KR101748764B1 - Method and Apparatus of detecting multichannel signal - Google Patents

Abstract

A method for detecting signals in multiple channels and an apparatus supporting the same are provided. A method for detecting signals in multiple channels according to the present invention includes the steps of obtaining interest band sensing data obtained by summing channel capture data obtained by sensing respective channels constituting multiple channels in a band of interest, And determining that no detection target signal exists in all of the channels constituting the interest band if the detection target signal is not detected as a result of the signal detection.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a multi-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a signal detection method and apparatus in a wireless communication system that operates multiple channels.

The signal detection algorithm is an algorithm which has been studied for a long time with the development of a communication system. In recent years, cognitive radio (CR) technology, which can dramatically improve the frequency utilization efficiency, has been spotlighted, and interest in spectrum sensing technology, which is one of the main technologies of cognitive radio technology, is increasing. The spectrum sensing technology in the cognitive radio system is a technology for judging whether or not the primary user, which is an authorized user in the frequency band, utilizes the frequency. Depending on whether or not the primary user's signal is detected in the spectrum as a result of spectral sensing, it can be determined whether the spectrum is being used by the primary user. Therefore, signal detection technology is getting popular again as a technique that is indispensable in cognitive radio technology that utilizes idle bands not used by the primary user.

An example of the conventional technique is a spectrum sensing technique using a fast Fourier transform (FFT). The spectral sensing technique using the FFT determines that a signal exists when a spectral peak value exists at a specific position (for example, a pilot position of an ATSC signal) after performing FFT on one channel. Meanwhile, when spectral sensing is performed for a plurality of channels using the conventional technique, each algorithm should be applied to each channel, which may be a burden on the system implementation. For example, in the UHF TV band, the entire frequency band of 470 to 698 MHz is divided into channels of 6 MHz, and spectral sensing is performed to determine whether there is a primary user for each channel. At this time, the cognitive radio system must perform spectral sensing for all 38 channels in order to find the empty channel and the candidate channel, and the amount of calculation for the cognitive radio system is burdened on actual implementation of the cognitive radio system.

It is necessary to consider a multi-channel signal detection method and apparatus for efficiently performing a signal detection algorithm for a plurality of channels and minimizing an operation required for signal detection when performing signal detection for a plurality of channels.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of reducing the amount of computation of a signal detection process by efficiently performing a signal detection algorithm for a plurality of channels in performing a signal detection process for a plurality of channels, Device.

In one aspect of the present invention, a method for detecting a signal in a multi-channel includes: obtaining interest-band sensing data including channel capture data obtained by sensing each channel constituting a multi-channel within a band of interest; And determining that no detection target signal exists in each of the channels constituting the interest band if the detection target signal is not detected as a result of the signal detection.

In this case, when the detection target signal is detected as the signal detection result, signal detection is sequentially performed until a detection target signal is detected for each channel constituting the interest band. When the detection target signal is detected, It can be determined that the signal detection for the channel of the detection target signal is stopped and that the detection target signal does not exist in the channel other than the channel for which the detection target signal is detected.

The band of interest may be a UHF TV band of 470 to 698 MHz.

Each of the channels may have a frequency bandwidth of 6 MHz.

A target channel to perform signal detection among the respective channels constituting the interest band is detected and signal detection is sequentially performed on the selected target channel, When the detection target signal is detected, the detected data of the detection target signal is subtracted from the interest band sensing data, and a new channel to perform signal detection is selected until the result of the subtraction becomes smaller than a predetermined threshold value Signal detection is performed, and the detection result signal data detected can be subtracted from the interest band sensing data.

According to another aspect of the present invention, there is provided a wireless communication system including a transceiver for sensing a channel of a band of interest and a processor operatively connected to the transceiver and performing signal detection, A channel estimation unit for acquiring interest band sensing data obtained by summing channel capture data obtained by sensing each channel and performing signal detection based on the interest bandwidth sensing data, and if the signal detection result detection target signal is not detected, Wherein the determination unit determines that the detection target signal does not exist in each of the channels constituting the terminal.

It is possible to terminate the signal detection process in an adaptive manner in an adaptive manner, and it is possible to shorten the calculation amount and time required for signal detection in multiple channels, thereby facilitating implementation of the system.

