608 results about "Cognitive user" patented technology

The invention provides a dynamic spectrum access method on the basis that the policy planning restricts Q learning, which comprises the following steps: cognitive users can divide the frequency spectrum state space, and select out the reasonable and legal state space; the state space can be ranked and modularized; each ranked module can finish the Q form initialization operation before finishing the Q learning; each module can individually execute the Q learning algorithm; the algorithm can be selected according to the learning rule and actions; the actions finally adopted by the cognitive users can be obtained by making the strategic decisions by comprehensively considering all the learning modules; whether the selected access frequency spectrum is in conflict with the authorized users is determined; if so, the collision probability is worked out; otherwise, the next step is executed; whether an environmental policy planning knowledge base is changed is determined; if so, the environmental policy planning knowledge base is updated, and the learning Q value is adjusted; the above part steps are repeatedly executed till the learning convergence. The method can improve the whole system performance, and overcome the learning blindness of the intelligent body, enhance the learning efficiency, and speed up the convergence speed.

The invention discloses a distribution method of united power and channels in a cognitive wireless network. The distribution method of the united power and the channels in the cognitive wireless network comprises the steps that (1) interference between a primary user and a cognitive user on each channel in the multi-channel cognitive wireless network and among cognitive users is quantized and limited; (2) a utility function defining the behavior that each cognitive user is accessed to a frequency spectrum serves as a handling capacity, and the optimal solution of the utility function of the cognitive users is solved in a distributed mode by constructing a non-cooperative game frame so that the performance of the entire network can be optimal; (3) a corresponding price function is introduced to price resource occupation behaviors of the cognitive users, and selfishness of the cognitive users is limited; (4) a potential game model is built by utilizing a non-cooperative game, and astringency of the potential game model is guaranteed. The distribution method of the united power and the channels in the cognitive wireless network has the advantages of solving the problem of distribution of the united power and the channels in a distributed mode by utilizing the price function and the potential game model, and improving distribution fairness of network resources and the utilization efficiency of the frequency spectrum.

The invention provides a utility function based distributed type power control method for a cognitive radio system, belongs to the technical field of wireless communication, and particularly relates to power control used in the cognitive radio system. The invention relates to a compromise solution not only meeting the requirement on protecting a main user, but also supporting the requirement on the service quality of the cognitive user. The scheme is based on the non-cooperative game theory, namely the self-regulation of transmitting power of various CRUs is only needed, so that the defect existing in the conventional distributed type power control that huge information interaction is needed is overcome. By analyzing the geometric characteristics of the utility function, skillfully setting the parameters of the utility function and simultaneously combining the access control, the convergence of power is ensured; simultaneously, by regulating the parameters, the needs for the prior network services are met; in addition, a frame structure and a protocol flow which are suitable for the power control method are designed, and the frame structure and the protocol flow are suitable for any distributed type cognitive radio system, so that the power control method has quite strong practicability.

The invention discloses an energy-carried cooperative CR-NOMA cooperative mode and a relay selection algorithm based on CR-NOMA, comprising: when relay assists two users for information transmission, if the main user is able to decode correctly, then, using all the collected energy to assist the cognitive user to transmit information at the next time slot; otherwise, using the NOMA to continue forwarding the information of the two users; for the multi-relay, proposing the relay selection strategy of the two stages, or solving the set of the correctly decoded relays first; then enabling that the energy remaining and the channel gain from the second jumped relay to the main user are maximized; and solving the closed solution to the interruption probability of the two users and the expression of the throughput. With the invention, while the performances of the main user are ensured, the performances of the sub-user can be increased further so that when the main user reaches the full gain, the cognitive user reaches three-order gain. The energy efficiency of the system is also raised.

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 relates to an idle frequency spectrum detecting method by using cyclic spectrum statistic value in a cognitive radio. The invention relates to a method for detecting idle frequency spectrums by using cyclic spectrum statistic value. The method solves the error judgment problem caused by that in the existing cognitive radio, owing to the influence of factors such as shadow, shading depth and the like, a cognitive user detects feeble signals of an authorized master user. The method comprises the following steps of: firstly, modeling the real part of the cyclic spectrum of signals received by the cognitive user to obeyed mean value and random variable of variance in a gauss white noise channel; step two, by probability distribution under the H0 assumed condition, and obtaining signal judgment threshold under the given false-alarm probability index; step three, allowing the idle frequency spectrum to be used when C is larger than or equal to 0 and the real part Z of the cyclic spectrum of the received signals is less than the judgment threshold T, or when C is less than 0 and the real part Z of the cyclic spectrum of the received signals is larger than the judgment threshold T; otherwise, not allowing the non idle frequency spectrum to be used. The method can cause the cognitive user to detect the signals of the authorized master user under the lower signal-to-noise ratio condition.

