KR101079928B1 - Cognitive Radio Communication Apparatus and Method for Cluster based Cooperative Sensing - Google Patents

Abstract

The present invention relates to a wireless cognitive communication apparatus and method for cooperative sensing based on the cluster, the same channel is sensed according to the change in the geographical position of the primary system (PS) and the channel occupancy situation of the primary system (PS) By adaptively controlling the number of secondary nodes (SN) to be clustered, to provide a wireless cognitive communication apparatus and method that the secondary node (SN) can perform the sensing operation more efficiently.

To this end, the present invention provides a wireless cognitive communication apparatus, comprising: an information receiving unit for receiving channel occupation information from an external secondary node; A spectrum sensing performing unit for spectrum sensing of the allocated channel using clustering information to obtain channel occupancy information; Clustering information on the clustered secondary node by performing clustering on the non-clustered channel and determining whether the channel is available using the channel occupancy information from the secondary node and the spectrum sensing performing unit; A clustering performing unit for obtaining available channel information; And an information transmitter for transmitting clustering information and available channel information from the clustering performer to the secondary node.

Wireless Cognitive Communications, Cluster Based, Cooperative Sensing, Clustering, Designated Channels, Sensing, Channel Occupancy Information

Description

Cognitive Radio Communication Apparatus and Method for Cluster based Cooperative Sensing}

The present invention relates to a wireless cognitive (CR) communication technology, and more particularly, to a wireless cognitive communication apparatus and method for performing cooperative sensing on a cluster basis.

Currently, the majority of radio frequency resources are statically allocated for broadcasting and communication systems, and thus, efficient spectrum utilization methods are required to meet the exponentially increasing demand for wireless communication services. According to a report by the Federal Communications Commission (FCC), only 15% to 85% of the resources in the licensed frequency bands are utilized, depending on location and time. Therefore, in time, a frequency band that is not used spatially (hereinafter, referred to as "white space") is generated, thereby effectively eliminating white space that is not used and wasted. Cognitive Radio (CR) technology is an issue as a method to utilize.

The wireless recognition technology is a spectrum sensing of the white space that is not used by the PU (Primary User) who has a license in the frequency band through intelligentization of terminal equipment and network, and uses the frequency by adapting to the wireless channel environment. It means technology that maximizes efficiency. As a representative example, the IEEE 802.22 Working Group (WG) uses the WRAN (Wireless Regional Area Network) standard, which is a fixed wireless communication network that can use channels without interfering with existing TV band users by utilizing channels that are not used temporally or spatially among TV bands. Is standardizing.

In order to successfully use the radio recognition technology, there is a need for a reliable spectrum sensing technique of whether a primary user (PU) who is licensed for a corresponding frequency is using or not using a frequency. Accordingly, wireless recognition (CR) technology uses white spectrum through spectrum sensing technology to ensure that the PU does not interfere in communication, and the frequency of secondary users (SU) The purpose is to improve the overall spectrum utilization efficiency by increasing the utilization rate. In particular, since PUs generally use licensed wide frequency bands, efficient spectrum use requires a spectrum sensing scheme capable of balancing the entire frequency bands used by PUs.

As described above, in order to use the frequency opportunity without interfering with the PUs distributed in the wide frequency band, a reliable spectrum sensing scheme for the PUs in the wide frequency band is required. In the related art, a method for determining the frequency of PUs in a wide band as a whole has been proposed by detecting a PU signal for one narrow band at a time by using an adjustable narrowband bandpass filter. .

However, since the conventional method can only obtain information on one narrow band at a time, after detecting the information on the entire band, the detection information on the previous narrow band may lose reliability. Even with an RF front-end capable of receiving a signal, a high speed analog-to-digital converter is required to obtain a sample of a wideband signal.

In addition, there is a problem that the result of spectral sensing for PUs may lose reliability due to the occurrence of shadowing or the like in detecting whether a single SU uses frequency for each narrowband.

Accordingly, as SUs share spectral sensing information, a cooperative sensing technique that uses spatial diversity theory to improve performance of spectral sensing has attracted attention.

However, in order to establish cooperative sensing for a plurality of narrow bands, it is necessary to have a suitable SU for each band to sense the narrow band, thereby maintaining the reliability of the use of frequencies within the entire band.

Therefore, in order to use the frequency in an opportunity without interfering with the PUs distributed in the wide frequency band, a reliable and efficient spectrum sensing scheme for the PUs in the wide frequency band is required.

As noted above, such prior art may detect that previous narrowband detection information may be unreliable, may require a fast analog-to-digital converter, or whether a single SU may use frequency. There is a problem in that the result of spectral sensing for PUs may lose reliability because of detection.

Accordingly, there is a need for a reliable and efficient spectrum sensing scheme for PUs in a wide frequency band.

Therefore, it is a problem of the present invention to solve the problems of the prior art as described above and to meet the needs.

Accordingly, the present invention can adaptively control and cluster the number of secondary nodes (SNs) sensing the same channel according to a change in the geographical position of the primary system (PS) and the channel occupancy situation of the primary system (PS). It is an object of the present invention to provide a wireless cognitive communication apparatus and method for enabling a secondary node SN to perform a sensing operation more efficiently.

