CN105187142A - Method and device for detecting idle spectrum - Google Patents

Abstract

The embodiment of the present invention discloses a method and device for detecting idle spectrum. The method includes: receiving a request sent by a first cognitive radio node to detect whether the authorized spectrum is an idle spectrum; Location information, to determine at least one cooperative cognitive radio node; the local decision information of the first cognitive radio node carried in the selected fusion criterion processing request after wavelet denoising processing, and the local decision information sent by all cooperative cognitive radio nodes Judgment information, determining a final decision result; sending the determined final decision result to the first cognitive radio node and all coordinated cognitive radio nodes, so that they can determine whether to Communications are performed on the licensed frequency spectrum. By applying the embodiments of the present invention, the accuracy of detecting idle spectrum can be improved, and it can be ensured that the communication of the primary user is not affected when the cognitive radio node uses the licensed spectrum.

Description

Method and device for idle spectrum detection

technical field

The present invention relates to the field of cognitive radio technology, in particular to a method and device for detecting idle frequency spectrum.

Background technique

In recent years, with the increasing demand for spectrum resources, the cognitive radio technology has become increasingly important. Cognitive radio is a dynamic spectrum sharing technology that dynamically perceives the surrounding environment and adjusts its own transmission parameters. The core problem that the cognitive radio needs to solve is how to accurately identify the spectrum occupancy and the working conditions of the primary user, that is, the first step of the cognitive radio work: spectrum occupancy detection. The main work of the spectrum occupancy detection is to detect the spectrum occupancy within a certain range, whether there is a situation that the primary user is occupying, and then distinguish the spectrum and use it on this basis. In the process of the sensing user acquiring the signal of the primary user, it is inevitably affected by factors such as multipath, shadows, and local interference. As a result, the signal intercepted by the sensing user is too weak, which leads to a judgment error and interferes with the primary user. At this time, it is necessary to use cooperative detection to help complete the process of spectrum occupancy detection.

In cooperative detection, cooperative users can improve the detection performance by fusing the detection information of multiple CR-Cognitive Radio (CR-CognitiveRadio) nodes, and at the same time relatively reduce the detection performance requirements of each node. But in cooperative detection, for multiple selected CR nodes, it cannot be sure that the local detection reliability of each node is high enough. When the selected CR nodes have many nodes with low reliability, the effect of cooperative detection may not be as good as the detection performance of a single user. Therefore, there must be certain reliability requirements for the CR nodes participating in the cooperation. When the channel environment to the primary user base station is poor, the node is also required to have better detection performance.

In the prior art, when the external communication environment is poor, that is, a low SNR-Signal to Noise Ratio (SNR-Signal to Noise Ratio) will cause sudden changes in detection performance, and will cause performance degradation during cooperative detection, resulting in large errors in detection results.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a method and device for detecting idle spectrum, which can improve the low signal-to-noise ratio, so as to improve the accuracy of idle spectrum detection.

In order to achieve the above purpose, the embodiment of the present invention discloses a method for detecting idle spectrum, which is applied to the network side, and the method includes the steps of:

Receive a request sent by the first cognitive radio node to detect whether the authorized spectrum is a free spectrum, the request includes: the location information of the first cognitive radio node and local decision information; the local decision information is the first cognitive radio node After the radio node performs wavelet denoising on the authorized spectrum signal, it is obtained by energy detection;

determining at least one cooperating cognitive radio node based on the location information of the first cognitive radio node;

According to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, select a preset fusion criterion, and process the received fusion criterion according to the selected fusion criterion The local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node determine a final decision result, where the final decision result includes determining whether the authorized spectrum is a free spectrum;

sending the determined final decision result to the first cognitive radio node and at least one cooperating cognitive radio node, so that they determine whether to communicate on the authorized spectrum according to the determined final decision result .

In order to achieve the above purpose, an embodiment of the present invention discloses a method for detecting idle spectrum, which is applied to a cognitive radio node, and the method includes steps:

Get your own location information;

After wavelet denoising is performed on the licensed spectrum signal, energy detection is performed to obtain local decision information;

Sending the location information and the local decision information to the network side; causing the network side to send the determined final decision result to the cognitive radio node and at least one cooperative cognitive radio according to the steps described in claim 1 node;

Receive the final judgment result sent by the network side;

According to the determined final judgment result, determine whether to perform communication on the authorized frequency spectrum.

