A system for optical communications may include a multiplicity of optical communications relay platforms that each move above a surface of the earth. Each relay platform may include a relay link for communications between adjacent relay platforms. The system may also include a plurality of ground stations. Each ground station may be configured to communicate with another of the ground stations through at least one of the relay platforms. Each ground station may include an optical communications link for optical communications with successive relay platforms. The optical link of each ground station may be configured for handover connections between the successive relay platforms as the relay platforms move relative to the earth. The system may additionally include a network operations center having a link controller. The link controller may be configured to control switching of the communications links for hitless transmission between the ground stations.

An embodiment method for managing connections on a communications network having an optical network portion includes receiving a request for a first connection at a controller in signal communication with one or more reconfigurable optical add-drop multiplexers (ROADMs) controlling an optical network portion of a communications network, wherein the controller is connected to the communications network. The controller determines a route on the communications network for the first connection according to conditions of the communications network, with the route comprising one or more first links of the optical network. The controller determines one or more first ROADMs controlling the one or more first links and sends commands from the controller to the one or more first ROADMs to allocate bandwidth on the one or more first links.

A matrix M indicating a minimum number of all optical paths between pairs of nodes may be generated in one embodiment using an algorithm for transitive closure. In various embodiments, different algorithms and methods may be used to generate matrix M. Once a convergent matrix M has been generated that attains transitive closure, any corresponding reachability matrix RM^a may be obtained from matrix M in a computationally efficient manner. Matrix M may be used to determine groups of potential regenerator placements and obtain end-to-end optical paths by selecting desired sequences of regenerators.

An embodiment method for managing connections on a communications network having an optical network portion includes receiving a request for a first connection at a controller in signal communication with one or more reconfigurable optical add-drop multiplexers (ROADMs) controlling an optical network portion of a communications network, wherein the controller is connected to the communications network. The controller determines a route on the communications network for the first connection according to conditions of the communications network, with the route comprising one or more first links of the optical network. The controller determines one or more first ROADMs controlling the one or more first links and sends commands from the controller to the one or more first ROADMs to allocate bandwidth on the one or more first links.

An apparatus stores information identifying unallocated channels for each of spans, where a span indicates a section between adjacent nodes of a plurality of nodes in a communication network. The apparatus extracts unallocated channels for each of all spans provided between a start point node and an end point node of a path in the communication network, by referring to the information, and determines a channel including consecutive unallocated spans which are arranged on routes including the path and spans outside the path, and whose number is minimum among the extracted unallocated channels, as a channel to be set to the path.

Validating a path in an optical layer of a communications network, for client traffic having an associated service level, involves setting an optical quality margin according to the service level associated with that client traffic. The optical quality margin indicates how close an estimated optical quality of the path can approach a level which produces a threshold error rate. This margin is used to check whether the estimated optical quality is within the optical quality margin set according to the client traffic service level. Making the optical quality margin dependent on client traffic service level, can enable increased optical reach. This can give more flexibility in path selection and enable better matching to service levels of client traffic.

There is provided a network management device to manage a network on which an existing optical path is operated, the network management device including: a first receiver configured to receive data related to a measurement result of signal quality of a first optical signal having a first wavelength on the existing optical path; a second receiver configured to receive a request for adding a second optical signal having a second wavelength to the existing optical path; at least one memory configured to store a procedure; and at least one processor configured to execute the procedure of estimating a variation quantity in the signal quality of the first optical signal when the second optical signal is added to the existing optical path based on the data related to the measurement result, when the request is received, and determining whether to add the second optical signal based on results of the estimating.

Provided is a monitoring apparatus capable of efficiently optimizing the transmission efficiency of an entire network. The monitoring apparatus (1) includes a variable parameter changing unit (2), a monitoring information acquisition unit (4), and an estimation unit (6). The variable parameter changing unit (2) changes a variable parameter for at least one of multiple network apparatuses that constitute an optical communication network transmitting an optical signal by wavelength division multiplexing. The monitoring information acquisition unit (4) acquires monitoring information related to a state of optical communication from at least one of the multiple network apparatuses. The estimation unit (6) estimates at least one penalty for a receiving side, using the monitoring information.

There is provided a distance-adaptive and fragmentation-aware all-optical traffic grooming (DFG) method, which addresses the all-optical traffic grooming problem while considering the transmission reach constraints. The DFG procedure provisions traffic demands in optical channels such that the spectrum requires for guard bands is minimized. The DFG procedure provisions optical channels such that network fragmentation is minimized while ensuring the transmission reach constrains over flexible-grid WDM networks.

Routing of optical paths through an optical network may account for both linear and non-linear effects of the physical layer when determining the route. The non-linear effects may be determined only as necessary, allowing the non-linear effects to be included in the routing determination for larger optical networks.