FIG. 1 shows a procedure of a general signal detection algorithm.
FIG. 2 shows an example of application of a multi-channel sensing algorithm using a conventional technique.
3 is a flowchart illustrating a multi-channel signal detection method according to an embodiment of the present invention.
4 is a flowchart illustrating a method of detecting signals in multiple channels according to another embodiment of the present invention.
5 is a block diagram illustrating a terminal in which an embodiment of the present invention is implemented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the sensing refers to detecting a signal in a frequency band of interest in order to know the frequency band of another user, that is, whether there is another user operating in the frequency band of interest.

The sensing may be performed by the terminal and the terminal may be referred to by another name such as a user equipment (UE), a mobile station (MS), a mobile terminal (MT), a handheld device, an interface card, A terminal is a wireless device capable of wireless communication using a frequency band of interest according to a method defined in various wireless communication standards. The protocol and channel approach used by the wireless device for wireless communication are outside the scope of the present invention and the technical idea of the present invention is to provide a channel access method of a wireless device and a protocol and frame structure for wireless communication, . For example, the terminal may be any functional medium including medium access control (MAC) and wireless-medium physical layer (PHY) interfaces that satisfy the IEEE 802.11 standard.

Also, the types of signals to be sensed in the band of interest may vary. The signal to be sensed may be a signal transmitted by a wireless device of another wireless communication system operating in the band of interest or a terminal of a wireless communication system of the same type as the sensing terminal. The technical scope of the present invention is not limited by the wireless device from which the signal to be detected by the sensing terminal is transmitted. The detection target signal may be an ATSC (Advanced Television Systems Committee) signal for DTV or a signal transmitted by a microphone.

In some cases, a given frequency band may only be used by a wireless device that is authorized to use that band. A user or a wireless device that is authorized to use the frequency band in this frequency band may be variously called an incumbent user, a primary user, a licensed device, and the like. Hereinafter, these are collectively referred to as an incumbent user.

In order to efficiently use a limited frequency resource, even if it is a specific frequency band for specific incumbent users, if the specific frequency band is not used by the incumbent users, It is preferable to make it usable. In order for the unauthorized user to use the corresponding band, it is necessary to prioritize whether or not the incumbent user is using the corresponding frequency band. Also, even if an uncommitted user is using the corresponding frequency band because a signal of the incumbent user is not detected in the corresponding frequency band, the incumbent user may desire to use the frequency band being used by the unauthorized user, It is necessary to sense whether a signal of the incumbent user is detected in the band.

If a signal of the incumbent user is detected in the corresponding frequency band in the preceding sensing process before using the corresponding frequency band, another frequency band should be sensed. Also, even if the signal of the incumbent user is not detected in the corresponding frequency band and the use of the corresponding frequency band is started, if the signal of the incumbent user is detected as the sensing result, the use of the corresponding frequency band should be stopped.

As described above, in order to use a channel of a specific frequency band or to detect whether a main user of the channel is in use during the use, sensing of a band of interest must be continuously performed, so that the efficiency of the sensing technique to be used is more urgently required . Therefore, the present invention can be applied more effectively in a cognitive radio communication system.

A method for sensing a channel of a frequency band of interest may be variously performed. A specific method of detecting a signal for a specific channel is not particularly limited, and the present invention relates to a method of detecting a specific user's signal in a channel within the band of interest in a whole band of interest with a multi-channel sensing method.

The present invention can be applied to a system in which a plurality of channels exist in a band of interest and a sensing is required to determine whether a specific signal exists in a plurality of channels. For example, a wireless communication system, which requires sensing of a band of interest, as a method for avoiding inter-system interference in a frequency band that can be shared between a wireless LAN system, a wireless LAN system operating in a TV WHITE SPACE, And can be applied to a wireless communication system in which priority is given to users using a specific frequency band.

FIG. 1 shows a procedure of a general signal detection algorithm.

In order to determine whether a signal exists in a channel of interest, the terminal must first capture data of the channel (S110). A signal detection operation is performed to determine whether a signal exists using the data captured in the corresponding channel (S120). The signal presence / absence result is derived as a result of the signal detection calculation process for signal detection (S 130)

FIG. 2 shows an example of application of a multi-channel sensing algorithm using a conventional technique. Where N is the number of channels for which the overall signal detection should be performed. The first channel to perform signal detection is selected (S210).

Thereafter, a signal is detected in a selected channel (S220), a new channel is selected (S240) until a signal detection is performed for all channels (S230), and a signal is detected for a newly selected channel.

As shown in the example of FIG. 2, in the conventional multi-channel sensing method, when the sensing target channel is composed of N channels, signal detection is performed on all channels. In other words, the signal detection for the channel is made by the number of channels existing in the band of interest to be sensed.

