10results about How to "Improve bit error performance" patented technology

The invention provides a LoRa system and a LoRa physical layer enhancement method based on intelligent reflective surface beamforming and index modulation, in the system, a transmitting side at least comprises Nk LoRa nodes equipped with single transmitting antennas and an RIS with N passive reflective elements, the RIS is used for improving a wireless propagation environment, beamforming is realized by controlling the phase of each passive reflective element, and the LoRa physical layer enhancement method is used for enhancing the physical layer of the LoRa. The instantaneous signal-to-noise ratio under the antenna combination is activated to the maximum, and the bit error rate performance is improved; a receiver at least comprises a LoRa gateway equipped with NR receiving antennas, multiple receiving antennas at the LoRa gateway are used for index modulation, and Nk receiving antennas in the NR receiving antennas are activated in each symbol period and serve as information transmission entities to bear additional information, so that the transmission throughput is remarkably improved. According to the LoRa physical layer enhancement method applied to the LoRa system, the wireless propagation environment is controlled through RIS beam forming to improve the quality of received signals, and the spectrum efficiency is improved by ingeniously utilizing the IM principle of multiple receiving antenna indexes, so that the LoRa physical layer enhancement method has high transmission rate and high reliability.

The present invention relates to a chaotic spread spectrum modulation multi-user access system of a joint PPM for short-distance communication. At the transmitting end, a chaotic signal is generated by a chaotic mapping method, and the chaotic signal is used as a reference segment of the first time slot, and a bit stream is divided into multiple symbol periods, each symbol period is mc+1 bit transmission bits, wherein mc mapping bits determine the selected pulse position of PPM, and 1 bit is modulated by DDCSK-WC; when multiple users transmit information at the same time, the information segment is redesigned by using an orthogonal Walsh code, and then the redesigned information segment is transmitted at the pulse position selected by PPM; at the receiving end, the received signal is multiplied by a corresponding Walsh code according to a certain method, and then the reference segment processed by the Walsh code and the information segment are calculated for correlation characteristics, and the position of the information segment is determined by comparing the absolute value of the correlation characteristic result, thereby judging the corresponding mc mapping bits and 1 modulation bit. The present invention effectively improves data transmission efficiency.

The invention relates to the technical field of coherent light communication, and provides a digital subcarrier multiplexing coherent light communication system and method, the system divides a single carrier signal into a plurality of subcarrier signals for respective modulation, and the system comprises a transmitting module, a channel unit and a receiving module; the transmitting module is used for modulating and transmitting a subcarrier multiplexing signal based on a DSP (Digital Signal Processor) algorithm, and comprises a wide-area complex recursive least square algorithm; the transmitting module performs hybrid modulation on the plurality of subcarrier signals; half of the subcarrier signals are configured with preposed pilots. According to the invention, based on the wide-area complex number recursive least square algorithm, the subcarrier signal is converted from a real number to a wide-area complex number, a significant modulation effect is still achieved under high-frequency attenuation, and the bit error rate performance is improved; the transmitting module performs hybrid modulation on a plurality of subcarrier signals, and configures different code rates of forward error correction codes according to the order of each subcarrier signal modulation format, so that the spectrum efficiency is improved; and only half of the subcarrier signals need to be configured with the preposed pilot frequency, so that the pilot frequency overhead is reduced.

The present invention discloses a non-orthogonal multiple access communication method based on Polar code. The information sent from the source is first encoded with Polar code, then modulated with GMSK and enters the channel; the signal is demodulated at the receiving end, then Polar code is decoded, and finally sent to the destination. Gaussian approximation (GA) structure and Tal-Vardy (TV) structure are used in Polar code construction. The present invention reduces the bit error rate and improves the performance of the NOMA system by encoding and decoding Polar code and modulating with GMSK; error control by Polar code can effectively improve the reliability of the communication system.

The embodiment of the invention relates to a low-complexity LDPC (Low Density Parity Check)-Hadamard code encoding and decoding method under OTFS (Over-The-Flight Switching) modulation, which comprises the following steps: a sending end performs LDPC-Hadamard code encoding after performing cyclic redundancy check on an information sequence to add check information, and performs inverse symplectic finite Fourier transform and Hisenberg transform on a complex value symbol after constellation mapping to output a time domain signal; a sending signal is generated after time delay and Doppler frequency shift are generated through a multi-path time-varying channel; a receiving end carries out Wigner transform and ShengFourier transform on the received sending signal to output a symbol matrix; and carrying out LDPC-Hadamard decoding processing on the received bit stream, removing check information through cyclic redundancy check, and outputting the original bit stream. According to the invention, through LDPC-Hadamard coding and decoding and OTFS modulation and demodulation, double selective fading channels in a high-speed mobile scene can be better dealt with; the LDPC-Hadamard code is combined with the OTFS, so that the error correction performance of the system under a low signal-to-noise ratio is improved, and the reliability of the system in a high-speed mobile environment is enhanced; and the bit error rate performance of the OTFS system under a low signal-to-noise ratio is improved.

