87 results about "Local spectrum" patented technology

The present invention increases the available spectrum in a wireless network by sharing existing allocated (and in-use) portions of the RF spectrum in a manner that will minimize the probability of interfering with existing legacy users. The invention provides interference temperature-adaptive waveforms, and a variety of physical and media access control protocols for generating waveforms based on measurement and characterization of the local spectrum. The invention measures the local spectrum at a receiving node, generates an optimal waveform profile specifying transmission parameters that will water-fill unused spectrum up to an interference limit without causing harmful interference to primary and legacy transmitters using the same frequency bands, and enables simultaneous transmit and receive modes at a multiplicity of transceivers in a wireless network. The invention also provides closed loop feedback control between nodes, co-site interference management, intersymbol interference mitigation, wide sense stationary baseband signaling and modulation, and power limited signaling for avoiding detection and interception.

Methods and systems for sharing white space with primary services and other emerging services are provided. Signal distribution within a specified location, such as a dwelling, is performed using a home gateway that identifies unused white space, reserves such white space spectrum, and delivers data to one or more devices at the respective location using the reserved spectrum. Signalling between the devices and the gateway is performed over a shared signalling channel, which enables the gateway to advise the devices from where and when to receive data. The gateway also uses a common spectrum reservation OFDM symbol to advise the neighbouring gateways of the local spectrum reservation.

The invention discloses a harmonic analysis method based on Kaiser self-convolution window dual-spectrum line interpolation FFT (Fast Fourier Transform) and a device thereof. The method comprises the following steps of sampling a signal: sampling a time-domain continuous signal, and discretizing to obtain an infinitely long discrete sequence; windowing a four-order Kaiser self-convolution window function: performing four-order Kaiser self-convolution window operation on the infinitely long discrete sequence; performing N-point FFT on a windowed and truncated signal to obtain the discrete spectrum of the signal; determining the peak parameter of the discrete spectrum: searching the local spectrum peak of each integer harmonic frequency around the integer harmonic frequency; and calculating a harmonic parameter: solving a coefficient alpha by adopting a discrete spectrum interpolation correction formula based on an LSM (Least Square Method), and calculating parameters such as a harmonic frequency, an amplitude, an initial phase angle and the like. Due to the adoption of the method, the fundamental and harmonic components of a tested signal can be detected rapidly and accurately, and accurate frequency measurement is realized; and the method is convenient for implementing an embedded system, and the tested signal can be detected continuously for a long time.

The invention relates to an improved double-threshold cooperative spectrum sensing method, which comprises the following steps that: a cognitive user in a cognitive radio system senses a local spectrum, compares and classifies sensed main user energy values, if the energy values are beyond two thresholds, can directly perform local judgment to obtain a hard judgment result whether a main user exists and send the result to a fusion center, if the energy values are between the two thresholds, the cognitive user needs to send the sensed main user energy values and signal to noise ratios to the fusion center, and the fusion center calculates a weight factor of each cognitive user according to the received signal to noise ratios and performs fusion judgment according to the received energy values to obtain a soft judgment result whether the main user exists; and the fusion center comprehensively processes the hard judgment result and the soft judgment result, and makes a final judgment whether the main user exists by using an 'or' rule. According to the method, the advantage of double-threshold cooperative spectrum sensing can be fully realized; and the spectrum sensing performance is improved.

The invention discloses a communication key generation method and a secure channel selection method for a cognitive radio system, and belongs to the field of secure communication and information security in radio communication. A common available channel set is established according to a local spectrum pool of received and transmitted nodes, the quantity of channels of the channel set is at least equal to one, beacon signals with random initial phases are received and transmitted multiple times by the aid of channels which are sequentially selected from the available channel set, and phases of the received signals are detected and utilized for generating a random key element matrix according to reciprocity of wireless transmission characteristics of the same channels within a coherent time and differentiation of wireless transmission characteristics of different channels, and finally communication keys are acquired by fusion processing of the matrix. The communication keys are used for encrypting transmitted information and are also used as random seeds for selecting secure communication channels. The communication key generation method and the secure channel selection method have the advantages that interaction of the communication keys among the received and transmitted nodes through the channels is omitted, hidden dangers such as wiretapping, tampering and saturation attack from attackers can be eliminated, and commutation security of the cognitive radio system can be guaranteed.