This conventional scheme increases the number of operations to be performed for signal detection in proportion to the increase in the number of channels existing in the band of interest, which results in increasing the time required for signal detection and / or complexity of implementation Respectively. The present invention proposes a method for solving the above-mentioned problems.

3 is a flowchart illustrating a multi-channel signal detection method according to an embodiment of the present invention.

Referring to FIG. 3, a terminal that is to perform sensing for each channel of a band of interest performs sensing on all channels in a band of interest, adds channel data captured for each channel, and acquires interest band sensing data (S310 ). At this time, the interest band sensing data may be captured and captured for each channel existing in the interested band, and the entire band within the interested band may be captured regardless of the channel existing in the interested band. The interest band sensing data obtained through step S310 includes information on signals existing in all channels of the interest band. It is possible to acquire the band sensing data of interest and select a channel for performing signal detection for the first time. In the flowchart, K = 1 is an example of selecting a channel to perform signal detection first when signal detection is performed for an individual channel thereafter. The selection of the channel may be sequentially selected in ascending or descending order according to the channel number in the band of interest, or may be selected arbitrarily. The selection of the channel may be performed after the signal detection (S320) procedure to be performed subsequently.

A signal detection algorithm is applied to the interest band sensing data obtained in S310 to determine whether a signal is included. That is, it is determined whether a signal (e.g., a signal of an incumbent user, a preamble of a DTV signal, etc.) is included in data including information on signals existing in all channels of the band of interest (S320). The signal detection algorithm applied at this time may be a transmitter detection method or a cooperative detection method.

The transmitter detection method is an uncooperative detection method, and the terminal detects a signal independently of the detection target signal through local observation. These include a matched filter detection scheme, an energy detection scheme, and a cyclostationary detection scheme. In the implementation of the present invention, various methods can be applied to the signal detection method of an individual channel, and the technical idea of the present invention is not limited by the signal detection method of an individual channel.

If it is determined that the detection target signal is not included in the signal detection result of S320, the channel sensing procedure of the band of interest ends. If there is no signal detection result signal for the interest band sensing data, it means that no detection target signal exists in all channels of the interest band. Therefore, since the channel of interest is not used by other users, the channel of interest can be used as needed.

Otherwise, if it is determined that the detection target signal is included in the signal detection result of S320, it is determined which of the channels in the interest band includes the detection target signal, in other words, which channel is used by another user A signal detection procedure for each channel is required.

The terminal performs a signal detection procedure in the selected channel (S330). As described above, various methods can be used for the signal detection method in the specific channel, and the present invention is not limited by the signal detection method of the specific channel. At this time, the channel on which signal detection is performed may be selected in step S310 as described above, or may be selected in step S320 when it is determined that signal detection for an individual channel is required.

When the signal detection result signal for the selected channel is detected, the channel sensing process for the channel of interest is terminated without detecting the signal for the remaining channel because the channel in which the signal exists is known. If the signal is not detected in the opposite case, the process proceeds to step S340.

If the signal is not detected in step S340, it means that a signal exists in another channel, so the signal detection for the remaining channel should be performed. In step S350, a new channel to perform signal detection is selected among the channels for which signal detection has not yet been performed, and the number K of channels for which signal detection has been performed is updated. The selection of a new channel can also be determined in the same way as channel selection in S310.

Thereafter, it may be determined whether signal detection has been performed for all N channels prior to selection of another channel (S360). If the number of channels for which the updated signal detection is performed is equal to the number (N) of all channels in the interested band, the sensing procedure is terminated. Conversely, if the number N of channels performing signal detection is not equal to the number N of all channels in the band of interest (if it is small) It is necessary to select another channel and perform signal detection.

And then performs sensing on another channel of the newly selected interest band. The selection of the new sensing target channel and the sensing process for the selected target channel may be repeated until a signal of the primary user is detected in the selected target channel. When a signal of the primary user is detected in the corresponding channel as a result of sensing, the sensing process for the channel of interest is terminated without sensing the remaining channels.

There is no particular limitation on the method of selecting the channel to be sensed in the sensing for the individual channel. Starting from a channel located at the edge of the band of interest and sequentially selecting the adjacent channel, or selecting any channel within the band of interest within a range not overlapping.

The signal detection method in multiple channels according to the present invention described with reference to FIG. 3 summarizes a whole channel in a band of interest, and determines whether or not a signal detection target signal exists in the band of interest from all channels in the band of interest. If a signal exists in interest bandwidth sensing data obtained by capturing an entire channel and adding signal data of all channels, a signal detection algorithm for each channel is performed because it is necessary to know which channel a signal exists.

