88results about How to "Improve bit rate" patented technology

The invention discloses a plug-and-play quantum secret key distribution system and method based on time-phase encoding, a transmitting end and a receiving end. The plug-and-play quantum secret key distribution system comprises the transmitting end and the receiving end which are in mutually optical connection, a coding module in the transmitting end comprises a Z basis vector time coding module coding optical signals according to any sequence and a phase coding module which is an X basis vector phase coding module, and a decoding module in the receiving end is matched with the coding module. The plug-and-play quantum secret key distribution method includes: after an Alice end receives and reflects optical signals from a Bob end, performing Z basis vector time coding and phase coding; sending the optical signals after going through Z basis vector time coding and phase coding to the Bob end for decoding and detecting, wherein phase coding refers to X basis vector phase coding. Improved time-phase coding is used, so that ultrahigh-contrast coding and decoding can be realized, and code generating rate can be increased.

The invention discloses a QKD system sending terminal based on a phase modulation light source, a receiving terminal, a QKD system and a method thereof. By using the QKD system based on the phase modulation light source, at the sending terminal, the phase modulation light source is adopted; and through X basis vector phase coding and Z basis vector time coding modes, a light pulse pair is coded and then the light pulse pair is sent to the receiving terminal. In the invention, the phase modulation light source is used and a low half-wave voltage is possessed so that energy is saved and a possible is provided for a high speed application of the system; and a bias point problem of an intensity modulator does not need to be considered.

Provided is a method of coding and decoding a moving image, which can optimize the coding rate and reduce the time required for decoding the first image frame during an operation of displaying the image. The coding method includes receiving an image, determining the number of frames in a GOP to be decoded with respect to the image, performing a 3D wavelet transformation on the GOP, and coding the results of the 3D wavelet transformation.

The invention discloses a video coding method which comprises the following steps: A. random access cut-in images in uncoded video sequences are coded by adoption of a first kind of prediction means; B. n images coding sequences of which are after the random access cut-in images are coded according to a fourth kind of prediction means by taking the random access cut-in images as reference images, and n is a presetted positive integer; C. other uncoded images coding sequences of which are after the random access cut-in images are coded by taking the random access cut-in images or / and coded images after the random access cut-in images as reference images. The invention also discloses a video decoding method, an encoder, a decoder and a coding and decoding device. Compared with the prior video random access technology, the proposal of the invention saves higher code rate.

The invention provides a quantum secret key distributing system and method. The quantum secret key distributing system comprises a sending end and a receiving end, wherein a quantum channel and a classical channel are formed between the sending end and the receiving end; the sending end comprises a laser device, a first quantum random number generator, a signal state and decoy state encoder, a phase modulator, a second quantum random number generator, a register, a first transceiver and a first quantum secret key generator; and the receiving end comprises a first beam splitter, a second beam splitter, a translation device, a third quantum random number generator, a first detector, a second detector, a second transceiver and a second quantum secret key generator. According to the quantum secret key distributing system, the requirements of the whole system for the number of signals can be reduced, the coding rate of the system can be increased, and the transmission distance of a quantumsecret key and the generation speed of the secret key can be increased.

The invention provides a visible light communication transmission method based on hybrid single-carrier and multi-carrier modulation, which effectively improves the spectrum utilization rate of a system and has good flexibility and low complexity. The method comprises the following steps: S1, performing QAM modulation on an input signal to generate a symmetrical ACO-OFDM signal matrix; S2, carrying out PAM modulation on the input signal to generate a symmetrical PAM-DMT signal matrix; S3, respectively and sequentially carrying out IFFT of N points, adding cyclic prefixes, carrying out parallel-serial conversion on the data, and adding the two groups of data to form an HACO-OFDM signal after the negative number end of the signal is cut down on the ACO-OFDM signal matrix and the PAM-DMT signal matrix; S4, performing symmetric operation on the OOK data to form symmetric OOK signals; S5, subtracting the time selective bias from the HACO-OFDM signal, and adding a symmetrical OOK signal to finally form a sending signal; and S6, transmitting the sending signal to a channel, demodulating the received signal at a receiver end, and recovering each path of signal.

