Embodiments of the disclosure relate to wireless distribution systems (WDSs) employing an optical star communications architecture based on quad small form-factor pluggable (QSFP) coarse wavelength division multiplexing (CWDM) transceivers. In one aspect, a selected QSFP CWDM transceiver among one or more QSFP CWDM transceivers wavelength multiplexes a plurality of downlink optical communications signals to generate a WDM downlink communications signal and provides WDM downlink communications signal to a selected remote unit branch among one or more remote unit branches in the WDS. In another aspect, the selected QSFP CWDM transceiver wavelength de-multiplexes a WDM uplink communications signal received from the selected remote unit branch into a plurality of uplink optical communications signals. By supporting an optical star communications architecture based on the selected QSFP CWDM transceiver, it may be possible to reduce total length of optical fibers in the WDS, thus leading to reduced optical fiber material and installation costs.

An optically-switch data network includes an optical data bus, an optical wavelength bus, and multiple nodes connected by the optical data bus and the optical wavelength bus. A first node determines that it has communication information to transmit to a second node, and determines if a first subscription signal is present on the optical wavelength bus. The first subscription signal includes a target frequency. If the first subscription signal is not present on the optical wavelength bus, the first node injects an optical communication signal onto the optical data bus. The optical communication signal includes the communication information and a carrier wave. The carrier wave includes the target frequency. The second node receives the optical communication signal using the optical data bus. If the first subscription signal is present on the optical wavelength bus, injection of the optical communication signal onto the optical data bus is postponed.

A distributed antenna system (DAS) includes a master unit; a plurality of remote units communicatively coupled with the master unit and distributed to provide coverage within a service area, each of the remote units remotely located from the master unit and other remote units; a coupler element coupled to receive a plurality of MIMO signals, the MIMO signals including first and second MIMO signals, the coupler element configured to: introduce a phase shift in a first portion of the first MIMO signal to generate a first phase shifted portion of the first MIMO signal; combine the first phase shifted portion with a second portion of the second MIMO signal to generate a combined MIMO signal; and present the combined MIMO signal at a first output port of the coupler element; at least one antenna coupled with each remote unit and configured to receive the combined MIMO signal for transmission.

A subsea optical communication network includes branch systems whereby transponders may be connected to trunk fibers carrying data to and from the transponders, e.g., to and from shore. Trunk nodes split transponder receive signals off the trunk and couple transponder transmit signals onto the trunk. Each trunk node also removes a wavelength/channel from the trunk signal to compensate for the wavelength being added with transponder data. Removed wavelengths may be selected from idler wavelengths, e.g., empty channels or noise, or previously dropped transponder wavelengths. Branch signals may be single wavelength in either direction, allowing the use of low-bandwidth repeaters, and the same wavelength may be used in both directions. Branch signals may alternatively contain plural wavelengths that load a standard wide-bandwidth commercial repeater, where an optical add drop multiplexer is used to select the wavelength of interest to the transponder after the repeater.

A dense wavelength-division multiplexing (DWDM) optical network comprises an optical bus, which includes an optical source configured to generate a plurality of unmodulated optical signals each having a different wavelength; an optical multiplexer configured to multiplex the unmodulated optical signals to produce a combined, unmodulated optical signal, and to transmit the combined, unmodulated optical signal through an optical fiber; a plurality of nodes connected in sequence to the output of the optical multiplexer. The plurality of nodes are connected by the optical fiber. A DWDM optical network and a method of operation of the DWDM optical network are also disclosed therein.

Optical solutions to address and overcome the issues of superseding/replacing electrical interconnection networks have generally exploited some form of optical space switching. Such optical space switching architectures required multiple switching elements, leading to increased power consumption and footprint issues. Accordingly, it would be beneficial for new optical, e.g. fiber optic or integrated optical, interconnection architectures to address the traditional hierarchal time-division multiplexed (TDM) space based routing and interconnection to provide reduced latency, increased flexibility, lower cost, and lower power consumption. Accordingly, it would be beneficial to exploit networks operating in multiple domains by overlaying mode division multiplexing to provide increased throughput in bus, point-to-point networks, and multi-cast networks, for example, discretely or in combination with wavelength division multiplexing.

Optical solutions to address and overcome the issues of superseding/replacing electrical interconnection networks have generally exploited some form of optical space switching. Such optical space switching architectures required multiple switching elements, leading to increased power consumption and footprint issues. Accordingly, it would be beneficial for new optical, e.g. fiber optic or integrated optical, interconnection architectures to address the traditional hierarchal time-division multiplexed (TDM) space based routing and interconnection to provide reduced latency, increased flexibility, lower cost, and lower power consumption. Accordingly, it would be beneficial to exploit networks operating in multiple domains by overlaying mode division multiplexing to provide increased throughput in bus, point-to-point networks, and multi-cast networks, for example, discretely or in combination with wavelength division multiplexing.

The present invention is directed to a low latency fiber optic local area network with a network and a plurality of nodes connected through optical fibers. Each node has a plurality of bi-directional input/output interfaces. Each bi-directional input/output interface has a demultiplexer, at least one optical power coupler, a plurality of wavelength converters, and a plurality of internal optical waveguides. The internal optical waveguides extend from each wavelength converter and are for communication with the demultiplexer, the input fiber optic interface, and the optical fiber. Each optical power coupler has a fiber optic output interface for communication with other nodes, and each demultiplexer has a input fiber optic interface for communication with other nodes.

The disclosures provide a method and apparatus for transmitting and receiving interface signals of a distributed base station. At least one channel of Common Public Radio Interface (CPRI) signals of a distributed base station are encapsulated into optical transport unitx (OTUx) signals in a frame structure of OTUx by adopting Generic Mapping Procedure (GMP) mapping scheme, wherein the x represents a transmission capacity and wherein the OTUx is adopted for providing a bandwidth required by the at least one channel of CPRI signals, and then the OTUx signals that bear the at least one channel of CPRI signals are sent.

A disclosed optical transport system is configured to use hierarchical modulation for better utilization of the available BER margin, e.g., to increase data-transport capacity per carrier wavelength in the system. For example, hierarchical modulation may be used to reduce the number of carrier wavelengths assigned to support a given volume of bidirectional data transport between a set of nodes in an optical backbone network. An embodiment of the disclosed optical transport system can advantageously be constructed by modifying a conventional WDM system, e.g., by adding configurable hierarchical-layer mappers at some of the nodes and modifying some of the ROADMs used therein to enable a drop-and-continue mode of operation.