KR20110018839A - Communication device and method in a cognitive wireless network - Google Patents

Abstract

The present invention relates to a cognitive radio device and a master device. The cognitive radio device of the present invention includes a channel information management unit managing information on a candidate channel to be channel switched in a transmission idle period of a reference channel, and a communication unit communicating a communication channel by switching a communication channel to a candidate channel according to occurrence of a transmission idle period. . Here, the communication unit performs at least one of general data communication and channel information reception through the candidate channel.

Description

COMMUNICATING APPARATUS AND METHOD IN COGNITIVE RADIO NETWORK}

The present invention relates to a cognitive radio system, and more particularly, to a cognitive radio device, a master device, and a data communication method thereof. "The present invention is derived from research conducted as part of the IT source technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development. [Task No. 2006-S-002-05, Title: Cognitive radio technology development]. "

Various communication technologies coexist in a wireless communication system. As a result, almost all frequency bands are allocated in a wireless communication system. Among the next generation wireless communication systems, a cognitive radio (CR) system that detects and uses an empty frequency band that is not actually used among allocated frequency bands and shares them has been proposed.

In a cognitive radio system, a Quiet Period (QP) exists on a channel so that CR devices do not interfere with an existing user (IU) device. The transmission idle section is a section for periodically checking whether the current channel is used by existing user equipments. This transmission pause period is necessary to protect the existing user equipment.

In the transmission idle period, the cognitive wireless device stops the data transmission operation to detect whether the existing user equipment uses a channel, and detects whether the existing user equipment uses a channel. Therefore, in the cognitive radio system, the transmission idle period is an essential element, but there is a problem that degrades the data transmission performance. Therefore, candidate channel management is a very important factor in cognitive radio devices.

An object of the present invention is to provide an apparatus and method for managing channel information in a cognitive radio system.

Another object of the present invention is to provide an apparatus and a communication method for improving data transmission performance by managing channel information in a cognitive radio system.

A cognitive radio device of the present invention is a cognitive radio device for performing communication in a cognitive radio network. The cognitive radio device measures a channel estimation signal and transmits measured channel state information to a master device, and when a transmission idle period of a reference channel arrives, the candidate channel. Receives and manages a communication unit for switching and communicating the communication channel, and channel information including the channel state information measured by the communication unit and the candidate channel to be switched in the transmission idle period of the reference channel received from the master device, And a channel information manager for controlling channel switching of the communication unit based on the channel information.

In an embodiment of the present invention, the channel information includes at least one of channel estimation information, channel set management information, network information, and broadcast information.

In an embodiment of the present invention, the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.

In an embodiment of the present disclosure, the communication unit performs channel information reception and general data communication when communicating in the candidate channel.

In an embodiment of the present disclosure, the channel information manager controls the communication unit to switch a channel from the candidate channel to the reference channel at the end of the transmission pause period.

The master device of the present invention is a master device for performing communication in a cognitive radio network, comprising: a channel signal estimator for generating a channel estimation signal for estimating a channel in the cognitive radio network; A communication unit which transmits a signal and performs communication on a reference channel and a candidate channel, and on candidate channels to be channel-switched in a transmission idle period of the reference channel and the reference channel based on channel state information received from cognitive wireless devices. And a channel allocator configured to control the communication unit by allocating at least one candidate channel of the reference channel or the candidate channels based on the channel information.

In an embodiment of the present invention, the channel information includes at least one of channel estimation information, channel set management information, network information, and broadcast information.

In an embodiment of the present invention, the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.

According to an embodiment of the present invention, when allocating the candidate channel, the channel allocator sets and assigns priorities of candidate channel usage to cognitive wireless devices.

In an embodiment of the present invention, the channel information management unit determines the priority in consideration of channel switching time according to channel switching between the reference channel and the candidate channel when selecting the candidate channel.

A communication method of a cognitive radio device may include: switching a communication channel from the reference channel to a candidate channel in the transmission idle period when a time point of a transmission idle interval of the reference channel arrives during communication in a reference channel; Measuring channel estimation signals and reporting the measured channel state information to a master device; and receiving channel information including a candidate channel to be channel-switched in the transmission idle period of the reference channel in the switched candidate channel. .

In an embodiment of the present invention, the channel information includes at least one of channel estimation information, channel set management information, network information, and broadcast information.

In an embodiment of the present invention, the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.

