WO2012036362A1 - Device and method for incumbent signal detection and channel allocation - Google Patents

Abstract

Disclosed are a device and a method for incumbent signal detection and channel allocation. An incumbent signal detection device comprises: a sensing unit which performs a plurality of intra-frame sensing functions during intra-frame sensing cycles on frames in which data is transmitted; and a setting unit which increases the sensing intervals of the intra-frame sensing functions if an incumbent signal is not detected through the plurality of intra-frame sensing functions. Disclosed are a channel allocation device and method. The channel allocation device comprises: an operating channel allocation unit which selects one channel from a plurality of backup channels by using state values of the backup channels according to the appearance of an incumbent user, and allocates the selected channel as an operating channel; and a backup channel allocation unit which selects a channel from a local priority set, and allocates the selected channel as a backup channel.

Description

Apparatus and Method for Detection of Incident Signals and Channel Allocation

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cognitive radio technology, and more particularly, to an apparatus and method for detecting an inclusive signal and assigning a channel in a communication system to which cognitive radio technology is applied.

In order to stably support next-generation communication services that are being accelerated, it is necessary to secure wide frequency bandwidth. However, because frequency resources are limited, and new radio access technologies and communication technologies can continue to emerge, managing and sharing limited frequency resources has become a very important issue.

In terms of the existing frequency utilization, the growth of the second generation mobile communication market in the 800 MHz and 1.8 GHz bands, the emergence of the third generation mobile communication services in the 2 GHz band, in addition to the activation of wireless LAN in the 2.4 GHz ISM band and 5 GHz Ahead of the commercialization of WiBro services in the 2.3GHz band, there is a continuing demand for broadband mobile Internet access services. Such rapidly developing wireless communication systems require the allocation of various frequency bands according to the application environment, and the requirements for the expansion of the required frequency bands are continuously increasing with the widening of wireless services. Therefore, a policy issue for allocating new frequency bands is expected ahead of standardization of 4G mobile communication, and efforts are needed to develop new technologies to maximize utilization of existing bands.

In order to solve the frequency shortage problem, it is necessary to maximize the efficiency of using the frequency, and to this end, it is necessary to change the frequency assignment from the national propagation policy to an open frequency allocation that can be used flexibly without permission. Currently, efforts are being made to develop frequency sharing technologies such as cognitive radio (CR) and UWB to solve the problem of frequency shortage and to efficiently use the allocated frequency.

Accordingly, the IEEE 802.22 Working Group is standardizing the Wireless Regional Areal Network (WRAN), which can utilize TV frequency bands without interfering with existing TV broadcasts in the TV band of 54 to 862 MHz.

A wireless communication system according to the IEEE 802.22 standard uses the frequency band while the frequency band of the incumbent user (original user) is not used by the incumbent user. Thus, the priority of the incumbent user should be guaranteed for the frequency band. Accordingly, a wireless communication system according to the IEEE 802.22 standard performs frame sensing for detecting an incumbent user during data transmission.

Such frame sensing requires an appropriate number of times and time required for improved reliability of the detection of the embedded signal and efficient data transmission. However, the IEEE 802.22 standard does not mention a specific technique for such frame sensing.

If an incumbent user appears, a customer premise equipment (CPE), which is a terminal device in a wireless communication system according to the IEEE 802.22 standard, must yield a corresponding frequency band to the incumbent user. That is, the customer premises device is assigned to use a channel that is not used by the incumbent user, and when the incumbent user appears, the channel must be reallocated.

The channel currently used by the customer premises device is called the operating channel, and the channel that the customer premises device can use immediately on behalf of the operating channel is called the backup channel.

The WRAN base station selects one of the plurality of backup channels when assigning a new operating channel to the customer premises device due to the appearance of the incumbent user. The backup channel is in a good state among a plurality of idle channels, but each backup channel is in various states. Therefore, in order to provide a service according to a required quality of service, a backup channel is required to be classified according to channel conditions. In other words, a backup channel having a channel state corresponding to the required quality of service should be selected as the operating channel.

In addition, the backup channel should be set to good channels because it is used in place of the operating channel. The IEEE 802.22 standard defines a local priority list from which backup channels can be selected. However, the IEEE 802.22 standard defines local priority lists as simply channels that are used less in neighboring cells. Therefore, a need exists for a method for assigning channels with better status to backup channels.

The present invention adaptively allocates a sensing period in which frame sensing is performed to detect an embedded signal in a wireless communication system according to the IEEE 802.22 standard.

In addition, the present invention allocates a backup channel having a channel state corresponding to a quality of service required in a wireless communication system according to the IEEE 802.22 standard as an operating channel.

