625results about How to "Improve bit error rate performance" patented technology

The embodiment of the invention provides a channel coding and decoding method and device, wherein the channel coding method comprises the steps that: a coder obtains an information bit index set; the coder generates a second bit vector according to a to-be-coded first information bit and the information bit index set; and the coder performs Polar code coding on the second bit vector to generate a coded first codeword. According to the technical scheme provided by the invention, the coder firstly obtains the information bit index set, generates the second bit vector according to the to-be-coded first information bit and the information bit index set, and performs Polar code coding on the second bit vector to generate the coded first codeword, thus the channel coding method can realize that a Polar code is converted into a system code at a lower level of complexity, and can reduce the bit error rate so as to improve the performance of the Polar code.

The invention supplies a method to gain the optimal guidance symbol power. It is used the factors that system noise signal ration in the channel estimating, base station and mobile platform relative move speed, coherent testing channel estimating interpolation filter coefficient and it depth, signal modulating module and the functional relation between the optimal guidance symbol power and the data symbol power ratio to gain the method used to gain the optimal power radio. The method of the invention is adopted to gain the optimal bit error ratio to the self-adapting OFDM system at the condition of giving the total emission power.

A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) modulation. Space-Time coding techniques improve transmission efficiency in radio channels by using multiple transmit and / or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. OFDM modulation allows for wideband transmission over frequency selective radio channels. A receiver demodulates the OFDM signal and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. The MIMO demapping and MAP decoding processes exchange likelihood information to improve the bit error rate performance over several iterations of demapping / decoding. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved.

The invention relates to a method for realizing hybrid automatic retransmission based on reliability, which comprises that: channel coding codewords are divided into a plurality of groups and each group is a set comprising one or more coding bits; when a coding error exists at a receiving terminal, the receiving terminal chooses a group with minimum reliability from all groups of the present codewords; the receiving terminal feeds back the position information of the group with minimum reliability and negative acknowledgement NACK signals to a sending terminal and the sending terminal is notified of coding error existing at the receiving terminal so that to start up retransmission operation; the sending terminal retransmits all coding bits in groups corresponding to the position information and corresponding redundant versions according to the position information and NACK signals fed back from the receiving terminal.

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. These performance advantages allow a noise margin target to be achieved using simpler component codes and a much shorter interleaver than was needed when using prior art codes such as Turbo codes. Decoders are also provided. Both encoding and decoding complexity can be lowered, and interleavers can be made much shorter, thereby shortening the block lengths needed in receiver elements such as equalizers and other decision-directed loops. Also, other advantages are provided such as the elimination of a error floor present in prior art serially-concatenated codes. That allows the present invention to achieve much higher performance at lower error rates such as are needed in optical communication systems.

Embodiments of the present invention provide a channel encoding and decoding method and apparatus, where a channel encoding method includes: acquiring, by an encoder, an information bit index set; generating, by the encoder, a second bit vector according to a to-be-encoded first information bit and the information bit index set; and performing, by the encoder, Polar code encoding on the second bit vector to generate an encoded first code word. In technical solutions of the present invention, an encoder first acquires an information bit index set, generates a second bit vector according to a to-be-encoded first information bit and the information bit index set, and then performs Polar code encoding on the second bit vector to generate an encoded first code word.

The invention discloses a pre-coding method, a system and a device in a MIMO system. The method, the system and the device which are related to by the invention can be applied in the orthogonal space-time coding circumstance. The inventive method adopts a non-unitary matrix for pre-coding, and the non-unitary matrix is obtained by judging the obtained optimal pre-coding vector construction. The inventive system includes a transmitter and a receiver, wherein, the transmitter includes a code list, a pre-coding matrix construction unit and a pre-coding unit; the receiver includes a channel estimation unit, the code list and a judgement unit. The simulation and the analysis show that, compared with the prior art, the usage of the inventive proposal can lower the bit error rate and reduce the complexity of decoding simultaneously in the situation of the same signal-to-noise ratio.