The application discloses a kind of target-oriented photovoltaic receiver light communication and energy integration system limited dynamic range constraint emission waveform design method, first generate MLS sequence, simultaneously to the original signal of input PAM modulation obtains PAM sequence, PAM sequence is as slow envelope to MLS sequence mean envelope modulation, and the alternating current signal after envelope modulation is obtained, direct current bias B is superimposed in the alternating current signal to constitute the final emission waveform.The application B determines reference light intensity and effective AC budget.In available budget, communication level interval and perception MLS amplitude are determined by amplitude allocation factor ρ together.Under fixed AC budget, ρ determines the trade-off between communication and perception, and B determines the upper limit of feasible dynamic range.The application makes full use of limited amplitude resources, realizes low-bandwidth photovoltaic receiver-oriented efficient information extraction, accurate echo perception and stable energy transmission, and realizes flexible coordination of communication and energy functions.

The present invention relates to a chaotic shift keying modulation and demodulation method combined with initial value index. At the transmitting end, the input bit stream is divided into N bit blocks, each bit block includes bits. The mapping bits are used to select a reference signal with a predefined initial value as the transmission carrier of the mapping bit, and the remaining one bit is a modulation bit. The polarity of the selected reference signal is flipped or maintained according to the transmission bit 0 or 1. The transmitter only transmits reference signals with different initial values ​​at the head of each frame signal, and the remaining N bit blocks share the reference signal with different initial values ​​during modulation. At the receiving end, the system distributes the first signals received in each frame to each demodulation branch, and then performs correlation operations on the remaining N information signals in each demodulation branch, selects the absolute value of the largest correlator output as the basis for judging the mapping bit, and then judges the modulation bit according to the polarity of the correlator output value. Compared with the prior art, the present invention has better bit error performance.

The application discloses a neural network equalization method and device, equipment, storage medium and program product, and relates to the technical field of optical communication. The method comprises the following steps: acquiring a received signal sequence on a high-speed optical interconnection link; inputting the received signal sequence into a neural network equalizer for equalization processing to obtain an equalized output signal sequence; wherein the neural network equalizer comprises at least one backbone network composed of a one-dimensional convolution network and at least one learnable nonlinear activation layer; the nonlinear activation layer and the one-dimensional convolution network are alternately cascaded; the nonlinear activation layer is composed of a plurality of base functions through linear combination of learnable weight coefficients and is used for approximating nonlinear response on the high-speed optical interconnection link. The neural network equalization method can significantly improve the compensation capability for nonlinear distortion such as bandwidth limitation, modulation soft saturation and mode coupling under the premise of maintaining full one-dimensional convolution streamable inference, so as to reduce the bit error rate.

The application provides an LDPC decoder of a CCSDS near-earth satellite standard and a decoding method thereof, and relates to the field of wireless communication and signal coding and decoding, wherein the decoder comprises a frame synchronization module, a channel LLR storage module, a control module, a variable node updating module, a check node updating module, a data rearrangement module, an address generation module, a data shift module, a node message storage module and an output module. The application divides the cyclic submatrix of the CCSDS near-earth satellite code group into smaller non-cyclic submatrices, improves the decoding parallelism, stores the node messages of the same cyclic submatrix after block division in the same address of the RAM, and alternately writes the variable node and check node messages into the RAM, thereby saving the storage resources; the check function is realized with low overhead by expanding one bit of the node message to store the decision result; and the error code performance is improved by optimizing the two kinds of node updating modules.

The invention discloses a zero-forcing frequency domain equalization-based molecular code division multiple access system detection method and device. The method comprises the following steps of: constructing a molecular code division multiple access system; each nano emitter performs spectrum spreading on data by using a spectrum spreading sequence, and represents a molecular concentration signal of bit information by releasing A-type and B-type molecules; sampling the received molecular concentration signal at the fusion center, and determining a concentration difference observation value of A type molecules and B type molecules; on the basis of the observation value, organizing data in a block transmission mode and inserting a cyclic prefix to eliminate inter-block interference, and forming a time domain observation vector; converting the time domain signal into a frequency domain signal; suppressing inter-symbol, inter-chip and multi-access interference by applying a zero-forcing frequency domain equalization algorithm; performing inverse fast Fourier transform on the equalized signal, converting the equalized signal back to a time domain, and obtaining a judgment variable through de-spreading operation; and comparing the judgment variable with a zero threshold, if the judgment variable is greater than 0, judging as 1, otherwise, judging as-1, and outputting a decoding bit sequence.