Preferably, said obtaining local judgment information includes:

The cognitive radio node performs energy detection according to the authorized spectrum signal it receives, wherein the authorized spectrum signal includes: a signal polluted by noise, and the energy detection includes: the signal polluted by noise undergoes wavelet denoising to obtain an estimated signal , and then judge whether the estimated signal is 0,

If the judgment result is that the estimated signal is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is an idle spectrum,

If the judgment result is that the estimated signal is not 0, the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node determines its local decision information according to the detection statistic;

The wavelet denoising includes: mapping the signal polluted by noise to the wavelet domain, generating a wavelet signal with wavelet coefficients, setting a mask operator so that the wavelet signal only retains the coefficient items of the preset wavelet coefficients, and other The wavelet coefficients are set to 0.

Preferably, the cognitive radio node determines its local decision information according to the detection statistics, including:

Comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, the cognitive radio node determines that there is a primary user on the authorized spectrum, and determines that the authorized spectrum It is a non-idle spectrum, and if the detection statistic is less than or equal to the preset threshold, the cognitive radio node determines that there is no primary user on the perceived licensed spectrum, and determines that the licensed spectrum is an idle spectrum.

Preferably, the method also includes:

During the communication process on the authorized spectrum, the cognitive radio node sends its own location information and local judgment results to the network side in real time; when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the primary user, stop Communications are performed using the licensed spectrum.

In order to achieve the above purpose, the embodiment of the present invention discloses a device for detecting idle spectrum, which is applied to the network side, and the device includes:

The request receiving module: used to receive the request sent by the first cognitive radio node to detect whether the authorized spectrum is a free spectrum, the request includes: the location information of the first cognitive radio node and local decision information; the local decision The information is obtained by performing energy detection after the first cognitive radio node performs wavelet denoising on the authorized spectrum signal;

A first determining module: configured to determine at least one cooperative cognitive radio node according to the location information of the first cognitive radio node;

Decision information determination module: for selecting a preset fusion criterion according to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, and according to the selected The fusion criterion processes the received local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node to determine a final decision result, the final decision result including determining whether the licensed spectrum is free spectrum;

A decision result sending module: used to send the determined final decision result to the first cognitive radio node and at least one coordinated cognitive radio node, so that they can determine whether to Communications are performed on the licensed frequency spectrum.

To achieve the above purpose, an embodiment of the present invention discloses a device for detecting idle spectrum, which is applied to a cognitive radio node, and the device includes:

Location information acquisition module: used to obtain its own location information;

Local judgment module: used to perform energy detection on authorized spectrum signals after wavelet denoising to obtain local judgment information;

An information sending module: used to send the location information and the local decision information to the network side; so that the network side sends the determined final decision result to the cognitive radio node and at least a cooperating cognitive radio node;

Final judgment information receiving module: used to receive the final judgment result sent by the network side;

The second determination module is configured to determine whether to perform communication on the authorized frequency spectrum according to the final decision result of the determination.

Preferably, the local judgment module is specifically used for:

The cognitive radio node performs energy detection according to the authorized spectrum signal it receives, wherein the authorized spectrum signal includes: a signal polluted by noise, and the energy detection includes: the signal polluted by noise undergoes wavelet denoising to obtain an estimated signal , and then judge whether the estimated signal is 0,

If the judgment result is that the estimated signal is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is an idle spectrum,

If the judgment result is that the estimated signal is not 0, the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node determines its local decision information according to the detection statistic;

The wavelet denoising includes: mapping the signal polluted by noise to the wavelet domain, generating a wavelet signal with wavelet coefficients, setting a mask operator so that the wavelet signal only retains the coefficient items of the preset wavelet coefficients, and other The wavelet coefficients are set to 0.

Preferably, when the local decision module determines its local decision information according to the detection statistics:

Comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, the cognitive radio node determines that there is a primary user on the authorized spectrum, and determines that the authorized spectrum It is a non-idle spectrum, and if the detection statistic is less than or equal to the preset threshold, the cognitive radio node determines that there is no primary user on the perceived licensed spectrum, and determines that the licensed spectrum is an idle spectrum.

Preferably, the information sending module is also used to: send its own location information and local judgment results to the network side in real time during the communication process on the authorized spectrum;

The device further includes a stop-use module, the stop-use module is specifically configured to: stop using the licensed spectrum for communication when the received final judgment result sent by the network side indicates that the licensed spectrum is occupied by the primary user.

