At a ground-based transmitting system, a first processor receives and performs an N-to-N wavefront-multiplexing (WFM) transform on N signals and outputs N WFM signals, N>1. The N WFM signals are orthogonal to one another and each of which is a unique linear combination of the N signals. The N-to-N WFM transform has a unique inverse. A transmit back-end transmits the N WFM signals over a transmission medium via propagation channels. At a user terminal, a receive front-end receives the N transmitted WFM signals and generates N received WFM signals. An equalizer generates N equalized signals from the N received WFM signals. A second processor performs the unique inverse of the N-to-N WFM transform on the N equalized signals and outputs N wavefront demultiplexed signals, each of which is a unique linear combination of the N equalized signals and is a recovered version of a respective one of the N signals.

The present invention discloses an optical switching apparatus, an optical cross-connect node, and an optical signal switching method. The optical switching apparatus includes: N input ports, N OAM modulators in a one-to-one correspondence with the N input ports, an OAM splitter, and M output ports, where the M output ports are in a one-to-one correspondence with M OAM modes; a first input port of the input ports is configured to input a first optical signal, a target output port of the first optical signal is a first output port; a first OAM modulator corresponding to the first input port modulates the first optical signal into an optical signal of a first OAM mode corresponding to the first output port; the OAM splitter transmits, to the first output port, the first optical signal received from the first OAM modulator; and the first output port outputs the first optical signal.

An apparatus includes a demultiplexing device, a bank of filters, a wavefront processor, and an optimizer. The demultiplexing device demultiplexes M data streams into N wavefront signals which include P pilot signals, N, M, and P being positive integers and N>M. The bank of filters filters the N wavefront signals using filter weights. The wavefront processor, having N input ports and N output ports, performs an N-to-N wavefront demultiplexing transform on the N wavefront signals at the N input ports and outputs N wavefront demultiplexed signals at the N output ports such that each of the N wavefront demultiplexed signals is a linear combination of the N wavefront signals. The N wavefront demultiplexed signals include P recovered pilot signals. The optimizer updates the filter weights using performance indices based on the P recovered pilot signals and known pilot signals corresponding to the P pilot signals.

According to a signal transmitting method, a signal receiving method, and a related device and system, a generated single-wavelength optical carrier may be split into N subcarriers with a same wavelength by using a splitting device, corresponding data modulation and corresponding amplitude spread spectrum modulation are performed on the N subcarriers by using N spreading codes and N low-speed data signals obtained by deserializing a received high-speed data signal, to obtain N spread spectrum modulation signals, and the N spread spectrum modulation signals are combined and output. A multicarrier generation apparatus or the like having a relatively complex structure does not need to be used for optical carrier splitting, and spectrum spreading does not need to be performed in a phase modulation manner in which a plurality of delay units or controllable phase units are required.

A system is provided for high speed optical fiber data transmission by generating artificial wavefronts along multiple paths exhibiting spatial mutual orthogonality. Multiple independent signal streams are structured over a group of different propagation paths that are coherently organized by wavefront multiplexing and dc-multiplexing techniques. Therefore, signal streams with enhanced throughput and reliability may be fully recovered at destinations via embedded diagnostic signals and optimization loops. Multiple optical channels are matched with multiple orthogonal wavefronts created by a signal pre-processor. A receiving end signal post-processor dynamically aligns propagation paths via diagnostic signals and orthogonality of the propagation wavefronts electronically. The multiple optical channels are coherently bonded into a single virtual channel, thereby increasing data bandwidth while reducing interference and unwanted multi-path effects. The wavefront multiplexing and de-multiplexing functions may be performed in a dedicated signal processor or may reside in a general-purpose microprocessor located in the user terminal.

A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.

A communications system comprises a ground hub in a background area, aerial vehicles flying in a formation with slowly varying spacing between the aerial vehicles, and a user terminal in a region within a foreground area. The foreground area is spatially separate from the background area. The ground hub comprises a ground-based beam forming facility (GBBF) for receiving and transforming input signals into beam-formed signals, and a first antenna system coupled to the GBBF for transmitting concurrently the beam-formed signals in a first frequency band to respective aerial vehicles via respective background links. The aerial vehicles receive respectively the beam-formed signals via the background links and transmit respectively the beam-formed signals as respective signal beams covering at least the region within the foreground area in a second frequency band. The user terminal comprises a second antenna system for receiving concurrently the signal beams via foreground links to the aerial vehicles.

A mode division multiplexing system that includes a transmitter system, a receiver system and an optical link that optically connects the transmitter and receiver systems. The optical link includes a rectangular-core optical fiber having a rectangular core with a short dimension and a long dimension. The rectangular-core optical fiber supports only a single mode in the short dimension and multiple modes in the long dimension. A method of transmitting optical signals includes converting single mode optical signals to respective multimode optical signals each having a select spatial mode as defined by the rectangular-core optical fiber. The multimode optical signals are multiplexed and transmitted from the transmitter system to the receiver system over the rectangular-core optical fiber where the multimode optical signals are demultiplexed and converted back to single mode optical signals, which are then detected by respective receivers. A rectangular-core optical fiber is also disclosed.

The present disclosure provides example data transmission methods and apparatuses. One example method includes obtaining a radio signal by using an input port. Based on a correspondence between an input port and a bearer channel, a bearer channel corresponding to the radio signal is determined. Code Division Multiple Access (CDMA) modulation and carrier modulation on the radio signal are performed according to a codeword and a frequency sub-band corresponding to the bearer channel, to obtain a modulated electrical signal. The modulated electrical signal is then modulated to an optical wavelength corresponding to the bearer channel to obtain a modulated optical signal, and the modulated optical signal is sent to an optical network.

An apparatus for despreading in an optical domain configured to split a received optical signal into a first optical signal and a second optical signal, perform phase deflection on the second optical signal, output a third optical signal, perform phase deflection on the first optical signal and the third optical signal, output a fourth optical signal and a fifth optical signal to a balanced receiver, and superimpose the fourth optical signal and the fifth optical signal to generate a first electrical signal. A multiplication operation in conventional code division multiple access (CDMA) despreading is transferred from an electrical domain to an optical domain such that a chip rate can be easily raised to 20 gigahertz (GHz) or even to 25 GHz, a maximum rate of 100 gigabits per second (Gbps) can be provided in a single wavelength, and a user requirement for high bandwidth can be met.