The invention provides a cross-layer cognitive radio network user access method based on frequency hopping, and belongs to the field of application of radio networks. According to the method, cognitive users in primary user network is divided into a plurality of clusters according to the cognitive base station service range; each cluster comprises a cognitive base station (cluster head) and a plurality of cognitive users (cluster nodes); the cognitive base station is connected with a primary user base station and is managed by the user base station; however, the communications of cognitive users are controlled and managed by the cognitive base station. Based on the fact that corresponding idle spectrum information is obtained through monitoring a primary user on the network physical layer and sensing the spectrum, a plurality of frequency hopping patterns are generated by using a frequency hopping technology, and the cognitive users are made to carry out hopping communications between a plurality of signal channels as per certain frequency hopping pattern within different frequency ranges at different time on the MAC (Media Access Control) layer, so that the cognitive user dynamic access is achieved. The invention has the excellent effects of small network expense, high utilization ratio of spectrum, small interference and flexible and efficient user access manner.

The invention applies for protecting a double coordination detection method for vacant frequency spectrum detection in a cognitive radio system, relating to a radio communication system. The method is as follows: a plurality of cognitive users which take part in coordination in a traditional coordination detection algorithm are partitioned into different groups; a cognitive user needing communication is a group leader of the group; then the purposes of reducing spending of a control channel and improving detection performance of a system are gained by coordination within groups and coordination between groups. The users within the group locally judge by using an energy-check algorithm whether a master user signal exists in a certain frequency band authorized to the master user and transmits a local judgment result to the group leader. The group leader syncretizes the local judgments to make a group judgment result. A cognitive base station further syncretizes the group judgment resultto make judgment, thus getting the final judgment of the system. Bit numbers of the judgment result transmitted to the cognitive base station are largely reduced by using the method, thus greatly saving bandwidth of the control channel, and detection performance is increased.

The invention relates to a method for sharing channels, comprising the following steps of: A. distributing an idle registration channel for a cognitive user; B. detecting whether an authorized user appears or not, if the authorized user appears, distributing the registration channel for the authorized user, and measuring an interference temperature threshold for ensuring that the authorized user normally uses the registration channel, acquiring the maximum available power of the cognitive user according to the interference temperature threshold, and if the authorized user does not appear, continue to detecting; and C. calculating whether the cognitive user can carry out data transmission or not by using the maximum available power, if so, regulating the transmitting power of the cognitiveuser, and if not, switching the cognitive user to the idle channel. Moreover, the invention also relates to a system for sharing channels. The method and the system for sharing channels judge whetherthe cognitive user can carry out data transmission or not by using the maximum available power to control the action of the cognitive user, which greatly reduces the frequency spectrum switching efficiency, improves the frequency spectrum use ratio and network performance and meanwhile also improves the effective data transfer rate.

The invention discloses a vandermonde frequency-division multiplexing method based on a multi-carrier modulation technology, which is characterized by constructing a vandermonde pre-coder matrix based on a technical model of orthogonal frequency division multiplexing of cognitive wireless network; obtaining system multiplexing gain by using cyclic prefix redundancy and channel frequency selectivity of an orthogonal frequency division multiplexing symbol; eliminating interference of a cognitive user on communication of a main user to obtain an achievable transmission velocity of the cognitive user; and further obtaining full-multiplexing gain of the system by using a frequency domain water-filling power allocation method and different cyclic prefix length values based on the obtained achievable transmission velocity such that the cognitive user can obtain a maximum transmission velocity and share the frequency spectrum with the main user.

The invention provides a novel double-threshold cooperative spectrum sensing algorithm based on energy detection, and belongs to the technical field of spectrum sensing of a wireless system. The method comprises the steps that: 1, a center unit or base station and M cooperative cognitive users are considered to participate in cooperative spectrum sensing, and the center unit is responsible for managing a cognitive radio system and all of the M cooperative cognitive users; and 2, each cooperative cognitive user participating in cooperative spectrum sensing firstly checks the energy of authorized user signals received by itself and judges whether an energy statistical magnitude Ti is less than a threshold [lambda]0 or larger than or equal to a threshold [lambda]1, if the energy statistical magnitude Ti is less than the threshold [lambda]0, a sensed authorization channel is considered to be idle at present, and a value 0 is awarded to the sensed authorization channel, and if the energy statistical magnitude Ti is larger than or equal to the threshold [lambda]1, authorized users are using the current frequency range. According to the invention, a K-order fusion strategy and an EGC soft fusion strategy are effectively combined, the cooperative spectrum sensing efficiency is effectively improved, and the system cost is saved; in addition, compared with single-user self-adaptive double-threshold energy detection, the double-threshold cooperative spectrum sensing algorithm detection is based on multiple fusion rules.