K = 1 is started and a signal detection algorithm is performed on the channel capture data of each individual channel to determine whether a signal exists. If it is determined that there is a signal processing result signal for the Kth channel, it is determined that a signal exists in the Kth channel, and the entire signal detection process is terminated. This signal detection method has an advantage that the number of operations for signal detection can be reduced. The channel detection is not performed on all the channels of the interest band, and when a signal is detected on the channel, the signal detection on the remaining channels is not performed, so that the signal detection algorithm is performed up to the (N-1) th channel. If no signal is present in the (N-1) -th channel as a result of signal detection to the (N-1) -th channel, it is determined that the signal exists in the N-th channel and the entire signal detection process can be terminated.

On the other hand, in signal detection including the above process, N is a natural number having a value of 2 or more. In addition, the channel detection order may be changed according to the system implementation for N channels to be subjected to the entire signal detection.

In the example of FIG. 3, only one environment exists for N channels in the multi-channel signal detection process. However, in the multi-channel signal detection method according to the present invention, It is applicable.

4 is a flowchart illustrating a method of detecting signals in multiple channels according to another embodiment of the present invention.

The example of FIG. 4 shows a method applicable when there are signals in a plurality of N channels among the N channels in the band of interest.

A terminal that desires to detect a signal in a channel within the band of interest obtains interest band sensing data obtained by sensing all channels (N channels) in the band of interest (S410). In this case, as in the example of FIG. 3, the channel to be performed first can be selected when signal detection for the individual channel is required.

The signal detection is performed on the band sensing data of interest (S420). If the result signal of S420 is not detected, it means that there is no detection target signal in all the channels in the interested band, so the signal detection procedure in multiple channels is terminated.

If it is determined that there is a signal in at least one channel in the band of interest as a result of S420, signal detection is performed on the individual channel thereafter (S430).

Based on the signal detection result, it is determined whether there is a signal in the corresponding channel (S440). If there is a signal, the captured image R of the signal is compared with the interest bandwidth sensing data S obtained as the sensing result of all the channels (S450).

If S = R, that is, if the value obtained by adding the captured data of all the channels of the interest band coincides with the captured data of the signal existing in the corresponding channel, The signal detection process for multiple channels is terminated because it means that there is no detection target signal.

If S and R do not match, this means that there is an additional signal on a channel other than that channel. In this case, the remaining part excluding the signal part detected in the corresponding channel in the first interest bandwidth sensing data is updated with the new interest bandwidth sensing data to be compared in the signal detection process in step S460.

If a signal is not detected in S440 or a signal is detected but it is determined in S450 that an additional signal exists in a channel other than the channel, a channel to perform signal detection is further selected and signal detection is performed The value of one channel is updated (S470).

If the number of channels for which the updated signal detection has been performed is compared with the total number N of all channels in the interested band and the signal is smaller than N, signal detection is performed for a new channel at step S430. Then, the procedure of S440 to S470 may be repeated.

4, the number K of channels subjected to signal detection is set to 1, and all of the captured data from 1 to N are added to the channel data captured for each channel for signal detection . The signal detection algorithm is applied to the added channel data, and the result is denoted by S.

If there is no signal for the signal detection result S for the captured data obtained by adding all of the channel data from 1 to N, then there is no signal for all the channels from 1 to N, And ends the entire signal detection process.

If there is a signal for a channel added with the entire channel capture data, it is necessary to know which channel a signal exists, so that a signal detection algorithm for each channel is performed.

K = 1 starts and the signal detection algorithm is performed on the channel capture data of each individual channel to judge whether or not there is a signal, and it is referred to as R. If it is determined that there is a signal processing result signal for the Kth channel, it is determined that a signal exists in the Kth channel, and the result S of the total channel sum and the signal detection result R of the Kth channel are compared do. At this time, if S and R are the same, it is determined that all signal components exist in the Kth channel, and the entire signal detection process is terminated. If S and R do not match, the signal component R in the Kth channel among the signal components S in the entire band is removed from S and the signal detection process is continued while increasing K.

In this way, the entire signal component S can be found individually, and at the moment when all the signal components are searched, S and R become equal to each other, so the entire signal detection process is ended. If there is no signal in the (N-1) -th channel, it is determined that the remaining signal component S exists in the N-th channel, and the entire signal detection process is terminated.

The signal detection method in the multiple channels proposed by the present invention has an advantage that the amount of calculation required for signal detection can be reduced by terminating the entire signal detection process when a signal is detected early.