The invention discloses a method and a device allocating distribution type spectrum resource, which relates to the technical field of radio. The invention aims to solve the problem that the distribution type network in the prior art can not realize dynamic allocation of discontinuous spectrum. The method for allocating distribution type spectrum resource comprises the following steps of: receiving request information, which carries a spectrum resource occupying condition list and parameters of the service to be transmitted at the sending end; acquiring an idle spectrum resource collection available for the service to be transmitted according to the received spectrum resource occupying condition list and the local spectrum resource occupying condition list, wherein the idle spectrum resource collection is the idle spectrum resource collection shared by the sending end and the transmitting end; and allocating at least one section of spectrum resource in the idle spectrum resource collection available for the service to be transmitted to the service to be transmitted according to the parameters of the service to be transmitted.

The invention relates to a cooperative spectrum sensing method capable of saving cost on network communication. The prior network communication has the defect of high cost. The method comprises the following steps: a cognitive radio user uses an energy detection technique to sense the spectrum of a target frequency range, thereby obtaining a local sensing result; a data fusion center collects andfuses the local sensing results of the cognitive radio users, and makes a judgment on the spectrum service conditions, thereby obtaining a cooperative sensing judgment result; and the data fusion center and the cognitive radio users communicate messages through a control channel, each cognitive radio user transmits the local spectrum sensing result, and the data fusion center transmits the cooperative sensing judgment result. On the premise of not reducing the cooperative sensing accuracy, the method of the invention reduces the cost on cognitive radio network communication. For the cognitiveradio users, the method reduces the transmission of unnecessary sensing results, saves the valuable energy and prolongs the service lives of batteries.

The invention discloses a selecting type cooperation spectrum sensing method based on double-threshold energy detection. The selecting type cooperation spectrum sensing method comprises the following steps: (1) in a master user signal detection stage, adopting a double-threshold energy detection method by various cognitive users in a cognitive radio system to carry out local spectrum sensing, if an energy value exceeds two thresholds, carrying out local judgment 'H0 or H1'by the cognitive users, and if the energy value is between the two thresholds, reserving the energy value as a primary energy detection value by the cognitive users; (2) in an initial detection result reporting stage, evenly distributing a master user frequency band by the cognitive users, adopting a selecting type strategy by the cognitive users to report initial detection results respectively to a fusion center, preventing cognitive detection results with unreliable parameters from being introduced, meanwhile, saving traditional exclusive control channel resources, adopting the equal gain criterion by the fusion center to carry out master user judgment on the received primary energy detection value, allowing the judgment result to be equivalent to a node strategy by the fusion center, and then adopting the 'or' criterion by the fusion center to make the final judgment whether a master user exists. The simulation results show that according to the selecting type cooperation spectrum sensing method based on the double-threshold energy detection, and on the premise that ROC properties are not lost, the exclusive control channel resources are effectively saved, and meanwhile higher detection efficiency can be obtained.

The invention discloses a cooperative spectrum detection method for cognitive radio based on a neural network, which comprises the following steps that: a cognitive user in a network unit has two states, namely a training period and a working period, and the cognitive user comprises a back propagation (BP) neural network module; the cognitive user in the training period carries out local spectrum detection, trains an own BP network by comparing detection results of a central node, predicts own correct detection probability, and does not participate in fusion; after the training period is over, the cognitive user enters the working period, uses the BP network to obtain a prediction value of the correct detection probability, carries out the local spectrum detection and participates in the fusion; the central node takes the prediction value of the correct detection probability of each cognitive user as reliability, and fuses each local detection result to obtain a final detection result; and the cognitive user in the working period judges whether the BP network is required to be corrected according to a particular case. In the method, factors of hidden terminal and instability of an electromagnetic environment are taken into full consideration in combination with the neural network and cooperative spectrum detection, so that the spectrum detection performance of a cognitive radio system is improved.

The invention discloses a method for identifying affiliations of spectrum lines of elements by laser-induced breakdown spectroscopy. Through selecting the size of a range of a spectrum band to be identified as the size of an analysis window, a local spectrum to be identified in the window is combined with a standard library of emitting spectrum lines of different elements, and the spectrum lines of the elements in the analysis window are accurately identified by local correlation analysis; and then through setting a movement step of the analysis window, the full-spectrum scanning analysis on a measuring spectrum is completed, and thus the affiliations of the spectrum lines of different elements in the measuring spectrum are identified. The method has the characteristics of high identification speed, high accuracy rate, high automation degree and the like, is completely realized in a computer system because of no artificial identification interference factors, and effectively solves the problems of speed and accuracy of identifying the affiliations of the spectrum lines of the elements when data of an existing laser-induced breakdown spectroscopy is processed, and automation degree of identifying the spectrum lines.

