398results about How to "Improve bit error performance" patented technology

The invention discloses a method for reducing a peak-to-mean ratio in OFDM (Orthogonal Frequency Division Multiplexing). The method comprises the following steps: dividing an OFDM mark needing to be transmitted into two sub-blocks according to two half sections including a front half section and a rear half section or an odd number position mark and an even number position mark; calculating a mark vector by selecting a mapping algorithm and selecting a signal with the minimum peak-to-mean ratio to transmit; reducing the peak-to-mean ratio of the OFDM mark by utilizing different rotary factors; and carrying out traversal to obtain a weighting scheme for enabling an PAPR (Peak To Average Power Ratio) to be minimum and searching the two sub-blocks of a sequence with the best PAPR performance to combine and transmit. According to the method disclosed by the invention, a previous OFDM mark flow is used for carrying out segment processing, and then an SLM (Source Library Maintenance) algorithm and a PTS (Partial Transmit Sequence) algorithm are used by segments to obtain good PAPR reduction performances of the SLM algorithm and the PTS algorithm; the performances of the PTS and SLM algorithms are subjected to simulation comparison and a PTS is better than SLM on the aspect of an error code performance; the effect of lowering a PAPR effect is slightly worse than the SLM. According to the method disclosed by the invention, a technology for reducing the peak-to-mean ratio in the OFDM has better PAPR inhibition effects and better same-level computation complexity compared with the SLM algorithm and the PTS algorithm.

The invention discloses a downlink power control method and a downlink power control device. The method comprises the following steps that: a base station side sends EPRE information which contains common pilot frequency, the cell dedicated parameter of ratio information of real EPRE of data in an OFDM signal which only contains the common pilot frequency to real EPRE of data in an OFDM signal which does not contain a reference signal, and user dedicated EPRE related information of initial EPRE of data in the OFDM signal which does not contain the reference signal; the base station side distributes each symbol power value on a resource block to be sent according to the cell dedicated parameter, the user dedicated EPRE related information and correction information of different user power and sends the resource block; and a terminal side receives a reference symbol, performs channel estimation, and detects and recovers the received reference symbol according to the ratio of data symbol EPRE and demodulated pilot frequency EPRE which are obtained by parametric computation. The method is favorable for improving the error code performance of a system so as to increase the information throughput of the user while realizing downlink power control.

The invention provides a Massive Multiple-Input Multiple-Output (Massive MIMO) pre-coding method, which aims to solve the problems of high error rate and low energy efficiency of a Massive MIMO system in the prior art. The method comprises the following steps: obtaining a mathematical optimization model of the Massive MIMO system; designing a receiving end base band decoding matrix; designing a sending end base band pre-coding matrix; designing a sending end radio frequency pre-coding matrix; and outputting the base band and radio frequency hybrid pre-coding matrixes. The Massive MIMO pre-coding method provided by the invention has the benefits that the base band and radio frequency hybrid pre-coding method adopts the principle of mean square error minimization, and combines the convex optimization method with the Particle Swarm Ant Colony Optimization (PSACO) method, so as to achieve a high iteration rate and obtain the hybrid pre-coding matrixes; compared with the traditional pre-coding method, the method can better reduce the error rate of the system; meanwhile, compared with the full-digital base band pre-coding, the method has the advantages of low hardware implementation cost and high energy efficiency.

The invention discloses a rotation constellation diagram based coding and decoding method for a spatial multiplex multi-aerial system. According to the method, the rotation constellation diagram based coding and decoding method and the spatial multiplex multi-aerial system are combined, a transmission signal is subjected to serial and parallel conversion at a transmitting end and a mapped onto a modulation constellation diagram, all constellation points rotate by using origin points as circle centers at set angles and reversely rotate at the same set angles after signs are detected at a receiving end, a signal sequence is modulated through the constellation diagram and is subjected to parallel and serial conversion, and the signal is output. By the method, the problem of error rate increase caused by constellation point overlap in a related channel is solved, and the error rate of the spatial multiplex multi-aerial system in the related channel is reduced better on the premise of not increasing system bandwidth resources and unnecessarily reducing transmission rate. Compared with the traditional spatial multiplex multi-aerial system, only a rotation factor is multiplied at the transmitting end and the receiving end, and the coding method is low in hardware cost and excellent in error code performance.