The multiple-antenna space multiplexing system using enhancement signal detection comprising: a code modulation module for coding and modulating bit information; a signal transmission module for transmitting the modulated signals; a signal reception module for receiving the signals; a signal form transform module for transforming form of a channel matrix H and the received signal vector r; a signal detection module for detecting the received signals; a signal reconstruction module for reconstructing the detection results of in the signal detection module, and obtaining a detected signal; a demodulation decoding module for demodulating and decoding the output of the signal reconstruction module, and outputting bit information. Compared with the conventional detection methods, the system performance is improved in considering the realization complexity.

The invention provides a two-level codebook selection method in an LTE-A (Long Term Evolution-Advanced) system, wherein a first-level codebook code word W1 is multiplied by a second-level codebook code word W2 to obtain a precoding matrix W, and according to different criteria, a user separately selects the W1 and the W2 and feeds back corresponding indexes PMI1 and PMI2. The two-level codebook selection method is applicable to the circumstance that linear and non-linear detectors are used by a receiver end, and under the premise of ensuring low computational complexity, the bit error rate of the system can be greatly decreased. In particular, for the circumstance that non-linear detectors, such as a maximum likelihood detector and a spherical detector, are used by the receiver end, the method can be used for sufficiently exploiting the potential performance advantages of the non-linear detectors. The two-level codebook selection method is applicable to the circumstance that the distance between cross polarised antennas of the transmitting end is the result of dividing the Lambda (the wavelength of transmitted electromagnetic waves) by 2 or the result of multiplying the Lambda by 4, and under both circumstances, the two-level codebook selection method can show high bit error rate performance.

The invention discloses a transmission diversity method based on space-frequency coding, which is applicable to an MIMO-OPDM system with a sending antenna which is more than 2. The method takes a combination of the SFBC and pre-coding weighing switching as a diversity mode of SFBC+PVS, taking the objective factor into the account that the stronger the channel correlation is, the weaker the diversity effect is, and uses a weighted vector to remove the effect resulted by the inclination angle between antennae and the channel correlation between different antennae. The method comprises the following steps: step one, two paths of data streams are obtained by carrying out SFBC coding to an input bit stream; step two, two groups of pre-coding weighing vectors are selected; and step three, a coding matrix after pre-coding weighing switching is obtained after the pre-coding weighing vector is adopted to carry out weighing to an SFBC coding data block, and finally an in-time signal obtained by inverse fast Fourier transform is transmitted. By adopting the diversity method, the space diversity effect can be utilized better and the effect on coding gains can be reduced.

A premodulation precoding method precodes a data sequence in a Gaussian minimum shift keying (GMSK) modulator to improve the bit error rate performance of a coherent Viterbi receivers generating estimates of the communicated data sequence without the use of differential decoding while preserving the spectrum of 2-ary and 4-ary GMSK signals over a wide range of bandwidth time products.

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. Constrained interleaving can be summarized in that it: 1) uses an outer code that is a block code or a non-recursive convolutional code, and as such, there are multiple codewords present in the constrained interleaver, 2) selects a desired MHD, 3) selects an interleaver size and a set of predefined interleaver constraints to prevent undesired (low-distance) error events so as to achieve the desired MHD, and 4) performs uniform interleaving among the allowable (non-constrained) positions, to thereby maximize or otherwise improve the interleaver gain subject to the constraints imposed to maintain the desired MHD.