The invention provides a method with the QoS requirement for distributing resources in a CR OFDM system, which comprises the following steps: selecting a cognitive user whose gamma m is maximal from a to-be distributed cognitive user set UM, distributing the proper sub-carrier wave, power and bit number for the cognitive user according to the principle that the gain factor gamma mn is larger than the priority or the bit numbers are approximate, newly confirming to-be distributed sub-carrier wave sets SN and UM, newly calculating the interference I generated to the users by the cognitive users, if the I is bigger than the interference threshold value Ith of the authorized users, canceling the sub-carrier wave and the distributing of the power and the bits and finishing the distributing work, if the UM has no to-be distributed cognitive users and the SN still has the to-be distributed sub-carrier wave resources, then distributing the residual carrier waver resources. The method considers the two restraining conditions of the interference threshold and the QoS requirement of the users, thereby further improving the availability ratio of the frequency spectrum and the distributing of the recourses.

The invention discloses a cooperative frequency spectrum sensing method for a cognitive radio network. The method comprises the following steps that: (1) the cognitive radio network which comprises N cognitive users SU and an information fusion center FC is configured in a network with an existing privileged user PU; (2) the cognitive user SU uses energy detection to independently judge whether aprivileged user PU signal is present, and transmits a binary hard decision result to the information fusion center FC, and the transmitting power of the cognitive user is adaptively adjusted according to the condition of a channel from the privileged user PU to the cognitive user SU; and (3) the information fusion center FC fuses the results of a plurality of cognitive users SU by adopting a maximum likelihood detector, and finally determines whether the privileged user PU is occupying the frequency spectrum. The cognitive user SU can independently process the signal without transmitting softinformation or interchanging information; and a detector in the information fusion center FC has a simple structure and is easy to implement. Meanwhile, the cooperative frequency spectrum sensing method has good performance such as low communication overhead, high diversity gain, low false alarm rate and lost detection rate and the like, and has high practical value.

The invention provides a solving method which coordinates a cognitive radio system to enhance robustness detection. The method for detecting a frequency spectrum hole in cognitive radio mainly comprises the following steps: independently sampling a frequency spectrum environment which needs to be detected by a plurality of cognitive users of a cognitive system in different geographical positions so as to obtain perceptive signals; sending perceptive data obtained by means of sampling by the cognitive user through a control channel in the cognitive system to a cognitive based station; receiving a plurality of perceptive signals and splitting the perceptive signals into a plurality of shorter perceptive signal sections with identical slot time by the cognitive based station, and obtaining a perceptive signal matrix through data infusion; and calculating the perceptive signal matrix and a covariance matrix, maximum and minimum eigenvalues of the covariance matrix and eigenratio of the maximum eigenvalues and minimum eigenvalues, comparing the eigenratio with a decision threshold, and judging whether the frequency spectrum hole exists or not. The method for detecting the frequency spectrum hole in the cognitive radio can effectively improve systematic detecting performance under the condition that the number of cooperative users are less.

The invention is applicable to the field of cognitive radio and provides a cognitive radio frequency spectrum sharing method and a cognitive radio frequency spectrum sharing system. The method comprises the following steps of: building an individual sequence for an authorized user and a cognitive user respectively; dividing a held frequency spectrum into N isostructural individual frequency points; distributing all individual frequency points to the authorized user or the cognitive user for use, wherein each channel is only distributed to one authorized user or cognitive user for exclusive use at any time; and recovering the channel to perform channel distribution for the next time after the authorized user or the cognitive user completes the service, wherein the value of N can be preset and corrected according to requirements. In the embodiment of the invention, a central control scheme is adopted, and the dependence of other schemes on aspects such as a network topology structure and the node density of the cognitive user is avoided. Meanwhile, the problem of the low service quality of the cognitive user in the conventional frequency spectrum sharing method is solved.

The invention discloses a channel and power joint distribution method for guaranteeing communication continuity in cognitive radio. The method includes that S1, a cognitive user periodically perceives radio environment, and a cognitive base station obtains sub-channel state information; S2, a cognitive user sends a communication request to the cognitive base station and informs the cognitive base station of amount of information required to be transmitted, and simultaneously the cognitive base station acquires service quality demand information of the cognitive user; S3, the cognitive base station distributes optimum channel and power of an initial phase for the cognitive user through solving an optimization problem, and the cognitive user starts to communicate; S4, when the communication of the initial phase is finished, the sub-channel state information and the service quality demand information are updated; S5, the cognitive base station performs the optimal joint distribution of channel and power of i phase; and S6, the cognitive user continues to periodically perceiving surrounding radio environment, and the optimal distribution of the channel and power of subsequent phases is achieved. The method can guarantee the communication continuity of the cognitive user at different resource distribution phases.