A signal and information transmission system for communications or radar and a method of achieving distortionless transmission of linear phase shift keying signals amplified by nonlinear power amplifiers or distorted by up-converters and RF circuits or the channel. Error correcting codes are used to jointly overcome both the distortion by the power amplifiers or up-converters and RF circuits or the channel and the noise. The modulator generates properly pulse shaped PSK signal, which does not have constant envelope. The signal-to-distortion power ratio is maximized to be above 20 dB at the fully saturated power amplifier output. The simplest linear receiver is provided to demodulate the received signal in the presence of radio distortion, channel distortion and noise. The decoder makes decision in the presence of radio distortion, channel distortion and noise. The method guarantees distortionless transmission of PSK signals for communications systems or radar employing power amplifiers of high DC-to-AC power conversion efficiency including class-F, class-E, class-D, class-C, or any of class-A, class-B, class-AB working in the saturation region. The method can achieve high bandwidth efficiency.

The invention discloses an adaptive free space optical communication (FSO)-orthogonal frequency division multiplexing (OFDM) transmission system. The transmission system comprises an adaptive orthogonal frequency division multiplexing (AOFDM) transmission part, an optical up-conversion module, an optical down-conversion module and an AOFDM receiving part which are sequentially connected. An adaptive FSO-OFDM transmission method of the invention has the advantages of expanding a carrier deviation estimation range and simultaneously solving problems on the estimation of carrier deviations underthe condition of inconsistency of each carrier deviation caused by the frequency-selective fading characteristic of an atmosphere channel by adopting a high-order cumulant-based carrier blind-synchronization algorithm, providing an effective way for improving a transmission rate and reducing the bit error rate of the system for free space optical communication by realizing the modeling of the optimal adaptive FSO-OFDM transmission system with maximum transmission capacity, and providing novel methods and theoretical bases for further improving the transmission efficiency of the adaptive system and improving system performance by adopting high-order cumulant-based blind channel estimation and blind signal detection technology.

A parallel-adaptive blind balancing method of high speed digital receiver includes utilizing iteration calculation error vector of K number iteration calculation to update tap weight coefficient of balancer and carrying out L path of parallel-adaptive blind balancing treatment on input serial data according to minimum mean square error rule with L being number of parallel path.

This invention discloses a method for hybrid encode modulation and power distribution including: 1,at the transmission end, the channel encoded data are separated and reorganized to bit sequences with multiple branches based on the different bit importance, 2, the bit sequences of multiple branches are interleaved separately, 3, the inter leaved bit sequences are modulated separately, 4, distributing power to symbols of the modulated branches, 5, imaging the modulated signals to the physical channel, 6, at the receive end, applying corresponding ways to demodulate the received symbols of different branches to be de-interleaved and de-separated so as to get the data sent by the transmission end.

The invention belongs to the wireless communication field and provides a frequency deviation, time delay and phase deviation combined synchronization method of continuous phase modulation signals. The combined synchronization method includes the following steps of: FFT-based frequency deviation estimation; frequency deviation correction; filtering and demodulation; error signal generation: timing error signals and phase error signals are generated by using demodulation code elements and decision information; and iterative update: a timing loop and a phase-locked loop update timing and phase estimated values by using the error signals. According to the frequency deviation, time delay and phase deviation combined synchronization method of the continuous phase modulation signals, based on an FFT-based frequency deviation estimation algorithm, and a timing and phase combined estimation algorithm is used in combination, and therefore, accurate estimation can be performed on frequency deviation, timing and phase information. The method of the invention is suitable for accurate estimation of the frequency deviation, timing and phase value of the continuous phase modulation signals under a condition that frequency deviation, frequency deviation primary rate of change, time delay and phase deviation exist. The method has the advantages of elimination of false lock, excellent bit error rate (BER) performance and high estimation precision.

The invention discloses a system and a method for power allocation in a wireless sensor network based on cooperative transmission. The method comprises the steps that: a ancillary estimation module of training sequence estimates the frequency impulse response value of a multi-path fading channel between source nodes, relay nodes and sink nodes; a power allocation calculation module calculates the parameters of a power allocation module according to the numerical relationship of the estimated channel coefficients; a feedback module feedbacks the parameters to the power allocation module; and finally the power allocation module sets its filter group parameters according to the feedback parameters, so that the total sending power of the sending data is self-adaptive allocated. It is the optimization aim of the invention to maximize the signal-to-noise of data received by sink nodes in block mode sink nodes, and the optimized system error rate has improved performance.