In addition, the present invention assigns a better channel to a backup channel using a regional priority list according to the IEEE 802.22 standard.

According to an aspect of the present invention, an apparatus for detecting an incumbent signal in a communication system using cognitive radio (CR) technology is disclosed.

According to an embodiment of the present invention, an apparatus for detecting an integral signal may include a sensing unit configured to perform a plurality of intra-frame sensing during an intra frame sensing period in a frame in which data is transmitted, and the plurality of intra frame sensing. And a setting unit for increasing the sensing interval of the intra frame sensing when the incumbent signal is not detected.

According to another aspect of the present invention, a method for detecting an incumbent signal in a communication system using cognitive radio technology is disclosed.

According to an embodiment of the present invention, a method of detecting an embedded signal includes starting data transmission through a frame, performing a plurality of intra frame sensing during an intra frame sensing period, and performing the intra frame sensing through the plurality of intra frame sensing. If is not detected, increasing the sensing interval of the intra frame sensing.

According to another aspect of the present invention, an apparatus for allocating a channel in a communication system using cognitive radio (CR) technology is disclosed.

In accordance with an embodiment of the present invention, an apparatus for allocating a channel may include an operating channel allocator configured to select one channel from a plurality of backup channels and assign the operating channel to an operating channel according to the appearance of an incumbent user; And a backup channel allocator for selecting a channel from a local priority set and assigning the channel to the backup channel.

According to another aspect of the present invention, a channel allocation method for allocating an operating channel according to the appearance of an incumbent user in a communication system using a cognitive radio (CR) technology is disclosed.

According to an embodiment of the present invention, a channel allocation method includes calculating a state value of a plurality of allocated backup channels, and a backup channel having a state value that is equal to or greater than a required level state value required by a customer indoor device of the communication system. And a step of selecting a backup channel having a state value equal to or greater than the required level state value and having a minimum difference from the required level state value, and allocating the selected backup channel as an operating channel.

According to another aspect of the present invention, a channel allocation method for allocating a backup channel in a communication system using cognitive radio (CR) technology is disclosed.

The channel allocation method according to an embodiment of the present invention includes the steps of starting spectrum etiquette for updating the channel list and allocating channels. Giving priority to each channel, and selecting a channel according to the priority and assigning it to a backup channel.

1 illustrates a WRAN in accordance with the IEEE 802.22 standard.

2 and 3 illustrate a frame structure showing a frame sensing period in accordance with the IEEE 802.22 standard.

4 illustrates a frame structure illustrating an adaptive sensing period of intra frame sensing.

5 is a block diagram schematically illustrating a configuration of an embedded signal detection apparatus.

6 is a flowchart illustrating a method of detecting an embedded signal.

7 is a graph illustrating the performance of a communication system to which fixed and adaptive sensing intervals are applied.

[Revision 18.05.2011 under Rule 91]
8 illustrates allocating an operating channel in accordance with the IEEE 802.22 standard.

[Revision 18.05.2011 under Rule 91]
9 is a flowchart illustrating a method for allocating an operating channel in a communication system in accordance with the IEEE 802.22 standard.

[Revision 18.05.2011 under Rule 91]
10 is a diagram for explaining a method of calculating a CINR value.

[Revision 18.05.2011 under Rule 91]
11 illustrates a method of assigning an operating channel.

[Revision 18.05.2011 under Rule 91]
12 is a flowchart illustrating a method of allocating a backup channel in a communication system according to the IEEE 802.22 standard.

[Revision 18.05.2011 under Rule 91]
13 illustrates allocation of a backup channel using a regional priority list.

[Revision 18.05.2011 under Rule 91]
14 is a block diagram schematically illustrating a configuration of a channel assignment apparatus.

The present invention may be variously modified and have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail with reference to the accompanying drawings. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, numerals (eg, first, second, etc.) used in the description process of the present specification are merely identification symbols for distinguishing one component from another component.

In addition, in the present specification, when one component is referred to as "connected" or "connected" with another component, the one component may be directly connected or directly connected to the other component, but in particular It is to be understood that, unless there is an opposite substrate, it may be connected or connected via another component in the middle.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the same reference numerals will be used for the same means regardless of the reference numerals in order to facilitate the overall understanding.

1 illustrates a WRAN according to the IEEE 802.22 standard.

WRAN is a system used by incumbent users while not using the VHF / UHF band using cognitive radio technology. Referring to FIG. 1, a WRAN includes at least one WRAN Base Station (BS) and at least one Customer Premise Equipment (CPE).

