CN105187142A - Method and device for detecting idle spectrum - Google Patents
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Abstract
The embodiment of the present invention discloses a method and device for detecting an idle spectrum. The method comprises: receiving a request whether a detected licensed spectrum sent by a first cognitive radio node is the idle spectrum; determining at least one cooperative cognitive radio node according to position information of the first cognitive radio node carried in the request; determining a final judgment result according to local judgment information of the first cognitive radio node carried in a selected fusion rule processing request after wavelet denoising processing and local judgment information sent by all cooperative cognitive radio nodes; and sending the determined final judgment result to the first cognitive radio node and all the cooperative cognitive radio nodes, so as to determine whether communication is performed on the licensed spectrum according to the determined final judgment result. Through the application of the embodiment of the present invention, the accuracy of detecting the idle spectrum can be improved, thereby ensuring that no influence exists on the communication of a master user when the licensed spectrum is used at the cognitive radio nodes.
Description
Technical Field
The present invention relates to the field of cognitive radio technologies, and in particular, to a method and an apparatus for detecting a white space spectrum.
Background
In recent years, with the increasing demand for spectrum resources, it has become increasingly important with regard to cognitive radio technology. Cognitive radio is a dynamic spectrum sharing technique that dynamically senses the surrounding environment and adjusts its own transmission parameters. The core problem to be solved by the cognitive radio is how to accurately identify the spectrum occupancy and the working condition of the primary user, i.e. the first step of cognitive radio operation: and detecting the frequency spectrum occupation condition. The main work of the spectrum occupation situation detection is to detect the spectrum occupation situation in a certain range and determine whether a primary user occupies the spectrum, and then judge the spectrum and utilize the spectrum on the basis. In the process of acquiring a master user signal by a perception user, the influence of factors such as multipath, shadow, local interference and the like inevitably causes that the signal intercepted by the perception user is weak, so that judgment is wrong, and the interference is caused to the master user. At this time, the cooperative detection is used to help complete the spectrum occupancy detection process.
In the cooperative detection, a cooperative user performs fusion processing on detection information of a plurality of cognitive radio (CR-cognitive radio) nodes to improve the detection performance and relatively reduce the requirement on the detection performance of each node. However, in the cooperative detection, it cannot be determined that the local detection reliability of each node is sufficiently high for a plurality of selected CR nodes. When the selected CR node has a large number of nodes with low reliability, the effect of cooperative detection may not be as good as the detection performance of a single user, so there is a certain reliability requirement for the CR node participating in the cooperation, and even when the channel environment from the selected CR node to the primary user base station is poor, the node is required to have good detection performance.
In the prior art, under the condition of poor external communication environment, that is, a low signal-to-noise ratio (SNR-SignaltoNoiseRatio) causes abrupt change of detection performance, performance degradation is caused during cooperative detection, and a detection result has a large error.
Disclosure of Invention
The embodiment of the invention aims to provide a method and a device for detecting an idle frequency spectrum, which can improve the low signal-to-noise ratio so as to improve the accuracy of idle frequency spectrum detection.
In order to achieve the above object, an embodiment of the present invention discloses a method for detecting a vacant spectrum, which is applied to a network side, and the method includes the steps of:
receiving a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request comprises: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection;
determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node;
selecting a preset fusion criterion according to the local judgment information of the first cognitive radio node and the received local judgment information sent by at least one cooperative cognitive radio node, processing the received local judgment information of the first cognitive radio node and the local judgment information of the at least one cooperative cognitive radio node according to the selected fusion criterion, and determining a final judgment result, wherein the final judgment result comprises the step of determining whether the authorized spectrum is an idle spectrum;
and sending the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the first cognitive radio node and the at least one cooperative cognitive radio node can determine whether to communicate on the authorized spectrum according to the determined final decision result.
In order to achieve the above object, an embodiment of the present invention discloses a method for detecting a vacant spectrum, which is applied to a cognitive radio node, and the method includes the steps of:
obtaining self position information;
performing wavelet denoising on the authorized spectrum signal, and then performing energy detection to obtain local judgment information;
sending the position information and the local judgment information to a network side; so that the network side sends the determined final decision result to the cognitive radio node and at least one cooperative cognitive radio node according to the steps of claim 1;
receiving a final judgment result sent by a network side;
and determining whether to communicate on the authorized spectrum according to the determined final judgment result.