It can be seen from the above technical solution that the embodiment of the present invention discloses a method and device for detecting idle spectrum. The method includes the step of receiving a request sent by the first cognitive radio node to detect whether the licensed spectrum is an idle spectrum. The request includes : the location information and local decision information of the first cognitive radio node; the local decision information is obtained by the first cognitive radio node after performing wavelet denoising on the licensed spectrum signal, and then performing energy detection; according to the first The location information of the cognitive radio node determines at least one cooperative cognitive radio node; according to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, select a A preset fusion criterion, processing the received local decision information of the first cognitive radio node and local decision information of at least one coordinated cognitive radio node according to the selected fusion criterion, and determining a final decision result, the final decision The result includes determining whether the authorized spectrum is a free spectrum; sending the final decision result of the determination to the first cognitive radio node and at least one cooperating cognitive radio node, so that they can make the final decision based on the determination As a result, it is determined whether to communicate on the licensed spectrum. In the embodiment of the present invention, the authorized spectrum signal is subjected to wavelet denoising processing, and the cooperative cognitive radio node is determined by the network side and the fusion judgment is performed, which improves the low signal-to-noise ratio and improves the precision for subsequent signal energy detection and finding idle spectrum. Spend. Of course, implementing any product or method of the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 provides a schematic flowchart of a method for detecting idle spectrum according to an embodiment of the present invention;

FIG. 2 provides a schematic flow chart of another method for detecting idle spectrum according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an apparatus for detecting idle spectrum according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of another device for detecting idle spectrum according to an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiments of the present invention provide a method and device for detecting idle spectrum. In this solution, a request for detecting whether the authorized spectrum is idle spectrum sent by the first cognitive radio node is received, and the request includes: the first cognitive radio node The location information of the radio node and the local decision information; the local decision information is obtained by performing energy detection on the authorized spectrum signal by the first cognitive radio node after wavelet denoising; according to the location information of the first cognitive radio node , determine at least one cooperative cognitive radio node; select a preset fusion criterion according to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, according to The selected fusion criterion processes the received local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node to determine a final decision result, the final decision result including determining the authorized spectrum Whether it is a free spectrum; sending the determined final decision result to the first cognitive radio node and at least one coordinated cognitive radio node, so that they can determine whether to use the Communicate on licensed spectrum.

The present invention will be described in detail below through specific examples.

FIG. 1 is a schematic flowchart of a method for detecting idle spectrum provided by an embodiment of the present invention, which is applied to the network side and includes the following steps:

S101: Receive a request sent by the first cognitive radio node to detect whether the authorized spectrum is a free spectrum, the request includes: the location information of the first cognitive radio node and local decision information; the local decision information is the first The cognitive radio node performs energy detection on the licensed spectrum signal after performing wavelet denoising.

According to the prior art, it is known that a cognitive radio node perceives and recognizes radio signals in its surrounding environment every moment, where the radio signals include the authorized spectrum signals and other radio signals.

Specifically, for example: the network side receives a request from the first cognitive radio node to detect whether the authorized spectrum is a free spectrum. The request includes: the location information and local judgment information of the first cognitive radio node, if the location information is the first A cognitive radio node is located in Shanghai, and the local decision information is obtained by energy detection after the first radio node performs wavelet denoising processing on the licensed spectrum signal received by the first radio node, after filtering out the interference noise signal, assuming that the first The local decision information of the radio node is that the authorized spectrum is an idle spectrum.

S102: Determine at least one cooperative cognitive radio node according to the location information of the first cognitive radio node.

According to the location information of the first cognitive radio node, a location range threshold can be set, and it is determined that the cognitive radio nodes within the location range threshold are determined to be at least one cooperative cognitive radio node; a specific distance ladder can also be set Selecting the cognitive radio node at the position of the set distance step is determined as at least one cooperative cognitive radio node.

For example, if the location range threshold is set to 200 kilometers, it is determined that the cognitive radio node within the location range threshold of 200 kilometers is determined as at least one cooperative cognitive radio node, and the determined at least one cooperative cognitive radio node is determined. There are three nodes, namely cognitive radio node A, cognitive radio node B, and cognitive radio node C.

It should be noted that this application does not limit the specific implementation manner of determining at least one cooperative cognitive radio node according to the location information of the first cognitive radio node, and any possible implementation manner can be applied in this application.

S103: According to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, select a preset fusion criterion, and process the The received local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node are used to determine a final decision result, where the final decision result includes determining whether the authorized spectrum is an idle spectrum.

Specifically, for example: according to step S102, three cognitive radio nodes are determined to be at least one cooperative cognitive radio node, namely cognitive radio node A, cognitive radio node B, and cognitive radio node C, wherein the cognitive radio node After the radio node A detects the authorized spectrum, the obtained local judgment information is that the authorized spectrum is an idle spectrum, and after the cognitive radio node B detects the authorized spectrum, the obtained local judgment information is the 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 it is determined as the three cognitive radio nodes of the cooperative cognitive radio node. The nodes respectively send the local decision information obtained by themselves to the network side.

