34results about How to "High signal-to-noise ratio gain" patented technology

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 invention belongs to the technical field of wireless communication, and specifically relates to a radio frequency fingerprint recognition method capable of defending multipath interference. According to the radio frequency fingerprint recognition method capable of defending multipath interference provided by the invention, aiming at the weak difference of the carrier frequency at radio frequency ends of radiation sources, two radio frequency fingerprint features of the radiation sources are respectively extracted from preambles by using an integral method and an envelope extraction method,and then the radiation sources are recognized and classified by using a K nearest neighbor classification method. Compared with the problem in the traditional radio frequency fingerprint recognitiontechnology that the impact of the multipath interference of wireless channels is not considered, leading to performance degradation of the traditional technology under multipath channel conditions, the radio frequency fingerprint recognition technology using the preamble as the research object has the advantages of extracting main path signals on a receiving end by using the autocorrelation of a pseudo random sequence and performing power normalization on dispreading signal by using the fast Fourier transform, thereby avoiding the pollution of random fading to radio frequency fingerprints of aradio while relieving the multipath interference.

The invention discloses a small infrared object detection method in a complex cloud sky background, and relates to the technical field of digital image processing, for the purposes of effectively detecting a small infrared object in a complex cloud sky background and solving the problems of quite high false alarm rate, quite high residual error rate and the like which are easily caused because the cloud layer boundary of an infrared image in a complex cloud layer background has a similar thermal imaging characteristic with an object. A multiple-dimensioned local difference contrast operator and a weight local image entropy operator are brought forward, and then a local weight difference graph is obtained through dot product operation, such that the complex cloud sky background and the noise are effectively inhibited, the object is enhanced, and the object detection rate is finally substantially improved, and the false alarm rate is reduced.

The invention discloses a pulse signal detection method based on multi-pulse envelope spectrum matching. The method comprises the following steps: step 1, acquiring a sampling data sequence of a to-be-processed pulse signal; 2, calculating discrete Fourier transform of a sampling data sequence; 3, generating filter parameters according to known pulse signal frequency parameters; 4, performing frequency domain filtering on the multi-pulse signal by utilizing the generated filter parameters; 5, extracting an envelope of the multi-pulse signal after frequency domain filtering; 6, calculating theamplitude spectrum of the envelope by using Fourier transform; and 7, carrying out detection judgment on the pulse signal by utilizing the multi-pulse signal envelope spectrum. According to the multi-pulse detection method, the pulse string signal envelope is extracted through frequency domain filtering, high signal-to-noise ratio gain can be obtained, the envelope spectrum of the multi-pulse signal is matched with the ideal periodic rectangular signal frequency spectrum, the matching result is detected and judged, the detection probability of the pulse signal can be improved, and the false alarm probability can be reduced.

The invention belongs to the communication signal detection field and the non-linear field and particularly relates to an adaptive stochastic resonance system and method based on an artificial fish swarm algorithm. The system comprises a normalized stochastic resonance module, an artificial fish swarm adaptive module, a step adjustment module, a noise adjustment module and an iteration control module. Through the system, not only can a problem of difficulty in setting an optimization searching initial value of an adaptive system be solved through normalized stochastic resonance, adaptability is improved, no stochastic resonance, excessive stochastic resonance and insufficient resonance caused by parameter selection are considered, relatively strong search capability is kept through a step function adjusted according to resonance convergence conditions, but also local optimum can be properly discovered and jumped out from, and optimal value convergence efficiency is accelerated. An input signal to noise ratio is optimized through the noise adjustment module, and system signal to noise ratio gain is substantially improved.

The invention discloses an orthogonal space-time block code transmission method based on an optimal relay linear weighting matrix, which solves the problems of high error rate and poor transmission performance in the traditional method. The orthogonal space-time block code transmission method is realized by the following steps: (1) a communication system formed by a source node S, a relay node R and a destination node D is set; (2) at a first time slot, the source node S sends signal vectors x1 and x2, and the relay node R receives data yr1 and yr2; (3) the relay node R carries out singular value decomposition on a channel matrix H1 from the source node S to the relay node R and a channel matrix h2 from the relay node R to the destination node D; (4) the relay node R constructs an optimal linear weighting matrix W; (5) at a second time slot, the relay node R constructs and sends signal vectors xr1 and xr2 to the destination node D; and (6) the destination node D receives data yd1 and yd2 and constructs a judgment vector to decode. The orthogonal space-time block code transmission method disclosed by the invention has the advantages that: since the signal-to-noise ratio of received signals is increased, the system error rate is reduced, and the system transmission performance is improved.