That is, the present invention improves the reliability of sensing through cooperative sensing by allocating an appropriate secondary user (SU) for a narrow band, and geographical location of PUs to detect primary users (PUs) distributed in a wide frequency band. The present invention provides a wireless cognitive communication apparatus and method capable of increasing the reliability of the use of the frequency in the entire band by allowing the SUs to sense efficiently in consideration of a change in channel occupancy.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention, which are not mentioned above, can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

An apparatus of the present invention for achieving the above object is a radio-cognitive communication device, comprising: an information receiving unit for receiving channel occupation information from an external secondary node; A spectrum sensing performing unit for spectrum sensing of the allocated channel using clustering information to obtain channel occupancy information; Clustering information on the clustered secondary node by performing clustering on the non-clustered channel and determining whether the channel is available using the channel occupancy information from the secondary node and the spectrum sensing performing unit; A clustering performing unit for obtaining available channel information; And an information transmitter for transmitting clustering information and available channel information from the clustering performer to the secondary node.

In addition, the apparatus of the present invention, the clustering performer further performs the function of identifying "information to be sensed to the secondary node for the non-clustered channel after performing the clustering", the information transmitter is the clustering And performing a function of transmitting, to the secondary node, "information to be sensed to the secondary node for non-clustered channels after performing clustering" from the performing unit.

On the other hand, another apparatus of the present invention for achieving the above object, the wireless cognitive communication device, comprising: an information receiving unit for receiving the clustering information and available channel information for each secondary node from an external radio recognition base station; A spectrum sensing performer configured to spectrally sense an allocated channel using the clustering information and available channel information from the information receiver to obtain channel occupancy information; And an information transmitter for transmitting the channel occupancy information from the spectrum sensing performer to the radio recognition base station.

In addition, the other apparatus of the present invention, the information receiving unit further receives from the radio aware base station "information to specify to the spectrum sensing performing unit for the non-clustered channel after performing the clustering".

On the other hand, the method of the present invention for achieving the above object, in a wireless cognitive communication method, the method comprising: obtaining channel occupancy information by spectrum sensing the assigned channel using the clustering information; Receiving channel occupation information from the secondary node; The clustering information and the available channel for the clustered secondary node are performed by performing clustering of the secondary node with respect to the non-clustered channel and using the obtained channel occupation information and the received channel occupation information. Performing clustering to obtain information; An information transmitting step of transmitting the obtained clustering information and available channel information to the secondary node; And performing communication over an available channel.

In addition, the method of the present invention further performs a process of identifying "information for sensing to the secondary node for the non-clustered channels after performing the clustering" in the clustering step, and in the information transmission step The method further includes transmitting the identified "information to be sensed to the secondary node for the non-clustered channels after performing the clustering" to the secondary node.

On the other hand, another method of the present invention for achieving the above object, in a wireless cognitive communication method, receiving clustering information and available channel information for each secondary node from a wireless cognitive base station; Spectrum sensing of an allocated channel using the received clustering information and available channel information to obtain channel occupancy information; Transmitting the obtained channel occupation information to the radio aware base station; And performing communication over an available channel.

On the other hand, in the present invention for achieving the above object, the superframe for communication between the radio recognition base station and the secondary node includes a total of N frames (N is a natural number of two or more) from frame 0 to frame N-1, The frame 0 may include: an initial sensing subframe field in which the radio base station and the secondary node perform sensing on a channel designated by the radio base station; A first reporting subframe field for transmitting, by the secondary node, channel occupancy information to the radio aware base station; After the radio-aware base station performs the clustering of the secondary node for each channel using the channel occupancy information and the channel occupancy information from the secondary node, and determines availability, the clustered secondary node is assigned to the clustered secondary node. A first clustering and available channel information subframe field for transmitting clustering information and available channel information for the secondary node; And a first data subframe field for performing data communication in the radio aware base station and the secondary node.

Also, in the present invention, a function of transmitting, to the secondary node, "information to sense to the secondary node for non-clustered channels after performing clustering" in the first clustering and available channel information subframe field. Do more.

Further, in the present invention, each frame from the frame 1 to the frame N-1, if the radio recognition base station and the secondary node is set as a member node of the clustering senses the assigned channel, and the member node A cluster information-based sensing subframe field configured to perform sensing on a channel designated by the radio aware base station among channels not clustered if not set; A second reporting subframe field in which the secondary node transmits channel occupation information to the radio aware base station; After the radio-aware base station performs clustering of the secondary node with respect to the non-clustered channel using its channel occupancy information and the channel occupancy information from the secondary node, and determines whether it is available, the clustered secondary A second clustering and available channel information subframe field for transmitting clustering information and available channel information for the node to the secondary node; And a second data subframe field for performing data communication in the radio aware base station and the secondary node.

Further, in the present invention, a function of transmitting, to the secondary node, "information to be sensed to the secondary node for non-clustered channels after performing clustering" in the second clustering and available channel information subframe field. Do more.

As described above, the present invention adaptively measures the number of secondary nodes (SNs) for spectral sensing of the same channel according to the geographical position of the primary system (PS) and the channel occupancy situation of the primary system (PS). By controlling and clustering, the secondary node SN can perform the spectrum sensing operation more efficiently.

