data received from the communication control device to the one or more VLC terminals. The communication control device determines and groups at least one of the two or more light sources to be included in a cell according to a generated user service, maps the grouped at least one light source to the cell, allocates a time slot used to provide the user service to the cell, transmits data associated with the user service to at least one of the one or more VLC terminals through the at least one light source mapped to the cell using the allocated time slot, detects a location of the at least one VLC terminal located in a service area of the cell on a real-time basis, and remaps the cell according to the detected location.

A LADAR apparatus and a method for use in receiving a LADAR signal are disclosed. The apparatus includes an optical pickup capable of picking up a plurality of optical signals; a timing synchronization reference; a time domain multiplexer capable of multiplexing the optical signals into a multiplexed optical signal relative to the timing synchronization reference; and an optical detector capable of detecting the multiplexed optical signal. The method include time domain multiplexing a plurality of LADAR signals into multiplexed LADAR signal; detecting the multiplexed LADAR signal; and demultiplexing the detected LADAR signal.

There is provided a transmission device including an optical signal generation section configured to generate an optical signal formed by arranging one or more of each of a plurality of kinds of same-color light beams each having different phase, and a transmission section configured to transmit the optical signal generated by the optical signal generation section.

Optical communication apparatuses capable of performing appropriate communication according to a distance to a receiving apparatus, optical communication methods, and an optical communication system are provided. A transmitting apparatus transmits an optical signal corresponding to data. The transmitting apparatus modulates intensity of the optical signal into intensity corresponding to a distance over which the data is to be delivered and outputs this intensity-modulated optical signal. This allows the transmitting apparatus to change the intensity of the optical signal corresponding to the data according to a distance to a receiving apparatus that receives the data, which thus allows the receiving apparatus to surely receive the data.

A Visible Light Communication (VLC) method in a VLC terminal, in which the VLC terminal requests initial access to an Access Point (AP) on a selected mini-slot among a plurality of mini-slots constituting a control slot, based on control information in a frame, sends an association request to the AP on an allocated uplink time slot, if the uplink time slot allocated to correspond to the selected mini-slot exists in control information in a next frame, and transmits data at a data rate appointed to the VLC terminal included in control information in the current frame using an association Identifier (ID) included in a response received in reply to the association request and the allocated uplink time slot.

A communications network, suitable, for example, for linking computer processors, is formed from a number of nodes and links. The nodes and links are configured as a multiplicity of directed trails. Each directed trail spans some only of the nodes, but in combination the directed trails span every node of the network. Packets are routed through the network by selecting the appropriate one of the directed trails which links the source node and destination node, and by outputting the packet at the source node onto the selected trail. The nodes throughout the network may switch between predetermined and prescheduled switching states, and a given trail may be selected by choosing appropriately the time slot in which the packet is put onto the network. The network may be a photonic network carrying optical packets.

A system and method for managing the optical layer network data communications of an optical fiber data network by an optical transceiver module is disclosed. The management of the optical layer network data communications comprising data link layer functions or layer 2 functions in an OSI model. Benefits include reduction in reduced cost of network deployments from consolidation of network equipment, such as switches, and reduction in power consumed as well as enabling point-to-multipoint network connections from previously only point-to-point network connection.

Data carrying optical signals are subjected to equalization or pulse shaping of the optical signal waveform. A plurality of optical tap signals derived from the optical signal are used to control a modulator operating on an input signal to provide an output signal having the desired waveform. A Mach-Zehnder interferometer having semiconductor optical amplifiers in each arm provides modulation by the effect of cross modulation induced by propagating the respective tap signals through a selected one of the semiconductor optical amplifiers. Various forms of transversal filter are provided by selecting the number of optical taps, assigning positive or negative weights and appropriate delays. The effects of dispersion in optical signals can be mitigated by utilizing optical taps with negative weights to subtract tail portions from the leading and trailing edges of a signal pulse. The invention has application to systems with high bit rates where equalization or pulse shaping in the electrical domain is difficult to implement.

An access point in an optical fiber-based high-speed optical wireless network is disclosed. The access point includes an antenna for receiving communication requirement signals, a switch for selectively outputting a corresponding signal according to the communication requirement signals, a bias control unit for selectively outputting bias current with variable intensity according to whether an output of the signal from the switch exists or not, on the basis of a threshold current; a bias operation unit for outputting input signals to the antenna when an input bias current is smaller than the threshold current and for outputting signals received by the antenna when an input bias current is larger than the predetermined threshold current, and a semiconductor optical amplifier for selectively performing an optical detection function of converting optical signals, which have been received through a first optical fiber from an central station, into electrical signals and sending the converted electrical signals to the bias operation unit, when a current smaller than the threshold current is input to the bias operation unit, and an optical modulation function of transmitting signals output from the bias operation unit through a second optical fiber to the central station, when a current larger than the threshold current is input to the bias operation unit.