The invention discloses an optical amplitude modulation method suitable for a CVQKD system. The modulation method comprises an optical isolator, a polarization-maintaining optical coupler BS, a phasemodulator PM and a delay optical fiber DL. Only two passive devices (an optical loop and a 2*2 optical coupler) and a phase modulator are needed to modulate the amplitude of the optical signal precisely by using the special structure of an optical fiber Sagnac (Sagnac) loop. As that amplitude modulation method of the invention does not have the bias drift of the working point when the amplitude ismodulate, the modulation accuracy is high, and the external feedback control is not needed at the same time, the realization structure is simple, the cost is low, and the requirement for the modulated signal is low. This method is especially suitable for amplitude modulation of quantum optical signals in continuous variable quantum cryptosystems. It can greatly improve the stability of continuousvariable quantum key distribution system and greatly promote the practical application of continuous variable quantum cryptosystems.

The invention discloses a method and a device for quantum key distribution and passive optical access network fusion. According to the method and the device, wave dividing and wave combining are performed when a quantum signal passes through a light dividing point, and furthermore the quantum signal bypasses an optical splitter, thereby preventing a light splitting loss caused by the optical splitter, and settling a problem that a splitting ratio restrains a transmission distance. Furthermore, a signal-to-noise ratio of QKD (quantum key distribution) is increased, thereby improving code forming rate of QKD and other performance indexes. WDM(wavelength division multiplexing) technology is utilized. The quantum signal is transmitted on an optical fiber which originally bears a classical channel. An optical fiber resource is saved. Furthermore a foundation is laid for large-scale engineering and practicalization in quantum communication.

Provided is a method of coding and decoding a moving image, which can optimize the coding rate and reduce the time required for decoding the first image frame during an operation of displaying the image. The coding method includes receiving an image, determining the number of frames in a GOP to be decoded with respect to the image, performing a 3D wavelet transformation on the GOP, and coding the results of the 3D wavelet transformation.

The invention belongs to the technical field of quantum secret communication, and particularly discloses a synchronizing device for a quantum key distribution (QKD) system. The synchronizing device comprises a transmitting device for transmitting synchronizing light and signal light, a photoelectric conversion device, an adjustable time delay module, a single photon detector and a data processing module, and is characterized in that the frequency of the signal light sent by the transmitting device is much greater than the frequency of the synchronizing light, the frequency of the signal light is several times that of the synchronizing light, the synchronizing light and the signal light are transmitted in the same optical fiber, a low jitter frequency doubler is arranged between the photoelectric conversion device and the adjustable time delay module and is used for doubling the frequency of a synchronized electrical signal output by the photoelectric conversion device to be the same as the frequency of the signal light, and then outputting the signal, the adjustable time delay module uses the signal to generate a door control signal of the single photon detector with the same frequency of the signal light, and the data processing module uses the signal to finish subsequent processing. The synchronizing device can reduce the impact of the synchronizing light on the signal light, can guarantee normal door control signal of the detector, and can effectively improve the code rate of the QKD system.

The invention discloses a receiving terminal for a quantum key distribution system. The receiving terminal comprises a decoding module for processing signal light from a sending terminal and a detector. At least one paths of signal light is provided. The detector is an array detector. Each path of signal light is decoded by the decoding module and then enters a corresponding detection unit in the array detector. In addition, the invention also discloses a quantum key distribution system using the receiving terminal. Therefore, when transmitted multi-path signal light needs to be detected, utilization of multiple sets of single photon detectors is avoided. Because of the array detector way, the costs are lowered and integration and miniaturization of the product can be realized well.

The invention provides a satellite intelligent data transmission method based on remote sensing state estimation and a system thereof, and the method comprises the steps: estimating the satellite-ground data transmission link loss in real time according to uplink power detection and link model estimation; calculating the maximum data transmission capability of data transmission according to the satellite-ground data transmission link loss; identifying an interested remote sensing region through preprocessing target detection and hot spot region designation; adjusting a remote sensing data compression ratio and compression quality according to the obtained maximum data transmission capability and the data volume of the interested remote sensing area; caching the preprocessed target detection data, the original remote sensing data and the compressed remote sensing data, and selecting and storing data information needing to be downloaded according to the maximum data transmission capability and the interested remote sensing area data volume; reading to-be-downloaded data, and adjusting a satellite data transmission link according to the to-be-downloaded data volume and the transmission link loss. The code rate, the coding mode, the modulation mode and the transmitting power of the remote sensing data link are optimized, and the remote sensing data transmission capacity is improved.