That is, the present invention improves the reliability of sensing through cooperative sensing by allocating an appropriate secondary user (SU) for a narrow band, and geographical location of PUs to detect primary users (PUs) distributed in a wide frequency band. And by allowing the SUs to efficiently sense the spectrum in consideration of the change in channel occupancy, it is possible to increase the reliability of the use of the frequency in the entire band.

In addition, the present invention can provide more efficient communication by providing a data frame structure for cooperative sensing.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the specification, when a part is "connected" to another part, this includes not only a "directly connected" but also a "electrically connected" between other elements in between. In addition, when a part is said to "include" or "include" a certain component, it means that it may further include or have other components, without excluding other components, unless specifically stated otherwise. .

1 is a diagram illustrating a primary system (PS) and a secondary system (SS) of a radio-cognitive communication system to which the present invention is applied.

Referring to FIG. 1, in the present invention, a primary system (PS) having a use right for a specific frequency band includes a primary base station (PBS) and a primary node (PN). The secondary system (SS) which does not have a right to use the specific frequency band includes a Cognitive Base Station (CBS) and at least one secondary node (SN). It is made to include.

At this time, the radio aware base station (CBS) and the secondary node (SN) knows the frequency band and channel units within the band to be used opportunistically, and some or all of the frequency resources used in the plurality of primary systems (PS) The spectrum may be sensed using a spectrum sensing technique, and may communicate with each other using frequency resources that are not temporarily used in the primary system (PS).

The radio aware base station (CBS) may transmit a signal to the secondary node (SN) at down-link time using available frequency resources, and the secondary node (SN) may use the available frequency resources A signal may be transmitted to a radio aware base station (CBS) in an uplink time.

At this time, even if the secondary node SN and the radio aware base station CBS are using available frequency resources, the signal may act as an interference to the primary node or the primary base station PBS. In addition, since the primary node or primary base station (PBS) has priority over the available frequency resources, if the primary node or primary base station (PBS) reuses the available frequency resources, the secondary node ( SN) and the radio aware base station (CBS) must empty the used frequency resources.

2A and 2B are diagrams illustrating a secondary system SS including a plurality of primary systems PS and a plurality of secondary nodes SN of a radio-cognitive communication system to which the present invention is applied.

Referring to Figures 2A and 2B, the secondary system (SS, 207) includes a radio aware base station (CBS, 208) and a plurality of secondary nodes (SN, 209 to 214). Primary system 1 201 includes primary base station 1 204, primary system 2 202 includes primary base station 2 205, and primary system 3 203 is primary base station 3. 206. In addition, although only three primary systems PS are illustrated in FIGS. 2A and 2B for convenience of description, a plurality of primary systems PS may exist in an actual wireless environment.

3 is a diagram showing a channel (channel usage status) being used in a plurality of primary systems (PS).

Referring to FIG. 3, the primary system 1 uses channels 1 (CH1) and channel 4 (CH4), and the primary system 2 uses channels 2 (CH2) and channel 5 (CH5), and the primary system. Channel 3 uses channel 3 (CH3) and channel 6 (CH6). In FIG. 3, for convenience of description, each primary system PS uses two channels, but in an actual wireless environment, each primary system PS may use a plurality of channels that do not overlap each other.

In addition, although not shown in FIG. 3, primary nodes belonging to each primary system PS may have mobility, and may repeat using or not using channels according to time or location. In this case, the channel occupancy situation of the primary system PS may change in real time.

Referring to FIGS. 2A and 2B and FIG. 3, although not shown in the drawings, the secondary nodes SN of the secondary system SS may use the entire channels CH1, CH2, CH3, and the like for the primary systems PS. CH4, CH5, and CH6) may be opportunistically sensed, and the spectrum sensing result for each channel of the secondary nodes (SNs) may vary according to the location and environment where the spectrum is sensed.

로 설정하고, 무선 인지 기지국(CBS) 자신 및 2차 노드(SN)로부터 수신한 스펙트럼 센싱 결과(채널 점유 정보)에 따라 하나의 클러스터에 포함될 2차 노드(SN)들을 제어하여 클러스터링을 수행하며, 클러스터링이 된 2차 노드(SN)들과 클러스터링이 되지 않은 2차 노드(SN)들을 구분하여 2차 노드(SN)들에게 결과를 통보한다.In addition, the radio aware base station (CBS) recognizes the number of channels to be spectrum sensed and the number of secondary nodes (SN) for each channel for cooperative sensing, and the number of initial setting nodes to allocate to one channel (that is, members of the cluster). Number)

Set to, control the secondary nodes (SN) to be included in one cluster according to the spectrum sensing result (channel occupancy information) received from the radio recognition base station (CBS) itself and the secondary node (SN), performing clustering, The clustered secondary nodes SN and the non-clustered secondary nodes SN are distinguished and the secondary nodes SN are notified of the result.

로 설정하며, 동일 채널을 스펙트럼 센싱한 2차 노드(SN)들의 채널 점유 정보를 이용하여 해당 채널의 초기 세팅 문턱값에 기초하여 클러스터링할 2차 노드(SN)들을 결정한다.Looking at the process of performing the clustering by the radio aware base station (CBS) as described above in detail, the radio base station (CBS) is the number of initial setting nodes to be allocated to one clustering

The second node (SN) to be clustered is determined based on the initial setting threshold of the corresponding channel by using channel occupancy information of the secondary nodes (SN) that have spectrum-sensed the same channel.