The invention discloses a polarization-state phase-adjustable wide-spectrum reflecting mirror. Three-dimensional integrated precise regulation and control of spectrum, polarization state and phase of the reflecting mirror is realized through optimal combination of a metal film material and various dielectric film materials. According to the reflecting mirror, high reflectivity in wide spectrum range is realized by the metal film material; enhancement of local spectrum reflectivity of the reflecting mirror and control of polarization sensitivity are realized by a periodic 1/4 full dielectric reflective film stack; precise regulation and control of the reflecting phase of the reflecting mirror is realized by multiple layers of irregular dielectric films. The reflecting mirror has the characteristics of wide reflecting spectrum range, precise and adjustable reflecting polarization state and phase, capability of enhancing local spectrum reflectivity and the like.

The invention belongs to the technical field of communications, and especially relates to a cooperative spectrum sensing implementation scheme based on a cognitive radio technology in a wireless communication system. The invention provides a perceptual information fusion method based on energy detection, wherein after local spectrum sensing based on energy detection of all cognitive nodes is completed, a fusion center and all users participating in spectrum sensing cognition adopt the perceptual information fusion method provided by the invention to realize fusion of perceptual information, therefore, the accuracy of a spectrum sensing result and the scope of spatial application can be improved, the time overhead of reporting a local perception judgment result to the fusion center by all cognitive nodes can be reduced and the cooperative sensing performance better than a traditional cooperative perception fusion rule can be obtained.

The invention discloses a soft-decision spectrum sensing method based on compression non-reconstruction. The method mainly comprises the steps that firstly, a sensing model is established, secondary users establish a local spectrum sensing model, a binary presumptive model is adopted, and the energy detecting method is adopted under the non-cooperative mode; secondly, compressed sampling is carried out, and the secondary users utilize a two-dimensional Gaussian measurement matrix to carry out compressed sampling on a receiving signal; thirdly, under the situation that the compressed sampling data are not reconstructed, the secondary users directly utilize the compressed sampling data to establish the test statistics amount based on energy, whether a primary user exists or not is not judged, and the test statistics amount is transmitted to a fusion center; fourthly, the soft decision of the fusion center is carried out, and after the fusion center collects the test statistics amount sent by all the secondary users, the unified test statistics amount is established and compared with the detecting threshold value, and a final decision result is given.

The invention provides a handheld fluorescence microscope. A local spectrum light source, a first optical filter, a second optical filter and an image sensing circuit are disposed in a shell of the handheld fluorescence microscope. The local spectrum light source is used for generating first light. The first optical filter is used for filtering the first light to generate second light. The second optical filter is used for filtering fluorescence generated by a sample irradiated by the second light so as to generate fourth light. The image sensing circuit is used for receiving the fourth light to generate fluorescent images. A light mask is disposed at one end of the shell and used for enclosing the sample so as to decrease or prevent light from entering the image sensing circuit from outside of the light mask. The second light irradiates an optical path of the sample, the optical path does not overlap with an optical path of the fluorescence which enters the second optical filter from the sample, and no splitter is disposed on the optical path of the fluorescence entering the second optical filter or the optical path of the fourth light entering the image sensing circuit. The handheld fluorescence microscope is capable of normally detecting fluorescent images in general environments.

The invention discloses a clustering cooperative spectrum sensing hard fusion method for a cognitive wireless sensor network. All cognitive sensing nodes are clustered firstly, a cluster head of each cluster is selected, the cognitive sensing nodes achieve spectrum sensing according to the signal energy of a master user, local spectrum sensing information is acquired, then first-time fusion is carried out on all the local spectrum sensing information in the clusters through the cluster heads, the spectrum sensing information of the corresponding cluster is acquired, and finally fusion is carried out on the spectrum sensing information of all the clusters through a fusion center to obtain the final spectrum sensing information. Through cluster head screening and two times of fusion, the computation burden of the fusion center is reduced, and the effect of fast judging whether frequency spectrum is free or not and improving the correct probability of detection is achieved.