The invention discloses a frequency spectrum perceiving method based on the estimation of a signal arrival direction, which comprises the steps: in a cognitive radio system to which smart antenna technology is applied, the direction and the angle of signal transmission are used as a frequency spectrum opportunity, and a master user signal is subjected to two-step perception: firstly, the master user signal is detected by using a method based on a generalized likelihood ratio test, namely that the ratio of the maximum eigenvalue to the sum of the eigenvalues of a sample covariance matrix is used as test statistics; the test statistics are compared with a decision threshold which is set according to a given false alarm probability so as to decide whether the master user signal exists or not; if a master user does not exist, then the channel can be used, and if the master user exists, then a classical MUSIC (Multiple Signal Classification) algorithm is further used to estimate the arrival direction of the master user signal. A cognitive user can select other directions for communication, which do not cause disturbance to the master user, and the frequency spectrum perceiving method can effectively perceive time, frequency and the frequency spectrum vacancy of a space domain, perceive the frequency spectrum vacancy of an angle domain, and increase the frequency spectrum opportunity.

The invention discloses a cognitive radio network master user spectrum allocation method based on a game theory, belongs to the technical field of wireless communications, and particularly relates to the field of cognitive radio networks. According to the cognitive radio network spectrum allocation method based on the game theory, the master user combined utility maximization is achieved by optimizing and pricing a sharing frequency spectrum in a cognitive radio network. Various component channel cognition user demand functions Dkl of master users and master user combined utility functions Utotal are established, a plurality of master users of the cognitive radio network are modeled to be a cooperative game model aiming at the optimizing and pricing problem of the cognition user sharing frequency spectrum, the master user combined benefits are maximized, a master user optimal frequency spectrum pricing strategy is obtained, the combined utility of the master users in the cognitive network and recognition user access performance are comprehensively considered, optimizing and sharing of spectrum resources can be effectively achieved, the utilization rate of system spectrum resources is improved, and the problem of lacking of the spectrum resources is solved.

The invention provides a resource utilization device and method of cognitive radio and a cognitive radio system. The resource utilization device comprises a detection value receiver, an evaluation value calculator and a resource allocator, wherein the detection value receiver is used for receiving signal strength detection values transmitted by a plurality cognitive user devices; the evaluation value calculator respectively calculates the signal strength evaluation values of a plurality of sub-bands of the broadband signals according to the signal strength detection values transmitted by the plurality of cognitive user devices; and the resource allocator is used for performing resource allocation on the broadband spectrum according to the signal strength evaluation values of the plurality of sub-bands. By means of the resource utilization device and method and the cognitive radio system, allocation of spectrum resources on the basis of synergy broadband spectrum sensing can be performed, interference on authorized user equipment is reduced furthest, and influence on spectrum detection caused by frequency selective channel fading is overcome.

The invention discloses a self-adaptive transmission power distribution method for a downlink of an unmanned aerial vehicle base station. The cognitive OFDM technology is adopted in the application scene of the method, and the requirement for signal bandwidth, the number of available channels, interference limitation and the like are all continuously changed. A resource allocation technology in atraditional wireless network is not completely applicable, so an efficient and flexible unmanned aerial vehicle base station wireless resource allocation method needs to be designed by adopting cognitive radio. In the downlink, the method assumes that a single cell covered by an unmanned aerial vehicle base station only has a single cognitive user and multiple main users; according to the size ofthe signal to interference plus noise ratio, a modulation mode is automatically selected, then the transmission rate is continuous, and a Lagrangian duality method based self-adaptive distribution algorithm for achieving the optimal power is provided, so that power distribution optimization and transmission rate maximization are achieved. The method is popularized to adaptive optimal power distribution and maximum transmission rate under the condition of multiple cognitive users and multiple main users. When the method is applied to an unmanned aerial vehicle base station adopting cognitive radio, better performance can be achieved compared with that of a traditional power algorithm, the bit error rate is reduced to a certain degree, optimal power is distributed in a self-adaptive mode, and the expected requirement can be met only through a small number of iterations.

The invention discloses a dynamic spectrum access method and a dynamic spectrum access system which are applied to cognitive radio networks. The method comprises the following steps of: after a service of a cognitive user arrives, detecting whether a channel is idle, and if so, capturing state transition of a recording system by using a continuous time Markov chain (CTMC), calculating optimal access information by combining relevant parameters of a master user and the cognitive user and transmitting the information to the cognitive user; allowing the cognitive user to access and transmitting the service according to the calculated optimal access information; if the service QoS of the cognitive user is detected to decline sharply in the process of transmission, forcing the cognitive user to exit the channel; and if not, allowing the cognitive user to exist the channel after the cognitive user finishes the service. The scheme provided by the invention ensures the QoS of the master user under the circumstances of a false alarm or an undetected error when the cognitive user carries out spectrum detection, and realizes the balance between operation efficiency and use fairness of the channel.

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.