Disclosed is a method for operating a wavelength-division-multiplexed passive optical network (WDM-PON) including an optical line terminal (OLT) and a plurality of optical network units (ONUs), each of which is connected to the OLT and communicates with the OLT. The method comprises the steps of transmitting a first control channel including allocation information of downstream data channels and allocation information of time slots for the downstream data channels to each of the plurality of ONUs; and transmitting downstream data to the plurality of ONUs using their associated downstream data channels, each having at least one time slot, based on the information included in the first control channel.

Systems and methods for visible light communication are disclosed. In part, illumination devices and related systems and methods are disclosed that can be used for general illumination, lighting control systems, or other applications. The illumination devices synchronize preferentially to the AC mains to produce time division multiplexed channels in which control information can be communicated optically by the same light source that is producing illumination. Such illumination devices preferentially comprise LEDs for producing illumination, transmitting data, detecting ambient light, and receiving data, however, other light sources and detectors can be used. The physical layer can be used with a variety of protocols, such as ZigBee, from the Media ACcess (MAC) layer and higher.

An optical fiber ring network includes a plurality of interconnected nodes, each pair of neighboring nodes being interconnected by a pair of optical links. Using coarse wavelength division multiplexing, data is transmitted in both directions over each link, using a first wavelength λ1 to transmit data in a first direction over the link and a second wavelength λ2 to transmit data in a second, opposite direction over the link. The two wavelengths λ1 and λ2 differ by at least 10 nm. Each of the data streams transmitted over the optical link has a bandwidth of at least 2.5 Gbps. Further, each data stream has at least two logical streams embedded therein. A link multiplexer at each node of the network includes one or more link cards for coupling the link multiplexer to client devices, and one or more multiplexer units for coupling the link multiplexer to the optical links. Each link card includes frame buffers capable of storing numerous Fiber Channel frames that are being transmitted to and from the client device(s) coupled to that link card. The link card also includes flow control logic for pre-filling the frame buffers with frames of data before the receiving client devices send flow control messages to request their transmission. The combined effect of the frame buffers and flow control logic is that the full bandwidth of the links can be utilized even when the network nodes are very far apart and the client devices have small input data buffers.

A radio-over-fiber (RoF) hybrid wired / wireless transponder is disclosed that is configured to provide both wireless and wired communication between a hybrid head-end and one or more client devices. The hybrid transponder includes optical-to-electrical (O / E) and electrical-to-optical (E / O) conversion capability and is configured to frequency multiplex / demultiplex electrical “wired” signals and electrical “wireless” signals. The electrical wireless signals are wirelessly communicated to the client device(s) via a multiple-input / multiple-output (MIMO) antenna system within a cellular coverage area. The electrical wired signals are communicated to the client device(s) via a wireline cable that plugs into a wireline cable port on the transponder. The hybrid RoF system includes a hybrid head-end capable of transmitting and receiving wired and wireless optical signals, and an optical fiber cable that is optically coupled to the hybrid head-end and to at least one hybrid transponder. Drop-down transponder configurations that allow for easy wired and wireless connectivity between the client device(s) to the transponder(s) are also disclosed.

To more fully utilize the available bandwidth of a network link, network nodes in accordance with the present invention allow TDM data to be combined with packet data. A Packet / TDM cross connect switch, having both a TDM switch and a packet switch, is used in these embodiments. Data packets are transformed into TDM packet columns. The TDM packet columns are combined with standard TDM data columns in the payload of a TDM data frame. Data packets may be sorted based on a priority scheme, in which high priority data packets are given precedence over lower priority data. However, both high priority and low priority may be combined in a TDM packet column.

A protocol for an optical network can control the time at which subscriber optical interfaces of an optical network are permitted to transmit data to a transceiver node. The protocol can prevent collisions of upstream transmissions between the subscriber optical interfaces of a particular subscriber group. With the protocol, a transceiver node close to the subscriber can allocate additional or reduced upstream bandwidth based upon the demand of one or more subscribers. That is, a transceiver node close to a subscriber can monitor (or police) and adjust a subscriber's upstream bandwidth on a subscription basis or on an as-needed basis. The protocol can account for aggregates of packets rather than individual packets. By performing calculation on aggregates of packets, the algorithm can execute less frequently which, in turn, permits its implementation in lower performance and lower cost devices, such as software executing in a general purpose microprocessor.

