37 results about "Closed expression" patented technology

The invention provides an accurate wireless security transmission technology based on a random frequency diversity array (RFDA) and directional modulation (DM). According to the invention, artificial noise (AN) is projected to the desired position-oriented vector zero space to interfere with surrounding potential eavesdroppers, which enhances the security of signal transmission. Compared with a traditional directional modulation technology based on a phased array (PA), the technology provided by the invention uses the random frequency diversity array to elevate security transmission from one dimension (angle) to two dimensions (distance and angle) to realize accurate point-to-point signal transmission. According to the invention, a closed expression of the lower bound of the traversal security rate is acquired; the influence of power allocation and frequency allocation on the performance of the technology provided by the invention is investigated; and compared with the original directional modulation technology, the technology can effectively improve the security transmission rate.

The invention relates to a half-blindness collaborative spectrum sensing method with reliable false-alarm performance. The method is used for constructing statistical decision amount by utilizing all characteristic values of a sample covariance matrix, and comprises the following steps: firstly, sampling a signal of a collaborative sensing node so as to form a received signal data vector; then calculating the sample covariance matrix of the received signal by utilizing the received signal data vector, and calculating all the characteristic values of the matrix; then constructing the statistical decision amount by utilizing the obtained characteristic values, and calculating the sensing decision threshold based on a simple closed expression; and finally, implementing multi-node collaborative sensing decision, wherein when the statistical decision amount is greater than the set threshold value, a master user signal exists, otherwise, when the statistical decision amount is less than the threshold value, the master user signal does not exist. The method provided by the invention can be used for achieving half-blindness detection under the condition of being lack of the master user signal and the statistical information of a wireless channel, and good detection performance is shown at the application occasions of the low signal to noise ratio, relatively weak relevance between received signal samples and the like.

The invention discloses an MPPM-FSO system hard demodulation error symbol rate calculating method based on an EW composite channel model. The method comprises the steps that 1) based on EW distribution, a point-to-point free space optical communication composite channel model is established by taking into account the influence of a point error; 2) the values of the optimal decision threshold and adynamic decision threshold are determined according to the cumulative distribution model and probability distribution model of an EW turbulence and point error composite channel model; 3) the probability of wrong decision for each time slot subject to the interference of an EW turbulence and point error complex channel is calculated; and 4) the Gaussian Laguerre polynomials are used to acquire the closed expression of the error symbol rate. According to the invention, compared with a single atmospheric turbulence model, the composite channel model in the method takes into account the influence of the point error on the system performance; and the method has low complexity, is better than other hard demodulation algorithms in the aspect of the error symbol rate system performance, and ismore in line with the actual situation.

The invention relates to a method for acquiring an electromagnetic field of an electromagnetic wave through an interface between sea and air. Conductivity of seawater is utilized for generating an induction current of an underwater radiation source at a seawater-air interface. According to a Huygens-Fresnel principle, distribution and area size of the induction current on the sea surface is determined. Furthermore, the induction current area on the sea surface is used as an antenna of a known current density distribution. A secondary radiation is performed to the air through the induction current area on the sea surface, thereby determining the electromagnetic field distribution in the air. The method prevents direct SI integration and overcomes high operation difficulty in prior art. Furthermore the method of the invention can simply and clearly generate the physical process and field distribution of the electromagnetic wave in cross-interface communication and furthermore contains a closed expression.

The invention relates to a resource allocation algorithm of D2D communication in a cellular network for solving the technical problem of improving the poor energy efficiency. The problem is well solved by the following technical scheme: establishing a cellular network D2D communication model, and defining constraint conditions; performing power control based on an improved power control algorithm,and eliminating users not meeting the condition from a reusable set, comprising: calculating a power allocation closed expression (the formula is shown in the specification) to serve as an optimal transmitting power combination satisfying the constraint conditions, wherein (the formula is shown in the specification) represents the optimal transmitting power of a D2D user m, and (the formula is shown in the specification) represents the optimal transmitting power of a cellular user n; and obtaining an optimal channel pair by using an improved matching algorithm, and obtaining an optical channel allocation scheme satisfying the constraint conditions. The resource allocation algorithm can be applied to the D2D communication.

The invention discloses a design method of millimeter wave communication codebook. The method comprises two steps of ideal codeword design and actual codeword design. The invention fully studies the codeword design method of the millimeter wave communication system, and provides an improved method for the ideal codeword design and the actual codeword design. In the ideal codeword design, a designthat is easy to calculate and has a closed expression is provided. In the actual codeword design, a fast design method is provided for a millimeter wave hybrid precoding architecture and a quantized phase shifter. The performance of the ideal codeword designed by the invention is superior to the prior art. Meanwhile, the performance of the actual codeword designed by the invention is superior to the prior art under the condition of a small number of radio frequency links.