The invention discloses a PN code FFT parallel acquisition method in wireless communication techniques. The method includes the steps of generation of a short pseudo code set of a transmitting end, generation of a base band modulating signal, up-conversion processing and signal transmission, generation of a short pseudo code set of a receiving end, signal receiving and down-conversion processing, frequency domain matching and correlation solving, and majority decision. According to the method, a long pseudo code is converted into G short pseudo codes, all the short pseudo codes are connected in a cascading mode to generate the short pseudo code sets, the short pseudo code sets in the same cascading mode are adopted in a receiver at the same time so as to carry out frequency domain matching coherent processing, and then majority decision based on chip delay is carried out; in this way, the method has the advantages that the sensitivity to channel noise is low, accurate channel estimation is not needed during acquisition, acquisition accuracy is high, and the robustness of decision criteria is improved as well due to the adoption of majority decision. A required signal-to-noise ratio in a Rayleigh channel is -13dB or so when the acquisition probability of the method is 95%, and the gain of the signal-to-noise ratio is improved by 12dB or so when compared with the required signal-to-noise ratio of -1dB in background technologies.

The invention discloses a method and a device for capturing navigation signals. The method comprises steps: to-be-processed data segments are selected, the to-be-processed data segments are delayed sequentially for a delay step, and N data groups are obtained; the coherent integral value of each data group is acquired, and the first largest coherent integral value, a left neighbor coherent integral value and a right neighbor coherent integral value are determined; when the absolute value of the difference between the left neighbor coherent integral value and the right neighbor coherent integral value is smaller than or equal to a threshold value, the first largest coherent integral value is determined to be the coherent integral value not including navigation data bit hopping and can be used for capturing and deciding the navigation signals; and when the absolute value of the difference between the left neighbor coherent integral value and the right neighbor coherent integral value is larger than the threshold value, through comparing the left neighbor coherent integral value and the right neighbor coherent integral value, a fine searching direction is determined, and through the fine searching, the coherent integral value not including the navigation data bit hopping is determined. Thus, the computational efficiency during the navigation signal capturing process can be improved, and the signal-to-noise ratio gains are improved.

The invention discloses a data transmission method which comprises the following steps: a base station sends a first data matrix S to a terminal; the terminal carries out space-time coding and decoding for the first data matrix to generate a first decoding result *, and sends a first retransmission request to the base station when the first decoding result does not pass check; the base station responds to the first retransmission request and sends a second data matrix S to the terminal; the terminal carries out space-time coding and decoding for the second data matrix to generate a second decoding result * and carries out combined space-time coding and decoding for the first data matrix and the second data matrix to generate a first combined decoding result *1 and a second combined decoding result *1; and the terminal combines the first decoding result, the second decoding result, the first combined decoding result and the second combined decoding result to generate a first synthesized result. With the invention, a higher signal-to-noise gain can be obtained under the condition of a slow fading channel or a quasistatic channel. The invention also discloses the terminal.

The invention discloses an airspace rotation direction estimation method applied to a uniform circular hydrophone array, and belongs to the technical field of sonar detection. The core technical content of the method is that a Heading angle provided by an azimuth attitude instrument is divided into two parts, a rough airspace rotation matrix and a fine airspace rotation matrix are respectively designed according to the angles of the two parts, and real-time rotation compensation is carried out on array data snapshot, so that target azimuth information in the array data snapshot is focused in the airspace. A covariance matrix constructed by utilizing the rotated data snapshot can be applied to a subspace type orientation estimation method to realize high-resolution orientation estimation ofa far-field target. According to the invention, the relative change of the target azimuth information in array data snapshot caused by the rotation motion of the uniform circular hydrophone array canbe compensated in real time, and the high-resolution azimuth estimation of the far-field target can be realized. The method can be better suitable for the working environment of the uniform circularhydrophone array, and has a certain practical guidance value.