In an embodiment of the present invention, the information for measuring the signal-to-interference noise ratio is used to select a candidate channel for the communication channel switching.

The method may further include switching a channel from the candidate channel to the reference channel at the end of the transmission pause period.

A communication method in a master device of a cognitive radio network according to the present invention comprises the steps of: allocating a reference channel and a candidate channel to a cognitive radio device based on channel information; Switching to the predetermined candidate channel based on the predetermined channel; generating and transmitting a channel estimation signal from the candidate channel; receiving channel state information from the cognitive radio devices and based on the channel state information; Generating and transmitting channel information on candidate channels to be channel switched in a transmission idle period of the channel and the reference channel.

In an embodiment of the present invention, the channel information includes at least one of channel estimation information, channel set management information, network information, and broadcast information.

In an embodiment of the present invention, the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.

In an embodiment of the present invention, information on candidate channels of the channel information is assigned by setting the priority of the candidate channels.

In an embodiment of the present invention, the method may further include performing data communication on the candidate channel.

According to the present invention, as the channel information is provided through the switched candidate channel in the cognitive radio system, the cognitive radio device can efficiently manage the candidate channels. In addition, in a cognitive radio system, a cognitive radio device may improve data transmission performance by performing data communication by switching a channel from a reference channel to a candidate channel in a transmission idle period.

1 illustrates a cognitive radio system according to an embodiment of the present invention;
2 is a view showing a master device shown in FIG.
3 is a diagram illustrating a cognitive radio device shown in FIG. 1;
4 is a diagram illustrating a data transmission operation in a transmission idle section of a cognitive wireless device according to an embodiment of the present invention;
5 is a diagram illustrating channel information transmitted on a candidate channel according to an embodiment of the present invention;
6 illustrates signal to interference noise estimation information transmitted on a candidate channel according to an embodiment of the present invention;
7 is a flowchart illustrating the operation of the master device shown in FIG. 1;
8 is a flowchart illustrating the operation of a cognitive radio device shown in FIG. 1, and
9 illustrates channel information sharing between a plurality of cognitive radio networks according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

The present invention will be described in the communication apparatus and method that can efficiently manage the candidate channels in the cognitive radio system, thereby reducing the degradation of data transmission performance.

1 is a diagram illustrating a cognitive radio system according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a cognitive radio (CR) system includes a master device 110, cognitive radio (CR) devices 120, 130, and 140, and an existing user (IU) device 150. , 160).

The master device 110 manages channel information for channel allocation of the cognitive wireless devices 120, 130, and 140. To this end, the master device 110 may obtain an assignable frequency band, for example, channel information, through communication with the cognitive radio devices 120, 130, and 140. The master device 110 may allocate a channel not used by the existing user devices 150 and 160 to each of the cognitive wireless devices 120, 130, and 140 based on the obtained channel information. The master device 110 may obtain channel information by detecting whether a channel of existing user devices included in another network is used. The master device 110 may share channel information with another master device (not shown).

On the other hand, the master device 110 may be a base station, a cognitive radio device, a server device (not shown). The master device 110 may detect whether the existing user devices 150 and 160 use channels and manage data transmission channels and rear channels.

In addition, the existing user devices 150 and 160 may be a user terminal, a base station, a repeater, a base station controller, or the like.

Cognitive wireless devices 120, 130, 140 are allocated a channel for communication from the master device 110, and communicates through the assigned channel. In this case, the allocated channels are channels not used by the existing user devices 150 and 160.

In the present invention, the master device 110 may allocate a candidate channel (or backup channel) to be used in a Quiet Period (QP) to each of the cognitive wireless devices 120, 130, and 140. . The transmission idle period is a period for periodically checking whether the current channel is used by the existing user devices 150 and 160 in the cognitive wireless devices 120, 130, and 140, respectively. The transmission pause period is used to protect existing user devices 150 and 160. The master device 110 may allocate a plurality of candidate channels to one cognitive wireless device.

As an example, it is assumed that the transmission idle section has occurred in the cognitive wireless device 120.

The cognitive wireless device 120 communicates data through a reference channel allocated from the master device 110. When the transmission idle period occurs in the reference channel, the cognitive wireless device 120 switches the channel to the candidate channel allocated from the master device 110.

The cognitive wireless device 120 may communicate over a candidate channel.