The network side selects a preset fusion criterion, processes the received local decision information of the first cognitive radio node and local decision information of the three coordinated cognitive radio nodes according to the selected fusion criterion, and determines a final decision result.

Assume that H ₀ indicates that the licensed spectrum is an idle spectrum, that is, no primary user uses it; H ₁ indicates that the licensed spectrum is a non-idle spectrum, that is, that it is used by a primary user.

The main measurement criteria in spectrum detection are detection probability, false alarm probability and missed detection probability, as follows:

P _d = Prob {judgment is H ₁ |H ₁ };

P _f = Prob {judgment is H ₁ |H ₀ };

P _m = Prob {judgment is H ₀ |H ₁ };

Assuming that a K/N fusion criterion is selected, the global false alarm probability and detection probability under this fusion criterion are respectively

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{{\mathrm{<span\; class="notranslate">\; \&Sigma;u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{{\mathrm{<span\; class="notranslate">\; \&Sigma;u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}$

in and respectively represent the false alarm probability and detection probability of a single cognitive radio node, u _i represents the local decision information of cognitive radio node i, that is, when u _i =1, the local decision is H ₁ , and when u _i =0, the local decision is H ₀ . When k=1, the K/N criterion is the OR criterion, and when k=n, the K/N criterion is the AND criterion, when , it is the MOST criterion.

Wherein, when k=n, when the fusion criterion is the AND criterion, only when all the local decision information is that the licensed spectrum is judged to be non-idle spectrum, that is, all u _i =1, the final decision result will consider that the primary user exists. The licensed spectrum is a non-idle spectrum, that is, u ₀ =1, otherwise the fusion center considers that the primary user does not exist, and the licensed spectrum is a free spectrum, that is, u ₀ =0. The detection conditions of the spectrum are harsh, making the detection probability low under the same conditions. N represents the total number of cognitive radio nodes; K represents the number of cognitive radio nodes whose decision result is that the primary user exists on the licensed spectrum.

When k=1, when using the fusion criterion as the OR criterion, contrary to the AND criterion, this criterion is that as long as there is a local decision information that the licensed spectrum is a non-idle spectrum, that is, when there is u _i =1, the final decision result is The primary user exists, that is, u ₀ =1, the licensed spectrum is a non-idle spectrum; on the contrary, only when all the local judgment information indicates that the licensed spectrum is a free spectrum, the final judgment result will consider that the primary user does not exist, that is, u ₀ =0, the licensed spectrum The frequency spectrum is an idle frequency spectrum. This criterion greatly increases the detection probability when the primary user exists, but also significantly increases the false alarm probability when the primary user does not exist.

when When , the fusion criterion used is the MOST criterion. At this time, the number of cognitive radio nodes whose local judgment information is that the licensed spectrum is an idle spectrum is greater than or equal to the number of cognitive radio nodes whose local judgment information is that the authorized spectrum is a non-idle spectrum. The final judgment result is that the licensed spectrum is a free spectrum, otherwise it is the opposite.

Assuming that the fusion criterion selects the MOST criterion, combined with the first cognitive radio node and the three cooperative recognition radio nodes A, B, and C, the final decision result is to determine that the licensed spectrum is a free spectrum.

It should be noted that the aforementioned K/N fusion criterion is just an example. In practical applications, any fusion criterion existing in the prior art may be used.

S104: Send the determined final decision result to the first cognitive radio node and at least one coordinated cognitive radio node, so that they can determine whether to use the authorized spectrum according to the determined final decision result to communicate.

Specifically, for example: according to step S103, it is determined that the authorized spectrum is an idle spectrum, and the final judgment result of determining that the authorized spectrum is an idle spectrum is sent to the first cognitive radio node and three cooperative cognitive radios Nodes A, B, and C, so that the first cognitive radio node and the three cooperating cognitive radio nodes A, B, and C determine whether to communicate on the authorized spectrum, assuming that the first cognitive radio node It is determined to perform communication on the authorized frequency spectrum.

By applying the embodiments of the present invention, the signals with low SNR received by the cognitive radio nodes can be thoroughly denoised, and the low SNR of the signals can be improved, so that the accuracy of the local decision of each cognitive radio node can be improved. , for the subsequent fusion processing, the accuracy of the final decision result is also greatly improved, making the detection of idle spectrum more accurate, enabling cognitive radio nodes to communicate on the idle spectrum without affecting the communication of the primary user , to avoid interference when the primary user uses the licensed spectrum.