The invention relates to the technical field of wireless communication, and specifically relates to a cooperative communication method based on a game theory in a multi-antenna relay system. A game model is established, and a new power distribution method is provided for the multi-antenna relay system based on selfishness of user nodes. Compared with the prior art, the method has the advantages that the multi-antenna relay selection system and the game theory are combined, thereby ensuring the performance of the whole system and the fairness among the individual users; on the basis of the selfishness of the user nodes, through adoption of the new power distribution scheme, the optimum efficacy of the system is realized; and moreover, the profits of the users are maximized. According to the method, the defects that the traditional non-cooperative communication is low in integral operation efficiency and the stability is low are overcome; the profits of the individual and the whole are ensured; and the Signal to Noise Ratio gain of the user nodes is improved.

A method and apparatus for capturing signals are disclosed. The method includes the steps of obtaining first signal segments, of which the length is integer multiple of the preset length, from a data sequence obtained by frequency mixing and related processing of intermediate frequency signals; dividing each second signal segments with preset length in the first signal segments into a third signal segment and a fourth signal segment; determining the position of the phase jump of each second signal segment for the m time according to the (2m+1) signal segment and the (2m+2) signal segment; determining whether each preset condition is satisfied; if all the preset conditions are not satisfied, determining m signal segment to be divided according to the position of the phase jump determined by the m time; dividing the determined m signal segment to be divided into the (2m+3) signal segment and the (2m+4) signal segment, wherein m is an integer greater than or equal to 1; if any one preset condition is satisfied, determining the coherent integration interval according to the position of the phase jump; and conducting coherent integration for the signal segments corresponding to the coherent integration interval.

The invention discloses a system and a method for assisting generalized spatial modulation based on dual-mode indexes. The system comprises a transmitting end module, a channel module and a receiving end module, the transmitting end module, the channel module and the receiving end module are connected in sequence; the transmitting end module is used for transmitting the information bits of each time slot through constellation modulated information; the channel module is used for transmitting the information of the transmitting end through the wireless channel module; and the receiving end module is used for carrying out information recovery on the information received from the wireless channel through a detection algorithm. By activating all transmitting antennas and using a constellation modulation scheme of different power modes, the performance loss of the system is reduced as much as possible on the premise of improving the spectrum efficiency of the system. Compared with a generalized spatial modulation system under the same spectrum efficiency, the system has larger signal-to-noise ratio gain. Compared with an MIMO system under the same spectrum efficiency, the system can also obtain better performance.

The embodiment of the invention provides a joint detection method and device for a broadband multi-user scene, and the method comprises the steps: carrying out the estimation of channel parameters ofa target sub-band, and obtaining the channel state information of the target sub-band; receiving a signal on a target sub-band to be accessed, and estimating the received signal by using the minimum Euclidean distance according to the channel state information to obtain an estimated signal; increasing the signal-to-noise ratio gain of the estimation signal in a time-frequency domain, and detectingthe signal after the signal-to-noise ratio gain in a space domain to obtain a detection statistic of an access target sub-band; receiving detection statistics sent by other secondary users of the target sub-band to be accessed, and fusing the detection statistics to obtain fused detection statistics; and comparing the fused detection statistics with a preset threshold value, and determining whether the target sub-band has a detection result of the main user or not. Visibly, by applying the method provided by the embodiment of the invention, the accuracy of accessing the secondary user can beimproved.

The invention discloses a network coding protocol power distribution method and system based on channel statistical information, and relates to a network coding protocol power distribution method based on channel statistical information. The method comprises the following steps: S11, an information source node sj respectively sending data signals to a relay node r and a target node di, and the relay node r and the target node di receiving the sent data signals; S12, sending a data signal received by the relay node r to a target node di; and S13, the relay node r calculating channel statisticalinformation received from the target node di according to a power algorithm in an orthogonal amplification forwarding protocol, and the relay node r transmitting power of the channel statistical information modulated through network coding and a signal source node. Closed power allocation of channel statistics information (SCK) reduces network overhead compared to instantaneous channel state information (CSI) based power allocation.