KR101298326B1 - Apparatus for Detecting Spectrum using Time Delay - Google Patents

Abstract

Provided is a spectrum detection apparatus using time delay. The apparatus includes an antenna, a first detector for receiving a signal and generating a first detection result, a first time delay for time delaying the received signal, and a second generating result for generating a second detection result from the output of the first time delayer. A second detector, a second time delayer for time delaying the output signal of the first time delayer, a third detector for generating a third detection result from the output of the second time delayer, and the first to third detection results It includes the co-judgment machine that receives the final decision result. In addition to detectors, time delays and co-determinants can be used for reliable spectral detection.

Description

Spectrum detection device using time delay {Apparatus for Detecting Spectrum using Time Delay}

1 is a block diagram of a detector according to an embodiment of the present invention.

FIG. 2 is a block diagram of an i th detector used in the spectrum detection device of FIG. 1.

3 is a graph for explaining an embodiment in which a co-determinant obtains a final determination result using a plurality of detection results.

4 is a block diagram of a spectrum detection apparatus according to an embodiment of the present invention.

5 is a block diagram of a spectrum detection apparatus according to an embodiment of the present invention.

6 is a block diagram showing the structure of a detector used in the spectrum detection apparatus of FIG.

FIG. 7 is a graph for explaining an exemplary embodiment of an algorithm for obtaining a final determination result using a plurality of detection results.

FIG. 8 is a graph for explaining another embodiment of an algorithm for obtaining a final determination result using a plurality of detection results.

9 is a block diagram of a spectrum detection apparatus according to an embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS OF THE MAIN PARTS OF THE DRAWINGS

110: antenna

120-1 to 120-n-1: time delay

130, 530: Joint Judge

200-1 to 200-n, 600-1 to 600-n: detector

The present invention relates to wireless communication, and more particularly, to a spectrum detection apparatus using time delay.

Currently, the trend of mobile communication systems is high speed and broadband, and various communication systems have been developed. As a result, frequency resource saturation due to the occupancy of various communication systems for a band below several GHz and a necessity for wideband wireless communication have arisen, thereby creating a new concept called CR (Cognitive Radio). CR is a technology for limited frequency resources and is achieved through coexistence with existing communication systems. That is, it is based on the recognition of the surrounding wireless environment, the determination of the parameters optimal for the wireless environment by itself, and the transmission and reception of wireless information without interfering with other devices. This concept is borrowed from the IEEE 802.22 Wireless Regional Area Network (WRAN) standard, which is being recently standardized, and utilizes a TV (Television) band in which the occupied bands are divided according to regions and broadcast times are fixed by time. Recognize the changing situation by time and region in the United States and make available unused bands. Spectrum detection, which primarily determines the use of CR communication for a specific frequency band, is a basic technique for this purpose. The purpose of this technology is to detect the user's frequency usage. Although the basic condition for using CR is frequency sharing, it is an important technology because it should not interfere with the existing licensed user or primary user.

As the spectrum detection method, Matched Filter Detection, Cyclostationary Feature Detection, and Energy Detection are typical. The matched filter detection method can optimally detect a signal. Although there is an advantage in that the signal-to-noise ratio (SNR) can be maximized due to the characteristics of the matched filter, it is difficult to detect signals in various environments because information on the transmission signal must be known in advance. For example, a TV signal includes a pilot signal for a narrowband audio image signal, and digital signals such as code division multiple access (CDMA) and orthogonal frequency division multiplexing (OFDM) also have various standards such as pilot and frame. Have. The signal type detection method uses a periodic property of the signal. That is, the presence or absence of a signal is detected by obtaining a correlation value of the received signal. This method shows robust detection performance for interfering signals.

In the energy detection scheme, the performance of spectrum detection deteriorates drastically in the presence of channel influences or interferences such as fading or shadowing. Therefore, if the main user exists but is not detected properly, it interferes with the main user and interferes with the communication. If the main user does not exist but is detected, the available spectrum is made to make use of the inefficient operation. do. Therefore, there is a need for a spectrum detection method capable of increasing reliability.

An object of the present invention is to provide a spectrum detection apparatus using a time delay.