FIG. 2 is a schematic flowchart of another method for detecting idle spectrum provided by an embodiment of the present invention, including the following steps:

S201: Obtain self-location information.

According to the prior art, a cognitive radio node can acquire its own location information, which will not be repeated here.

S202: After wavelet denoising is performed on the licensed spectrum signal, energy detection is performed to obtain local judgment information.

In the actual communication environment, radio signals usually suffer from shadows and information fading during transmission, which leads to low signal-to-noise ratio of cognitive radio nodes when receiving signals, which will affect cognitive radio nodes according to the received signal. Signal, the probability of misjudgment of judging whether the licensed spectrum is a free spectrum will increase, so when performing fusion processing based on the local judgment information of each cognitive radio node, the accuracy of the final judgment result will also be less accurate ,

Then, before the cognitive radio node makes a local decision, it is very feasible to perform denoising processing on the signal to improve the low signal-to-noise ratio when the cognitive radio node receives the signal, so as to reduce the probability of misjudgment. According to the prior art, it is known that when spectrum detection is performed, signal energy is actually detected.

Specifically, the acquisition of local judgment information includes:

The cognitive radio node performs energy detection according to the authorized spectrum signal it receives, wherein the authorized spectrum signal includes: a signal polluted by noise, and the energy detection includes: the signal polluted by noise undergoes wavelet denoising to obtain an estimated signal , and then judge whether the estimated signal is 0,

If the judgment result is that the estimated signal is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is an idle spectrum,

If the judgment result is that the estimated signal is not 0, the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node determines its local decision information according to the detection statistic;

The wavelet denoising includes: mapping the signal polluted by noise to the wavelet domain, generating a wavelet signal with wavelet coefficients, setting a mask operator so that the wavelet signal only retains the coefficient items of the preset wavelet coefficients, and other The wavelet coefficients are set to 0.

For example: assume that the signal obtained after wavelet denoising is the estimated signal f'(n), and the received signal polluted by noise is s(n)=f(n)+σe(n), where s(n) is the signal polluted by noise, f(n) is the signal sent by the main user base station, e(n) is the noise, and σ is the noise intensity. In an ideal state, the noise can be completely filtered out. If there is a primary user (H ₁ ), then f'(n)=f(n), if there is no primary user (H _{0 )} , then f'(n)=0 . That is, it is judged whether the estimated signal f'(n) is 0, and if the judgment result is that the estimated signal f'(n) is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is idle Spectrum; if the judgment result is that the estimated signal f'(n) is not 0, then the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node obtains the detection statistic according to the detection statistic Determine its local decision information, where the detection statistics can be expressed as

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; ~</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; W</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}\right.$

in, Represents a central χ-square distribution with 2TW degrees of freedom, Indicates that the degree of freedom is 2TW, the non-central χ-square distribution of the non-central parameter 2γ, γ is the signal-to-noise ratio, and TW represents the product of sampling time and sampling frequency band bandwidth.

The wavelet denoising process includes: mapping the noise-contaminated signal s(n) to the wavelet domain to generate a wavelet signal with wavelet coefficients, and the mask operator B _c can be set so that the wavelet signal only retains the preset wavelet coefficients Coefficient item, other wavelet coefficients are set to 0, which can be expressed as:

Wherein, Q represents a preset wavelet coefficient, and c _m,n represents a single wavelet coefficient item.

Of course, the noise-polluted signal s(n) is mapped to the wavelet domain to generate a wavelet signal with wavelet coefficients, and the modulus threshold Y _C can also be set so that the wavelet coefficients with small modulus values are set to 0 and only the modulus values are retained The large wavelet coefficient term, namely

Among them, δ represents the set modulus threshold.

Specifically, the cognitive radio node determines its local decision information according to the detection statistics, including:

Comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, the cognitive radio node determines that there is a primary user on the authorized spectrum, and determines that the authorized spectrum It is a non-idle spectrum, and if the detection statistic is less than or equal to the preset threshold, the cognitive radio node determines that there is no primary user on the perceived licensed spectrum, and determines that the licensed spectrum is an idle spectrum.

Specifically, for example, the detection statistic S obtained according to the above steps is compared with the preset threshold λ, and if any detection statistic S is greater than the preset threshold λ, that is, S>λ, the cognitive radio node determines that the There is a primary user on the authorized spectrum, and it is determined that the authorized spectrum is a non-idle spectrum. If there is a detection statistic S that is less than or equal to the preset threshold λ, that is, S≤λ, the cognitive radio node determines that the sensing There is no primary user on the licensed spectrum, and it is determined that the licensed spectrum is an idle spectrum.