The invention discloses an amplifying and transmitting power distribution transmission proposal based on a distributed linear dispersive code. The proposal comprises the steps that: 1) in a two-hop wireless transducer network, a transmitting terminal as an information source node transmits a RTS packet to a potential relay node to perform a reservation request for a channel; 2) each relay node receiving the RTS packet estimates a signal-to-noise ratio of the RTS packet, embeds information of the signal-to-noise ratio into a RTS packet of remote communication, and transmits a reservation channel of the RTS packet to an information sink which estimates the signal-to-noise ratio of the RTS packet from each relay node; 3) the estimated signal-to-noise ratio of the RTS packet of the remote communication is embedded into a CTS packet by the information sink and is returned to the relay node, and is embedded into a CTS packet in local communication and is returned to the information source node after being received by the relay node, so that the information source node, the relay node and an information sink node can understand information of the signal-to-noise ratio of the RTS packets of all channels; 4) an information source calculates optimized transmitting power of the information source to broadcast signals to relays, after a received signal is normalized by the relay node, a structure of the linear dispersive node is formed by adopting an amplifying and transmitting protocol, thereby transmitting the signal to the information sink with the optimized transmitting power; 5) a receiving terminal of the information sink also can calculate transmitting power of the information source and each relay node, and the decoding can be performed by combining the information and adopting maximum likelihood algorithm or sphere decoding algorithm. The proposal sufficiently represents diversity gain of the distributed linear dispersive code.

The method includes following steps: 1) the system is initialized; the numbers of cyclic prefix inserted into OFDM system are selected by actual measurement of multi path time delay; according to the cyclic prefix, the frequency inserted into by the frequency domain pilot frequency is determined ; 2) SINAD threshold of each kind modulation mode like BPSK, QPSK, 16QAM, 64QAM is set by high layer protocol, the SINAD value obtained from step 1 is compared with the threshold corresponding to each modulation mode; 3) Doppler shift is estimated out, it is decided that the product of Doppler shift and frame length is which range; 4) for first sub-carrier in each group, the modulation mode is presented by using GRAY CODE, the transmission of signal uses 4 bit; 5) the transmitting end assigns the modulation mode to next frame data according to received TMC instruction.

The invention relates to a frequency hopping fountain code system and a transmission method thereof, in particular to a transmission method of a frequency hopping fountain code system introduced by using a novel interweaving technology, and belongs to relevant technical fields of wireless communication systems, communication signal processing, channel coding and decoding and the like. The frequency hopping fountain code system can be used for transmitting data under the condition that a part of frequency points are blocked completely under the action of interference, so that the reliability of a communication system in a severe channel environment is enhanced. A bit-interleaved coded modulation technology is adopted, so that the bit error rate performance of the system is improved. Meanwhile, the redundancy is not increased, so that the rate of information transmission is not influenced. A bit-level interleaver is adopted, and can be used for encrypting under the condition that an interleaving rule cannot be obtained by an enemy, so that the safety of information transmission is enhanced.

The invention relates to the technical field of communication anti-jamming, in particular to a superposition coded modulation (SCM) technology communication system, subcarrier index modulation (SIM) and related time domain detecting technologies. According to an SCM method based on SIM-orthogonal frequency division multiplexing (OFDM), ideas of SIM-OFDM and spatial modulation (SM) are used as reference, a part of a string of bit data is used for transmission, the other part of the string of bit data is used as indexing bits, and the indexing bits are respectively coded. During transmission in an OFDM system, particular subcarrier is selected for transmitting data according to the bit data after coding of the indexing bits. A maximum likelihood method is used at a receiving end to obtain soft information of the indexing bits, and the indexing bits are decoded. Compared with prior SCM methods, the SCM method based on the SIM-OFDM has the advantages that the SCM superposition layers are reduced, the complexity is reduced, and error rate performances can be maintained or even improved to a certain degree. Meanwhile, the SCM is used for replacing quadrature amplitude modulation (QAM), and performances can be improved under the same transmission efficiency.