According to one aspect of the present invention, there is provided a spectrum detection apparatus using a time delay. The apparatus includes an antenna, a first detector for receiving a signal and generating a first detection result, a first time delay for time delaying the received signal, and a second generating result for generating a second detection result from the output of the first time delayer. A second detector, a second time delayer for time delaying the output signal of the first time delayer, a third detector for generating a third detection result from the output of the second time delayer, and the first to third detection results It includes the co-judgment machine that receives the final decision result.

According to another aspect of the present invention, there is provided a spectrum detection apparatus using time delay. The apparatus includes an antenna, a plurality of time delays for time delaying a signal, a detector that receives signals from each of the plurality of time delays, and generates a plurality of detection results, and generates a final determination result using the plurality of detection results. It includes a joint judge.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present embodiment is not limited to the embodiments disclosed below, but will be implemented in various forms, and only this embodiment is intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Shapes of the elements in the drawings may be exaggerated parts to emphasize a more clear description, elements denoted by the same reference numerals in the drawings means the same element.

1 is a block diagram of a spectrum detection apparatus 100 according to an embodiment of the present invention.

Referring to FIG. 1, the spectrum detection apparatus 100 includes an antenna 110, time delay units 120-1 to 120-n-1, detectors 200-1 to 200-n, and a co-determinant 130. ). The output of the antenna 110 becomes an input of the first detector 200-1 and the first time delayer 120-1. The output of the first time delayer 120-1 becomes an input of the second detector 200-2 and the second time delayer 120-2, and the output of the second time delayer 120-2 is The third detector 200-3 and the third time delay unit 120-3 are input. The output of the i-th time delayer 120-i-1 is input to the i-th detector 200-i and the i-th time delayer 120-i. Finally, the output of the n-th time delay unit 120-n-1 becomes an input of the n-th detector 200-n. The output of each of the n detectors 200-1 to 200-n is an input of the co-determinator 130.

Each of the time delay units 120-1 to 120-n-1 delays the input signal by a predetermined time T. When the first time delay unit 120-1 passes, it is delayed by T. When the second time delay unit 120-2 passes, the unit delays by 2T, and the n-1 time delay unit 120-n-1 ), It is delayed by (n-1) T. In other words, the time delay cumulatively after each time delay. The delay time T is a value that can be variably set by the designer.

Reference will be made to FIG. 2 to describe the structures of the detectors 200-1 to 200-n.

FIG. 2 is a block diagram of an ith detector used in the spectrum detection device of FIG. 1 (1 ≦ i ≦ n).

Referring to FIG. 2, the i th detector 200-i includes a band pass filter 210, a squarer 220, an integrator 230, and a comparator 240. The band pass filter 210 selects a center frequency of the received signal x (t) and determines a bandwidth. The squarer 220 squares its magnitude to measure the energy value of the signal that has passed through the bandpass filter 210. The integrator 230 determines the observation time T and integrates the received signal in the 0 to T time period. The comparator 240 compares the output of the integrator 230 with a threshold value Ec and detects a signal when the output is greater than the threshold value (hereinafter referred to as ^Hi ₁ ), and when the output is smaller than the threshold value. The signal is not detected (hereinafter referred to as ^Hi ₀ ). The superscript i in H ⁱ ₁ represents the i th detector 200-i, and the subscript 1 represents detection of a signal. I.e., H ⁱ is ₁ indicates that the signal is detected in the i-th detection period (200-i). H ⁱ ₀ Denotes the non-detection of the signal in the i th detector 200-i. The detection or non-detection of the signal of the i th detector 200-1 generated in this way (H ⁱ _{1) or 0} ) is referred to as the i th detection result (1 ≦ i ≦ n). The detection result may be a Boolean. That is, H ⁱ _{1, which} is the detection of a signal, may be _{1, which} is _one of the digital signal values, and H ⁱ _{0, which} is not detected, may be 0, the other of the digital signal values.