S203: Send the location information and the local decision information to the network side; make the network side perform fusion processing, determine the final decision result, and send the determined final decision result to the cognitive radio node and at least one coordinated Cognitive radio nodes.

For example: a cognitive radio node acquires its own location information, makes a local decision based on the authorized spectrum signal it receives, and sends the acquired location information and local decision results to the network side, and the network side The location information of the radio node determines at least one cooperative cognitive radio node, and receives the local judgment result of the at least one cooperative cognitive radio node, fuses and processes the local judgment result of the cognitive radio node and the at least one cooperative cognitive radio node, and determines the final judgment As a result, the final decision is sent to the cognitive radio node and at least one cooperating cognitive radio node.

S204: Receive the final decision result sent by the network side.

S205: Determine whether to perform communication on the authorized frequency spectrum according to the determined final decision result.

For example: the cognitive radio node determines whether to communicate on the licensed spectrum according to the final judgment result sent by the network side, and when the final judgment result is that there are authorized users in the licensed spectrum, that is, the licensed spectrum is a non-idle spectrum, then The cognitive radio node will never choose to communicate on the authorized spectrum; when the final judgment result is that there is no authorized user in the authorized spectrum, that is, the authorized spectrum is an idle spectrum, the cognitive radio node can choose to communicate in the authorized spectrum. communicate on the authorized spectrum, or choose not to communicate on the authorized spectrum.

Specifically, the method also includes:

During the communication process on the authorized spectrum, send its own location information and local judgment results to the network side in real time; when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the primary user, stop using the authorized spectrum spectrum for communication.

Assume that the cognitive radio node has determined the free spectrum P and is communicating on the free spectrum P. At this time, the cognitive radio node is still receiving the signal of the authorized spectrum P to detect whether the primary user of the spectrum P is using The authorized spectrum P communicates, and sends the detection result and its own location information to the network side in real time, and the network side makes a fusion decision. When the cognitive radio node receives the final decision result from the network side, it indicates that the If the authorized spectrum P is occupied by the primary user, the cognitive radio node stops using the authorized spectrum P for communication.

Applying the embodiment of the invention in Fig. 2, the authorized spectrum can be judged in real time to determine whether there is a primary user and whether it is an idle spectrum, so as to ensure that the communication of the cognitive radio node does not affect the communication of the primary user when the primary user communicates on the idle spectrum. When using the licensed spectrum for communication, the cognitive radio node stops using the licensed spectrum, which ensures the normal communication of the primary user.

Fig. 3 is a schematic structural diagram of a device for detecting idle spectrum provided by an embodiment of the present invention, which corresponds to the process shown in Fig. 1 and is applied to the network side. The device includes: a request receiving module 301, a first determining module 302, decision information determination module 303 and decision result sending module 304,

Request receiving module 301: used to receive a request sent by the first cognitive radio node to detect whether the authorized spectrum is a free spectrum, the request includes: location information and local decision information of the first cognitive radio node; the local The decision information is obtained by the first cognitive radio node performing energy detection on the authorized spectrum signal after performing wavelet denoising.

The first determining module 302 is configured to determine at least one cooperative cognitive radio node according to the location information of the first cognitive radio node.

Decision information determination module 303: for selecting a preset fusion criterion according to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, and according to the selected The fusion criterion processes the received local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node to determine a final decision result, and the final decision result includes determining whether the licensed spectrum is Free spectrum.

The decision result sending module 304: configured to send the determined final decision result to the first cognitive radio node and at least one coordinated cognitive radio node, so that they can determine whether to Communicating on the licensed spectrum.

Applying the embodiment of the invention shown in Fig. 3, it is possible to perform relatively thorough denoising processing on signals with low signal-to-noise ratio received by cognitive radio nodes, and improve the low signal-to-noise ratio of the signal, so that the local decision of each cognitive radio node The accuracy is improved. For the subsequent fusion processing, the accuracy of the final judgment result is also improved a lot, making the detection of idle spectrum more accurate, enabling cognitive radio nodes to communicate on the idle spectrum without affecting the main The user's communication avoids interference when the primary user uses the licensed spectrum.

As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for related parts, please refer to the part of the description of the method embodiment.

Fig. 4 is a schematic structural diagram of another device for detecting idle spectrum provided by an embodiment of the present invention, which corresponds to the process shown in Fig. 2 and is applied to a cognitive radio node. The device includes: a location information acquisition module 401, a local judgment module 402, information sending module 403, final decision information receiving module 404 and second determination module 405,

Location information acquisition module 401: used to obtain the own location information.