The WRAN detects and avoids whether existing TV broadcasts, wireless microphones, etc. are using the corresponding frequency through cognitive radio (CR) technology, thereby providing communication services while reducing interference to existing services. Currently, WRAN is standardized to provide wireless data services to single-family homes, multi-family buildings, schools, etc., which are distributed in large rural areas using unused TV broadcasting channels.

That is, the WRAN detects an empty frequency band in the TV broadcasting band and provides a communication service by using the point that the frequency utilization of the TV broadcasting band is drastically lowered. Here, the WRAN regards an existing broadcast signal as an incumbent signal, and cognitive radio technology is used to provide a communication service without interrupting the incumbent signal.

When cognitive radio technology detects a variety of information about the surrounding wireless environment and detects that a spectrum of frequencies already allocated for other uses is idle, it ensures the priority of the incumbent user who is an existing user of the spectrum, It is a technique for temporary use. That is, it is a concept of resource sharing that provides an unlicensed user (WRAN) with a band not used by an incumbent user having a frequency license. If an incumbent user appears in a band that is temporarily in use, the WRAN must give priority to the incumbent user and free the band.

2 and 3 illustrate a frame structure showing a frame sensing period according to the IEEE 802.22 standard.

2, a frame according to the IEEE 802.22 standard is composed of N superframes (Superframes).

As shown in FIG. 2, frame sensing consists of two stages of intra-frame sensing and inter-frame sensing. That is, intra frame sensing is performed a plurality of times for each super frame, and inter frame sensing is performed once in the Nth super frame.

Referring to FIG. 3, intra frame sensing is performed a plurality of times in one frame, and inter frame sensing is performed once in one frame.

That is, intra frame sensing may be performed a plurality of times in one frame, and inter frame sensing may be performed once in one frame or a plurality of frames.

Intra frame sensing mainly uses a detection device such as an energy detector to roughly determine the presence or absence of a signal. In addition, the inter frame sensing is performed for a much longer time than the intra frame sensing, and a detection device such as a characteristic detector or a cyclo stationary detector is used to detect not only the presence of a signal but also the specific characteristics of the signal. Detect.

Intra-frame sensing and inter-frame sensing differ greatly in the time spent for one-time sensing as their detection purposes are different. Inter-frame sensing, which takes a long time for one-time detection, should be performed only when reliability is secured as much as possible, thereby saving time resources spent on sensing, which directly affects the yield improvement for data transmission. For this purpose, proper operation of intra frame sensing is required. If frequent intra frame sensing is performed only for high reliability, the sensing takes a lot of time, and thus yield deterioration is expected. If very rare intra frame sensing is performed, the possibility of detection of the incumbent signal is degraded. Can not affect the yield.

4 is a diagram illustrating a frame structure illustrating an adaptive sensing period of intra frame sensing.

Referring to FIG. 4, intra frame sensing is performed at a preset minimum sensing interval during one intra frame sensing period. At this time, if all of the incumbent signals are not detected through the intra frame sensing performed a plurality of times, the sensing interval of the intra frame sensing performed in the next intra frame sensing period is increased.

For example, when the intra-band signal is not detected through intra frame sensing performed during one intra frame sensing period, the sensing interval of the next intra frame sensing period may be calculated by Equation 1 below.

[Equation 1]

Delta = Delta_initial Ｘ n

Here, Delta is a sensing interval of intra frame sensing, Delta_initial is a minimum sensing interval, and n is the number of intra frame sensing periods in which the incumbent signal is not detected.

Accordingly, the length of the intra frame sensing period is increased.

For example, when the intra-band signal is not detected through intra frame sensing performed during one intra frame sensing period, the length of the next intra frame sensing period may be calculated by Equation 2 below.

[Equation 2]

Length = Length_initial Ｘ n

Here, Length is the length of the intra frame sensing period, Length_initial is the minimum length of the intra frame sensing period, and is the number of intra frame sensing periods in which the incumbent signal is not detected.

The sensing interval or sensing period of the increased intra frame sensing may be maintained at the maximum sensing interval or the maximum sensing period length when the preset maximum sensing interval or maximum sensing period length is reached.

In addition, the sensing interval or the sensing period may be initialized to the minimum sensing interval or the minimum sensing period length when the incident signal is detected. For example, if an incumbent signal is detected once during one intra frame sensing period or a predetermined number of times, the sensing interval may be initialized to a minimum sensing interval. Accordingly, when the incident signal is detected less than a predetermined number of times, the sensing interval of the intra frame sensing may be increased.

5 is a block diagram schematically illustrating a configuration of an embedded signal detection apparatus.

Referring to FIG. 5, the incident signal detecting apparatus 100 may include a communication unit 10, a sensing unit 20, and an adjusting unit 30. The incident signal detecting apparatus 100 may be generally provided in the WRAN base station, but may be provided as a separate device in the WRAN and connected to the WRAN base station.