As described above, according to the present invention, when the transmission idle section occurs in the cognitive wireless device 120, the channel for transmitting data is switched to the candidate channel. Therefore, the cognitive radio device 120 may prevent the degradation of data transmission performance according to the transmission idle period of the reference channel by performing communication through the candidate channel in the transmission idle period of the reference channel.

The cognitive wireless device 120 may communicate general data through a candidate channel or receive channel information for managing the corresponding candidate channel. As the channel information is received through the candidate channel, the cognitive wireless device 120 may obtain a list of candidate channels based on the received channel information. In addition, the cognitive wireless device 120 may estimate the channel state through a signal or a message capable of estimating channel information, and transmit the channel state to the master device 110 to manage the candidate channels in the master device 110. . In addition, the cognitive wireless device may transmit channel information to another cognitive wireless device.

FIG. 2 is a diagram illustrating the master device shown in FIG. 1.

Referring to FIG. 2, the master device 110 includes a channel information management unit 111, a channel allocator 112, a channel estimation signal generator 113, and a communication unit 114.

The channel information manager 111 collects channel information through the communication unit 114 and manages channel information of each of the plurality of channels using the collected channel information. In addition, the channel information manager 111 may update the changed channel information.

The channel allocator 112 allocates a reference channel or a candidate channel for data communication to each of the cognitive radio devices 120, 130, and 140 based on the channel information of the channel information manager 111. The channel allocator 112 may allocate one or more candidate channels when allocating a channel to at least one of the cognitive wireless devices 120, 130, and 140.

The channel allocator 112 selects a channel having the least frequency of appearance of the existing user devices 150 and 160 for candidate channel assignment and minimizing interference with the existing user devices 150 and 160 operating in the adjacent channel. You can choose. The channel allocator 112 may determine the priority of the candidate channel use among the cognitive wireless devices 120, 130, and 140 when allocating the candidate channel. The channel allocator 112 may allocate a plurality of channels to each of the cognitive wireless devices 120, 130, and 140.

The channel allocator 112 may allocate the reference channel or the candidate channel to the cognitive radio device when there is an optimal reference channel or candidate channel to be allocated to the cognitive radio device based on the channel information. The channel allocator 112 may transmit channel information on the allocated reference channel or candidate channel to corresponding cognitive wireless devices. In addition, the channel allocator 112 may provide channel information corresponding to the candidate channel to the cognitive wireless device that switched the channel to the candidate channel during the transmission pause period.

Here, the channel information may include, for example, at least one of channel estimation information, channel set management information, network information, and broadcast information.

The channel estimation information is information for estimating channel state. The channel estimation information may include at least one of synchronization acquisition information for synchronization acquisition with a cognitive wireless device, channel estimation information for removing channel influence of SINR estimation information, and SINR estimation information for SINR measurement.

The channel set management information is information for managing a channel set. The channel set information includes at least one of channel set list information including all or part of channel information (channel identifier, etc.), channel management parameter information including parameters for channel use, and channel state feedback information for feeding back channel status. do. The channel state feedback information includes a channel estimation result. An embodiment of the transmission of the channel state feedback information will now be briefly described.

First, the channel state is measured in the t-1 th idle period (QP), and then the measured channel state information is transmitted for management of the t th idle period (QP), which is the next idle period (QP). That is, the channel state feedback information is information for managing a channel up to the next transmission idle period QP by transmitting the channel state measured in the previous transmission idle period QP.

Alternatively, the feedback information may be transmitted in the form of general data even during data communication in the general data communication section, that is, the reference channel, instead of the transmission idle section QP.

The network information is information for providing information for network management and control. Accordingly, the network information includes at least one of network management information for managing a network, network control information for network control, and network sharing data information for providing information shared between adjacent networks.

The broadcast information is information for periodically providing information broadcast from the master device to the recognized wireless devices.

The communication unit 114 receives the state information of each of the channels received from devices around the master device 110 and provides the channel information to the channel information management unit. The communication unit 114 transmits channel information about the reference channel or the candidate channel allocated through the channel allocator 111 to the corresponding cognitive wireless devices. When transmitting channel information on the candidate channel, the communication unit 114 may provide channel information through the corresponding candidate channel to the recognized wireless terminal that has changed the channel to the candidate channel by the transmission pause period.

FIG. 3 is a diagram illustrating a cognitive radio device shown in FIG. 1.

Referring to FIG. 3, the cognitive wireless device 120 includes a channel information manager 121 and a communicator 122.