Local decision module 402: used to perform energy detection on the licensed spectrum signal after wavelet denoising to obtain local decision information.

Specifically, the local judgment module is specifically used for:

The cognitive radio node performs energy detection according to the authorized spectrum signal it receives, wherein the authorized spectrum signal includes: a signal polluted by noise, and the energy detection includes: the signal polluted by noise undergoes wavelet denoising to obtain an estimated signal , and then judge whether the estimated signal is 0,

If the judgment result is that the estimated signal is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is an idle spectrum,

If the judgment result is that the estimated signal is not 0, the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node determines its local decision information according to the detection statistic;

The wavelet denoising includes: mapping the signal polluted by noise to the wavelet domain, generating a wavelet signal with wavelet coefficients, setting a mask operator so that the wavelet signal only retains the coefficient items of the preset wavelet coefficients, and other The wavelet coefficients are set to 0.

Specifically, when the local decision module determines its local decision information according to the detection statistics:

Comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, the cognitive radio node determines that there is a primary user on the authorized spectrum, and determines that the authorized spectrum It is a non-idle spectrum, and if the detection statistic is less than or equal to the preset threshold, the cognitive radio node determines that there is no primary user on the perceived licensed spectrum, and determines that the licensed spectrum is an idle spectrum.

Information sending module 403: used to send the location information and the local decision information to the network side; make the network side perform fusion processing to determine the final decision result, and send the determined final decision result to the cognitive radio node and at least one cooperating cognitive radio node.

Final decision information receiving module 404: for receiving the final decision result sent by the network side.

The second determination module 405 is configured to determine whether to perform communication on the authorized frequency spectrum according to the final decision result of the determination.

Specifically, the information sending module is also used to: send its own location information and local judgment results to the network side in real time during the communication process on the authorized spectrum;

The device also includes a stop-use module (not shown in the figure), and the stop-use module is specifically configured to: stop using the licensed spectrum when the received final judgment result sent by the network side indicates that the authorized spectrum Licensed spectrum for communication.

Applying the embodiment of the invention in Fig. 4, the authorized spectrum can be judged in real time to determine whether there is a primary user and whether it is an idle spectrum, so as to ensure that the communication of the cognitive radio node does not affect the communication of the primary user when the primary user communicates on the idle spectrum. When using the licensed spectrum for communication, the cognitive radio node stops using the licensed spectrum, which ensures the normal communication of the primary user.

As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for related parts, please refer to the part of the description of the method embodiment.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. any such actual relationship or order exists between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Those of ordinary skill in the art can understand that all or part of the steps in the implementation of the above method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, referred to herein as Storage media, such as: ROM/RAM, disk, CD, etc.