The invention discloses a signal emission and reception method of a GFDM system based on weight fraction Fourier transform, relating to the signal emission and reception technology of the GFDM system based on the weight fraction Fourier transform. The invention can obtain better bit error rate and reduces the peak-to-average power ratio. The invention can flexibly regulate the subcarrier and the WFRFT order in the unit carrier wave block according to the channel state information and user demands, and the order in each subcarrier can maintain different in order to achieve to the need of the system performance. Besides, the invention performs precoding through WFRFT and reasonably chooses the appropriate transformation order according to the channel condition, which enables the encoded system to obtain a better bit error rate performance and have lower peak-to-average power ratio.

The invented method includes following steps with characters of supporting hybrid automatic feed back request (HARQ) technique. In preparing step, the dispatching cycle is fixed. Several adjacent subcarrier waves constitute the sub band. The resource composed of several sub bands is dispatched once a time in each time slot. Then, the mobile station feeds back the word of data rate control (DRC) obtained by quantizing average S / N ratio based on each sub band. In the step of dispatching retransmission data, after calling out the parameters of the scheme at last transmission for retransmission data, the retransmission data are fed back for several transmissions, which have largest DRC, in user's all available sub bands. The invention uses the low error rate of HARQ method and gives attention to both of fairness and system efficiency, and processes low feedback quantity and control amount of information.

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. These performance advantages allow a noise margin target to be achieved using simpler component codes and a much shorter interleaver than was needed when using prior art codes such as Turbo codes. Decoders are also provided. Both encoding and decoding complexity can be lowered, and interleavers can be made much shorter, thereby shortening the block lengths needed in receiver elements such as equalizers and other decision-directed loops. Also, other advantages are provided such as the elimination of a error floor present in prior art serially-concatenated codes. That allows the present invention to achieve much higher performance at lower error rates such as are needed in optical communication systems.

The invention provides a channel estimation method for improving receiving sensitivity of an OQAM (Offset Quadrate Amplitude Modulation)-OFDM (Orthogonal Frequency Division Multiplexing) light transmission system, and aims at solving the problems that the traditional channel estimation algorithm for the light OQAM-OFDM cannot treat intersymbol interference and inter-subcarrier interference caused by the orthogonal damage of a subcarriers, and the decrease of the receiving sensitivity of the system caused by the accompanying gaussian noise and the like produced by devices in the system is ignored. The channel estimation method has the advantages that the interference approximating utilization based time-domain averaging channel estimation method (IATA-CE) comprising the steps of first-order LS channel estimation, second-order LS channel estimation and ZF balancing is performed during receiving to accurately estimate complex gain and phase response of a fiber channel; in addition, the interference from gaussian noise produced by the devices in the system can be resisted well; therefore, accurate channel estimation coefficients can be obtained, and as a result, the BER performance and receiving sensitivity of the system can be improved.

The invention discloses a cyclic prefix-free OFDM receiving method based on model driving depth learning, comprising the following steps: (1) transforming a pilot frequency signal yp in a received signal y to obtain a frequency domain pilot signal, performing least square estimation initialization on the frequency domain pilot signal and a local frequency domain pilot signal to obtain a least square channel estimation result, then, inputting the least square channel estimation result to a fully-connected first deep neural network for improvement, and performing Fourier inverse transformation on an improvement result to obtain a time domain channel estimation signal (formula); (2) performing inter-symbol interference on the received signal y and then converting the received signal into a real-number domain received signal (formula); (3) taking the real-number domain received signal (formula) as an input, and using a second deep neural network to perform iterative solution according to the time domain channel estimation signal (formula) to obtain a final estimated modulation signal (formula); and (4) demodulating the modulation signal (formula) to obtain a transmitted information bit(formula). The method is less in time consumption and high in detection performance.