The channel information manager 121 may manage channel information received through the communication unit 122. The channel information manager 121 manages information about the reference channel or the candidate channel. The channel information manager 121 updates the channel information according to the change of the channel information received from the master device 110.

When the channel information manager 121 receives the channel estimation information from among the channel information, the channel information management unit 121 uses the channel estimation information to determine the channel state (eg, SINR, link margin, and channel response characteristic (eg, a multi-path channel environment (RMS Relay)). ), Etc.) can be measured.

The channel information manager 121 may determine a communication parameter of the corresponding candidate channel, for example, initial transmission power, modulation order, channel code, code rate, etc. based on the measured channel state. In addition, the channel information manager 121 may use the SINR to select an optimal candidate channel to be switched in the transmission idle period and to select a priority among the candidate channels.

The channel information manager 121 may receive, measure, and manage channel information, for example, channel estimation information, channel set management information, network information, and broadcast information from the master device 110. The channel information managed by the channel information manager 121 may be provided to the master device 110 through the communication unit 122 with information received from the master device 110 or measured and managed when necessary. That is, the channel information manager 121 may manage information on candidate channels and reference channels required for channel switching.

The channel information manager 121 may perform sensing on the candidate channel before using the candidate channel. As a result of the sensing, when a candidate channel is used by another cognitive wireless device or an existing user device, the channel information manager 121 does not use the candidate channel. In addition, when a candidate channel is used by an existing user device, the candidate channel is reported to the master device 110 and the updated candidate channel information is received from the master device 110.

The communication unit 122 receives channel information from the master device 110, and provides the received channel information to the channel information manager 121. In addition, the communication unit 122 may perform general (streaming) data communication, that is, data communication, through the reference channel, and the communication unit 122 may receive a candidate channel when a transmission idle period preset for the reference channel arrives. The information manager 121 may switch to one of the preselected candidate channels from the master device 110 to perform data communication.

The communication unit 122 may receive channel information through the candidate channel, and provide the received channel information to the channel information manager 121.

The communication unit 122 may utilize a communication parameter determined according to channel information managed by the candidate channel information management unit 121 in communication of the corresponding candidate channel.

In addition, the communicator 122 may transmit the channel estimation result to the master device 110 or may transmit the channel estimation result to another cognitive wireless device. In more detail, the communication unit 122 of the cognitive wireless device may transmit a channel estimation result to the master device 110. In addition, when communicating with other cognitive wireless devices, the channel estimation result may be transmitted to the cognitive wireless device performing communication.

FIG. 4 is a diagram illustrating a data communication operation of the cognitive radio device illustrated in FIG. 3.

Referring to FIG. 4, the cognitive wireless device 120 communicates on channel A (eg, a reference channel). Channel A includes data communication sections 210 and 230 and a transmission pause section 220.

The cognitive wireless device 120 performs data communication in the first data communication section 210 of the channel A.

Thereafter, when the cognitive radio device 120 reaches the start point of the transmission idle period 220 of the channel A, the cognitive radio device 120 switches the channel to the channel B (eg, the candidate channel). The transmission idle period (QP) is a time point at which both the master device and the cognitive wireless device are known in advance. In addition, in FIG. 4, the channel B to be channel transitioned, that is, channel B, is a channel previously known between the master device 110 and the cognitive wireless device 120. In this way, the target channel to be switched channels is notified in advance by the master device 120))))) station equipment to all other recognized wireless devices. In addition, after the channel switch is made, the cognitive wireless devices and the communication order in which communication with other cognitive wireless devices will be determined are predetermined. For example, the reception order of cognitive radio devices and the transmission order of cognitive radio devices are determined.

In addition, the cognitive wireless device 120 detects whether the channel A is used by the existing user device in the transmission idle period of the channel A (for example, in-band sensing).

The cognitive wireless device 120 may perform data communication or receive channel information through the channel B in the transmission pause section 220 of the channel A. That is, general (streaming) data or channel information may be transmitted and received through channel B (candidate channel).

Data or channel information transmitted on the candidate channel during the transmission pause period 220 between the cognitive radio device 120 and the master device 110 may minimize transmission power through data spreading and repetitive transmission, respectively. Also, during the idle period 220, the cognitive wireless device 120 may minimize the candidate channel occupancy time or may select and use different candidate channels in each of the plurality of idle periods.