The communication unit 10 communicates with the customer premises device. For example, the communication unit 100 may transmit / receive data with the customer premises device through the established channel.

The sensing unit 20 performs frame sensing during data transmission. That is, the sensing unit 20 performs intra frame sensing and inter frame sensing.

For example, the sensing unit 20 may perform intra frame sensing a plurality of times in one frame and inter frame sensing in one frame or a plurality of frames once.

The sensing unit 20 performs intra frame sensing at a sensing interval set during the intra frame sensing period.

The setting unit 30 sets a sensing interval of intra frame sensing.

That is, the setting unit 30 initially initializes the sensing interval of the intra frame sensing to the minimum sensing interval, and increases the sensing interval when the incumbent signal is not detected through a plurality of intra frame sensing performed during the intra frame sensing period. Reset it. The increased sensing interval is maintained at the maximum sensing interval when the maximum sensing interval is reached, and initialized to the minimum sensing interval when the incumbent signal is detected. Accordingly, the length of the intra frame sensing period is also changed.

Since the method of calculating the sensing interval or the sensing period of the intra frame sensing has been described above with reference to FIG. 4, a detailed description thereof will be omitted.

6 is a flowchart illustrating a method of detecting an embedded signal.

In operation S610, the incident signal detecting apparatus 100 starts data transmission with the customer premises apparatus.

In operation S620, the incident signal detecting apparatus 100 performs intra frame sensing. Here, the integrated signal detecting apparatus 100 performs intra frame sensing a plurality of times within a frame in which data is transmitted. Intra frame sensing may be performed a plurality of times a set number of times in one frame. In addition, the incident signal detecting apparatus 100 may perform inter frame sensing. Inter frame sensing may be performed once in one frame or a plurality of frames.

In operation S630, the incumbent signal detecting apparatus 100 determines whether the incumbent signal is detected through intra frame sensing performed during one intra frame sensing period.

In operation S640, when the incumbent signal is not detected, the incumbent signal detecting apparatus 100 determines whether the current sensing interval is the maximum sensing interval.

In operation S650, the incident signal detecting apparatus 100 increases the sensing interval when the current sensing interval is not the maximum sensing interval. Intra frame sensing performed later is performed according to an increased sensing interval. Accordingly, the length of the intra frame sensing period is also increased.

As a result of the determination in step S630, when the incumbent signal is detected, in step S670, the incandescent signal detecting apparatus 100 initializes the sensing interval to the minimum sensing interval.

As a result of the determination in step S640, when the current sensing interval is the maximum sensing interval, in step S660, the incident signal detecting apparatus 100 maintains the sensing interval as the maximum sensing interval.

The integrated signal detection apparatus 100 may perform intra frame sensing according to an adaptive sensing period to improve performance of a communication system. Referring to FIG. 7, FIG. 7 is a graph illustrating the performance of a communication system to which fixed and adaptive sensing intervals are applied. As shown in FIG. 7, when intra frame sensing is performed according to the adaptive sensing interval, it can be seen that the channel utilization efficiency is increased compared to the fixed sensing interval.

8 is a diagram illustrating allocating an operating channel according to the IEEE 802.22 standard. 8 shows seven cell environments, and the numbers shown in each cell represent channel numbers. That is, in each cell, the underlined channel number represents the backup channel, and the underlined channel number represents the operating channel. Each cell may include one WRAN base station and a plurality of customer premises equipment (CPEs).

Referring to FIG. 8, in the center cell, channel 1 is allocated as an operating channel and channel 7 is allocated as a backup channel. Thereafter, when the incumbent user appears in the center cell, the incumbent user is assigned channel 1 (indicated by a circle). The center cell receives channel 7 as a backup channel as an operating channel and channel 5 as a new backup channel.

The IEEE 802.22 standard defines spectral etiquette for channel selection while avoiding or minimizing intercell interference. Spectral etiquette defines the method for updating the channel list and assigning channels.

For example, the channel list for the center cell shown in FIG. 8 may be represented as shown in Table 1 below.

Table 1

List of channels in the center cell	Before Incumbent User Appears	After the appearance of the incumbent user
Operating channel	One	7
Backup channel	7	5
Channels occupied by WRAN	3, 4, 5, 6, 8	3, 4, 5, 6, 8
Ambient backup channel	4, 5, 6, 7, 8	4, 5, 6, 7, 8
Regional Priority List1	-	-
Regional Priority List2	-	-
Regional Priority List3	3, 4, 5, 6, 8	3, 4, 5, 6, 8

Here, the channel occupied by the WRAN is a channel being used by the neighbor cell, and the surrounding backup channel is a channel being used as the backup channel by the neighbor cell. The channel list may further include candidate channels. The candidate channel is a channel that can be a backup channel.