Preferably, the obtaining the local decision information includes:
the cognitive radio node performs energy detection according to a received authorized spectrum signal, wherein the authorized spectrum signal comprises: a noise-contaminated signal, the energy detection comprising: denoising the signal polluted by the noise by wavelet to obtain an estimated signal, then judging whether the estimated signal is 0 or not,
if the judgment result is that the estimation signal is 0, the cognitive radio node determines that no main user exists on the authorized spectrum, determines that the authorized spectrum is an idle spectrum,
if the judgment result is that the estimation signal is not 0, the estimation signal is subjected to analog-to-digital conversion, squaring and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics;
the wavelet denoising comprises: and mapping the signal polluted by the noise to a wavelet domain, generating a wavelet signal with a wavelet coefficient, and setting a mask operator to ensure that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and setting other wavelet coefficients to be 0.
Preferably, the determining, by the cognitive radio node, the local decision information according to the probe statistic includes:
and comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, determining that a master user exists on the authorized spectrum and determining that the authorized spectrum is a non-idle spectrum by the cognitive radio node, and if the detection statistic is less than or equal to the preset threshold, determining that the master user does not exist on the perceived authorized spectrum by the cognitive radio node and determining that the authorized spectrum is an idle spectrum.
Preferably, the method further comprises:
the cognitive radio node sends self position information and a local judgment result to a network side in real time in the communication process on the authorized spectrum; and when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the master user, stopping using the authorized spectrum for communication.
In order to achieve the above object, an embodiment of the present invention discloses a device for detecting a white space spectrum, which is applied to a network side, and the device includes:
a request receiving module: the method includes the steps of receiving a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request includes: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection;
a first determination module: the cognitive radio node is used for determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node;
a decision information determination module: the device comprises a first cognitive radio node, a second cognitive radio node and a third cognitive radio node, wherein the first cognitive radio node is used for receiving local judgment information of the first cognitive radio node and receiving local judgment information sent by at least one cooperative cognitive radio node;
a judgment result sending module: and the terminal node is configured to send the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the terminal node determines whether to communicate on the licensed spectrum according to the determined final decision result.
In order to achieve the above object, an embodiment of the present invention discloses a device for detecting a vacant spectrum, which is applied to a cognitive radio node, and the device includes:
a position information acquisition module: used for obtaining self position information;
a local judgment module: the device is used for performing wavelet denoising on the authorized spectrum signal and then performing energy detection to obtain local judgment information;
an information sending module: the local judgment module is used for sending the position information and the local judgment information to a network side; so that the network side sends the determined final decision result to the cognitive radio node and at least one cooperative cognitive radio node according to the steps of claim 1;
a final judgment information receiving module: the system is used for receiving a final judgment result sent by a network side;
a second determination module: and the terminal is used for determining whether to communicate on the authorized spectrum according to the determined final decision result.
Preferably, the local decision module is specifically configured to:
the cognitive radio node performs energy detection according to a received authorized spectrum signal, wherein the authorized spectrum signal comprises: a noise-contaminated signal, the energy detection comprising: denoising the signal polluted by the noise by wavelet to obtain an estimated signal, then judging whether the estimated signal is 0 or not,
if the judgment result is that the estimation signal is 0, the cognitive radio node determines that no main user exists on the authorized spectrum, determines that the authorized spectrum is an idle spectrum,
if the judgment result is that the estimation signal is not 0, the estimation signal is subjected to analog-to-digital conversion, squaring and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics;
the wavelet denoising comprises: and mapping the signal polluted by the noise to a wavelet domain, generating a wavelet signal with a wavelet coefficient, and setting a mask operator to ensure that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and setting other wavelet coefficients to be 0.
Preferably, when the local decision module determines the local decision information according to the detection statistics:
and comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, determining that a master user exists on the authorized spectrum and determining that the authorized spectrum is a non-idle spectrum by the cognitive radio node, and if the detection statistic is less than or equal to the preset threshold, determining that the master user does not exist on the perceived authorized spectrum by the cognitive radio node and determining that the authorized spectrum is an idle spectrum.
Preferably, the information sending module is further configured to: in the communication process on the authorized spectrum, sending self position information and a local judgment result to a network side in real time;
the device further comprises a use stopping module, wherein the use stopping module is specifically used for: and when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the master user, stopping using the authorized spectrum for communication.