When the transmission idle period 220 of the channel A ends, the cognitive wireless device 120 switches the channel from the channel B to the channel A again.

The cognitive wireless device 120 requires a first switching time 240 according to channel switching from channel A to channel B and a second switching time 250 according to channel switching from channel B to channel A. Therefore, the cognitive wireless device used as the master device should select the candidate channel in consideration of the switching times 240 and 250 for selecting the candidate channel in the transmission idle period.

In the present invention described with reference to FIG. 4, the present invention has been described on the assumption that one channel occupied by the cognitive radio device of the cognitive radio system may be used by occupying two or more channels.

Next, the types of signals that can be transmitted in the candidate channel will be described below.

First, information related to channel set management may be transmitted and received. For example, it may be a channel set list, channel management parameters, channel state feedback information, and the like. Secondly, the master device 110 may transmit information regarding network management and control to each cognitive wireless device and receive a response signal from each cognitive wireless device. Third, it is possible to transmit / receive data such as a general data service, for example, a streaming service. Fourth, data information to be shared with the neighboring network may be communicated between the master device or between the cognitive radio device or between the cognitive radio device and the master device of the neighboring network. Fifth, a specific signal, such as a training symbol and / or a preamble signal, may be transmitted so that the channel state, signal-to-interference noise ratio (SINR), etc. of the current candidate channel may be known.

In addition to the salping signal, transmission may be performed in a candidate channel if necessary. As such, the master device 110 transmits information to be periodically broadcast to other cognitive wireless devices when the channel is switched to the candidate channel, thereby increasing resource utilization efficiency.

5 illustrates channel estimation information transmitted on a candidate channel according to an embodiment of the present invention.

Referring to FIG. 5, the channel estimation information 300 may include at least one of a synchronization sequence 310, a channel estimation sequence 320, and an SINR estimation sequence 330. It includes. The channel estimation information 300 corresponds to one of the channel information.

The synchronization sequence 310 is a sequence for obtaining synchronization between signals.

The channel estimation sequence 310 is a sequence for compensating the SINR estimation sequence 330. Information included in the channel estimation sequence 310 minimizes the influence of noise, noise, etc. on the channel to the SINR estimation sequence.

The SINR estimation sequence 330 may be compensated for by the channel estimation sequence. The SINR estimation sequence may include information for determining the SINR. For example, it may include a training signal, a preamble, a pilot signal, and the like.

The channel estimation information 300 may include at least one of a data identifier, a device identifier, and a network identifier (or network address). At least one of the data identifier, the device identifier, and the network identifier may be mapped to respective sequences, for example, the synchronization sequence 310, the channel estimation sequence 320, and the SINR estimation sequence 330. Such identifier information may be used to classify candidate bands commonly used among cognitive radio networks located in adjacent areas.

The sequences included in the channel estimation information 300 are described as an example, and may include some of various sequences including the synchronization sequence 310, the channel estimation sequence 320, and the SINR estimation sequence 330. .

As described above, the channel estimation information 300 described with reference to FIG. 5 may be received from the master device to the cognitive wireless device through the candidate channel.

6 illustrates channel estimation information transmitted on a candidate channel according to another embodiment of the present invention.

In FIG. 6, unlike in FIG. 5, only a signal-to-interference noise ratio (SINR) is transmitted. In this case, synchronization and channel estimation may be possible.

Referring to FIG. 6, the SINR estimation sequence 400 includes a plurality of Orthogonal Frequency Division Multplexing (OFDM) symbols 410 and 420. Accordingly, it is assumed that a cognitive wireless device that receives the SINR estimation sequence 400 supports, for example, an OFDM communication scheme.

The SINR estimation sequence 400 may transmit such that the phase is continued between the OFDM symbols 410 and 420.

The first OFDM symbol 410 includes information obtained from a guard period (CP) and fast Fourier transform (FFT). The second OFDM symbol 420 includes a guard period (CP) and fast Fourier transform (FFT) information.

The OFDM symbols 410 and 420 may include the same information.

The cognitive wireless device receiving the OFDM symbols 410 and 420 may measure the SINR by comparing signals on constellation points after performing a Fast Fourier Transform (FFT) with a reference signal.

In the candidate channel, the SINR estimation sequence described in FIG. 6 may be received from the master device to the cognitive radio device.

Assuming that the power to be used for transmission of information for SINR estimation shown in FIGS. 5 and 6 is predetermined at the master device, the cognitive wireless device can predict the loss on the channel.