Here, the clustering method may be divided into a soft decision method and a hard decision method. The soft decision method has a spectrum of each secondary node (SN). The sensing result (channel occupancy information) is received by the radio aware base station (CBS) and finally determined. In the hard decision method, each secondary node (SN) makes an initial decision and the result is the radio aware base station. When transmitting to the (CBS), the radio recognition base station (CBS) makes a final decision using an OR rule, an AND rule, a integrity rule, and the like. As an example of an OR rule, a radio aware base station (CBS) has a number of secondary nodes (SNs) that have passed an initial setting threshold 1/2 times the number of initial setting nodes to be allocated to one clustering (channel). If larger, clustering is performed. If the number of secondary nodes (SNs) that pass the initial setting threshold is less than 1/2 times the number of initial setting nodes to be allocated to one clustering, clustering is not performed for the corresponding channel. . As a result, the radio aware base station (CBS) performs clustering of the secondary nodes (SN) according to the geographic location of the primary systems (PS) and the occupancy of the channel, the spectrum sensing of the secondary nodes (SN) of each cluster By cooperating the results, the accuracy of sensing for one cluster (channel) can be increased.

4 is a block diagram of an embodiment of a radio aware base station (CBS) and a secondary node (SN) device according to the present invention.

Referring to FIG. 4, the CBS 401 according to an embodiment of the present invention may include an information receiver 402, a clustering performer 403, a clustering and available channel information transmitter 404, and spectrum sensing. It includes a performer 405. The secondary node SN 406 according to an embodiment of the present invention includes a clustering and available channel information receiver 407, a spectrum sensing performer 408, and an information transmitter 409.

Here, the information receiving unit 402 of the radio recognition base station (CBS) 401 receives channel occupancy information sensed by at least one secondary node (SN).

In addition, the clustering unit 403 may use the channel occupancy information received from the at least one secondary node SN and the non-clustered channel by using the spectrum sensing information (channel occupancy information) of the radio recognition base station (CBS) itself. After performing clustering and determining availability of the secondary nodes (SNs), the clustering information for the clustered secondary nodes (SNs), available channel information, and " secondary nodes for channels not clustered after performing clustering. Information to designate (SN) spectrum detection. Here, the process of identifying "information for specifying spectrum sensing to secondary nodes SN for non-clustered channels after clustering" is an additional process.

로 설정한다.In this case, the clustering execution unit 403 grasps the number of channels to be spectrum-sensed and the number of secondary nodes (SN) for each channel for cooperative sensing and assigns an initial setting node (ie, cluster Number of members)

.

In addition, the clustering execution unit 403 determines the secondary nodes (SN) to be clustered based on the initial setting threshold of the corresponding channel by using channel occupancy information of the secondary nodes (SN) that have sensed the same channel. .

만큼 임의로 선택하여 할당한다.In addition, the clustering unit 403 includes, in the clustering, the radio aware base station (CBS) or the secondary node (SN) that is not clustered when the radio aware base station (CBS) or the secondary nodes (SN) are not clustered. On unchannelized

Select as many as you want.

In addition, the clustering and available channel information transmitter 404 may perform spectrum sensing to the secondary nodes SN with respect to the clustering information from the clustering performer 403, the available channel information, and channels that are not clustered after the clustering. "Specified information" is transmitted to at least one secondary node (SN, 406). Here, the process of transmitting "information for specifying spectrum sensing to secondary nodes SN for non-clustered channels after performing clustering" is an additional process.

In addition, the spectrum sensing unit 405 performs spectrum sensing on the allocated channel when the CBS is configured as a member node of the clustering, and when not configured as a member node of the clustering, the spectrum sensing unit 405 performs The CBS performs spectrum sensing on a channel determined by itself.

On the other hand, the clustering and available channel information receiving unit 407 of the secondary node (SN) from the radio recognition base station (CBS, 401) information (clustering information), and the available channel for the clustering of each secondary node (SN) Receive information. In this case, it may further receive “information for specifying spectrum sensing to secondary nodes (SNs) for non-clustered channels after performing clustering”.

The spectrum sensing execution unit 408 performs spectrum sensing on the allocated channel using the clustering information and the available channel information from the clustering and available channel information receiver 407.

In addition, the spectrum sensing performing unit 408 performs spectrum sensing on the assigned channel if the secondary node (SN, 406) is set as a member node of clustering, and is not clustered if it is not set as a member node of clustering. Spectrum sensing is performed on the channel determined by the wireless recognition base station (CBS).

In addition, the information transmitter 409 transmits the information related to the channel occupancy situation (channel occupancy information) to the radio recognition base stations CBS 401 as a result of the spectrum sensing performed by the spectrum sensing execution unit 408.

5 is a structural diagram of a frame in a radio aware base station (CBS) and at least one secondary node (SN) of a secondary system (SS) according to an embodiment of the present invention.