The threshold refers to a minimum energy value for determining that a signal is present. The threshold is a value that can vary variably. This is to detect the signal more reliably by adaptively changing the threshold value according to the channel condition. The factors for determining the change of the threshold value may be channel estimation information, an ACK / NACK (Acknowledge / Not Acknowledge) signal, and channel quality information. When the estimated information of the channel is used, the threshold is lowered if the channel is not good according to the estimated channel information, and the threshold is increased if the channel is good. When the ACK / NACK signal is used, the threshold value is increased when the ACK signal is received, and the threshold value is lowered when the NACK signal is received. In the case of using the channel quality information, the threshold value is increased if the channel quality is good, and the threshold value is lowered if the channel quality is bad.

Referring back to FIG. 1, the first detector 200-1 receives the signal x (t) from the antenna 110 and receives a first detection result H ¹ _{1. or 0} ) is generated and sent to the co-determinator 130. The second detector 200-2 receives a signal delayed by a time T more than x (t) through the first time delayer 120-1, and receives a second detection result H ² _{1. or 0} ) is generated and sent to the co-determinator 130. The third detector 200-3 receives a signal delayed by 2T time from x (t) through the first and second time delays 120-1 and 120-2 and generates a third detection result H ³ _{1. or 0} ) is generated and sent to the co-determinator 130. In the same manner, the n th detector 200-n receives a signal delayed by (n-1) T times rather than x (t) through the first to n-1 time delays 120-1 to 120-n-1. Receiving the nth detection result (H ⁿ _{1) or 0} ) is generated and sent to the co-determinator 130. A total of n detection results generated from the n detectors 200-1 to 200-n are input to the co-determinator 130 from the first detection result to the nth detection result. .

The joint determiner 130 generates a final determination result H ^f _{1 or 0} by using the n detection results. The superscript f in H ^f ₁ indicates the final judgment result regarding the existence of the signal issued by the co-judgment machine, and the subscript 1 indicates that the final judgment result is the presence of the signal. H ^f ₀ indicates that the final decision result is no signal. The joint determiner 130 generates the final determination result using various algorithms.

3 is a graph for explaining an embodiment in which the co-determinator 130 obtains a final determination result using a plurality of detection results.

Referring to FIG. 3, the top graph shows the magnitude of the energy value of the signal x (t) according to the time t. The dotted line Ec in the upper graph is a threshold. The bottom graph shows the detection results generated from a total of 11 detectors according to the delay time T. The i-th detector generates a signal detection result (0 or 1) in the period (i-1) T to iT of x (t). That is, the first detector generates a detection result in the 0 to T section, and the second detector generates a detection result in the T to 2T section.

The first detector 200-1 measures the energy value E 1 of the time 0 to T section of x (t) received from the antenna 110 and compares it with the threshold value Ec. Since E1> Ec, the first detection result of the first detector 200-1 becomes H ¹ ₁ . The second detector 200-2 measures the energy value E 2 of the time T to 2T section of x (t) delayed by T time through the first time delayer 120-1, and since E 2> E c, the second detection is performed. The result is H ² ₁ . In the same manner, the third and fourth detectors 200-3 and 200-4 measure the energy values at intervals of 2T to 3T and 3T to 4T, respectively, and E3> Ec and E4> Ec. Output H ³ ₁ and H ⁴ ₁ respectively. The fifth to seventh detectors 200-5 to 200-7 measure energy values E5 to E7 in the periods 4T to 5T, 5T to 6T, and 6T to 7T, and E5 to E7 are smaller than Ec. H ⁵ ₀ , H ⁶ ₀ , and H ⁷ ₀ are output as the fifth to seventh detection results. In the same manner, the eighth and ninth detectors 200-8 and 200-9 in the periods 7T to 8T and 8T to 9T of x (t) may use H ⁸ ₁ and H ⁹ ₁ as the eighth and ninth detection results. The tenth and eleventh detectors 200-10 and 200-11 in the intervals 9T to 10T and 10T to 11T of x (t) output H ¹⁰ ₀ and H ¹¹ ₀ as the tenth and eleventh detection results. Therefore, a total of 11 detection results are calculated from the time 0 to 11T interval, and a total of 6 H ₁ and 5 H ₀ are obtained as the detection result.