S = R does not necessarily match the signal detection determination criterion in S460, and various criteria such as (S-R) < threshold value can be utilized in consideration of influence of noise or the like.

In the signal detection method for multiple channels proposed by the present invention, in performing signal detection for a plurality of channels, channel capture data for a plurality of channels are added together and processed at one time, and the signal detection process is terminated early when no signal is detected. There is a main purpose. In addition, if signal detection is performed for each individual channel in the middle of the signal detection process to find all the signal components existing in the entire channel, the signal detection process is terminated early, So that various values may be utilized depending on the system implementation, and the present invention is not limited to the above examples.

5 is a block diagram illustrating a terminal in which an embodiment of the present invention is implemented.

The terminal 500 includes a processor 510, a memory 520, and a transceiver 530. The transceiver 530 transmits / receives wireless signals and senses signals on the channels. The processor 510 is functionally coupled to the transceiver 530 to perform signal detection on the data of the channel sensed through the transceiver. Various types of signal detection methods can be used for signal detection. The terminal may operate as a terminal of a cognitive radio communication supporting the IEEE 802.11 station or the IEEE 802.22 standard according to the wireless communication protocol and the configuration implemented in the processor 510.

Processor 510 and / or transceiver 530 may include an application-specific integrated circuit (ASIC), other chipset, logic circuitry and / or data processing device. The memory 520 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module is stored in the memory 520 and may be executed by the processor 510. The memory 520 may be internal or external to the processor 510 and may be coupled to the processor 510 by various well known means.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (10)

A method for detecting signals in multiple channels,
Capturing the entire band corresponding to the multiple channels in the band of interest to obtain the interest band sensing data,
Perform signal detection based on the interest band sensing data, and
And determining that no detection target signal exists in each of the channels constituting the multiple channels if the detection target signal is not detected as the signal detection result,
Wherein capturing the entire band comprises sensing the entire band regardless of each channel without sensing each channel constituting the multiple channels. The method according to claim 1,
When the detection target signal is detected as the signal detection result,
Performing signal detection sequentially for each channel constituting the multiple channels until a detection target signal is detected,
Wherein when the detection target signal is detected, the signal detection for each channel is stopped, and it is determined that the detection target signal does not exist in a channel other than the channel in which the detection target signal is detected. The method according to claim 1,
Wherein the band of interest is a UHF TV band of 470 to 698 MHz. The method according to claim 1,
Each channel having a frequency bandwidth of 6 MHz. 2. The apparatus according to claim 1, wherein when the detection target signal is detected as the signal detection result,
Selecting a target channel to perform signal detection among the channels constituting the multiple channels,
Sequentially performs signal detection on the selected target channel,
Wherein when the detection target signal is detected in the target channel, the detected data of the detection target signal is subtracted from the interest band sensing data,
Performing a signal detection by selecting a new channel to perform signal detection until the result of the subtraction becomes smaller than a predetermined threshold value and repeating subtracting the detected detection result signal data from the interest band sensing data Lt; / RTI &gt; A transceiver for sensing an entire band corresponding to multiple channels in a band of interest; And
A processor operatively connected to the transceiver and performing signal detection,
The processor captures the entire band corresponding to the multiple channels in the band of interest to obtain the interest band sensing data,
Performing signal detection based on the interest band sensing data,
If no detection target signal is detected as the signal detection result, it is determined that no detection target signal exists in each of the channels constituting the multiple channels,
Wherein capturing the entire band comprises sensing the entire band regardless of each channel without sensing each channel constituting the multiple channels. The method according to claim 6,
When the detection target signal is detected as the signal detection result,
Performing signal detection sequentially for each channel constituting the multiple channels until a detection object signal is detected,
Wherein when the detection target signal is detected, the signal detection for each channel is stopped, and it is determined that no detection target signal exists in a channel other than the channel in which the detection target signal is detected. The method according to claim 6,
Wherein the band of interest is a UHF TV band of 470 to 698 MHz. The method according to claim 6,
Wherein each channel has a frequency bandwidth of 6 MHz. The method according to claim 6,
When the detection target signal is detected as the signal detection result,
Selecting a target channel to perform signal detection among the channels constituting the multiple channels,
Sequentially performs signal detection on the selected target channel,
Wherein when the detection target signal is detected in the target channel, the detected data of the detection target signal is subtracted from the interest band sensing data,
Performing a signal detection by selecting a new channel to perform signal detection until the result of the subtraction becomes smaller than a predetermined threshold value and repeating subtracting the detected detection result signal data from the interest band sensing data Terminal.

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