The local priority set 1 is a set of channels among the backup channel and the candidate channel that are not used by neighboring cells and are not used as backup channels. The regional priority list 2 is a set of channels, which are not used as backup channels by neighboring cells, among backup channels and candidate channels. Local Priority List 3 is a collection of channels being used by neighboring cells.

Referring to Table 1, after the appearance of the incumbent user, channel 7 is assigned to the operating channel and channel 5 is assigned to the backup channel according to the performance of spectrum etiquette. Here, the backup channel is selected from the regional priority lists 1 to 3. That is, the backup channel is selected by sequentially checking the regional priority lists 1 to 3. That is, referring to Table 1, since the regional priority lists 1 and 2 are empty, the backup channel is randomly selected from the local priority list 3. In the backup channel illustrated in Table 1, channel 5 is randomly selected from the regional priority list 3.

9 is a flowchart illustrating a method for allocating an operating channel in a communication system according to the IEEE 802.22 standard. 9 illustrates a method of allocating a new operating channel when an incident user appears. The channel assignment may be performed by the WRAN base station including the channel assignment apparatus 200 or by the channel assignment apparatus 200 connected to the WRAN base station. In the following description, it is assumed that channel allocation is performed by the channel allocation apparatus 200 for convenience of understanding and explanation.

In operation S910, the channel allocation apparatus 100 calculates a state value of each backup channel. For example, the state value may be a carrier-to-interference-and-noise ratio (CINR) value.

Hereinafter, with reference to FIG. 10, the method of calculating CINR value is demonstrated.

10 is a diagram for explaining a method of calculating a CINR value. Referring to FIG. 10, in a seven cell environment, a number located at the center of each cell refers to an operating channel. In addition, it is assumed that the WRAN base station is located at the center of each cell, and the displayed triangle is assumed to be the location of the customer premises equipment. Here, d value means the distance between the customer premises equipment and the WRWN base station in the center cell, di value means a distance between the customer premises equipment of the surrounding cell and the WRWN base station of the center cell using the same operating channel. 3 illustrates a method of calculating a CINR value of channel 1 when channel 1 is allocated to a center cell.

First, a carrier / noise (C / N) value is calculated by the following equation.

[Equation 3]

Where cnedge values are C / N values at cell boundaries, alpha and sigma values are constant values for calculating path loss and shadowing values, and randn values are PDFs of a normal distribution with a mean of 0 and a standard deviation of 1. (probability density function).

Next, an I / N (Interference / Noise) value, which is an interference generated by the customer premises apparatus existing in the attention cell, is calculated by Equation 4 below.

[Equation 4]

Next, the CINR value is calculated by the following equation (5) using equations (3) and (4).

[Equation 5]

In operation S920, the channel allocating apparatus 200 uses a status value of each backup channel calculated in operation S910 to present a backup channel that satisfies a state value (hereinafter, required level state value) required by the customer indoor device. Determine whether or not. That is, the channel allocation apparatus 100 determines whether a backup channel having a state value equal to or greater than a required level state value exists. Here, the state value of the level required by the customer premises device may be represented by a CINR value, and may be determined according to the quality of service provided by the customer premises device.

In operation S930, the channel assignment apparatus 200 selects a backup channel that is close to the required level when there is a backup channel that satisfies the required level. That is, the channel assignment apparatus 100 selects a backup channel having a state value that is equal to or greater than the required level state value and the difference with the required level state value is minimum.

In operation S940, the channel assignment apparatus 200 allocates the selected backup channel to the operating channel.

As a result of the determination in step S920, when there is no backup channel that satisfies the required level state value, in step S950, the channel assignment apparatus 200 fails to allocate the operating channel.

11 is a diagram illustrating a method of allocating an operating channel. In FIG. 11, two cases of an operating channel allocation method will be described. Case 1 illustrates the operating channel allocation method described above with reference to FIG. 9, which corresponds to a good example, and case 2 illustrates an operating channel allocation method according to the existing IEEE 802.22 standard. In the seven cell environment shown in Fig. 11, the numbers in each cell represent channel numbers and status values of an operating channel or a backup channel. That is, the number located at the top of each cell represents the operating channel or the required level status value (in parentheses), and the underlined number represents the status value (in parentheses) of the backup channel or backup channel. It is assumed that the state value shown in FIG. 11 is a CINR value.

In the following description, it is assumed that an incumbent user appears in two adjacent cells sequentially and a new operating channel needs to be allocated.

