An optical transmission system in which a transmitting station and a plurality of receiving stations are connected via an optical splitter, wherein the transmitting station includes: a controller configured to determine whether to perform intensity modulation or phase modulation on optical signals based on information on transmission distances to the receiving stations and modulation bands; an intensity modulator configured to perform intensity modulation on an optical signal; and a phase modulator configured to perform phase modulation on an optical signal, and wherein one of an intensity modulation signal and a phase modulation signal is transmitted from the transmitting station to each of the receiving stations.

A transmission device includes: a first mapper that maps a first bit stream of a first data series to generate a first modulated symbol stream of the first data series; a second mapper that maps a second bit stream of a second data series to generate a second modulated symbol stream of the second data series; a converter that subjects the second modulated symbol stream to conversion in accordance with the first modulated symbol stream; a superposition unit that superposes the first modulated symbol stream and the second modulated symbol stream at a predetermined amplitude ratio to generate a multiplexed signal, the second modulated symbol stream having been subjected to the conversion in accordance with the first modulated symbol stream; and a transmitter that transmits the multiplexed signal.

A fixed communication network is disclosed in which a plurality of transmitters feed signals via tributary transmission lines of different lengths onto a shared network component. A timing reference signal is distributed to the transmitters. The shared network component in some embodiments takes the form of a transmission line. In order to enable the sharing of the capacity of the shared network component, each of the plurality of transmitters codes data for transmission in accordance with a code division multiple access scheme. The efficiency of usage of the shared network component is improved by synchronizing the arrival of the encoded bits at the shared network component. This is achieved by populating a store within each transmitter with a pre-set timing offset, and timing the transmission of data in accordance with the timing reference signal received by the transmitters and the pre-set timing offset.

Embodiments of the present invention provide a receiver and a data receiving method. The receiver includes: two first input ends, configured to receive a digital signal of an X-polarization state and a digital signal of a Y-polarization state; a despreading module, configured to despread the digital signal of the X-polarization state and the digital signal of the Y-polarization state based on N delay values and spreading codes of N transmitters, to obtain N first baseband signals and N second baseband signals; and a multiple-input multiple-output equalization module, configured to perform equalization filtering processing on the N first baseband signals and the N second baseband signals, to obtain recovered data of the first polarization states and recovered data of the second polarization states of the N transmitters. In the embodiments of the present invention, the coherent CDMA multipoint-to-point data transmission in an optical communications system is implemented.

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 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.

A compact system for active co-boresight measurement includes a detector, a steering mirror, and a controller. The detector detects a portion of a transmission beam emitted by a transceiver and a portion of a received beam that is received from a remote terminal. The controller measures an offset between the detected portion of the received beam and the detected portion of the transmission beam. The controller controls a position of the steering mirror to align the portion of the received beam with a defined position on the detector, the defined position based in part on the offset.

Embodiments of this application provide a data transmission method, a terminal device, and a network side device. Encoding, by a terminal device, a first identifier by using a first code word which is selected from at least one code word by the terminal device; sending, by the terminal device, the encoded first identifier to a network side device; receiving, by the terminal device, a second identifier sent by the network side device; decoding, by the terminal device, the second identifier by using the first code word; when the decoded second identifier is the same as the first identifier, encoding, by the terminal device, subsequent data by using the first code word; and sending, by the terminal device, the encoded subsequent data to the network side device.

An optical transmission system in which a transmitting station and a plurality of receiving stations are connected via an optical splitter, wherein the transmitting station includes: a controller configured to determine whether to perform intensity modulation or phase modulation on optical signals based on information on transmission distances to the receiving stations and modulation bands; an intensity modulator configured to perform intensity modulation on an optical signal; and a phase modulator configured to perform phase modulation on an optical signal, and wherein one of an intensity modulation signal and a phase modulation signal is transmitted from the transmitting station to each of the receiving stations.

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.