The invention provides a data transmitting method, a data receiving method, a data transmitting device, a data receiving device and a system, wherein the transmitting method comprises the following steps of: processing data generated by information sources, thereby obtaining the processed serial data sequence; converting the serial data sequence into a parallel data signal sub stream according to a layered space-time coding mode, wherein the parallel data signal sub stream is in one-to-one correspondence with each transmitting antenna; framing the data of the data signal sub stream on each transmitting antenna according to certain length, thereby obtaining the corresponding data frame; carrying out frequency deviation treatment on frequency domain data in the corresponding data frame on the frequency domain; adding a protection interval in each data frame after frequency deviation processing, so that the lengths of the data frames of each transmitting antenna after the protection intervals are added are equal; carrying out orthogonal frequency division multiplexing modulation on data frames after the protection intervals are added, thereby obtaining a digital base band signal on each transmitting antenna; and modulating the digital base band signal on each transmitting antenna into a radio frequency signal, and transmitting the radio frequency signal.

The invention provides an ACO-OFDM system integrated PAPR inhibition method and system based on a neural network. A self-encoder network is used to realize Q-I mapping and demapping of a transmissionsignal, and an extended SLM method and a Clipping method are added into the network structure. The method comprises the following steps: carrying out serial-parallel conversion of an input signal andtransmitting the input signal to an encoder part of a self-encoder network to obtain I-Q constellation mapping output; transmitting a PAPR signal to a phase rotator to generate an alternative low PAPRoutput sequence; carrying out Hermitian symmetry of the replaced output sequence and carrying out fast Fourier inverse transformation to obtain a time domain OFDM signal; carrying out the parallel-serial conversion and cyclic prefix addition of the time domain OFDM signal, and then enabling the OFDM signal to be suitable for the limited emission range of an LED through amplitude limiting; and enabling the receiving end to recover the distorted signal through an opposite process. In network training, two factors of bit error rate and PAPR are considered at the same time, and the automatic encoder is trained by adopting a combined loss function. According to the comprehensive scheme based on the neural network, the PAPR is effectively reduced by more than 12dB.

Hierarchical modulation preferably uses a 16-ary quadrature amplitude modulation (QAM) modulator with a convolutional encoder that combine to effectively provide unequal protection to two different segments of streaming input data, with improved power efficiency with the same bandwidth efficiency, by encoding the first segment as coded data as LSBs as the second segment remains uncoded as uncoded MSBs, with the MSBs used for QAM constellation modest reliability interquadrant demodulation and detection, and with the LSBs used for low reliability intraquadrant detection, but with the LSBs subject to convolutional encoding and decoding rendering the LSBs with high reliability detection, such that, the two segments have unequal coding and modulation for providing unequal levels of reliability detection.

The invention discloses a mapper and a mapping method based on a bit interleaving coding modulation system, and mainly solves problems of the prior coding modulation system including low spectrum efficiency and high bit error rate. The mapper adopts a structure in which interblock is based on approximate Gaussian distribution and intrablock is based on the rule of minimum hamming distance. The mapping method for mapping 32 information symbols to a 16-QAM constellation comprises the following mapping steps: 1) ensuring that every five bits in an input bit sequence are corresponding to an information symbol; 2) realizing grouping of different information symbols and respectively mapping each group to a constellation map and constellation points at different Euclidean distances from an origin; 3) setting the front two bits of an information symbol identical in each quadrant of the constellation map, and ensuring that the different number of the last three bits of different symbols corresponding to each constellation point is one or two; and 4) mapping all information bit sequences to a selected constellation map and converting the information bit sequences into symbol sequences. The mapper and the mapping method have the advantages of high spectrum efficiency and low bit error rate, and can be used for data transmission of a demodulation and decoding joint iterative system.