A cognitive radio device of the present invention manages candidate channel information, and the cognitive radio devices preferentially consider channel states of candidate channels when selecting a candidate channel to communicate in a transmission idle period. A cognitive wireless device must check the channel status of each of the candidate channels for candidate channel selection. However, in the absence of a transmission signal, the cognitive wireless device cannot receive the noise signal and the interference signal and accurately measure the channel state.

The channel state is measured using, for example, a signal to interference plus noise ratio (hereinafter referred to as SINR). Here, the channel state cannot be accurately measured unless there is a signal, that is, a transmission signal.

To this end, the master device of the present invention provides channel estimation information as shown in FIG. 5 or 6 through the candidate channel so that the SINR can be measured by the cognitive radio device.

According to the present invention, since the cognitive wireless device can measure the state of the candidate channel from the channel estimation signal transmitted from the candidate channel in the transmission pause period, the channel state of the plurality of candidate channels can be managed.

FIG. 7 is a flowchart illustrating an operation of the master device shown in FIG. 1. In FIG. 7, a situation in which an existing device is newly introduced and a channel needs to be changed is excluded.

Referring to FIG. 7, in operation 510, the master device 110 communicates with a reference channel. Such communication may basically be data communication or channel state information between the master device 110 and the cognitive wireless device or the cognitive wireless device. In addition, if necessary, communication from a cognitive wireless device of another network to a master device or communication with a master device of another network may be performed, and between the cognitive wireless device of another network and the cognitive wireless device existing under the network of the master device 110. Communication may be made.

In operation 512, the master device 110 determines a candidate channel for channel switching in the transmission idle period QP of the reference channel, and transmits information related to communication in the channel to be switched. Such communication related information may be a transmission / reception sequence as described above.

In addition, although FIG. 7 illustrates the steps of the reference numeral 510 and the reference numeral 512, the order may be interchanged. That is, step 510 may be performed after step 512. In addition, after performing step 510, step 512 may be performed at a specific time point, and step 510 may be continued. That is, steps 510 and 512 of FIG. 7 are not time-ordered steps, but are for explaining communication in the reference channel.

In operation 514, the master device 110 checks whether a preset channel switching time has arrived. As described above, the channel switching point is to check whether the channel switching point of the reference channel to the candidate channel, that is, the timing of the transmission idle period (QP) of the reference channel, has arrived.

If it is determined in step 514 that the channel switching time is reached, the master device 110 proceeds to step 516 and, if not, continues to step 510 and / or step 512.

On the other hand, if the process proceeds from step 514 to step 516, the master device 110 performs channel switching to a predetermined candidate channel. That is, the master device 110 switches the channel by controlling the communication unit 114 to the candidate channel to be switched stored in the channel information manager 111. Since the channel switching operation to the candidate channel has been described above, it will not be described in detail here.

After channel switching is performed, the master device 110 communicates on the candidate channel, updates the channel state, and broadcasts the updated result to cognitive wireless devices included in the network of the master device 110. Since the type of data that can be transmitted during communication in the candidate channel has been described above, it will not be described in more detail.

In operation 520, the master device 110 checks whether a return time has arrived. This return time is based on the information transmitted to each cognitive radio device in the reference channel communication by defining a time for which the candidate channel is to be used when switching from the reference channel to the candidate channel. In step 520, when the return time arrives, the master device 110 returns to the reference channel again. If the return time does not arrive, the master device 110 continues to communicate in the candidate channel in step 518.

FIG. 8 is a flowchart illustrating an operation of a cognitive radio device shown in FIG. 1. In FIG. 8, a situation in which an existing device newly emerges and a channel to be changed is excluded, and one cognitive radio device is described as an example, but it should be noted that all cognitive radio devices perform the same operation in their own network.

Referring to FIG. 8, in operation 610, the cognitive wireless device 120 performs communication on a reference channel. As described above, the communication performed by the cognitive wireless device 120 will be briefly described in step 610. The cognitive wireless device 120 may communicate with a master device 110 of a network to which it belongs, or may communicate with other cognitive wireless devices of a network to which it belongs, or communicate with a cognitive wireless device of another network. It may be able to communicate with a master device of another network.