Referring to FIG. 5, a data frame format of a radio recognition base station (CBS) and at least one secondary node (SN) belonging to a secondary system (SS) according to an embodiment of the present invention is one superframe. 501 consists of N frames 502 (N is a natural number of two or more). In this case, the frame number N may be modified and used according to a user's situation. Here, frame 0 includes an initial sensing subframe 503, a report subframe 504, a clustering and available channel information subframe 505, and a data subframe 506, and frame 1 To frame N-1 includes a cluster information-based sensing subframe 507, a reporting subframe 508, a clustering and available channel information subframe 509, and a data subframe 510, respectively.

In addition, in the initial sensing subframe 503 of the frame 0, a radio aware base station (CBS) and at least one secondary node (SN) belonging to the secondary system (SS) are wireless among the channels of the primary systems (PS). A spectral base station (CBS) performs spectrum sensing on a channel assigned to itself and secondary nodes (SN), respectively.

In addition, in the reporting subframe 504 of the frame 0, at least one secondary node SN transmits channel occupation information to the radio aware base station CBS.

In addition, in the clustering and available channel information subframe 505 of the frame 0, the radio aware base station (CBS) receives from the secondary node (SN) information (channel occupancy information) that the radio aware base station (CBS) itself has sensed. After performing clustering of secondary nodes (SNs) for each channel using the channel occupancy information and determining availability, clustering information, cluster information available for clustered secondary nodes (SNs), and "clustering" Information is sent to the secondary nodes SN specifying that the secondary nodes SN should be subjected to spectrum sensing for non-clustered channels after execution.

Further, in the data subframe 506 of frame 0, data communication is performed at the radio aware base station (CBS) and at least one secondary node (SN).

In addition, in the cluster information-based sensing subframe 507 from frame 1 to frame N-1, if the wireless acknowledgment base station (CBS) and the secondary node (SN) that receives the clustering information are set as member nodes of the clustering. Spectrum sensing of the allocated channel is performed, and if not set as a member node, spectrum sensing is performed on a channel designated by the radio recognition base station (CBS) among the non-clustered channels.

In addition, in the reporting subframe 508 from frame 1 to frame N-1, at least one secondary node SN transmits channel occupation information to the radio aware base station CBS.

In addition, in the clustering and available channel information subframe 509 from frame 1 to frame N-1, information (channel occupancy information) and second-order information sensed by the radio aware base station (CBS) itself by the radio aware base station (CBS) After performing clustering of the secondary nodes (SNs) with respect to the non-clustered channel using the channel occupancy information received from the node (SN), and determining availability, the clustering information for the clustered secondary nodes (SNs). , Available channel information, and " information that specifies spectrum sensing to secondary nodes SN for non-clustered channels after performing clustering " to the secondary nodes SN.

Further, in the data subframe 510 from frame 1 to frame N-1, data communication is performed at the radio aware base station (CBS) and at least one secondary node (SN).

FIG. 6 is a diagram illustrating an embodiment of a channel occupancy situation over time, and FIG. 7 is a diagram illustrating an embodiment of a clustering result in a radio aware base station (CBS) according to a channel occupancy situation over time. .

로 설정하고, 각각의 채널에 초기 세팅 노드수만큼 무선 인지 기지국(CBS) 및 2차 노드(SN)들을 임의로 선택하여 할당한다. 또한, 무선 인지 기지국(CBS)은 무선 인지 기지국(CBS) 자신 및 2차 노드(SN)로부터 수신한 스펙트럼 센싱 결과(채널 점유 정보)에 따라 문턱값에 기초하여 클러스터링을 수행할 채널과 수행하지 않을 채널을 구분하며, 클러스터링을 수행할 채널에 대하여 클러스터에 포함될 2차 노드(SN)들을 제어하여 클러스터링을 수행하고, 클러스터링이 된 2차 노드(SN)들과 클러스터링이 되지 않은 2차 노드(SN)들을 구분하여 2차 노드(SN)들에게 결과를 통보한다. 상기 시간 T1에서의 스펙트럼 센싱 결과에 따라 채널 1, 채 널 3, 그리고 채널 5가 클러스터링된다.Referring to FIGS. 3, 6, and 7, at time T1, primary system 1 is using channel 1, primary system 2 is using channel 5, and primary system 3 is using channel 3. Channel 4 of the primary system 1, channel 2 of the primary system 2, and channel 6 of the primary system 3 are unused and empty channels. As described above with reference to FIG. 5, during the initial sensing subframe 503 time, the radio aware base station (CBS) and each secondary node (SN) are channels (primary channel 1, channel 2) of the primary systems PS. After performing spectrum sensing on the channel designated by the wireless recognition base station (CBS) among the channel 3, channel 4, channel 5, and channel 6 to its own and secondary nodes (SN), the spectrum sensing result (channel occupancy) Information) to a radio aware base station (CBS). The radio aware base station (CBS) determines the number of channels to be sensed for spectrum and the number of secondary nodes (SNs) for sensing in an initial sensing subframe, and the number of initial setting nodes to allocate to one channel (that is, the number of cluster members). To

The radio access base station (CBS) and the secondary nodes (SN) are arbitrarily selected and assigned to each channel by the number of initial setting nodes. In addition, the radio aware base station (CBS) and the channel to perform clustering based on the threshold value according to the spectrum sensing results (channel occupancy information) received from the radio aware base station (CBS) itself and the secondary node (SN) and do not perform. Clustering is performed by classifying channels and controlling secondary nodes (SN) to be included in the cluster for the channel to be clustered, and clustering secondary nodes (SN) and non-clustered secondary nodes (SN). These results are then notified to the secondary nodes (SNs). Channel 1, channel 3, and channel 5 are clustered according to the spectral sensing result at the time T1.