Referring to case 1, an incumbent user first appears in the first cell 1, and one backup channel of channels 5, 6, and 7 must be allocated as a new operating channel. Since the required level state value of the first cell 1 is 10, each backup channel satisfies the required level state value. Here, channel 5 near the required level state value 10 is selected as the operating channel.

Next, an incumbent user appears in the second cell 2 so that one backup channel of channels 2, 6, and 7 must be allocated as a new operating channel. Since the required level state value of the second cell 2 is 16, the backup channel satisfying the required level is channel 7. Thus, channel 7 is allocated to the new operating channel of the second cell 2.

Case 1 shows that a backup channel having a state value corresponding to a required level state value is allocated to the first cell 1 as the operating channel, so that the operating channel is stably allocated to the second cell 2.

On the other hand, referring to case 2, an incumbent user first appears in the first cell 1, and one backup channel among channels 5, 6, and 7 is selected, and the best channel is selected. That is, the required level state value is 10, but channel 7 having the highest state value is selected as the operating channel. If an incumbent user appears in the second cell 2 and one of the backup channels of channels 2, 6 and 7 has to be allocated as a new operating channel, channel 7 is the operating channel of the first cell 1. Since one is assigned to, one backup channel from channels 2 and 6 except channel 7 must be selected. Since neither channel 2 nor channel 6 satisfies the required level state value, a new operating channel cannot be allocated to the second cell 20.

Case 2 shows a problem in which the operating channel cannot be allocated to another cell when the best channel is allocated to the operating channel while satisfying the required level state value.

12 is a flowchart illustrating a method of allocating a backup channel in a communication system according to the IEEE 802.22 standard. In FIG. 12, a method of allocating a backup channel according to performing spectrum etiquette will be described.

In operation S1210, the channel allocation apparatus 200 determines whether a channel exists in the local priority lists 1 and 2 when the procedure of spectrum etiquette starts.

In operation S1220, when a channel exists in the local priority lists 1 and 2, the channel allocation apparatus 100 gives priority to each channel of the local priority lists 1 and 2 according to the occurrence probability of the incumbent user. That is, the channel allocation apparatus 200 may assign high priority to each channel of the regional priority lists 1 and 2 in the order of low occurrence probability of the incumbent user. Here, the occurrence probability of the incumbent user may be measured and calculated for each channel in advance.

In operation S1230, the channel allocation apparatus 200 determines whether the number of channels included in the regional priority lists 1 and 2 satisfies the required number of backup channels. Since the number of backup channels in the cell can be set to be large, it is necessary to check whether the backup channel can be set only by the channels included in the local priority lists 1 and 2.

As a result of the determination in step S1210, if no channels exist in the regional priority lists 1 and 2, or if the number of channels included in the regional priority lists 1 and 2 does not satisfy the required number of backup channels, the process proceeds to step S1240. do.

In operation S1240, the channel allocation apparatus 200 gives priority to each channel of the regional priority list 3. Here, the channel assignment apparatus 200 gives high priority to each channel of the local priority list 3 in the order of the smallest interference in accordance with the interference with the neighboring cells.

For example, the channel assignment apparatus 200 may calculate a state value of each channel of the regional priority list 3 and give priority to the state value. Here, the CINR value may be applied to the state value. Since the method for calculating the CINR value has been described above with reference to FIG. 10, the detailed description thereof will be omitted.

When the CINR value is applied as the status value, each channel of the regional priority list 3 may be given a high priority in the order of high CINR value.

For example, prioritization of the regional priority list can be shown in Table 2 below.

TABLE 2

Channel list	Before granting priority	After giving priority
Operating channel	One	One
Backup channel	5, 7	4, 3
Channels occupied by WRAN	2, 5, 6, 7	2, 5, 6, 7
Ambient backup channel	5, 6, 7, 8	5, 6, 7, 8
Regional Priority List1	3 (0.6), 4 (0.3)	4 (0.3), 3 (0.6)
Regional Priority List2	3 (0.6), 4 (0.3), 8 (0.5)	4 (0.3), 8 (0.5), 3 (0.6)
Regional Priority List3	2 (15), 5 (4), 6 (12), 7 (1)	2 (15), 6 (12), 5 (4), 7 (1)

Referring to Table 2, the numbers in parentheses for each channel number in Local Priority Lists 1 and 2 indicate the probability of occurrence of an incumbent user for that channel, and the numbers in parentheses for each channel number in Local Priority List 3 indicate the It means the status value. Here, the state value may be a CINR value.