The invention discloses a symbol-based physical-layer network coding method for a two-way relay communication system. The method comprises the following steps that: in a first time slot, during the receiving of information through a relay node, two source nodes send respective modulated signals to the relay node respectively, and the relay node performs self-correlation operation on the received superposed signals to obtain a self-correlation matrix and detects a network coding symbol to be broadcast from the self-correlation matrix by using a maximum-likelihood (ML) detection algorithm to reduce a detection space of the network coding symbol, so the difficulty of signal detection is reduced, a receiving diversity gain is obtained, and the error code performance of the system is guaranteed; and in a second time slot, during the broadcasting of the information through the relay node, the relay node broadcasts the detected network coding symbol, and the two source nodes respectively decode the received signals by using a self-interference elimination method to obtain the information of the opposite-side node, so a communication process is finished. The invention has the advantages that: the operation complexity of a relay processing signal is reduced by using the characteristics of an M-ary phase shift keying (MPSK) signal; the receiving diversity gain is obtained; and the method is applicable to an MPSK modulation system at symmetric and asymmetric speed rates under a two-way relay channel.

The invention discloses a wireless aviation burst communication system, which comprises a burst frame construction module, a receiving digital front-end processing module, a burst detector, a carrier and phase parameter extraction and recovery module, and a timing parameter extraction and recovery module, wherein the burst frame construction module is used for constructing a burst frame, and the burst frame is composed of an AGC training sequence, two identical repeated CAZAC training sequences, and a data block; the receiving digital front-end processing module is used for acquiring an initial demodulation signal with frequency offset, phase offset and timing errors; the burst detector is used for adopting the repeated CAZAC training sequences for carrying out matched filter on the initial demodulation signal, acquiring a burst sign and outputting two related peak values and related peak sidelobe values; the carrier and phase parameter extraction and recovery module is used for estimating carrier and phase parameters and completing recovery; and the timing parameter extraction and recovery module completes timing recovery. The burst frame detection probability can be effectively improved, and complexity of burst communication carrier, phase and timing recovery is reduced.

The invention discloses a feeble pulse optical signal detection device and a detection method thereof. The device comprises a high-sensitivity multiplier phototube, a preamplifier, a high-speed digital signal processor and a computer; the high-speed digital signal processor is divided into a high-speed A/D unit, an automatic threshold value setting unit, a single-photon discrimination output unit, a self-adapting pulse width matched filtering unit, a pulse extraction, positioning and output unit and a demodulation unit; the high-speed digital signal processor realizes the single-photon discrimination and communication signal processing by software. The detection device and the detection method can solve the difficult problems of detecting and extracting the pulse optical signal under the different applied occasions, background noise and pulse distortion; and the device is based on a high-speed DSP chip, has low cost, high integration level, certain intelligence, high sensitivity, strong antinoise capacity, low error rate, a simple structure and light weight, and can be used in detection for modulating the feeble pulse optical signal of the pulse position in free space laser communication.

The invention discloses an MIMO secret communication method based on differential chaos shift keying (DCSK). Due to improvement, information is made to be dispersed on two channels for transmission, the reference signal of each way of information is transmitted on the other way, and therefore even when a certain way of information is intercepted in the transmission process, an original signal can not be decoded, and meanwhile, the problem that the utilization rate of the channels is low is solved. Meanwhile, in order to solve the multi-path fading problem, the MIMO technology is used for suppressing the channel noise and the multi-path fading, and the system bandwidth and the transmission power do not need to be increased. By comparing the bit error rate of an original system with the bit error rate of an improved system, it is found that the bit error rate of the MIMO-DCSK secret communication system is lower than that of a traditional system in data transmission, meanwhile, the utilization rate of the channels is higher, and the secrecy is higher.

The invention discloses a multivariate orthogonal chaos shift keying modulation/demodulation method. According to the method, Hilbert orthogonal transformation and orthogonal Walsh sequence weighting are carried out chaos signals to construct a plurality of mutually- orthogonal chaos carrier signals; and the modulation/demodulation is carried out by utilizing a multivariate orthogonal modulation method. According to the multivariate orthogonal chaos shift keying modulation/demodulation method, the delay units in the existing binary/N-nary DCSK receivers are eliminated, the delay units in transmitters are decreased, the realizing complexity is reduced, the bit transmission speed of the system is greatly improved and the bit error rate performance of the system is enhanced to a relatively great extent.