As can be seen from the above technical solutions, an embodiment of the present invention discloses a method and an apparatus for detecting a free spectrum, where the method includes the steps of receiving a request for detecting whether an authorized spectrum sent by a first cognitive radio node is a free spectrum, where the request includes: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection; determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node; selecting a preset fusion criterion according to the local judgment information of the first cognitive radio node and the received local judgment information sent by at least one cooperative cognitive radio node, processing the received local judgment information of the first cognitive radio node and the local judgment information of the at least one cooperative cognitive radio node according to the selected fusion criterion, and determining a final judgment result, wherein the final judgment result comprises the step of determining whether the authorized spectrum is an idle spectrum; and sending the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the first cognitive radio node and the at least one cooperative cognitive radio node can determine whether to communicate on the authorized spectrum according to the determined final decision result. In the embodiment of the invention, the authorized spectrum signal is subjected to wavelet denoising processing, and the cooperative cognitive radio node is determined and subjected to fusion judgment by the network side, so that the low signal-to-noise ratio is improved, and the accuracy is improved for subsequent signal energy detection and idle spectrum searching. Of course, it is not necessary for any product or method of practicing the invention to achieve all of the above-described advantages at the same time.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart illustrating a method for detecting a white space according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating another method for detecting a white space according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an apparatus for detecting a white space according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another apparatus for detecting a white space according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a method and a device for detecting an idle frequency spectrum, wherein in the scheme, a request for detecting whether an authorized frequency spectrum sent by a first cognitive radio node is the idle frequency spectrum is received, and the request comprises the following steps: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection; determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node; selecting a preset fusion criterion according to the local judgment information of the first cognitive radio node and the received local judgment information sent by at least one cooperative cognitive radio node, processing the received local judgment information of the first cognitive radio node and the local judgment information of the at least one cooperative cognitive radio node according to the selected fusion criterion, and determining a final judgment result, wherein the final judgment result comprises the step of determining whether the authorized spectrum is an idle spectrum; and sending the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the first cognitive radio node and the at least one cooperative cognitive radio node can determine whether to communicate on the authorized spectrum according to the determined final decision result.
The present invention will be described in detail below with reference to specific examples.
Fig. 1 is a flowchart of a method for detecting a white space spectrum according to an embodiment of the present invention, which is applied to a network side, and includes the following steps:
s101: receiving a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request comprises: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection.
As known in the art, a cognitive radio node senses and identifies radio signals in its surrounding environment every moment, wherein the radio signals include the licensed spectrum signal and other radio signals.
Specific examples thereof include: the network side receives a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request comprises: the position information and the local judgment information of the first cognitive radio node, for example, the position information is that the first cognitive radio node is located in the Shanghai, the local judgment information is obtained through energy detection after the first radio node performs wavelet denoising processing on an authorized spectrum signal received by the first radio node to obtain a signal with interference noise removed, and the local judgment information of the first radio node is assumed to be that the authorized spectrum is an idle spectrum.
S102: determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node.
According to the position information of the first cognitive radio node, a position range threshold value can be set, and the cognitive radio node determined to be within the position range threshold value is determined to be at least one cooperative cognitive radio node; a specific distance step may also be set, and the cognitive radio node at the position of the set distance step is selected to be determined as at least one cooperative cognitive radio node.
Specific examples thereof include: setting the position range threshold to be 200 kilometers, determining the cognitive radio nodes within the position range threshold of 200 kilometers as at least one cooperative cognitive radio node, and ending the determination of at least one cooperative cognitive radio node, wherein the three cooperative cognitive radio nodes are respectively a cognitive radio node A, a cognitive radio node B and a cognitive radio node C.
It should be noted that, in the present application, a specific implementation manner of determining at least one cooperative cognitive radio node according to the location information of the first cognitive radio node is not limited, and any possible implementation manner may be applied in the present application.
S103: selecting a preset fusion criterion according to the local judgment information of the first cognitive radio node and the received local judgment information sent by the at least one cooperative cognitive radio node, processing the received local judgment information of the first cognitive radio node and the local judgment information of the at least one cooperative cognitive radio node according to the selected fusion criterion, and determining a final judgment result, wherein the final judgment result comprises the step of determining whether the authorized spectrum is an idle spectrum.
Specific examples thereof include: according to step S102, it is determined that the three cognitive radio nodes are at least one cooperative cognitive radio node, and the three cognitive radio nodes are respectively a cognitive radio node a, a cognitive radio node B, and a cognitive radio node C, where after the cognitive radio node a detects the authorized spectrum, the obtained local judgment information is that the authorized spectrum is an idle spectrum, after the cognitive radio node B detects the authorized spectrum, the obtained local judgment information is that the authorized spectrum is an idle spectrum, after the cognitive radio node C detects the authorized spectrum, the obtained local judgment information is that the authorized spectrum is a non-idle spectrum, and the three cognitive radio nodes determined as the cooperative cognitive radio nodes respectively send the local judgment information obtained by the three cognitive radio nodes to the network side.