In addition, if the wireless device 120 performs the communication on the reference channel, whether or not step 610, the information broadcasted by the master device 110 must be received. Such broadcast information may include information on a candidate channel to be switched at a transmission pause time and a transmission pause time. Details of this have been described above, and thus will not be further examined here.

The cognitive wireless device 120 performs communication on the reference channel, and proceeds to step 612 to check whether a transmission stop time arrives. This transmission stop time is obtained from the information broadcast from the master device 110 is a point in time known in advance. When the transmission of the test result stops in step 612 arrives, the recognition wireless device 120 proceeds to step 614, otherwise continues to step 610.

In step 614, the cognitive wireless device 120 controls the communication unit 122 to change from the reference channel to the candidate channel based on the candidate channel information stored in the channel information manager 121.

When channel switching is made from the reference channel to the candidate channel, the cognitive radio device 120 resumes communication according to a method previously set in the candidate channel in step 616. In addition, the cognitive wireless device 120 measures the channel state in step 616 and provides it to the master device 110. Thereafter, the cognitive wireless device 120 may update the channel information by using the information broadcast by the master device 110. These operations do not necessarily have priority over any particular operation. For example, data communication may be performed, and then channel information may be updated after channel measurement and reporting is performed, or data communication may be performed after channel information update is performed after channel measurement and reporting. That is, in the present invention, there is no particular limitation on the order of communication.

In the channel measurement, when the information described in FIG. 4 or / and 5 is broadcast from the master device 110 to the cognitive radio device 120, the cognitive radio device 120 estimates SINR using the broadcast information. The estimated information is reported back to the master device 110. Through this, the master device 110 may obtain information on candidate channels, and determine transmission priority of candidate channels using information of candidate channels transmitted from cognitive wireless devices.

In this case, the channel estimation method using the SINR may be applied differently according to the manufacturing method of the device. For example, assuming that an OFDM signal is used between the master device 110 and the cognitive radio device 120, the SINR is estimated by comparing the signal after the fast Fourier transform (FFT) of the received signal with a reference signal on the constellation point. It may be.

Thereafter, the cognitive wireless device 120 performs step 616 and checks whether a return time to the reference channel arrives in step 618. If the return time to the reference channel arrives in step 616, the cognitive wireless device 120 returns to the reference channel in step 620. On the other hand, if the return time has not arrived, step 616 is continued.

9 illustrates channel information sharing between a plurality of cognitive radio networks according to an embodiment of the present invention.

Referring to FIG. 9, a cognitive radio system includes two networks, a first network 701 and a second network 702.

The first network 701 includes a first network management device 710, a first cognitive wireless device 711, and a second cognitive wireless device 712. The second network 702 also includes a second network management device 750, a third cognitive wireless device 751, and a fourth cognitive wireless device 752.

It is assumed that the first network 701 uses the A channel, and the second network 702 uses the B channel. In an overlapped area of the first network 701 and the second network 702, the C channel may be used, and the A channel or the B channel may be used.

The first network management device 710 communicates with the first cognitive wireless device 711 and the second cognitive wireless device 712 via the A channel.

The second network management device 750 communicates with the third cognitive wireless device 751 and the fourth cognitive wireless device 752 via the B channel.

Meanwhile, the first network management device 710 may communicate with the fourth cognitive wireless device 752 through the C channel in the transmission idle period of the A channel. At this time, the fourth cognitive radio device 752 receives (or data communication) channel information from the first network management device 710. The fourth aware wireless device 752 may receive channel information (or data) of the second network. Therefore, the fourth cognitive wireless device 752 may transmit channel information (or data) to the second cognitive wireless device 712 through the C channel in the transmission idle period of the A channel.

The second cognitive radio device 712 may communicate through the A channel, which is a reference channel, and receive channel information (or data) from the fourth cognitive radio device 752 through the C channel in a transmission idle period of the A channel. Can be.

Meanwhile, the first network management device 710 and the second network management device 750 may be master devices. Here, the fourth cognitive wireless device 752 that transmits channel information to the second cognitive wireless device 712 may be a master device with respect to the second cognitive wireless device 752.

In FIG. 9, when there is a common candidate channel (C channel) among the candidate channel sets, each of the two network signals is simultaneously transmitted through the candidate channel (C channel) so that the presence of another network can be confirmed by the cognitive wireless device. . In addition, the cognitive wireless device may identify the presence of another network through a candidate channel (C channel) through sensing or the like.