The invention discloses a visible light point-to-point and broadcast communication system signal generation and capacity computing method, relates to the technology of visible light communication andis used for solving the problem that the method that at present, many researchers relax constraints as a peak power constraint and a mean optical power constraint to search approximation of the optimum transmission signal is not practicable. For the visible light communication, a point-to-point channel capacity and multiuser channel reachable rate domain is still an open problem. At present, the researchers devote themselves to search an excellent enough estimation method, an upper bound and a lower bound. The SISO point-to-point and SISO multiuser-targeted visible light point-to-point and broadcast communication system signal generation and capacity computing method is provided. The transmission signal generation method has a closed expression and satisfies the constraints for limited peak power, limited mean optical power and limited mean electric power. The method can be proved to be superior to the other method in theory. The method is simple in form and is easy to apply.

The invention provides a high energy efficiency power distribution method in a distributed antenna system. The method comprises the steps that the maximum energy efficiency of the distributed antenna system is used as the optimization target; the power of each remote antenna of the distributed antenna system is used as an optimization variable to construct an energy efficiency model; derivative analysis and classified discussion are used to select the number of remote antennas used for signal transmission; and classified discussion and the Lambert function are used to give the closed expression of power distribution. The method provided by the invention can effectively realize the optimal power distribution of each remote antenna, provides the closed solution to avoid iterative computation, and has the advantage of greatly reduced computational complexity compared with the existing method.

The invention provides a spectrum-energy efficiency balance method for a double-layer ultra dense heterogeneous network based on stochastic geometry. The method comprises the following steps: step 1, constructing the double-layer ultra dense heterogeneous network by using a Poisson point process in the stochastic geometry; step 2, obtaining a total system throughput based on a probability density function and a probability generation function of the Poisson point process; step 3, obtaining a relation among spectrum efficiency, energy efficiency and network density of the overall system from the definitions of spectrum efficiency and energy efficiency; and step 4, obtaining a relation closed expression between the spectrum efficiency and the energy efficiency via the optimization theory. The method has the advantages: 1) the network coverage is enlarged, and the network capacity is improved; and 2) the density of the network can be effectively changed to realize spectrum-energy efficiency balance of the system. Therefore, the method has better mobile user experience, and provides an effective reference for 5G honeycomb deployment.

The invention provides an optimization method of a five-degree-of-freedom first-end symmetric mechanical arm inverse kinematics calculation. The optimization method comprises the following steps thata virtual rotary joint with the rotation angle being always zero is added, and mechanical arm DH parameters are calculated; the position coordinates of the center of the spherical wrist are calculated, the obtained target rotation angle is obtained by homogeneous transformation matrix and converting. The inverse kinematics solving process of the five-degree-of-freedom first-end symmetrical mechanical arm is not subjected to technical means such as iteration, classification and trial and error, and the closed expression of joint angles and the joint morpheme is directly obtained according to the parameters of the mechanical arm, so that the inverse kinematics problem of the five-degree-of-freedom first-end symmetric mechanical arm can be rapidly solved, the calculation precision and the calculation speed are improved, and the real-time response of the mechanical arm can be realized.

The invention relates to a mixed channel fading based interference analysis method for a satellite terrestrial integration system and belongs to the technical field of telecommunication. According to the method, first of all, by use of a mixed fading model EGK, probability distribution density of ground link receiving signals is established, wherein the mixed fading model internally comprises shadow fading and multipath fading; then by use of Gamma distribution, power spectrum density of set total interference of other ATC base stations is represented; power spectrum density of satellite set total interference is represented by use of a Shadowed-Rician model; ATC user interruption probability Pout is defined according to a signal-to-interference ratio threshold gamma th of user receiving power; and a closed expression of the ATC user interruption probability Pout is obtained, the Pout is calculated according to the expression by use of a Matlab tool, and ATC user downlink same-frequency interference analyzing is performed. By use of the method, interference analysis is more comprehensibly and accurate, calculation is more rapid, interference calculation is faster, more convenient and easier, and interference conditions can be rapidly and conveniently obtained.

The invention provides a hybrid medium communication system outage probability calculation model based on an AF/DF protocol and a self-adaptive relay method. The outage probability calculation model derives a closed expression of a system outage probability when a relay adopts AF and DF protocols by utilizing a two-dimensional LogN approximation algorithm and an MGF of an output signal-to-noise ratio; according to the adaptive relay method, on the basis of the outage probability calculation model, a signal-to-noise ratio equation is solved to obtain a threshold value of adaptive relay, and anappropriate AF or DF protocol is adaptively selected according to the threshold value for information forwarding, so that an efficient relay process is realized. According to the invention, the outageprobability calculation model has high accuracy and reliability; the self-adaptive relay method effectively overcomes the defects of the AF and the DF, the AF or DF forwarding protocol is dynamicallyselected according to the channel quality, and the relatively optimal outage probability performance is obtained on the premise of not increasing the system complexity, so that the optimal communication quality is obtained.