As shown in Table 2, the channels of the Local Priority Lists 1 and 2 are listed in the order of occurrence of the incumbent user, and the channels of the Local Priority List 3 are listed in the order of the high state value. Thus, when a backup channel is selected in the regional priority list, if the backup channels are selected in order from the front, a channel less affected by interference and incumbent users may be selected as the backup channel.

In operation S1250, the channel allocation apparatus 100 selects a channel according to the priority given to each channel of the regional priority lists 1 to 3 and assigns the channel to the backup channel.

13 is a diagram illustrating allocation of a backup channel using a regional priority list. In FIG. 13, a channel having a low interference is selected as a backup channel using a CINR value.

The central cell is assumed to select a channel from local priority list 3. Here, the regional priority list 3 includes the channels being used in the neighbor cell.

Referring to FIG. 13, the center cell should select one of channels 3, 4, and 5 being used in the neighbor cell. If the interference is calculated in small order by calculating the CINR value of each channel, they may be listed in the order of 5, 3, and 4.

According to the existing IEEE 802.22 standard, since channels 3, 4, and 5 are all used by neighboring cells, a channel arbitrarily selected from these three channels may be allocated as a backup channel. However, if a randomly selected channel 3 or 4 is assigned as a backup channel, the customer premises device (indicated by a triangle) of the cell using channel 3 or 4 is located near the WRAN base station of the center cell. , Channel 3 or 4 is subject to high interference. On the other hand, since the customer premises of the cell using channel 5 exists at a long distance from the WRAN base station of the center cell, channel 5 receives relatively little interference.

Therefore, it is preferable to allocate channel 5 with low interference, and when channel 4 is selected, the performance of the system may be degraded.

14 is a block diagram schematically illustrating a configuration of a channel assignment apparatus.

Referring to FIG. 14, the channel allocation apparatus 200 includes an operating channel allocator 40 and a backup channel allocator 50.

The operating channel allocator 40 calculates a state value of the backup channel, selects the backup channel close to the required level state value, and assigns the backup channel to the operating channel using the calculated state value of the backup channel.

The operating channel allocator 40 includes a calculator 41 and an operating channel selector 43.

The calculator 41 calculates a state value of each backup channel. For example, the state value may be a carrier-to-interference-and-noise ratio (CINR) value. Since the method of calculating the CINR value has been described above with reference to FIG. 10, detailed description thereof will be omitted.

The operating channel selector 43 selects as the operating channel a backup channel having a state value that is equal to or greater than the required level state value and minimizes a difference from the required level state value.

The backup channel allocator 50 assigns priority to each channel of the regional priority list, selects a channel according to the priority, and assigns it to the backup channel.

The backup channel assigning unit 50 includes a priority granting unit 51 and a backup channel selecting unit 53.

The priority granting unit 51 gives priority to the local priority lists 1 and 2 according to the probability of occurrence of the incumbent user of the channel, and gives the priority according to the state value of the channel. Here, the state value may be a CINR value.

For example, the priority granting unit 51 may assign the high priority to the channels of the local priority lists 1 and 2 in the order in which the probability of occurrence of the incumbent user is low. In addition, the priority granter 51 may assign the channels of the regional priority list 3 to the higher priority in order of the higher CINR value of the channels.

The backup channel selector 53 selects a channel according to the priority of each channel given by the priority granter 51 and assigns the channel to the backup channel. That is, the backup channel selector 53 selects a channel having a high priority from the local priority list as the number of preset backup channels and assigns it to the backup channel. In this case, a channel having a high priority may be a channel having a low probability of generating an inconvenient user or receiving a small interference.

On the other hand, the embedded signal detection method and the channel allocation method according to an embodiment of the present invention can be implemented in the form of program instructions that can be executed through various electronic means for processing information can be recorded in the storage medium. The storage medium may include program instructions, data files, data structures, etc. alone or in combination.

The program instructions recorded in the storage medium may be those specially designed and constructed for the present invention, or may be known and available to those skilled in the software art. Examples of storage media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic-optical media such as floppy disks. hardware devices specifically configured to store and execute program instructions such as magneto-optical media and ROM, RAM, flash memory, and the like. In addition, the above-described medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, and the like. Examples of program instructions include not only machine code generated by a compiler, but also devices that process information electronically using an interpreter, for example, high-level language code that can be executed by a computer.

The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

The present invention can adaptively allocate a sensing period in which frame sensing for detecting an embedded signal is performed in a wireless communication system according to the IEEE 802.22 standard.

In addition, according to the present invention, frame sensing is performed according to an adaptively allocated sensing period, thereby improving efficiency of data transmission and reliability of sensing.

In addition, the present invention can allocate a channel to many users while satisfying a desired quality of service by allocating a backup channel having a channel state corresponding to the required quality of service as an operating channel.