The invention discloses a transmitting end and a receiving end of a quantum communication system for time phase encoding, and the transmitting end comprise a seed light laser, a first beam splitter, a quantum light laser, a synchronous light laser, an encoder and a first polarization beam splitter, wherein the seed light laser is used for preparing seed light; the first beam splitter is used for splitting the seed light and inputting the two split light beams into the quantum light laser and the synchronous light laser in an injection locking mode; the quantum light laser is used for preparing pulse light consistent with the seed light in wavelength; the synchronous light laser is also used for inputting the synchronous light into the first polarization beam splitter through the second optical transmission element; the encoder is used for encoding the to-be-transmitted information according to the time sequence and the intensity of the pulsed light to obtain quantum light containing the to-be-transmitted information, so the starting time of the quantum communication system is shortened, the practicability of quantum key distribution is improved, and the code rate of the quantum communication system is improved.

The invention discloses a video bitrate adjusting method and a device, which relate to the technical field of communication. The method and the device provided by the embodiment of the invention can continuously acquire video data of bitrate of a higher level under the condition of guaranteeing smoothness of playing of a video. The method comprises the following steps: if a client side determinesthat buffer time of the video data of a first bitrate in a video buffer zone exceeds buffer lower-limit time of the bitrate, the client side sends a second scheduling request to a server; the server sends video increment data to the client side according to the second scheduling request; the client side updates the video data of the first bitrate in the video buffer zone according to the video increment data, generates the video data of second bitrate and consequently buffers the video data of the second bitrate in the video buffer zone, wherein the video buffer zone of the client side internally comprises the video data of at least two types of bitrate, and the second bitrate is the bitrate one level above the first bitrate. The method and the device are applied to online video playing.

The invention discloses an avalanche photodiode detection array applicable to an ultra high-speed quantum secure communication system. The detection array is used for receiving external signal light and detecting information. The detection array comprises a first circulator which is equipped with an input light path and two output light paths, and is used for receiving the external input signal light, outputting the signal light in two ways and controlling the output direction of the signal light; a first Sagnac interference ring; and two spectroscopic detection units. Each spectroscopic detection unit comprises a Sagnac interference ring and a single photon detection assembly. Each Sagnac interference ring is composed of a polarization beam splitter, a phase modulator and a Faraday rotator which are connected through a light path clockwise. Each polarization beam splitter is connected with one output light path of the circular. Each single photon detection assembly is composed of a detection polarization beam splitter, and two single photon detectors connected with the detection polarization beam splitter through the light path. The total detection efficiency of the single photon detection array is avoided from being reduced, the working speed of the quantum secure communication system is improved, and moreover, the code rate is improved.

The invention discloses a quantum communication time phase encoding device and method and a key distribution system. The quantum communication time phase encoding device includes a first interferometer configured to receive an optical signal and generate a first signal and a second optical signal having a time difference, and a second interferometer configured to generate a third optical signal transmitted along the first optical path and a fourth optical signal transmitted along the second optical path based on the first signal, and generate a fifth optical signal transmitted along the firstoptical path and a sixth optical signal transmitted along the second optical path based on the second signal, wherein the first phase modulator of the first optical path and the second phase modulatorof the second optical path respectively increase or decrease a pi phase for one of the third optical signal and the fourth optical signal; or the pi phase is increased or decreased for one of the fifth optical signal and the sixth optical signal; and the first phase modulator in the first optical path and the second phase modulator in the second optical path increase or decrease pi phases for both of the third optical signal and the fourth optical signal, respectively; or the pi phase is increased or decreased for both the fifth optical signal and the sixth optical signal. For the quantum communication time phase encoding device and method, time phase encoding is realized by adding pi phases, and the encoding method is simple and convenient, and the phase modulation precision is high, andthe code forming rate is high.