The invention discloses a D2D (Device-to-Device) cooperative transmission method under a rician fading channel condition. The method comprises the following steps of (1), scheduling cell users and D2D users participating in cooperative transmission; (2), estimating Doppler frequency offset of the cell user US <0> and a D2D link receiving end user D <1 > and obtaining a channel time delay correlation coefficient; (3), estimating performance gains obtained in two transmission modes and determining to adopt a cooperative transmission mode by a base station; (4), estimating own channel information by the user, quantizing the information and feeding back the information to the base station; and (5), transmitting data under a precoding scheme of the selected mode. According to the cooperative transmission method provided by the invention, a reachable rate is fitted with statistical properties of a real system well; through utilization of a closed expression, before the system feeds back the channel information actually, the base station is assisted in carrying out judgment rapidly and effectively; the user only feeds back necessary channel state information to the base station according to a cooperative demand; and transmission loads of a feedback link are reduced.

The invention discloses a design method of a distributed antenna wireless energy transmission network architecture, specifically, the distributed antenna wireless energy transmission network architecture. A rounded covering residential area is taken into account, and uniform circular antenna layout is also taken into account. When a power beacon (PB) distributed antenna is used, a closed expression of averagely collected direct-current power of users in the residential area and average wireless energy transmission efficiency of the PB distributed antenna is solved; the electromagnetic radiation requirement of FCC is taken into account, and a closed expression of the minimum antenna height of the distributed antenna when the residential area is free of a radiation forbidden zone is firstly solved; and secondly, in order to maximize the average wireless energy transmission efficiency of the distributed antenna, a closed expression of optimal distributed antenna concentric circle radius is solved and obtained. Experimental results show that the average transmission efficiency of wireless energy transmission is obviously improved compared with the performance of an integrated antenna by using the distributed antenna wireless energy transmission architecture disclosed by the invention.

The invention discloses a method for establishing a multi-wall penetration loss model, and an application thereof, and belongs to the technical field of wireless communication. The received power in the presence or absence of two walls is described by a product of two independent Gamma variables. A closed expression is proposed to represent the small-scale distribution characteristics of signal loss caused by passing through the two walls, the problem that the signal fluctuation caused by the existing multiple walls is more complex, such that the characteristics cannot be accurately describedby the traditional model is solved, the wall penetration loss of a wireless signal in an ultra-dense small cell network can be accurately predicted, thereby better solving the coverage hole of the indoor communication and enhancing the user experience quality.

The invention relates to a decoding method based on maximum posterior probability in analog coding, the method comprises the following steps: S1, by a sending end, sending a signal, subjected to analog coding, and a block variance to a receiving end through introducing pseudo-analog transmission SoftCast of a set chaos function; S2, modeling a noise of the received analog signal into a gaussian noise, and obtaining a to-be-decoded signal of equivalent modeling; S3, calculating a coding gain; S4, through the set chaos function and a closed expression of a MAP decoder gaussian distribution function, obtaining a MAP decoding closed expression of 1/2 analog coding and 1/3 analog coding; S5, performing IDCT reconstruction for a IDCT reconstruction coefficient matrix to obtain a decoding outputof a noisy coding symbol. Compared with the prior art, the method provided by the invention makes full use of prior probability distribution information of an information source and known received data, simultaneously balances performance and computation complexity and has the advantage of being easy to use in actual systems.

The invention discloses a synthetic aperture radar image modeling method and a synthetic aperture radar image modeling device. The synthetic aperture radar image modeling method comprises the steps of a first step, creating a gray scale histogram Y; a second step, creating a generalized gamma mixture model; and a third step, based on an HECM-MML-GgammMM algorithm, estimating the mixed weight value of the generalized gamma mixture model, the parameter of each generalized gamma component and an optimal number of the mixture model components, thereby determining the constructed generalized gamma mixture model and finishing image modeling. The synthetic aperture radar image modeling method and the synthetic aperture radar image modeling device can be widely applied on accurate modeling of the SAR image with single-peak or multi-peak distribution characteristic on amplitude and strength and same-texture or heterogeneous-texture characteristic. The parameter has a closed expression form, and furthermore easy realization and high computing efficiency are realized. The synthetic aperture radar image modeling method and the synthetic aperture radar image modeling device have advantages of keeping details in the image, reducing information loss and effectively acquiring image classification result.

The invention discloses an error rate calculation method for UWOC system hard demodulation based on GGD channel model. The method comprises the following steps: based on GGD, a point-to-point underwater wireless optical communication system model is established by adopting MPSK modulation; by using the Gauss Laguerre polynomials, the closed expressions of point-to-point MPSK modulation error ratewithout using the channel coding are obtained, the average error rate of LDPC- UWOC system is statistically analyzed, based on the GGD distribution, a multi-hop wireless optical communication system model with MPSK modulation is established, the closed expressions of MPSK modulation error rate without using the channel coding are obtained, a multi-hop wireless optical communication system model with LDPC channel coding is established and the performance of the system is statistically analyzed by using Monte Carlo simulation. The complexity of this method is low, and the performance of error rate system is better than that of systems without channel coding; the new GGD channel model is adopted, which accords with the experimental condition.