In addition, the present invention can assign a better channel to a backup channel using a local priority list according to the IEEE 802.22 standard.

Claims (20)

1. An apparatus for detecting an incumbent signal in a communication system using a cognitive radio (CR) technology,

   A sensing unit configured to perform a plurality of intra-frame sensing during an intra frame sensing period in a frame in which data is transmitted; And

   And a setting unit to increase a sensing interval of the intra frame sensing when the intra signal is not detected through the plurality of intra frame sensing.
2. The method of claim 1,

   And the setting unit increases the sensing interval in proportion to the number of intra frame sensing periods in which the incumbent signal has not been detected.
3. The method of claim 2,

   And the setting unit maintains the sensing interval as the maximum sensing interval when the increased sensing interval is a preset maximum sensing interval.
4. The method of claim 1,

   And the setting unit initializes the sensing interval to a preset minimum sensing interval when the incumbent signal is detected.
5. The method of claim 1,

   And the setting unit increases the length of the intra frame sensing period in proportion to the number of intra frame sensing periods in which the intra signal is not detected.
6. The method of claim 1,

   And the setting unit initializes the intra frame sensing period to a preset minimum sensing period length when the incumbent signal is detected.
7. The method of claim 1,

   And the setting unit initializes the sensing interval when the number of detection of the incident signal is greater than or equal to a preset number of times, and increases the sensing interval when less than the preset number of times.
8. The method of claim 1,

   The setting unit initializes the length of the intra frame sensing period when the number of times of detection of the integral signal is greater than or equal to a preset number, and increases the length of the intra frame sensing period when less than the preset number. Device.
9. In the method for detecting the incident signal in a communication system using a cognitive radio technology,

   Starting data transmission through the frame;

   Performing a plurality of intra frame sensing during an intra frame sensing period; And

   And increasing the sensing interval of the intra frame sensing when the incumbent signal is not detected through the plurality of intra frame sensing.
10. The method of claim 9,

    And initiating the sensing interval to a preset minimum sensing interval when the incumbent signal is detected.
11. The method of claim 9,

    And if the increased sensing interval is a preset maximum sensing interval, maintaining the sensing interval as the maximum sensing interval.
12. In the apparatus for allocating channels in a communication system using a cognitive radio (CR) technology,

    An operating channel allocator configured to select one channel from a plurality of backup channels and assign the operating channel to an operating channel according to the appearance of an incumbent user; And

    And a backup channel allocator for selecting a channel from a local priority set and assigning the channel to the backup channel.
13. The method of claim 12,

    The operating channel assignment unit

    A calculator configured to calculate a state value of the backup channel; And

    An operation of allocating a backup channel to the operating channel having a state value equal to or greater than a required level state value required by a customer premise equipment (CPE) of the communication system and having a minimum difference from the required level state value; Channel allocation apparatus including a channel selector.
14. The method of claim 12,

    And the required level state value corresponds to a quality of a communication service provided to the customer premises device.
15. The method of claim 12,

    The backup channel allocation unit

    A priority assigning unit that gives priority to the channels of the local priority lists 1 and 2 according to the occurrence probability of the incumbent user for each channel of the local priority lists 1 and 2; And

    And a backup channel selector which selects channels in order from the local priority list according to the priority and assigns the channels to the backup channels.
16. The method of claim 15,

    And the priority assigning unit calculates a state value of each channel of the local priority list 3 and gives priority to the channel of the local priority list 3 according to the calculated state value.
17. In a channel allocation method for allocating an operating channel in accordance with the appearance of an incumbent user in a communication system using a cognitive radio (CR) technology,

    Calculating status values of a plurality of assigned backup channels;

    Checking whether there is a backup channel having a state value equal to or greater than a required level state value required by the customer premises apparatus of the communication system;

    Selecting a backup channel having a status value equal to or greater than the required level status value and the difference from the required level status value is minimum; And

    Allocating the selected backup channel as an operating channel.
18. The method of claim 17,

    And the required level state value corresponds to a quality of a communication service provided to the customer premises device.
19. In a channel allocation method for allocating a backup channel in a communication system using a cognitive radio (CR) technology,

    Initiating spectral etiquette for updating the channel list and assigning channels;

    If channels exist in local priority lists 1 and 2, prioritizing each channel according to an probability of occurrence of an incumbent user for each channel; And

    Selecting a channel according to the priority and assigning the channel to a backup channel.
20. The method of claim 19,

    Calculating a state value of each channel of the regional priority list 3 if the channels are not present in the local priority list 1 and 2; And

    And assigning priority to each channel of the regional priority list 3 according to the calculated state value.

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