In a plurality of networks, as shown in FIG. 9, when one network allocates a transmission idle period at a predetermined interval, a CR device of another network receives channel information (or data) during a transmission idle period or equipment of another network (network Channel information (or data) from a management device or a cognitive wireless device). Through this, channel information may be exchanged between a plurality of networks.

The cognitive radio system of the present invention may include one network using a plurality of channels, or may include a plurality of networks having different channels.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be defined by the equivalents of the claims of the present invention as well as the following claims.

110: master device 120, 130, 140: cognitive radio devices
150, 160: existing user devices 111: channel information management unit
112: channel allocation unit 113: channel estimation signal generation unit
114: communication unit 121: candidate channel information management unit
122: communication unit

Claims (20)

A cognitive radio device for performing communication in a cognitive radio network,
A communication unit which measures the channel estimation signal and transmits the measured channel state information to the master device, and switches a communication channel to a candidate channel when the transmission idle period of the reference channel arrives;
Receives and manages channel state information including the channel state information measured by the communication unit and the candidate channel to be channel switched in the transmission stop period of the reference channel received from the master device, and based on the channel information channel switching of the communication unit A cognitive wireless device in a cognitive wireless network, comprising a channel information management unit for controlling the control.
The method of claim 1,
And the channel information comprises at least one of channel estimation information, channel set management information, network information, and broadcast information.
The method of claim 2,
And the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel. The method of claim 3, wherein
And the communication unit performs channel information reception and general data communication when communicating in the candidate channel.
The method of claim 1,
And the channel information management unit controls the communication unit to switch a channel from the candidate channel to the reference channel at the end of the transmission pause period.
A master device for performing communication in a cognitive wireless network,
A channel signal estimator for generating a channel estimation signal for estimating a channel in the cognitive radio network;
A communication unit transmitting a signal generated by the channel signal estimating unit and performing communication on a reference channel and a candidate channel;
A channel information manager configured to manage channel information of candidate channels to be channel-switched in the transmission idle period of the reference channel and the reference channel based on channel state information received from cognitive radio devices; And
And a channel allocator configured to control the communication unit by allocating at least one candidate channel among the reference channel or the candidate channels based on the channel information.
The method according to claim 6,
The channel information includes at least one of channel estimation information, channel set management information, network information, and broadcast information.
The method of claim 7, wherein
And the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.
The method of claim 10,
And the channel allocator sets and assigns priorities of candidate channel usage to each of the cognitive radio devices when allocating the candidate channel.
The method according to claim 6,
The channel information management unit determines the priority in consideration of the channel switching time according to the channel switching between the reference channel and the candidate channel when selecting the candidate channel, the master device in the cognitive radio network.
A communication method in a cognitive radio device of a cognitive radio network,
Switching a communication channel from the reference channel to a candidate channel in the transmission idle period when a time point of the transmission idle interval of the reference channel arrives during communication in the reference channel;
Measuring a channel estimation signal in the candidate channel and reporting the measured channel state information to a master device; And
And receiving channel information including a candidate channel to be channel switched in a transmission idle period of the reference channel in the switched candidate channel.
The method of claim 11,
Wherein the channel information includes at least one of channel estimation information, channel set management information, network information, and broadcast information.
The method of claim 12,
And the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.
The method of claim 13,
And the information for measuring the signal-to-interference noise ratio is used for selecting a candidate channel for switching the communication channel.
The method of claim 11,
And switching the channel from the candidate channel to the reference channel at the end of the transmission idle period.

A communication method in a master device of a cognitive wireless network,
Allocating a reference channel and a candidate channel to the cognitive wireless device based on the channel information;
Switching to the candidate channel predetermined based on the channel information when a time point of a transmission idle section arrives in the reference channel;
Generating and transmitting a channel estimation signal in the candidate channel; And
Receiving channel state information from the cognitive wireless devices, and generating and transmitting channel information on candidate channels to be channel-switched in the transmission idle period of the reference channel and the reference channel based on the channel state information. , Communication method in master device of cognitive wireless network.
17. The method of claim 16,
And the channel information comprises at least one of channel estimation information, channel set management information, network information, and broadcast information.
The method of claim 17,
And the channel estimation information includes information for measuring a signal-to-interference noise ratio of the candidate channel.
17. The method of claim 16,
Information about candidate channels of the channel information,
And assigning and assigning priorities to the candidate channels.
17. The method of claim 16,
And performing data communication on the candidate channel.

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