The invention belongs to the field of quantum secret communication technologies and particularly relates to a synchronous method of a quantum key distribution system. The synchronous method comprises the following steps that a sender sends synchronous light and signal light, the frequency of the synchronous light is far smaller than that of the signal light, two frequencies have multiplied relationship, and the synchronous light and the signal light are both transmitted in one optical fiber; the synchronous light is converted to a synchronous electric signal, frequency multiplication is carried out on the synchronous electric signal to obtain the frequency which is the same as the signal light, and the synchronous electric signal is output through a delay module as a gate control signal of a photon detector of a receiver; the signal light enters the photon detector of the receiver and is detected in the valid time of the gate control signal of the detector; and the synchronous electric signal output through the delay module and the output signal of the photon detector of the receiver enter a data processing module of the receiver to carry out follow-up processing. According to the synchronous method, the influence of the synchronous light on the signal light can be reduced, the normal gate control signal of the detector is guaranteed and the code rate of the QKD (Quantum Key Distribution) system can be effectively improved.

The invention discloses a measurement equipment independent quantum key distribution method based on time slice auxiliary Bell state measurement. The method comprises the following steps of a user 1 and a user 2 randomly selecting a single photon state and sending the single photon state to a third-party measurement device; performing hyper-entangled Bell state analysis on the single photon stateand publishing a measurement result; publishing selection of momentum and polarization degree of freedom bases, reserving the same coding information selected by any degree of freedom base, and discarding the coding information of which the selection of the bases on the two degrees of freedom is different; operating the coded information on different degrees of freedom to form an original key; repeating the steps till enough original keys are obtained; performing safety detection; forming a final security key. According to the method, the two-degree-of-freedom quantum state of the single photon is transmitted in the MDIQKD, and the two-degree-of-freedom quantum state of the single photon is used for encoding information, so the utilization rate and the code rate of the security key are effectively improved; and after the original key is obtained, quantum bit error rate analysis is carried out, so security of the transmission process is ensured.

The embodiment of the invention discloses a quantum key charging method, device and system. A quantum random number generator is used for replacing a quantum key distribution device, as a source of aquantum key. The quantum random number generator generates the quantum random number to serve as the quantum key, so that a key distribution center can obtain the generated quantum random number, namely the quantum key, from the quantum random number generator and then sends the quantum key to the quantum key charging machine, and then the quantum key charging machine can charge the quantum key into the quantum key storage device. Therefore, according to the embodiment of the invention, the quantum random number generator is used for replacing quantum key distribution equipment, so that the filling of the quantum key is realized, a special quantum network is not needed any more, the application range is not limited any more, the cost is reduced, and the code forming rate is also improved.

The invention discloses a quantum communication system, a transmitting end thereof and a quantum communication method. An initial laser signal is emitted at a transmitting end through the same laser;the consistency of laser pulses is ensured; the polarization state of the laser pulse in the laser signal emitted by the emitting end is controlled; the polarization states of two adjacent laser pulses are different, the transmission paths of the laser pulses in different polarization states can be conveniently controlled at a receiving end, and when the laser pulses in different polarization states interfere with each other, the utilization of 100% interference energy can be realized, the energy loss is avoided, and the energy utilization rate and the code rate are improved. Therefore, according to the quantum communication system and the quantum communication method provided by the technical scheme of the invention, the energy utilization rate, the safety and the code forming rate are improved, and popularization and application of the quantum communication system and the quantum communication method are facilitated.

The invention provides a high-speed quantum key encoding device and method, and relates to the technical field of quantum communication. The encoding device comprises a first signal light source, a second signal light source, an unequal-arm interferometer, a first phase modulator, an intensity modulator, and a fourth beam splitter. The first signal light source and the unequal-arm interferometer are sequentially connected in series, the second signal light source is sequentially connected with the intensity modulator in series, and the fourth beam splitter comprises two input ends and an output end; the unequal-arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter; the unequal-arm interferometer comprises a long arm and a short arm, the first phase modulator is arranged at the long arm or the short arm, and the driving signal frequencies of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator are the same. According to the invention, the high-speed quantum key coding exceeding gigahertz can be realized with high precision.

An audio encoder converts an input sound signal into a plurality of compressed frame data pieces in an sound signal compression coder, determines the importance of each bit in a classification unit of a transmission line coder based on the decoding quality in the presence of a transmission error, and classifies the bits into a plurality of classes. The audio encoder selects one of the three types of processing including convolution coding and addition of CRC check codes, convolution coding only, and no coding, in descending order of importance in the presence of a transmission error for each class. Then, the audio encoder adds preamble information and a synchronization signal in a multiplexer to generate a bit stream. It becomes possible to suppress degradation of a decoded sound signal without additional redundant bits.