And the network side selects a preset fusion criterion, processes the received local judgment information of the first cognitive radio node and the local judgment information of the three cooperative cognitive radio nodes according to the selected fusion criterion, and determines a final judgment result.
Suppose H0Indicating that the authorized spectrum is a free spectrum, namely, no main user uses; h1And indicating that the authorized spectrum is a non-idle spectrum, namely, the authorized spectrum is used by a main user.
The main metrics in spectrum probing are detection probability, false alarm probability and missed detection probability, which are as follows:
Pdprob { decision is H1|H1}；
PfProb { decision is H1|H0}；
PmProb { decision is H0|H1}；
Suppose a K/N fusion criterion is selected, and the global false alarm probability and the detection probability under the fusion criterion are respectively
WhereinAndrespectively representing the false alarm probability and the detection probability, u, of a single cognitive radio nodeiRepresenting local decision information of cognitive radio node i, i.e. uiWhen 1, the local decision is H1，uiWhen 0, the local decision is H0. When K is 1, the K/N criterion is OR criterion, AND when K is N, the K/N criterion is AND criterion, whenTime is MOST criteria.
When k is equal to n, AND the fusion criterion is the AND criterion, all the local judgment information is only used for judging that the authorized spectrum is the non-idle spectrum, namely all uiWhen the number of the primary users is 1, the primary users are considered to exist only by the final judgment result, and the authorized spectrum is a non-idle spectrum, namely u0Otherwise, the fusion center considers that the main user does not exist, and the authorized spectrum is a free spectrum, i.e. u00. The detection condition of the frequency spectrum is harsh, so that the detection probability is low under the same condition. N represents the total number of cognitive radio nodes; k represents that the judgment result is the node number of the cognitive radio nodes which determine that the main user exists on the authorized spectrum.
When k is 1, the fusion criterion is an OR criterion, which is contrary to an AND criterion, that is, if there is one local decision information that the licensed spectrum is a non-idle spectrum, there is one uiWhen the value is 1, the final judgment result is that the master user exists, namely u0When the number of the licensed spectrum is 1, the licensed spectrum is a non-idle spectrum; otherwise, only when all the local judgment information is that the authorized spectrum is the idle spectrum, the final judgment result considers that the main user does not exist, namely u0The authorized spectrum is a free spectrum, the detection probability of the criterion is greatly improved when the main user exists, but the false alarm probability of the criterion is obviously improved when the main user does not exist.
When in useAnd then, the used fusion criterion is an MOST criterion, the number of the cognitive radio nodes of which the local judgment information is that the authorized spectrum is the idle spectrum is larger than or equal to the number of the cognitive radio nodes of which the local judgment information is that the authorized spectrum is the non-idle spectrum, and the final judgment result is that the authorized spectrum is the idle spectrum, otherwise, the opposite is realized.
Assuming that the fusion criterion selects the MOST criterion, the final decision result is to determine that the authorized spectrum is the idle spectrum by combining the first cognitive radio node and the three cooperative cognitive radio nodes A, B, C.
It should be noted that the K/N fusion criterion is only used as an example. In practice, any fusion criterion known in the art may be used.
S104: and sending the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the first cognitive radio node and the at least one cooperative cognitive radio node can determine whether to communicate on the authorized spectrum according to the determined final decision result.
Specific examples thereof include: according to the step S103, when the authorized spectrum is determined to be a free spectrum, the final determination result of determining that the authorized spectrum is a free spectrum is sent to the first cognitive radio node and the three cooperative cognitive radio nodes A, B, C, so that the first cognitive radio node and the three cooperative cognitive radio nodes A, B, C determine whether to communicate on the authorized spectrum, assuming that the first cognitive radio node determines to communicate on the authorized spectrum.
By applying the embodiment of the invention, the signals with low signal to noise ratio received by the cognitive radio nodes can be thoroughly denoised, the low signal to noise ratio of the signals is improved, the accuracy of local judgment of each cognitive radio node is improved, the accuracy of the final judgment result obtained by subsequent fusion processing is improved greatly, the detection of the idle frequency spectrum is more accurate, the cognitive radio nodes can communicate on the idle frequency spectrum, the communication of a master user is not influenced, and the master user is prevented from being interfered when using the authorized frequency spectrum.
Fig. 2 is a flowchart of another idle spectrum detection method according to an embodiment of the present invention, including the following steps:
s201: self-position information is obtained.