Referring to FIGS. 6 and 7, at time T2, cluster 1 only spectrum 1 senses, cluster 3 only spectrum 3 senses, cluster 5 only spectrum 5 senses, and nonclustered secondary node. The SNs perform spectrum sensing on a channel designated by a radio aware base station (CBS) among channels 2, 4, and 6. According to the spectrum sensing result at the time T2, the CBS performs clustering of channels 2, 4, and 6.

Referring to FIGS. 6 and 7, at time T3, cluster 1 only spectrum 1 senses, cluster 2 only spectrum 2 senses, cluster 3 only spectrum 3 senses, and cluster 4 only spectrum 4 senses Sensing, Cluster 5 spectrum sensing only channel 5, Cluster 6 spectrum sensing only channel 6.

FIG. 8 is a flowchart illustrating a method of operating within a frame in a radio aware base station (CBS) and at least one secondary node (SN) of a secondary system (SS) according to an embodiment of the present invention.

First, when spectrum sensing is performed in one frame, it is checked whether the current frame corresponds to frame 0 of the corresponding superframe (801).

As a result of the check 801, if the current frame is frame 0, the radio recognition base station (CBS) and at least one secondary node (SN) belonging to the secondary system (SS) is a radio among the channels of the primary system (PS) The cognitive base station (CBS) performs spectral sensing on the channel assigned to itself and the secondary nodes (SN), respectively (802), the secondary node (SN) is a wireless cognitive base station based on the spectrum sensing result (channel occupancy information) And transmits to (CBS) (803).

Then, the radio aware base station (CBS) performs clustering of the secondary nodes (SN) for the corresponding channel by using the channel occupation information received by the spectrum occupancy information and the channel occupation information received from the at least one secondary node (SN). And after determining availability, the clustering information for the clustered secondary nodes (SN), available channel information, and information for designating the secondary nodes (SN) for spectrum sensing for non-clustered channels. Send to node SNs (804).

Thereafter, the radio aware base station (CBS) and the at least one secondary node (SN) perform data communication through available channels (805).

On the other hand, if the check result 801, if the current frame is not any frame 0, but any one of frame 1 to frame N-1, the radio recognition base station (CBS) belonging to the secondary system (SS) and at least one secondary The node SN checks whether it is set as a member node of the cluster (806).

As a result of the check 806, if it is set as a member node of the clustering, the radio recognition base station (CBS) and the at least one secondary node (SN) belonging to the secondary system (SS) are subjected to spectrum sensing of the channel allocated for sensing, The secondary node SN transmits the spectrum sensing result (channel occupancy information) to the radio aware base station CBS (807).

Then, the radio aware base station (CBS) determines whether it is available for the corresponding channel using channel occupancy information received by the spectrum sensing and channel occupancy information received from at least one secondary node (SN), and then available channel information, And 808, sending information to the secondary nodes SN specifying the spectrum sensing for the non-clustered channels.

Thereafter, the radio aware base station (CBS) and at least one secondary node (SN) perform data communication through available channels (809).

On the other hand, if the check result 806 is not set as a member node of the clustering, the radio aware base station (CBS) and at least one secondary node (SN) belonging to the secondary system (SS) is in the non-clustered channel. Spectrum sensing is performed on the channel designated by the radio recognition base station (CBS), and the secondary node (SN) transmits the spectrum sensing result (channel occupancy information) to the radio recognition base station (CBS) (810).

Then, the radio aware base station (CBS) performs clustering of the secondary nodes (SN) for the corresponding channel by using the channel occupation information received by the spectrum occupancy information and the channel occupation information received from the at least one secondary node (SN). And after determining availability, the clustering information for the clustered secondary nodes (SN), available channel information, and information for designating the secondary nodes (SN) for spectrum sensing for non-clustered channels. Transmit to the nodes SN (811).

Thereafter, the radio aware base station (CBS) and at least one secondary node (SN) perform data communication through available channels (812).

Looking at the differences between the present invention and the conventional method as described above, in the conventional method, each secondary node (SN) in the secondary system (SS) to allow the spectrum sensing of any particular narrow band of the band of interest By integrating the results, it was determined whether to use the primary system (PS) frequency in the band of interest. However, this existing approach assigns spectrum sensing to the secondary nodes (SNs) in an environment that cannot have the reliability of sensing for a particular narrowband in the band of interest, thereby ensuring the reliability of sensing for that narrowband as a whole. Will result in the loss of. In order to improve this, in the present invention, the secondary system (SS) takes into account the geographical location and channel occupation of the primary system (PS), and the like. SN) allows multiple selection cycles to properly select specific narrowbands for each spectrum sensing.

9 is a diagram illustrating a distribution diagram of one secondary system including a primary system and a plurality of secondary nodes according to an exemplary embodiment of the present invention.