The joint determiner 130 has the detection result and uses the various algorithms to determine the final decision result (H ^f _{1). or 0} )

As an example of the algorithm for generating the final determination result, the final determination result is H ^f ₁ when the number of H ₁ is K or more of the plurality of detection results, the final when the number of H ₁ is less than K determination coefficient The result of the determination is H ^f ₀ . That is, when Num (H ₁ ) ≥ K, the final judgment result is H ₁ , and when Num (H ₁ ) <K, the final judgment result is H ₀ . Here, the determination coefficient K is a coefficient which is set in advance in order to obtain a reliable final determination result using the detection result, and Num (H ₁ ) is the total number of H ₁ in n detection results. The value of K may vary depending on the reliability required. For example, assuming K = 6, since Num (H ₁ ) = 6 = K, the final judgment result is H ₁ . Also, if K = 3 for high reliability, Num (H ₁ ) = 3 <K, so the final judgment result is H ₀ .

As another example of the above algorithm, the number of H ₁ obtained from the detection result and the number of H ₀ may be compared to generate a final decision result with a larger number. That is, when H ₁ ≥ H ₀ , the final determination result is H ₁ , and when H ₁ <H ₀ , the final determination result is H ₀ . That is, since H ₁ = 6> H ₀ = 5, the final judgment result is H ₀ .

As another example of the algorithm, there is a method of generating a final determination result with N-P detection results except P among N detection results. Comparing all thresholds when the detectors of the detector is variable to exclude the combined results P having a threshold value that is beyond the standard deviation threshold based on the average threshold value, the P detection results are excluded from other detection results This is to obtain a more reliable final decision result using the remaining detection results except this because it is a detection result of a section having a relatively low reliability.

4 is a block diagram of a spectrum detection apparatus 300 according to an embodiment of the present invention.

Referring to FIG. 4, the spectrum detection apparatus 400 includes an antenna 110, time delayers 120-1 to 120-n-1, a detector 200-i, and a co-determinator 130. . The spectrum detection apparatus 400 of FIG. 4 is different from the spectrum detection apparatus 100 of FIG. 1 in that the remaining components are the same but include only one detector 200-i rather than a plurality of detectors. That is, the outputs of the antenna 110 and the n-1 time delays are input to the detectors 200-i in parallel and independently at intervals of the delay time T, respectively, and the detectors 200-i are the inputs of the detectors 200-i. N detection results are generated using the input signal. The n detection results are input to the co-determination unit 130, and the co-determination unit 130 uses the n detection results to determine a final determination result (H ^f _{1). or 0} ) The algorithm used by the co-determinator 130 to generate a final determination result is as described with reference to FIG. 3.

5 is a block diagram of a spectrum detection apparatus 500 according to an embodiment of the present invention.

Referring to FIG. 5, the spectrum detection apparatus 500 includes an antenna 110, time delay units 120-1 to 120-n-1, detectors 600-1 to 600-n, and a co-determinator 130. ). Compared to the spectrum detection apparatus 100 of FIG. 1, the spectrum detection apparatus 500 of FIG. 5 has the same connection structure between the time delay unit 120-1 and each component, but the structure of the detector and the determination of the co-determinant are as follows. There is a difference in the way. The structure of the detector 600-i used in the spectrum detection apparatus 500 of FIG. 5 is the same as that of FIG. 6 (1 ≦ i ≦ n).

FIG. 6 is a block diagram illustrating a structure of the detector 600-i used in the spectrum detection apparatus 500 of FIG. 5.

Referring to FIG. 6, the detector 600-i includes a bandpass filter 610, a squarer 620, and an integrator 630. The bandpass filter 610 selects the center frequency of the received signal x (t) and determines the bandwidth. The squarer 620 squares the magnitude of the signal to measure an energy value of the signal passing through the bandpass filter 610. The integrator 630 determines the measurement time T and integrates the received signal in a time 0 to T section. The output of the detector 600-i is referred to as an i th detection result, and the i th detection result is an average energy value E i of a time 0 to T section of the signal x (t). The detector 600-i of FIG. 6 has a difference in that the comparator 240 is excluded compared to the detector 200-i of FIG. 2. That is, the detection result of the detector 200-i of FIG. 2 is H ⁱ ₁ , which is an inoperable value. _{or 0} (which may be 0 or 1), while the detection result of the detector 600-i of FIG. 6 becomes Ei, which is an analog value.