According to the prior art, the cognitive radio node may obtain its own location information, which is not described herein again.
S202: and after performing wavelet denoising on the authorized spectrum signal, performing energy detection to obtain local judgment information.
In an actual communication environment, radio signals are usually subjected to the phenomena of shadow and information fading in the transmission process, so that the low signal-to-noise ratio of the cognitive radio node is very low when receiving the signals, which affects the probability of misjudgment that the cognitive radio node judges whether the authorized spectrum is the idle spectrum according to the received signals, and the accuracy of the final judgment result is not very accurate when performing subsequent fusion processing according to the local judgment information of each cognitive radio node,
then, before the cognitive radio node performs local decision, the signal is denoised, so that the low signal-to-noise ratio when the cognitive radio node receives the signal is improved, and the misdecision probability is reduced, which is very feasible. According to the prior art, when spectrum detection is carried out, signal energy is actually detected.
Specifically, the obtaining the local judgment information includes:
the cognitive radio node performs energy detection according to a received authorized spectrum signal, wherein the authorized spectrum signal comprises: a noise-contaminated signal, the energy detection comprising: denoising the signal polluted by the noise by wavelet to obtain an estimated signal, then judging whether the estimated signal is 0 or not,
if the judgment result is that the estimation signal is 0, the cognitive radio node determines that no main user exists on the authorized spectrum, determines that the authorized spectrum is an idle spectrum,
if the judgment result is that the estimation signal is not 0, the estimation signal is subjected to analog-to-digital conversion, squaring and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics;
the wavelet denoising comprises: and mapping the signal polluted by the noise to a wavelet domain, generating a wavelet signal with a wavelet coefficient, and setting a mask operator to ensure that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and setting other wavelet coefficients to be 0.
Specific examples thereof include: assuming that a signal obtained after wavelet denoising is an estimated signal f' (n), and a received signal polluted by noise is s (n) ═ f (n) + σ e (n), where s (n) is a signal polluted by noise, f (n) is a signal sent by a primary user base station, e (n) is noise, and σ is noise intensity. Under ideal conditions, noise can be completely filtered, and H is the main user if the main user exists1If there is f' (n) ═ f (n), if there is no primary user, then H is present0Then f' (n) ═ 0. Judging whether the estimation signal f '(n) is 0 or not, if the judgment result is that the estimation signal f' (n) is 0, determining that no main user exists on the authorized spectrum by the cognitive radio node, and determining that the authorized spectrum is an idle spectrum; if the judgment result is that the estimation signal f' (n) is not 0, the estimation signal is subjected to analog-to-digital conversion, squarer and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics, wherein the detection statistics can be expressed as
Wherein,represents a central χ -square distribution with a degree of freedom of 2TW,representing a degree of freedom of 2TW, a non-central χ -squared distribution of a non-central parameter 2 γ, γ being the signal-to-noise ratio, TW representing the product of the sampling time and the bandwidth of the sampling band.
The wavelet denoising process comprises the following steps: mapping the signal s (n) polluted by noise to wavelet domain to generate wavelet signal with wavelet coefficient, setting mask operator BcSo that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and the other wavelet coefficients are set to be 0, which can be expressed as:
wherein Q represents a preset wavelet coefficient, cm,nRepresenting a single wavelet coefficient term.
Of course, the signal s (n) polluted by noise is mapped to wavelet domain to generate wavelet signal with wavelet coefficient, and the module value threshold Y can be setCThe wavelet coefficients with small modulus values are set to 0, and only the wavelet coefficient items with large modulus values are retained, i.e.
Wherein, the set module value threshold value is shown.
Specifically, the determining, by the cognitive radio node, local decision information according to the probe statistic includes:
and comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, determining that a master user exists on the authorized spectrum and determining that the authorized spectrum is a non-idle spectrum by the cognitive radio node, and if the detection statistic is less than or equal to the preset threshold, determining that the master user does not exist on the perceived authorized spectrum by the cognitive radio node and determining that the authorized spectrum is an idle spectrum.
Specifically, for example, the detection statistic S is obtained according to the above steps, and is compared with a preset threshold λ, if the detection statistic S is greater than the preset threshold λ, that is, S > λ, the cognitive radio node determines that a primary user exists on the authorized spectrum, and determines that the authorized spectrum is a non-free spectrum, and if the detection statistic S is less than or equal to the preset threshold λ, that is, S is not greater than λ, the cognitive radio node determines that a primary user does not exist on the perceived authorized spectrum, and determines that the authorized spectrum is a free spectrum.
