199results about How to "Improve communication capacity" patented technology

The invention belongs to the field of satellite communication technologies and particularly relates to a ground station system and a method for avoiding collinear interference with a geostationary satellite. The system comprises a ground station located at one position of the earth and a non-geostationary satellite constellation connected to the ground station, wherein the ground station traces one satellite in the non-geostationary satellite constellation through controlling antenna beam and establishes a communication link with the satellite; when a connecting line between the ground station and one non-geostationary satellite points at the geostationary satellite, the ground station adjusts the beam direction and selects another non-geostationary satellite in the different direction in view to communicate, so that the collinear interference with the geostationary satellite is avoided. According to the ground station system and the method, the restriction that shutdown of the non-geostationary satellite is needed or the transmitting power of the non-geostationary satellite is greatly reduced when the collinear interference occurs is avoided, and the satellite communication of the ground station keeps continuous, so that the availability and the message capacity of the non-geostationary satellite constellation are improved and the same frequency coexistence of the non-geostationary satellite and the geostationary satellite is realized.

The invention relates to a serial-parallel connection modulation optical frequency multiplication millimeter-wave RoF (Radio Over Fiber) system and a QPSK (Quadrature Phase Shift Keying)/16QAM (Quadrature Amplitude Modulation) modulation method thereof. The system comprises a central station, a base station and fiber connection thereof, wherein the central station comprises a single longitudinal mode laser, a double-electrode Mach-Zehnder optical modulator, an IQ optical modulator, two microwave signal sources, a pi phase shifter, a pi/2 phase shifter and an erbium doped fiber amplifier; and the base station comprises an optical detector, a front low-noise amplifier, two millimeter-wave bandpass filters, two millimeter-wave amplifiers, a millimeter-wave duplexer and a millimeter-wave antenna. In the method, the cascading of the double-electrode Mach-Zehnder optical modulator and the IQ optical modulator is adopted, and a balanced optical waveguide structure formed by integrating the two optical modulators avoids the influence of optical source phase interference noise caused by support arm optical delay inequality on modulation signals.

The invention relates to a method for improving the message capacity of a mobile ad-hoc network by the combination of the link layer messages, belonging to the computer communication field. The method includes that firstly, the newly-produced network layer message is added into the different buffer queues of a sending buffer at the sending terminal according to the next hop address and the network layer message is combined with the message at the tail of the former queue and processed according to the length of the network layer message or is stored as an opposite message; when the received link layer message is extracted at the receiving terminal, the data length of the link layer is compared with the length of the network layer message and then judged, and each network layer message extraction is completed through cyclic processing. With the method of the invention, only little modification to the current protocol stack can help obviously improve the message capacity in the mobile ad-hoc network under high busy state; the method has the advantages of simple computation, small computation complexity and easy achievement.

The invention discloses a millimeter wave full duplex unmanned aerial vehicle communication relay transmission method, and belongs to the technical field of millimeter wave communication. The method comprises the following steps: constructing a communication scene from a ground base station to a ground user by taking an unmanned aerial vehicle as a relay, and establishing a channel model of a downlink communication system from the ground base station to the user by taking the unmanned aerial vehicle as the relay by utilizing a spatial position model; in the simultaneous same-frequency full duplex mode, enabling the ground base station to transmit a signal to the unmanned aerial vehicle, and enabling the unmanned aerial vehicle to transmit a signal to user equipment; designing the optimal position of the unmanned aerial vehicle under the ideal beamforming condition, giving the position optimization beamforming vector of the unmanned aerial vehicle, and giving the beamforming vector to optimize the power of the base station and the unmanned aerial vehicle transmitting signal. According to the method, for a downlink transmission system taking an unmanned aerial vehicle as a relay, thecoverage range of millimeter wave communication is expanded, the communication capacity of the system is improved, and optimal power control under any given unmanned aerial vehicle relay position andbeam forming is provided.

