A manner of managing data transmission and operating-mode transitions in a communication network. A network node having a transmitter and receiver is selectively transitioned into a Transmit state, where the Transmit state is a condition wherein the transmitter is turned on for data transmission only during timeslots provided for by a PBW (pre-allocation bandwidth) and remains off otherwise. The PBW and clock drift allowance permits the receiver to remain off during all or most of the Transmit state.

A method implemented by a wireless fronthaul unit, the method comprises aggregating a plurality of first wireless channel signals to produce a first aggregated signal via digital frequency-domain mapping (FDM), wherein the first wireless channel signals are positioned in the first aggregated signal in non-overlapping first frequency bands, each non-overlapping first frequency band having a first bandwidth and a center frequency, wherein each respective center frequency is an odd integer multiple of a lowest center frequency, converting the first aggregated signal into a first modulated signal, and transmitting the first modulated signal to a wireless fronthaul link.

A method implemented by a wireless fronthaul unit, the method comprises aggregating a plurality of first wireless channel signals to produce a first aggregated signal via digital frequency-domain mapping (FDM), wherein the first wireless channel signals are positioned in the first aggregated signal in non-overlapping first frequency bands, each non-overlapping first frequency band having a first bandwidth and a center frequency, wherein each respective center frequency is an odd integer multiple of a lowest center frequency, converting the first aggregated signal into a first modulated signal, and transmitting the first modulated signal to a wireless fronthaul link.

Multiple network controllers are interconnected in a full mesh structure, e.g., through a cyclical cross connector, to form a distributed control system for a network of a large number of nodes. A network controller acquires characterizing information of links emanating from a respective set of nodes, communicates the information to each other network controller, and determines a route set from each node of the respective set of nodes to each other node of the network. The network controller may determine, for each link included in the route set, identifiers of specific route sets which traverse the link. Accordingly, a state-change of any link in the network can be expeditiously communicated to network controllers to take corrective actions where necessary. A network controller may rank routes of a route set according to some criterion to facilitate selection of a favourable available route for a connection.

In order to prevent, without significantly reducing the power of a transmission path, a signal unnecessary for a branch station from being intercepted at the branch station, a node apparatus comprises: a first optical unit that outputs a first optical signal received from a first terminal station and addressed to a second terminal station and also outputs a second optical signal received from the first terminal station and addressed to a third terminal station; and a second optical unit that receives the first and second optical signals outputted from the first optical unit, optically removes a portion of the spectrum of the first optical signal, thereby generating a fourth optical signal, and passes the second optical signal as it is, thereby transmitting the second optical signal together with the fourth optical signal to the third terminal station.

Methods, systems, and devices for network communications to reduce optical beat interference (OBI) in upstream communications are described. For example, a fiber node may provide a seed source to injection lock upstream laser diodes. Therefore, upstream communications from each injection locked laser diode may primarily include the wavelength associated with each seed source. The seed sources may be unique to each end device and configured to minimize OBI. That is, the upstream laser diodes may be generic, but the collected seed source may enable upstream communications at varying wavelengths. The end device may provide upstream communications by externally modulating a signal generated by the injection locked laser diode.

A spatial multiplexing optical receiver includes a plurality of coherent receivers configured to coherently receive each of spatially multiplexed and transmitted signals of a plurality of modes by using continuous wave light independent for each mode as local oscillator light, a plurality of frequency offset compensators configured to perform frequency offset compensation based on a correlation between a known training signal and a signal of each mode independently for each mode, for each of the coherently received signals of the plurality of modes, and a MIMO signal processing unit configured to perform MIMO signal processing on the signals of the plurality of modes subjected to the frequency offset compensation in the frequency offset compensator.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

Data center interconnections, which encompass WSCs as well as traditional data centers, have become both a bottleneck and a cost/power issue for cloud computing providers, cloud service providers and the users of the cloud generally. Fiber optic technologies already play critical roles in data center operations and will increasingly in the future. The goal is to move data as fast as possible with the lowest latency with the lowest cost and the smallest space consumption on the server blade and throughout the network. Accordingly, it would be beneficial for new fiber optic interconnection architectures to address the traditional hierarchal time-division multiplexed (TDM) routing and interconnection and provide reduced latency, increased flexibility, lower cost, lower power consumption, and provide interconnections exploiting scalable optical modular optically switched interconnection network as well as temporospatial switching fabrics allowing switching speeds below the slowest switching element within the switching fabric.