An optical communication system includes a transmission unit that performs error correction encoding on information to be transmitted, and outputs a result of the error correction encoding as an optical signal, an optical coupler that branches the optical signal, and outputs a first and second optical signals, first and second error correction decoding units that each perform error correction decoding on an optical signal, and a communication disconnection detection unit that, upon detection of a disconnection of communication of the first optical signal, notifies, of the disconnection, the second error correction decoding unit. The second error correction decoding unit performs error correction decoding on the second optical signal when a notification of the disconnection has been received. The first error correction decoding unit performs the error correction decoding with a smaller number of iterations than the number of iterations used by the second error correction decoding unit.

We disclose a method for controlling access to an optically switched network, which connects N end-nodes, and is organized into a virtual data plane and a virtual control plane, which both communicate through the same underlying physical optical network. The virtual data plane provides any-to-all parallel connectivity for data transmissions among the N end-nodes, and the virtual control plane is organized as a ring that serially connects the N end-nodes, wherein a control token circulates around the ring. During operation, an end-node in the ring receives the control token, which includes a destination-busy vector with a busy flag for each of the N end-nodes. If the end-node has data to send and the busy flag for the destination end-node is not set, the system: sets the busy flag; commences sending the data to the destination end-node; and forwards the control token to a next end-node in the ring.

A transport network is configured to connect one or more optical rings of optical add and drop devices with one or more digital units in a radio access network. The transport network comprises a first electronic cross-connect and a second electronic cross-connect. A switch is provided for connecting the first electronic cross-connect and/or the second electronic cross-connect to the one or more digital units. The first and second electronic cross-connects are each coupled to at least one of the one or more optical rings of optical add and drop devices.

An optical network has an optical line termination coupled to a backbone network, in particular to an optical long haul network and a local exchange coupled to an optical access network. The local exchange provides an optical connection between an optical network unit of a tree topology and the optical line termination, which is part of a ring topology. There is also described a method for processing data in such an optical network.

The present disclosure discloses a method for training time slot synchronization of nodes in an Optical Burst Transport Network (OBTN), a node device and a network. The method includes that: a node trains a reference time delay between receiving of a control frame and receiving of a data frame, wherein the data frame and the control frame are within one period; and the node trains a sending time slot between sending of adjacent data packets in the data frame.

A high data rate distribution network for low-earth orbit (LEO) satellite constellations is described. The high data rate distribution network includes multiple LEO constellations, each constellation including a number of LEO spacecraft orbiting in a LEO plane that are all connected together by by-directional free space optical links. The distribution network further includes geostationary earth orbit (GEO) spacecraft in communication with a number of ground gateways. The GEO spacecraft can receive forward communication traffic including radio-frequency (RF) and/or optical data streams uplinked from the ground gateways and can convert the received forward communication traffic into a forward aggregated traffic. The GEO spacecraft can further optically downlink the forward aggregated traffic to LEO spacecraft in a LEO constellation that is in line of sight of the GEO spacecraft. The forward aggregated traffic is then disaggregated among and received by the LEO spacecraft in the LEO constellation. Return communication traffic from each LEO spacecraft can also be aggregated into a return aggregated traffic from the LEO constellation. The return aggregated traffic is optically uplinked to a GEO spacecraft by a LEO spacecraft of the LEO constellation that is in line of sight of the GEO spacecraft. The GEO spacecraft converts the received return aggregate traffic into multiple RF and/or optical data streams that are down linked to a number of ground gateways.

Provided are a method, a system and a node for implementing APS in an OBRing network. The method comprises: a master node and a slave node separately perform optical power monitoring on respective channels, and aggregate monitoring results to the master node; when determining, according to the monitoring results, that a fault occurs, the master node sends a switching operation instruction to the slave node; and the slave node performs a switching operation and enters a protection working state. With the disclosure, a protection switching mechanism is introduced to the OBRing, which implements the processing on fault and ensures the communication quality of the OBRing.

A network capable of being used in a datacenter is described. The network can comprise a set of optical fiber rings, wherein each optical fiber ring carries data traffic on multiple wavelengths, and wherein each optical fiber ring is partitioned into multiple sectors. In some embodiments, each sector in the multiple sectors can comprise: (1) only one add-wavelength-selective-switch (add-WSS) communicatively coupled to only one optical fiber ring in the set of optical fiber rings, wherein the only one add-WSS is used for sending all data traffic that originates from the sector and is destined to other sectors; (2) an add-electro-optical-switch (add-EOS) communicatively coupled to the add-WSS; (3) a set of drop-wavelength-selective-switches (drop-WSSs) communicatively coupled to the set of optical fiber rings, wherein the set of drop-WSSs are used for receiving data traffic from other sectors; and (4) a drop-electro-optical-switch (drop-EOS) communicatively coupled to a drop-WSS in the set of drop-WSSs.

The disclosure provides a method for bandwidth assignment of an Optical Burst Ring (OBRing), which includes that: a master node acquires current bandwidth resources, and excludes bandwidth resources occupied by over-the-master-node connections from the current bandwidth resources to obtain bandwidth resources to be assigned; and the master node assigns the bandwidth resources to be assigned to each node according to bandwidth requests of each node in the OBRing. The disclosure also provides a device for bandwidth assignment of an OBRing. According to embodiments of the disclosure, the bandwidth resources occupied by the over-the-master-node connections are excluded before bandwidth assignment is started, so that the problem of receiving conflict caused by an over-the-master-node service data connection is solved.

LEO satellites of orbital planes are configured to communicate with at least one GEO satellite based at least on present line of sight. GEO satellites are configured to communicate with ground gateways and convert among uplink communications and optical communications of GEO-to-LEO optical links established with selected LEO satellites and comprising optical beams within a wavelength multiplexed arrangement individually assigned to corresponding LEO satellites in each orbital plane. Selected LEO satellites are configured to optically demultiplex a GEO-to-LEO optical link into local optical beams on optical fibers, direct a demultiplexed assigned optical beam of an incoming LEO optical link from a previous in-plane LEO satellite to an onboard destination with an optical splitter on a corresponding optical fiber, and multiplex the local optical beams on the optical fibers for an outgoing free space LEO optical link directed to a subsequent in-plane LEO satellite.