The invention provides a traffic flow characteristic based dynamic grouping resource distribution method. The traffic flow characteristic based dynamic grouping resource distribution method comprises the steps of firstly dividing V2V communication links into two types, wherein one type is a traffic safety type and the other type of an entertainment type; selecting a suitable grouping number value m based on a specific traffic flow characteristic and grouping the two types of the V2V communication links respectively; then selecting a cellular user resource corresponding to the maximum communication capacity utility value and distributing the cellular user resource to each V2V link under the precondition of guaranteeing the communication quality of the cellular user, wherein the V2V communication links in each group reuse the same cellular user resource. A simulation result shows that the method disclosed by the invention, although is not as good as a greedy algorithm in the aspects of the communication capacity utility value and the number of the V2V links for obtaining the communication resource successfully, has great advantages when being compared with a random distribution algorithm. In addition, the method disclosed by the invention is obviously superior to the greedy distribution algorithm and the random distribution algorithm in the aspects of running time and spectrum frequency; and the two performance indexes are particularly important for the complex and changeful V2V communication link environment and the existing spectrum resource scarcity condition.

The invention discloses a 1.2m feedback full-automatic portable emergency satellite communication antenna servo system which comprises a portable box, an antenna structure unit and an antenna control unit, wherein the antenna structure unit and the antenna control unit are arranged in the portable box; the antenna structure unit comprises an antenna mount, a six-section carbon fiber antenna main reflection surface and a feed source component support frame, wherein the six-section carbon fiber antenna main reflection surface and the feed source component support frame are connected to the antenna mount, an antenna auxiliary reflection surface is installed at the end part of the feed source component support frame, a feed source component support plate is installed in the middle of the feed source component support frame, a feed source component is installed on the feed source component support plate, a direction drive device and an elevation drive device are arranged in the antenna mount, and the feed source component comprises a feed horn, a polarizer, a duplexer and a polarization power transmission mechanism. The 1.2m feedback full-automatic portable emergency satellite communication antenna servo system is reasonable in design, convenient in implementation, increased in communication bandwidth, expanded in communication capacity, high in degree of intelligence and working reliability, convenient to carry and good in use effect, provides communication guarantee for the emergency handling and is convenient to popularize and apply.

The invention provides a silicon-based WDM optical transceiver module comprising a silicon photonic chip including a modulator array and a detector array; and a wavelength division multiplexer and a demultiplexer achieved based on a planar lightwave circuit (PLC). The wavelength division multiplexer and the modulator array are connected through packaging. The demultiplexer is connected to the detector array connected through packaging. A WDM optical module is achieved by packaging the wavelength division multiplexer chip and the demultiplexer chip through the silicon photonic chip and the PLC so as to avoid process difficulty of the silicon-based wavelength division multiplexer/demultiplexer. In view of low integration and high power consumption of a traditional WDM optical transceiver module based on discrete devices and PLC, the modulator array and the detector array are integrated by using silicon photon technology so as to greatly improve the integration of optical transceiver module and to reduce power consumption.

The invention provides a joint resource optimization method based on an underwater acoustic OFDM-NOMA (Orthogonal Frequency Division Multiplexing-Non-Orthogonal Multiple Access) system downlink and isused for solving a problem that in the prior art, no underwater non-orthogonal multiple access network resource allocation mechanism with high feasibility exists. An underwater acoustic wireless communication system based on OFDM-NOMA is established. A base station (BS) and K anchor nodes are deployed in the system. A channel information state of each anchor node is known. A constraint conditionis given. The constraint condition comprises a total transmitting power Pt of the base station and a constraint of subcarrier allocation number. A system rate sum is taken an objective function. In order to solve a joint resource optimization problem, the provided optimization problem is finished step by step. Subcarrier allocation is carried out through adoption of a greedy algorithm with relatively low algorithm complexity, so a system subcarrier allocation optimization objective is satisfied. For power allocation, an optimization objective is converted from a transmitting power to a communication rate, a power allocation model is converted into a strict convex optimization problem, and an optimum value is solved through adoption of a GP (Geometric Programming) algorithm. The method is scientific and reasonable, is low in algorithm complexity and is applicable to an underwater bad communication environment.