S203: sending the position information and the local judgment information to a network side; and performing fusion processing on the network side, determining a final judgment result, and sending the determined final judgment result to the cognitive radio node and at least one cooperative cognitive radio node.
Specific examples thereof include: the cognitive radio node acquires position information of the cognitive radio node, makes local judgment according to an authorized spectrum signal received by the cognitive radio node, sends the acquired position information of the cognitive radio node and a local judgment result to a network side, the network side determines at least one cooperative cognitive radio node according to the position information of the cognitive radio node, receives the local judgment result of the at least one cooperative cognitive radio node, merges the local judgment results of the cognitive radio node and the at least one cooperative cognitive radio node, determines a final judgment result, and sends the final judgment result to the cognitive radio node and the at least one cooperative cognitive radio node.
S204: and receiving a final judgment result sent by the network side.
S205: and determining whether to communicate on the authorized spectrum according to the determined final judgment result.
For example: the cognitive radio node determines whether to communicate on the authorized spectrum according to a final judgment result sent by a network side, and when the final judgment result is that an authorized user exists in the authorized spectrum, namely the authorized spectrum is a non-idle spectrum, the cognitive radio node does not select to communicate on the authorized spectrum; when the final judgment result shows that no authorized user exists in the authorized spectrum, that is, the authorized spectrum is an idle spectrum, the cognitive radio node may select to communicate on the authorized spectrum or not select to communicate on the authorized spectrum.
Specifically, the method further comprises:
in the communication process on the authorized spectrum, sending self position information and a local judgment result to a network side in real time; and when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the master user, stopping using the authorized spectrum for communication.
Assuming that a cognitive radio node determines a free spectrum P and is carrying out communication on the free spectrum P, at the moment, the cognitive radio node continuously receives a signal of an authorized spectrum P, detects whether a master user of the spectrum P uses the authorized spectrum P for communication, sends a detection result and position information of the detection result to a network side in real time, carries out fusion judgment on the network side, and stops using the authorized spectrum P for communication when the cognitive radio node receives a final judgment result of the network side, wherein the final judgment result indicates that the authorized spectrum P is occupied by the master user.
By applying the embodiment of the invention shown in the figure 2, the authorized spectrum can be judged in real time, whether the authorized spectrum exists in the authorized spectrum or not is determined, whether the authorized spectrum is the idle spectrum or not is determined, the communication of the master user is not influenced when the cognitive radio node communicates on the idle spectrum, and when the master user communicates by using the authorized spectrum, the cognitive radio node stops using the authorized spectrum, so that the normal communication of the master user is ensured.
Fig. 3 is a schematic structural diagram of an apparatus for detecting a white space according to an embodiment of the present invention, which corresponds to the flow shown in fig. 1 and is applied to a network side, where the apparatus includes: a request receiving module 301, a first determining module 302, a decision information determining module 303 and a decision result transmitting module 304,
the request receiving module 301: the method includes the steps of receiving a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request includes: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection.
The first determination module 302: the method comprises the step of determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node.
The decision information determining module 303: the method comprises the steps of selecting a preset fusion criterion according to the local judgment information of the first cognitive radio node and the received local judgment information sent by at least one cooperative cognitive radio node, processing the received local judgment information of the first cognitive radio node and the local judgment information of the at least one cooperative cognitive radio node according to the selected fusion criterion, and determining a final judgment result, wherein the final judgment result comprises the step of determining whether the authorized spectrum is an idle spectrum.
The decision result sending module 304: and the terminal node is configured to send the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the terminal node determines whether to communicate on the licensed spectrum according to the determined final decision result.
By applying the embodiment of the invention shown in fig. 3, the signals with low signal-to-noise ratios received by the cognitive radio nodes can be subjected to relatively thorough denoising processing, the low signal-to-noise ratios of the signals are improved, the accuracy of local judgment of each cognitive radio node is improved, the accuracy of the final judgment result obtained by subsequent fusion processing is improved greatly, the detection of the idle spectrum is more accurate, the cognitive radio nodes can communicate on the idle spectrum, meanwhile, the communication of a master user is not influenced, and the master user is prevented from being interfered when using the authorized spectrum.
For the device embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, refer to the partial description of the method embodiment.
Fig. 4 is a schematic structural diagram of another idle spectrum detection apparatus provided in an embodiment of the present invention, which corresponds to the flow shown in fig. 2 and is applied to a cognitive radio node, where the apparatus includes: a location information acquisition module 401, a local decision module 402, an information transmission module 403, a final decision information reception module 404 and a second determination module 405,
the position information acquisition module 401: for obtaining self-location information.