Referring to FIG. 9, the radio aware base station (CBS) of the secondary system is present at (0,0) and the secondary nodes (SN) exist within a radius of 30 km around (0,0). The number of Ns is fixed to 3 so that the primary base station 1 of the primary system is (150,0) km, the primary base station 2 is (-140,0) km and the primary base station 3 is (0, -130) It is set to exist in km. At this time, the power of the transmission signal is set such that the signal-to-noise ratio (SNR) of the signal received by the radio recognition base station (CBS) from the primary base station 1 is -20 dB, and the primary base station 1 and the primary base station 2 and the primary base station. 3 is set to transmit a signal of the same power, respectively.

At this time, Monte Carlo simulation of detection probability or false alarm probability with respect to the frame number M in one superframe was performed. At this time, the secondary nodes (SNs) participating in the cooperative sensing use an energy detector, and in the CBS, based on hard decision information of all the secondary nodes (SNs). An OR rule was applied to determine whether to use a frequency. In addition, when the CBS performs decision fusion, the total false alarm probability is set to satisfy 0.1 and the number of secondary nodes (SN) is fixed to 30. It was performed by.

FIG. 10 shows the number of frames M of the existing cooperative sensing method and the method proposed by the present invention when N = 3, M <= 20 and P = 30 according to an embodiment of the present invention. FIG. 7 shows the Monte Carlo simulation results of false alarm probability.

In this case, the existing cooperative sensing method (reference) is set so that any ten secondary nodes (SN) cooperatively sense each primary system every frame.

Referring to FIG. 10, it can be seen that false alarm probability satisfies 0.1 in both the existing cooperative sensing scheme and the proposed method proposed in the present invention in every frame.

FIG. 11 shows the number of frames M of the existing cooperative sensing method and the proposed method according to the present invention when N = 3, M <= 20 and P = 30 according to an embodiment of the present invention. The Monte Carlo simulation results of the detection probability according to the drawings.

Referring to FIG. 11, it can be seen that the detection probability of the method proposed by the present invention is gradually increased to reach the highest point when M = 10 and remain constant in a subsequent frame. On the other hand, the existing cooperative sensing reference can be found to keep the detection probability constant in every frame. Therefore, by using the proposed method proposed by the present invention by assigning the second node (SN) that can have the reliability of sensing to sense the narrow band, the existing cooperative sensing scheme (reference) for the corresponding narrow band as a whole It is possible to improve the reliability of sensing.

On the other hand, the method of operation of the radio recognition base station (CBS) and the secondary node (SN) according to the present invention as described above may be implemented in the form of program instructions that can be executed by various computer means to be recorded on a computer readable medium. have. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Various permutations, modifications and variations are possible without departing from the spirit of the invention.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

The present invention can be used for a radio recognition (CR) communication system.

1 is a diagram illustrating a primary system (PS) and a secondary system (SS) of a radio-cognitive communication system to which the present invention is applied;

2A and 2B are diagrams illustrating a secondary system SS including a plurality of primary systems PS and a plurality of secondary nodes SN of a radio-cognitive communication system to which the present invention is applied;

3 is a diagram showing a channel (channel usage status) being used in a plurality of primary systems (PS),

4 is a block diagram of an embodiment of a radio aware base station (CBS) and a secondary node (SN) device according to the present invention;

5 is a structural diagram of a frame in a radio aware base station (CBS) and at least one secondary node (SN) of a secondary system (SS) according to an embodiment of the present invention;

6 is a diagram illustrating an embodiment of a channel occupation situation over time;

7 is a diagram illustrating an embodiment of a clustering result in a radio aware base station (CBS) according to channel occupancy according to time;

8 is a flowchart illustrating a method of operating within a frame in a radio aware base station (CBS) and at least one secondary node (SN) of a secondary system (SS) according to an embodiment of the present invention;

9 is a diagram illustrating a distribution diagram of one secondary system including a primary system and a plurality of secondary nodes according to an embodiment of the present invention;

10 is the number of frames (M) of the existing cooperative sensing method (reference) and the proposed method (proposed) when N = 3, M <= 20 and P = 30 according to an embodiment of the present invention Diagram showing Monte Carlo simulation results of false alarm probability according to

FIG. 11 shows the number of frames M of the existing cooperative sensing method and the proposed method according to the present invention when N = 3, M <= 20 and P = 30 according to an embodiment of the present invention. The Monte Carlo simulation results of the detection probability according to the drawings.

* Explanation of symbols for the main parts of the drawings

401: radio recognition base station (CBS) 402: information receiving unit

403: clustering unit

404: clustering and available channel information transmitter

405 and 408: spectrum sensing performing unit 406: secondary node (SN)

407: Clustering and available channel information receiver

409 information transmitter

Claims (16)

In the radio-cognitive communication device, An information receiver configured to receive channel occupation information from an external secondary node; A spectrum sensing performing unit for spectrum sensing of the allocated channel using clustering information to obtain channel occupation information; Clustering information on the clustered secondary node by performing clustering on the non-clustered channel and determining whether the channel is available using the channel occupancy information from the secondary node and the spectrum sensing performing unit; A clustering performing unit for obtaining available channel information; And An information transmitter for transmitting clustering information and available channel information from the clustering performer to the secondary node. Wireless cognitive communication device comprising a. The method of claim 1, The clustering execution unit, Further performs a function of identifying "information to be sensed to the secondary node for non-clustered channels after performing clustering", The information transmitter, And transmitting, to the secondary node, information indicating to sense to the secondary node about non-clustered channels after performing clustering. The method according to claim 1 or 2, The clustering execution unit, Determine the number of channels to be sensed and the number of secondary nodes to determine the number of initial setting nodes (number of members of the cluster) to be allocated to one channel.