Loss of optical signal is detected in a synchronous communications system by detecting features of a monitor signal occurring at a detection frequency corresponding to the frame rate. Since the frame rate is substantially less than the bit rate, monitoring and detection can be performed at a lower bandwidth than the bit rate. An auto-correlation circuit utilises delays which are an integral multiple of the frame rate and produces a detection value which is compared with a threshold value. Alternatively, detection may be based on a power measurement of a band pass filtered monitor signal by setting the lower bandwidth limit above zero frequency and normalizing the measurement of power relative to an average power measurement. A loss of signal may then be detected by a change in power measurement relative to a threshold and can be used for asynchronous systems as well as synchronous systems. Loss of signal detection may be utilised to control an optical switch to re-route optical signals and generate alarm signals. The use of such detection in all optical networks avoids the requirement for electronic processing at the bit rate as a means of detection of loss of signal.

A signal strength corresponding to an incoming optical burst from each of a plurality of optical nodes is measured. The measurements can be performed at system start-up, configuration / installation of the optical nodes and / or at certain intervals of operation of the optical nodes. Signal strength information for the optical nodes based on the measurements is stored in memory. When scheduling the optical nodes for transmission, a preferred transmission order is determined in response to the stored signal strength information. In an embodiment, the preferred order is determined to reduce differences in signal strength levels between consecutive optical bursts.

A protocol for an optical network can control the time at which subscriber optical interfaces of an optical network are permitted to transmit data to a transceiver node. The protocol can prevent collisions of upstream transmissions between the subscriber optical interfaces of a particular subscriber group. With the protocol, a transceiver node close to the subscriber can allocate additional or reduced upstream bandwidth based upon the demand of one or more subscribers. That is, a transceiver node close to a subscriber can monitor (or police) and adjust a subscriber's upstream bandwidth on a subscription basis or on an as-needed basis. The protocol can account for aggregates of packets rather than individual packets. By performing calculation on aggregates of packets, the algorithm can execute less frequently which, in turn, permits its implementation in lower performance and lower cost devices, such as software executing in a general purpose microprocessor.

An optical device includes, a first Mach-Zehnder modulator that produces a first output, and a second Mach-Zehnder modulator which produces a second output. A splitter couples the first and second Mach-Zehnder modulators. A combiner combines the first and second outputs. A phase shifter is coupled to the first and second Mach-Zehnder modulators. The first Mach-Zehnder modulator, second Mach-Zehnder modulator, splitter, combiner and the phase shifter are each formed as part of a single chip made of electro-optical material. Such two similar optical device integrated together with polarization combiner provide a two-polarization performance.

The polarization direction of an optical signal is changed by a polarization controller so as to be orthogonal to a main axis of a polarizer. A control pulse generator generates control pulses from control beam with a wavelength which is different from the wavelength of the optical signal. The optical signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the optical signal, during a time period in which the optical signal and the control pulse coincide, is amplified with optical parametric amplification around a polarization direction of the control pulse. The optical signal, during the time period in which the optical signal and the control pulse coincide, passes through the polarizer.

The present invention discloses a method for transmitting signal between a central channel processing Main Unit (MU) and one or more Remote Radio Units (RRUs) by using SDH / OTN in Centralized Base Transceiver Station system using remote radio head (RRH) technology. The method includes: dividing the communication interface between the MU and the RRUs into a user plane and a control plane, the user plane mainly for carrying I / Q sampling data concerning the user data, and the control plane mainly for carrying the data concerning control signaling; forming the I / Q sampling data concerning the user data carried by the user plane into an I / Q data frame via an I / Q data frame adaptation layer, then forming the I / Q data frame into a GFP frame via GFP and transmitting it on SDH / OTN; and carrying the control signaling of the control plane on UDP / IP and / or TCP / IP, and further carrying IP packet on PPP and forming it into a frame by HDLC, transmitting the HDLC frame including the control plane signaling on the SDH / OTN via the control character channel of the GFP frame. According to the present invention, the existing SDH / OTN transmission network is utilized directly, which further reduces the management and maintenance operation needed for signal transmission, as well as networking cost.