The invention discloses a method and a system of the coding of rate compatible polar codes based on puncturing. In the invention, the range of punctured code words is limited within the code word set irrelevant to information bits first. An improved random puncturing algorithm is provided. Based on the puncturing algorithm, Parallel Concatenated Polar Codes (PCPP) are constructed. Moreover, a rate compatible transmission scheme based on puncturing is provided. The channel is estimated according to the final transmission rate of a data packet and the initial transmission rate of the subsequent data packets is determined. In the method of the invention, the BER and FER of the punctured polar codes are lowered. Besides, the error flat brought by the random puncturing algorithm is modified. At the meantime, the rate compatible transmission of a plurality of polar code data packets in time-varying channels is realized by using the rate compatible transmission scheme of the PCPP in the method, wherein the average retransmission times for each data packet are only 1.8.

The invention provides a pre-coding method for restraining inter-user interference. The pre-coding method mainly comprises firstly designing a linear merging matrix of a user side, enabling the linear merging matrix to be combined with feedbacks of a customer satisfaction index (CSI), and reasonably using degree of spatial freedom; then precoding each user at each base station end, restraining user interference leaked from each user to other users; and finally adopting a maximization standard of signal-to-leakage-and-noise ratio (SLNR) to conduct joint optimization on an obtained precoding matrix and an obtained channel matrix and further promote system performance. The pre-coding method is not obvious in improvement of complexity and has practical application value compared with the SLNR precoding, the inter-user interference is effectively restrained, bit error rate performance and transmission rate are both obviously improved along increase of the signal noise ratio (SNR), and accordingly the precoding performance is better than BT precoding.

The invention provides a hysteretic all feedback neural network-based signal blind detection method. According to the method, hysteresis activation functions used by two sequential cycles just form a hysteresis loop, so that not only the stability of a network is guaranteed, but also the network shows better flexibility; the domain of attraction of a pseudo equilibrium point is effectively avoided by using the method in the all feedback neural network, so that the blind detection performance is improved; and in a synchronous updating mode or an asynchronous updating mode, the error code performance of the hysteretic all feedback neural network-based signal blind detection method is superior to that of the conventional Hopfield signal blind detection algorithm.

The invention discloses a low-complexity super-Nyquist transmission method. Information sequence is Gaussian pulse shaped and performs super-Nyquist code element speed transmission, a receiving end uses a gaussian pulse shaping filter matched with a transmitting end to perform matching filter on a received signal, and the receiving end performs sampling on output of a matching filter with the same super-Nyquist sampling rate with the transmitting end. The maximum likelihood sequence estimation (MLSE) is performed on a sampling signal to compensate the intersymbol interference (ISI) of the receiving signal, soft value output information is obtained, and the system bit error rate (BER) performance can be further improved through performing iteration exchange on prior soft value information between a channel decoder and a FTN equalizer. The adopted gaussian shaping pulse can make the FTN transmission system ISI tap energy to rapidly decay, the MLSE equalization algorithm is adopted, only less ISI tap amount can acquire quasi-optimal BER performance, and the system realization complexity is greatly reduced.

The invention discloses a method for reducing the PAPR of an OFDM system through an improved SLM algorithm and relates to an OFDM technology. The method for reducing the PAPR of the OFDM system through the improved SLM algorithm aims to solve the problem that the system error rate of an existing non-sideband transmission SLM algorithm is high, and includes the first step of determining a frequency domain data vector of an OFDM signal, the second step of processing the input vector X through the improved SLM algorithm, the third step of carrying out IFFT on obtained D paths of independent output vectors S(d) to obtain D paths of time-domain signals, the fourth step of selecting and sending the path of signal with the minimum PAPR value, the fifth step of carrying out FFT on the received D paths of signals by a receiving end, the sixth step of carrying out module picking on the obtained D paths of signals after FFT, the seventh step of estimating out which path of signal is emitted by an emitting end and the eighth step of recovering original signal information. The method is applied to the field of wireless communications.

The invention relates to a method for coding low-density parity check code of multi-code length and multi-code rate, in particular to an extended code taking the low-density parity check code with the code length of 2032 bits and the code rate of 1/2 as core and a high-efficiency coding method for correcting channel error data, belonging to the technical field of communication channel coding. The method comprises the following steps of: firstly pre-processing an information sequence with the length of KC bit and leading the information sequence length to be 1062 bits; establishing a check matrix H; calculating the checking sequence according to the information sequence and the check matrix H; synthesizing the information sequence S and the check matrix P to obtain the code sequence with the code length of 2032 bits and code rate of 1/2; and deleting and superposing the code sequence, processing the operated code sequence, thus obtaining the code sequence with the code length of NC. The coding method has the advantages of no loss on bit error code performance, more excellent error code performance at local points, extremely low realization complexity, being extremely beneficial to hardware realization, and having extremely strong application prospect.