Wireless cognitive communication device set to. The method of claim 3, wherein The clustering execution unit, And determining a secondary node to cluster based on an initial setting threshold of the corresponding channel using channel occupancy information from the secondary node sensing the same channel. The method according to claim 1 or 2, The clustering execution unit, If the radio aware base station or the secondary node is not clustered, the radio aware base station or the secondary node is not clustered.

A radio-cognitive communication device that selects and assigns as many channels as are not included in clustering. The method according to claim 1 or 2, The spectrum sensing performing unit, If the wireless-aware base station is configured as a member node of clustering, spectrum sensing is performed on the assigned channel. If the wireless-aware base station is not set as a member node of clustering, spectrum sensing is performed on a channel determined by the wireless-aware base station among the non-clustered channels. A wireless cognitive communication device performing. In the radio-cognitive communication device, An information receiver configured to receive clustering information and available channel information for each secondary node from an external radio recognition base station; A spectrum sensing performer configured to spectrally sense an allocated channel using the clustering information and available channel information from the information receiver to obtain channel occupancy information; And An information transmitter for transmitting the channel occupancy information from the spectrum sensing performing unit to the radio recognition base station. Wireless cognitive communication device comprising a. The method of claim 7, wherein The information receiver, And receiving "information to sense to the spectrum sensing performing unit for non-clustered channels after clustering" from the radio recognition base station. The method of claim 8, The spectrum sensing performing unit, If the wireless cognitive communication device is configured as a member node of clustering, the allocated channel is sensed. If the wireless cognitive communication device is not configured as a member node of clustering, the wireless cognitive communication senses a channel designated by the wireless cognitive base station among the non-clustered channels. Device. In the radio-cognitive communication method, Spectrum sensing of the allocated channel using clustering information to obtain channel occupancy information; Receiving channel occupation information from the secondary node; The clustering information and the available channel for the clustered secondary node are performed by performing clustering of the secondary node with respect to the non-clustered channel and using the obtained channel occupation information and the received channel occupation information. Performing clustering to obtain information; An information transmitting step of transmitting the obtained clustering information and available channel information to the secondary node; And Performing communication over an available channel Wireless cognitive communication method comprising a. 11. The method of claim 10, The clustering step, Further performing a process of identifying "information to be sensed to the secondary node for non-clustered channels after performing clustering", The information transmission step, And transmitting the identified “information to be sensed to the secondary node for non-clustered channels after performing clustering” to the secondary node. In the radio-cognitive communication method, Receiving clustering information and available channel information for each secondary node from a radio aware base station; Spectrum sensing of an allocated channel using the received clustering information and available channel information to obtain channel occupancy information; Transmitting the obtained channel occupation information to the radio aware base station; And Performing communication over an available channel Wireless cognitive communication method comprising a. The method according to any one of claims 10 to 12, The superframe for communication between the radio recognition base station and the secondary node includes a total of N frames (N is a natural number of 2 or more) from frame 0 to frame N-1, The frame 0, An initial sensing subframe field in which the radio aware base station and the secondary node sense the channel designated by the radio aware base station; A first reporting subframe field for transmitting, by the secondary node, channel occupancy information to the radio aware base station; After the radio-aware base station performs the clustering of the secondary node for each channel using the channel occupancy information and the channel occupancy information from the secondary node, and determines availability, the clustered secondary node is assigned to the clustered secondary node. A first clustering and available channel information subframe field for transmitting clustering information and available channel information for the secondary node; And A first data subframe field for performing data communication at the radio aware base station and the secondary node; Wireless cognitive communication method comprising a. The method of claim 13, In the first clustering and available channel information subframe field, And transmitting the "information to be sensed to the secondary node for non-clustered channels after clustering" to the secondary node. The method of claim 13, Each frame from the frame 1 to the frame N-1, If the radio aware base station and the secondary node are configured as member nodes of the clustering, the allocated channel is sensed. If the radio node is not configured as a member node, sensing is performed on a channel designated by the radio aware base station among the non-clustered channels. Cluster information based sensing subframe field for performing; A second reporting subframe field in which the secondary node transmits channel occupation information to the radio aware base station; After the radio-aware base station performs clustering of the secondary node with respect to the non-clustered channel using its channel occupancy information and the channel occupancy information from the secondary node, and determines whether it is available, the clustered secondary A second clustering and available channel information subframe field for transmitting clustering information and available channel information for the node to the secondary node; And A second data subframe field for performing data communication in the radio aware base station and the secondary node; Wireless cognitive communication method comprising a. The method of claim 15, In the second clustering and available channel information subframe field, And transmitting the "information to be sensed to the secondary node for non-clustered channels after clustering" to the secondary node.

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