The invention discloses a two-dimensional grating coupling-based silicon-based QPSK (Quadrature Phase Shift Keying) photomodulator, comprising a two-dimensional grating coupler, four mode transducers, a single-mode waveguide, an optical cross and four radio frequency phase shifters, wherein the two-dimensional grating coupler, serving as a vertical optical coupling interface and a four-channel powder divider, averagely splits a coupling light into four channel waveguides; the four mode transducers are used for carrying out mode conversion and insulated optical transmission between the two-dimensional grating and the single-mode waveguide; the single-mode waveguide is used for carrying out low-loss single-mode transmission of an optical signal; the optical cross is used for carrying out non-crosstalk low-loss optical cross transmission between two waveguides; the four radio frequency phase shifters are used for loading electric signals of in-phase road data DATAI and quadrature road data DATAQ, thus achieving BPSK (Binary Phase Shift Keying) light phase modulation of two roads. Two of three MMI beam combiners are applied to light beam combination of two branch circuits in the in-phase road and the quadrature road; the other MMI beam combiner is applied to light beam combination of the in-phase road and the quadrature road; two thermal optical phase shifters are used for adjusting an optical wave phase difference between the in-phase road and the quadrature road by direct current, so as to meet pi/2, and thus the optical signals of the in-phase road and the quadrature road are synthesized into a QPSK modulation signal.

The invention discloses a latent communication system and method based on a non-cooperative blind source. The latent communication system comprises an information coding and transmitting end, an information receiving and demodulating end and a non-cooperative blind source signal, a non-cooperative blind source is used as a communication carrier wave, double antennas or multiple antennas are used as receiving ends, received electromagnetic waves are demodulated in a receiver, and therefore hidden transmission and passive transmission communication of information are achieved. By adopting the technical scheme of the invention, a signal emission source is not needed, the carrier emission power is saved, and new spectrum resources are not occupied; the circuit structure is simplified, and thehardware cost is reduced; concealed communication is guaranteed in the physical level, and indoor directional fixed-point communication can be achieved. Information can be sent to a sensor at a specific position in the Internet of Things, energy is provided for the radio frequency identification tag, and the wireless communication quality is improved.

The invention discloses a channel quality indication predicting and compensating method and a channel quality indication predicting and compensating system. The method comprises the following steps of: accumulating CQI values of the same subband or full bandwidth at same intervals to form a CQI time sequence; identifying an autoregressive summarization moving average model, namely according to the CQI time sequence, identifying the process of the autoregressive summarization moving average model and determining parameters in the autoregressive summarization moving average model; estimating the parameters of the autoregressive summarization moving average model to determine the autoregressive summarization moving average model; and predicting the CQI values based on the determined autoregressive summarization moving average model. The method can effectively reduce the difference of the original CQI values and a true value at the current moment so as to save communication resources and energy and improve the system communication capacity; and the method also has the advantages of low complexity of algorithms and convenient implementation.

The invention discloses a flip-chip structure micro-size photonic crystal LED array chip and a preparation method thereof. The LED array chip of the invention has four light emitting units connected in parallel, the metal connecting line of the positive electrode and the semiconductor material are separated by a dielectric insulation layer, and the negative electrode is directly covered on the upper surface of the semiconductor material. The active region of the light-emitting unit has a photonic crystal with periodic distribution, and the depth of the photonic crystal exceeds the depth of theactive layer. Except electrode pad, DBR is distributed on the whole chip surface. Metal electrodes form metal mirrors. The preparation method of the invention adopts the scheme that an ohmic contactlayer and an electrode are firstly prepared and then a photonic crystal is etched without planarizing and the like traditional process flow; Using thick strip dielectric insulating layer to insulate the electrode from semiconductor material and thin dielectric mask layer and adhesive mask layer to etch together is conducive to the deposition of DBR and the rapid escape of photon mode. The processflow of the invention is simple and reliable.

The invention is applicable to the field of communication, and provides an antenna and a wireless router. The antenna comprises a radiator, a director, at least one wave absorber and a reflector, wherein relative to the radiation direction of the radiator, the director is in front of the radiator, the reflector is behind the radiator, and the wave absorber is located on a side face of the radiator; and the radiator comprises a base plate, a composite left and right hand transmission line unit attached to a front face of the base plate, an electromagnetic field band gap EBG structure attached to a bottom face of the base plate, and a flat metal plate located on the side of the EBG structure and connected with the composite left and right hand transmission line unit to serve as the ground. The antenna provided by the invention has the advantages of small size, low profile, horizontal omnidirectional radiation, high efficiency and wide bandwidth.