Each embodiment in this specification is described in a related manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for the related parts, please refer to the part of the description of the method embodiment.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A method for idle spectrum detection, characterized in that it is applied to the network side, and the method comprises steps: Receive a request sent by the first cognitive radio node to detect whether the authorized spectrum is a free spectrum, the request includes: the location information of the first cognitive radio node and local decision information; the local decision information is the first cognitive radio node After the radio node performs wavelet denoising on the authorized spectrum signal, it is obtained by energy detection; determining at least one cooperating cognitive radio node based on the location information of the first cognitive radio node; According to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, select a preset fusion criterion, and process the received fusion criterion according to the selected fusion criterion The local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node determine a final decision result, where the final decision result includes determining whether the authorized spectrum is a free spectrum; sending the determined final decision result to the first cognitive radio node and at least one cooperating cognitive radio node, so that they determine whether to communicate on the authorized spectrum according to the determined final decision result . 2. A method for idle spectrum detection, characterized in that it is applied to a cognitive radio node, and the method comprises steps: Get your own location information; After wavelet denoising is performed on the licensed spectrum signal, energy detection is performed to obtain local decision information; Sending the location information and the local decision information to the network side; causing the network side to send the determined final decision result to the cognitive radio node and at least one cooperative cognitive radio according to the steps described in claim 1 node; Receive the final judgment result sent by the network side; According to the determined final judgment result, determine whether to perform communication on the authorized frequency spectrum. 3. The method according to claim 2, wherein said obtaining local judgment information comprises: The cognitive radio node performs energy detection according to the authorized spectrum signal it receives, wherein the authorized spectrum signal includes: a signal polluted by noise, and the energy detection includes: the signal polluted by noise undergoes wavelet denoising to obtain an estimated signal , and then judge whether the estimated signal is 0, If the judgment result is that the estimated signal is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is an idle spectrum, If the judgment result is that the estimated signal is not 0, the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node determines its local decision information according to the detection statistic; The wavelet denoising includes: mapping the signal polluted by noise to the wavelet domain, generating a wavelet signal with wavelet coefficients, setting a mask operator so that the wavelet signal only retains the coefficient items of the preset wavelet coefficients, and other The wavelet coefficients are set to 0. 4. The method according to claim 3, wherein the cognitive radio node determines its local decision information according to the detection statistics, comprising: Comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, the cognitive radio node determines that there is a primary user on the authorized spectrum, and determines that the authorized spectrum It is a non-idle spectrum, and if the detection statistic is less than or equal to the preset threshold, the cognitive radio node determines that there is no primary user on the perceived licensed spectrum, and determines that the licensed spectrum is an idle spectrum. 5. The method according to claim 2, characterized in that the method further comprises: During the communication process on the authorized spectrum, the cognitive radio node sends its own location information and local judgment results to the network side in real time; when the received final judgment result sent by the network side indicates that the authorized spectrum is occupied by the primary user, stop Communications are performed using the licensed spectrum. 6. A device for idle spectrum detection, characterized in that it is applied to the network side, and the device includes: The request receiving module: used to receive the request sent by the first cognitive radio node to detect whether the authorized spectrum is a free spectrum, the request includes: the location information of the first cognitive radio node and local decision information; the local decision The information is obtained by performing energy detection after the first cognitive radio node performs wavelet denoising on the authorized spectrum signal; A first determining module: configured to determine at least one cooperative cognitive radio node according to the location information of the first cognitive radio node; Decision information determination module: for selecting a preset fusion criterion according to the local decision information of the first cognitive radio node and the received local decision information sent by at least one cooperative cognitive radio node, and according to the selected The fusion criterion processes the received local decision information of the first cognitive radio node and the local decision information of at least one coordinated cognitive radio node to determine a final decision result, the final decision result including determining whether the licensed spectrum is free spectrum; A decision result sending module: used to send the determined final decision result to the first cognitive radio node and at least one coordinated cognitive radio node, so that they can determine whether to Communications are performed on the licensed frequency spectrum. 7. A device for idle spectrum detection, characterized in that it is applied to a cognitive radio node, and the device comprises: Location information acquisition module: used to obtain its own location information; Local judgment module: used to perform energy detection on authorized spectrum signals after wavelet denoising to obtain local judgment information; An information sending module: used to send the location information and the local decision information to the network side; so that the network side sends the determined final decision result to the cognitive radio node and at least a cooperating cognitive radio node; Final judgment information receiving module: used to receive the final judgment result sent by the network side; The second determination module is configured to determine whether to perform communication on the authorized frequency spectrum according to the final decision result of the determination. 8. The device according to claim 7, wherein the local judgment module is specifically used for: The cognitive radio node performs energy detection according to the authorized spectrum signal it receives, wherein the authorized spectrum signal includes: a signal polluted by noise, and the energy detection includes: the signal polluted by noise undergoes wavelet denoising to obtain an estimated signal , and then judge whether the estimated signal is 0, If the judgment result is that the estimated signal is 0, the cognitive radio node determines that there is no primary user on the licensed spectrum, and determines that the licensed spectrum is an idle spectrum, If the judgment result is that the estimated signal is not 0, the estimated signal is subjected to analog-to-digital conversion, a squarer, and sampling summation to obtain a detection statistic, and the cognitive radio node determines its local decision information according to the detection statistic; The wavelet denoising includes: mapping the noise-contaminated signal to the wavelet domain, generating a wavelet signal with wavelet coefficients, setting a mask operator so that the wavelet signal only retains the coefficient items of the preset wavelet coefficients, and other The wavelet coefficients are set to 0. 9. The device according to claim 8, wherein when the local decision module determines its local decision information according to the detection statistics: Comparing the detection statistic with a preset threshold, if the detection statistic is greater than the preset threshold, the cognitive radio node determines that there is a primary user on the authorized spectrum, and determines that the authorized spectrum is a non-idle spectrum, and if the detection statistic is less than or equal to the preset threshold, the cognitive radio node determines that there is no primary user on the perceived licensed spectrum, and determines that the licensed spectrum is an idle spectrum. 10. The device according to claim 7, wherein the information sending module is further configured to: send its own location information and local judgment results to the network side in real time during the communication process on the authorized spectrum; The device further includes a stop-use module, the stop-use module is specifically configured to: stop using the licensed spectrum for communication when the received final judgment result sent by the network side indicates that the licensed spectrum is occupied by the primary user.