The local decision module 402: the method is used for performing wavelet denoising on the authorized spectrum signal and then performing energy detection to obtain local judgment information.
Specifically, the local judgment module is specifically configured to:
the cognitive radio node performs energy detection according to a received authorized spectrum signal, wherein the authorized spectrum signal comprises: a noise-contaminated signal, the energy detection comprising: denoising the signal polluted by the noise by wavelet to obtain an estimated signal, then judging whether the estimated signal is 0 or not,
if the judgment result is that the estimation signal is 0, the cognitive radio node determines that no main user exists on the authorized spectrum, determines that the authorized spectrum is an idle spectrum,
if the judgment result is that the estimation signal is not 0, the estimation signal is subjected to analog-to-digital conversion, squaring and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics;
the wavelet denoising comprises: and mapping the signal polluted by the noise to a wavelet domain, generating a wavelet signal with a wavelet coefficient, and setting a mask operator to ensure that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and setting other wavelet coefficients to be 0.
Specifically, when the local decision module determines the local decision information according to the detection statistics:
and comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, determining that a master user exists on the authorized spectrum and determining that the authorized spectrum is a non-idle spectrum by the cognitive radio node, and if the detection statistic is less than or equal to the preset threshold, determining that the master user does not exist on the perceived authorized spectrum by the cognitive radio node and determining that the authorized spectrum is an idle spectrum.
The information sending module 403: the local judgment module is used for sending the position information and the local judgment information to a network side; and performing fusion processing on the network side, determining a final judgment result, and sending the determined final judgment result to the cognitive radio node and at least one cooperative cognitive radio node.
The final decision information receiving module 404: and the terminal is used for receiving the final judgment result sent by the network side.
The second determination module 405: and the terminal is used for determining whether to communicate on the authorized spectrum according to the determined final decision result.
Specifically, the information sending module is further configured to: in the communication process on the authorized spectrum, sending self position information and a local judgment result to a network side in real time;
the device further comprises a decommissioning module (not shown), which is specifically configured to: and when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the master user, stopping using the authorized spectrum for communication.
By applying the embodiment of the invention shown in the figure 4, the authorized spectrum can be judged in real time, whether the main user exists or not and whether the main user is the idle spectrum or not are determined, the communication of the main user is not influenced when the cognitive radio node communicates on the idle spectrum, and when the main user communicates by using the authorized spectrum, the cognitive radio node stops using the authorized spectrum, so that the normal communication of the main user is ensured.
For the device embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, refer to the partial description of the method embodiment.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Those skilled in the art will appreciate that all or part of the steps in the above method embodiments may be implemented by a program to instruct relevant hardware to perform the steps, and the program may be stored in a computer-readable storage medium, which is referred to herein as a storage medium, such as: ROM/RAM, magnetic disk, optical disk, etc.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. A method for detecting idle spectrum, applied to a network side, the method comprising:
receiving a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request comprises: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection;
determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node;
selecting a preset fusion criterion according to the local judgment information of the first cognitive radio node and the received local judgment information sent by at least one cooperative cognitive radio node, processing the received local judgment information of the first cognitive radio node and the local judgment information of the at least one cooperative cognitive radio node according to the selected fusion criterion, and determining a final judgment result, wherein the final judgment result comprises the step of determining whether the authorized spectrum is an idle spectrum;
and sending the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the first cognitive radio node and the at least one cooperative cognitive radio node can determine whether to communicate on the authorized spectrum according to the determined final decision result.
2. A method for idle spectrum detection is applied to a cognitive radio node, and the method comprises the following steps:
obtaining self position information;
performing wavelet denoising on the authorized spectrum signal, and then performing energy detection to obtain local judgment information;
sending the position information and the local judgment information to a network side; so that the network side sends the determined final decision result to the cognitive radio node and at least one cooperative cognitive radio node according to the steps of claim 1;
receiving a final judgment result sent by a network side;
and determining whether to communicate on the authorized spectrum according to the determined final judgment result.