The invention relates to the technical field of a semiconductor laser, and proposes a single-mode emission orbital angular momentum (OAM) laser. A cavity body of a resonant cavity of the laser is of amicro column, micro ring or micro disc structure for supporting an echo wall mode, a grating or defect is etched on an outer side surface of the cavity body of the laser, the echo wall mode with special angular quantum number can be selected as a hot shot mode of the laser, the selected mode is vertically scattered and output by a top grating, the output is a travelling wave mode with a vortex phase, namely an OAM mode, the top grating is arranged at a position, near to an outer side edge of a micro column, of a grating layer and comprises a real part and a virtual part, the real part and thevirtual part comprise two groups of gratings and are used for respectively modulating effective reflectivity of the mode, so that scattering output of the travelling wave mode is formed. The laser issmall in cavity volume and low in loss, and thus, ultrahigh-speed modulation can be achieved. The semiconductor laser has the characteristics of small volume, single-mode working and low threshold current, and is convenient to detect, a two-dimensional array is easy to integrate, output light is easy to couple to optical fiber, and various advantages can be achieved on different material systems.

The invention discloses a free space laser communication system based on quantum encryption. The system comprises a receiving module and a data decryption module, wherein the receiving module capturesa laser signal and a communication request signal, amplifies, processes and quantizes the laser signal through broadband amplification and pulse code modulation, codes the laser signal and then converts the laser signal into a digital signal. A computer module processes data, and then records communication node information and freely organizes a communication network according to a communicationrequest and transmits data to a data encryption module; a quantum key terminal obtains a quantum key, the data encryption module encrypts the data, and the encrypted data is transmitted to a counter party of communication through a transmitting module. A receiving party communication node obtains the quantum key through the quantum key terminal and decrypts the received data through the data decryption module, and further transmits the decrypted data to the computer module for processing. For the system provided by the invention, fixing communication nodes or paving electric cables/optical cables is not needed, and the system can perform long-distance transmission and avoid obstacles and bad weather regions.

The invention discloses a multi-input and multi-output optical communication system and a signal recovery method thereof. The multi-input and multi-output optical communication system comprises an optical signal transmitting end and an optical signal receiving end, wherein the optical signal transmitting end comprises a light intensity modulation unit and an optical signal sending unit which are mutually connected, the optical signal sending unit comprises n broadband light sources which have mutually overlapped, but not totally identical frequency spectra, and the light intensity modulation unit is used for respectively modulating n lines of signals to corresponding optical modulation signals generated by the n broadband light sources; the optical signal receiving end comprises a light splitter, an optical signal receiver and a signal processing unit; the light splitter enables incident light at different frequencies to form different light intensity distributions after the incident light passes the light splitter, and the light intensity angle distributions generated by the incident light at the same frequency after the incident light passes the different parts of the light splitter are also different; the optical signal receiver is an optical detector array constituted by n optical detectors with same frequency spectral response. The multi-input and multi-output optical communication system disclosed by the invention can realize large-capacity signal transmission while illuminating and is further simple in structure and easy to implement.

The invention discloses a quantum secure direct communication method based on photon orbital angular momentum coding, comprising the following steps: constructing two unitary operators and giving two groups of complete intrinsic quantum states; when quantum secure direct communication is carried out, based on an intrinsic quantum state space, randomly preparing, by a receiving party, a group of photon sequences, and sending to a sending party; randomly choosing, by the sending party, a check photon from the photon sequences to measure Z<^>p or X<^>p and comparing a measurement basis and a measurement result by a public channel; judging whether a communication channel is secure according to an error rate of the measurement result; if the channel is secure, carrying out coding operation on the photons by the sending party; measuring the received photons by the receiving party, comparing an initial state and a final state of a photon orbital angular momentum, obtaining the coding operation carried out by the sending party and constructing coded logic bit information sent by the sending party. According to the method disclosed by the invention, by using the photon orbital angular momentum coding, the communication capacity and the spectral efficiency of the quantum secure direct communication are improved.

The invention relates to a method for reducing media access conflict of a wireless local area network through cross-layer architecture, belonging to the computer communication field. The method comprises two parts of processing of node interception messages and processing of transmitted messages during the process of message transmission; a sequence mark is set for each node; following status information is stored in various nodes: node sequence marks used for transmission of the prior message of the nodes, node sequence marks of messages intercepted lately and physical addresses of the node sequence marks; node interception reads corresponding control information for all received messages; and the status that whether a transmitting buffer of the node is empty and a transmitting node sequence mark which is represented by a nonnegative integer are added into a message header during the process of packaging the messages into frames. The method fully utilizes the status information of the various nodes in the network through the cross-layer architecture to reduce the probability of the conflict in a small-scale wireless local area network and then further achieve the aim of improving the message capacity in the wireless local area network.