The invention relates to a method for inhibiting MPSK narrowband interference of a direct sequence spread spectrum system (DSSS), and belongs to the technical field of anti-interference of communication. In the method, a main lobe and a side lobe of a MPSK narrowband interference signal are inhibited respectively by adopting a method of combining a frequency domain and a time domain. The method comprises the following steps of: by adopting a method of segmentation overlay processing, inhibiting the main lobe of the MPSK narrowband interference signal as many as possible, and simultaneously ensuring that the energy loss of the useful signal is reduced as much as possible by using the difference between the noise characteristics of the DSSS communication signal in the frequency domain and the energy focusing characteristics of the MPSK narrowband interference signal; and inhibiting the side lobe of the MPSK narrowband interference signal in the time domain so as to effectively separate the interference signal from the useful signal, achieve high performance of bit error rate and guarantee reliable communication of the DSSS by using the characteristics that the frequency spectrum of the side lobe of the MPSK narrowband shows an impulse form. In addition, the method has low computational complexity and is easily implemented by the system in real time.

The present invention provides a polarization code cascade space-time code system and a cascade polarization code coding method thereof. The polarization code cascade space-time code system comprises the following steps that S1 a channel distribution information estimated value of a sending terminal is sent to a polarization code coder, the space-time code coding is carried out on a generated polarization code after modulation, and then the polarization code is sent to an MIMO channel; S2 a signal passes the MIMO channel and then is received by a reception antenna of a reception terminal, and then a space-time code signal reformer reforms the received signal according to a channel side information estimator of the reception terminal; S3 the demodulation and decoding operations are carried out according to the reformed signal and the channel side information of the reception terminal to obtain the original source bit. The present invention provides the reasonable polarization code cascade space-time code system, and according to the analysis in a Rayleigh fading MIMO antenna, each polarization code word equalizes the polarization code cascade space-time code system as a single transmission channel, and the channel gain and addition noise distribution of the equivalent channels is given out.

The invention discloses a channel estimation method of an OFDM / OQAM system, which solves the problem of the poor error rate performance of the system caused by the fact that the traditional channel estimation method of the OFDM / OQAM system only uses a line of 0 to protect a Preamble symbol. In the receiving process, the channel estimation process comprises the steps of ZF(191), ZF(192), CE(18) and PIC(22). Based on the prefix interference cancellation method, the invention eliminates the interference of channel estimation coefficients, acquires more accurate channel estimation coefficients and improves the error rate performance of the OFDM / OQAM system.

The invention provides a method for reducing a peak to average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. In the method, the PAPR is reduced by a cascade selected mapping (SLM) method or a partial transmit sequence (PTS) method and an amplitude limiting method. The SLM or PTS with a small packet number is used for primarily reducing the PAPR of the signal, and a chipping ratio of time domain data which is output by the PTS or the SLM is set by the amplitude limiting method so as to reduce the PAPR to a target value. Compared with the method only using the PTS or SLM method, the method has the advantages that the implementation complexity is low due to the small used packet number. Compared with the amplitude limiting method, the method has the advantage that the PAPR of the signal is primarily reduced before the amplitude is limited so signal distortion is few at the same chipping ratio. The method integrates the advantage of few signal distortion of the PTS or SLM method, and the advantage of the amplitude limiting method that the PAPR is direct and the method is easy to implement. Under the gauss channel, the performance of the bit error rate is reduced to certain extent compared with that of original data, but the performance loss is not large in the range of the signal to noise ratio which is concerned by the design.

The invention discloses a differential chaos shift keying modem and a differential chaos shift keying modulation method based on two-path index modulation, and relates to the technical field of chaoscommunication. A two-path index modulation method is used for transmitting a chaos reference signal and a Hilbert reference signal orthorhombic with each other, and an index mapping rule and an inverted index mapping rule are used for modulating and demodulating the signals. According to the modulation method provided by the invention, delay units are used in a transmitting terminal and a receiving terminal; compared with an existing carrier-index differential chaos shift keying (CI-DCSK) technology, under the premise of occupying a same frequency band, the method synchronously transmits two information signals, so that a bit transmission rate of the system is doubled; in addition, the higher spectrum utilization rate and better data security are achieved, and the method provided by the invention is reduced in bit error rate (BER), and shows better bit error rate performance, and the advantages of the BER performance becomes more significant along with the increasing of a bit signal tonoise ratio.