3. The method of claim 2, wherein obtaining local decision information comprises:
the cognitive radio node performs energy detection according to a received authorized spectrum signal, wherein the authorized spectrum signal comprises: a noise-contaminated signal, the energy detection comprising: denoising the signal polluted by the noise by wavelet to obtain an estimated signal, then judging whether the estimated signal is 0 or not,
if the judgment result is that the estimation signal is 0, the cognitive radio node determines that no main user exists on the authorized spectrum, determines that the authorized spectrum is an idle spectrum,
if the judgment result is that the estimation signal is not 0, the estimation signal is subjected to analog-to-digital conversion, squaring and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics;
the wavelet denoising comprises: and mapping the signal polluted by the noise to a wavelet domain, generating a wavelet signal with a wavelet coefficient, and setting a mask operator to ensure that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and setting other wavelet coefficients to be 0.
4. The method of claim 3, wherein the cognitive radio node determines its local decision information based on the probe statistics, comprising:
and comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, determining that a master user exists on the authorized spectrum and determining that the authorized spectrum is a non-idle spectrum by the cognitive radio node, and if the detection statistic is less than or equal to the preset threshold, determining that the master user does not exist on the perceived authorized spectrum by the cognitive radio node and determining that the authorized spectrum is an idle spectrum.
5. The method of claim 2, further comprising:
the cognitive radio node sends self position information and a local judgment result to a network side in real time in the communication process on the authorized spectrum; and when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the master user, stopping using the authorized spectrum for communication.
6. An apparatus for idle spectrum sounding, applied to a network side, the apparatus comprising:
a request receiving module: the method includes the steps of receiving a request for detecting whether a licensed spectrum sent by a first cognitive radio node is a free spectrum, wherein the request includes: location information and local decision information of the first cognitive radio node; the local judgment information is obtained by performing wavelet denoising on the authorized spectrum signal by the first cognitive radio node and then performing energy detection;
a first determination module: the cognitive radio node is used for determining at least one cooperative cognitive radio node according to the position information of the first cognitive radio node;
a decision information determination module: the device comprises a first cognitive radio node, a second cognitive radio node and a third cognitive radio node, wherein the first cognitive radio node is used for receiving local judgment information of the first cognitive radio node and receiving local judgment information sent by at least one cooperative cognitive radio node;
a judgment result sending module: and the terminal node is configured to send the determined final decision result to the first cognitive radio node and at least one cooperative cognitive radio node, so that the terminal node determines whether to communicate on the licensed spectrum according to the determined final decision result.
7. An apparatus for idle spectrum sounding, applied to a cognitive radio node, the apparatus comprising:
a position information acquisition module: used for obtaining self position information;
a local judgment module: the device is used for performing wavelet denoising on the authorized spectrum signal and then performing energy detection to obtain local judgment information;
an information sending module: the local judgment module is used for sending the position information and the local judgment information to a network side; so that the network side sends the determined final decision result to the cognitive radio node and at least one cooperative cognitive radio node according to the steps of claim 1;
a final judgment information receiving module: the system is used for receiving a final judgment result sent by a network side;
a second determination module: and the terminal is used for determining whether to communicate on the authorized spectrum according to the determined final decision result.
8. The apparatus according to claim 7, wherein the local decision module is specifically configured to:
the cognitive radio node performs energy detection according to a received authorized spectrum signal, wherein the authorized spectrum signal comprises: a noise-contaminated signal, the energy detection comprising: denoising the signal polluted by the noise by wavelet to obtain an estimated signal, then judging whether the estimated signal is 0 or not,
if the judgment result is that the estimation signal is 0, the cognitive radio node determines that no main user exists on the authorized spectrum, determines that the authorized spectrum is an idle spectrum,
if the judgment result is that the estimation signal is not 0, the estimation signal is subjected to analog-to-digital conversion, squaring and sampling summation to obtain detection statistics, and the cognitive radio node determines local judgment information according to the detection statistics;
the wavelet denoising comprises: and mapping the signal polluted by the noise to a wavelet domain, generating a wavelet signal with a wavelet coefficient, and setting a mask operator to ensure that the wavelet signal only retains the coefficient item of the preset wavelet coefficient, and setting other wavelet coefficients to be 0.
9. The apparatus of claim 8, wherein the local decision module, when determining its local decision information based on the probe statistics:
and comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, determining that a master user exists on the authorized spectrum and determining that the authorized spectrum is a non-idle spectrum by the cognitive radio node, and if the detection statistic is less than or equal to the preset threshold, determining that the master user does not exist on the perceived authorized spectrum by the cognitive radio node and determining that the authorized spectrum is an idle spectrum.
10. The apparatus of claim 7, wherein the information sending module is further configured to: in the communication process on the authorized spectrum, sending self position information and a local judgment result to a network side in real time;
the device further comprises a use stopping module, wherein the use stopping module is specifically used for: and when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the master user, stopping using the authorized spectrum for communication.
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