The present application provides a polarization code encoding and decoding method, transmitting device and receiving device, and is beneficial to improve the shortcomings in medium and short packets,code rate, reliability, and complexity in the prior art. The method includes: a transmitting device pre-stores at least one mother code sequence, each mother code sequence is composed of at least onesub-sequence and at least one sub-set, and each element in the sub-sequence or sub-set is a serial number of a polarized channel, and each sub-sequence or sub-set includes at least one sequence number, and relative positions of the sequence numbers in each subsequence are arranged in order of the reliability of the polarization channel; the transmitting device determines a set of information bit numbers from the at least one mother code sequence according to a code length of a target polarization code; the transmitting device performs polarization coding on the information bits according to the information bit number set.

The invention discloses a QKD system and a transmitting end, a receiving end and a communication method thereof. In the technical scheme of the invention, the transmitting end can carry out polarization and phase modulation on an optical pulse, coding in a preset four-dimensional space is realized, the optical pulse comprising polarization information and time information is emitted, and the receiving end can acquire the optical pulse emitted by the transmitting end, carry out polarization and phase decoding on the optical pulse and detect the optical pulse. Visibly, the technical scheme of the invention can realize high-dimensional coding quantum communication, so that one quantum state can carry more bit information, and the code forming rate of the QKD is greatly improved.

A decoding chip for quantum key distribution comprises: an input waveguide for receiving and transmitting an optical signal to be decoded; directional couplers which comprise a first directional coupler, a second directional coupler and a third directional coupler, wherein the first directional coupler is used for splitting input light into two beams of light, and the second directional coupler and the third directional coupler are used for achieving light quantum interference; a phase modulator which comprises a first phase modulator and a second phase modulator and is used for modulating thephase of the optical signal; a delay line structure which is used for delaying the optical signal and inhibiting the influence of the temperature on the bit error rate; and an output waveguide whichis used for outputting the demodulated optical signal. According to the decoding chip, the beam splitting ratio can be adjusted, and the double-time-gap pulsed light power is balanced, so that the interference visibility is optimized, and the bit error rate is reduced. The interference visibility of the decoding chip is insensitive to temperature change, namely the bit error rate caused by an optical device is insensitive to the temperature change.

The invention discloses a time-phase quantum key encoding device, system and method. The time-phase quantum key encoding device comprises a seed laser which emits a seed light pulse; a first encodinglaser, a second encoding laser and a third encoding laser which receive split seed light pulses, and emit pulse light signals with the same central wavelength as the seed light pulse by adopting an injection locking technology; an unequal-arm interferometer which is used for receiving the pulse light signal to form an encoded signal and outputting the encoded signal; and an optical modulation unitwhich can be used for preparing decoy-state quantum key codes. The method is high in safety, easy in code forming implementation technology, high in encoding speed, high in code forming rate, low inerror rate and low in application cost.

The invention discloses a quantum key distribution method and system with free side channels, and belongs to the technical field of quantum key distribution. Aiming at the defects in the prior art, the invention provides the quantum key distribution method and system with free side channels, a quantum key distribution protocol sending end provided by the scheme only needs to use weak coherent optical pulses. Meanwhile, a measurement equipment end only needs to carry out interference operation, absolute safety can be ensured in safety analysis. The scheme satisfies the side-channel-free property of the side channel, has compatibility for imperfect sending end equipment, does not need to monitor the transmission channel, and also has the property irrelevant to measurement equipment. On the basis, according to the scheme. The transmission noise immunity. The key code rate and the transmission distance of the key are improved.

The invention discloses a multi-user TF-QKD network system and a multi-user TF-QKD network method. The system comprises N sending ends, N measuring ends, N optical path selection modules and an annular quantum network, and the N sending ends, the N measuring ends and the N optical path selection modules are connected through the annular quantum network. Each sending end comprises a laser, an intensity modulator, a phase modulator and an optical attenuator; the measuring end is configured to emit single photon interference and comprises two single photon detectors and a beam splitter; and the scheme that multiple users carry out multiple sets of TFQKD protocols at the same time is achieved, the high code forming rate is achieved under long-distance quantum communication, attacks on a measuring end can be resisted, expansibility is achieved, the number of the users can be continuously increased, the function that quantum information of any two users can be detected at any measuring end is achieved, the utilization rate of quantum network resources is greatly improved, and meanwhile a large number of quantum network resources are saved.