Referring back to FIG. 5, the first detector 600-1 receives the signal x (t) from the antenna 110 and generates a first detection result (energy value E1) to the co-determiner 530. send. The second detector 600-2 receives a signal delayed by T time than x (t) through the first time delayer 120-1 and generates a second detection result E2 to determine the co-determinator 530. Send to). The nth detector 600-n receives a signal delayed by (n-1) T times from x (t) through the first to n−1th time delays and generates an nth detection result En to generate the joint. To the determiner 530. A total of n detection results generated from the n detectors 600-1 to 600-n are input to the co-determiner 530 from the first detection result to the nth detection result. . The co-determinator 530 uses the n detected results to input a final decision result (H ^f _{1). or 0} )

7 and 8 will be described to explain how the joint determiner 530 generates the final determination result.

FIG. 7 is a graph for explaining an exemplary embodiment of an algorithm in which the joint determiner 530 obtains a final determination result using a plurality of detection results.

Referring to FIG. 7, the upper graph shows the magnitude of the energy value of the signal x (t) according to the time t. The lower graph shows the energy values En generated from the first to eleventh detectors (1 ≦ n ≦ 11). En represents an average energy value in the interval (n-1) T to nT of x (t), Ec is a threshold value, and Eav1 is an average value of E1 to E11. The nth detector generates a signal detection result En in a time (n-1) T to nT section of x (t). That is, the first detector generates E1 in the 0 to T section, and the second detector generates E2 in the T to 2T section.

The co-determinator 530 calculates an average value of the energy values E1 to E11 as the detection result and compares it with a threshold value Ec to determine that a signal exists when Eav1 ≥ Ec to generate H ^f ₁ as the final determination result. , it is determined that there is no signal when the Eav1 <Ec generates H ^f ₀ to a final decision result. In the bottom graph of Figure 7, so Eav1 ≥ Ec the final determination result is the H ^f _1.

8 is a graph illustrating another embodiment of an algorithm in which the co-determinator 530 obtains a final determination result using a plurality of detection results.

Referring to FIG. 8, the upper graph of FIG. 8 is the same as the upper graph of FIG. 7, and the lower graph of FIG. 8 is the remaining energy values except for the values of E2 and E6 in the lower graph of FIG. E5 and E7 to E11 are the same.

The cavity determiner 530 determines that a signal is present when obtaining the average value Eav2 from the remaining values other than the maximum and minimum values of the energy values by comparing them with a threshold value Ec Eav2 ≥ Ec generate H ^f _1, and If Eav2 <Ec, it determines that there is no signal and generates H ^f ₀ . In the lower graph of FIG. 8, the average value Eav2 of the remaining energy values excluding the maximum value E2 and the minimum value E6 is Eav2> Ec, and thus the co-determiner generates H ^f ₁ .

Another embodiment of an algorithm for obtaining the final decision result is as follows. A method of generating a final determination result with N-P energy values except P among N energy values is given. Comparing all thresholds when the detectors of the detector is variable to exclude the combined results P having a threshold value that is beyond the standard deviation threshold based on the average threshold value, the P detection results are excluded from other detection results This is to obtain a more reliable final decision result using the remaining detection results except this because it is a detection result of a section having a relatively low reliability.

9 is a block diagram of a spectrum detection apparatus 700 according to an embodiment of the present invention.

Referring to FIG. 9, the spectrum detection apparatus 700 includes an antenna 110, time delayers 120-1 to 120-n-1, a detector 600-i, and a co-determinator 530. . The connections between the time delay units 120-1 to 120-n-1 and the components of the spectrum detection apparatus 700 of FIG. 9 are the same as those of the spectrum detection apparatus 400 of FIG. There is a difference in the structure and the determination method of the co-determination 530. That is, the outputs of the antenna 110 and the n-1 time delay units 120-1 to 120-n-1 are independent of each other in parallel with the delay time T, and the inputs of the detectors 600-i are in parallel. The detector 200-1 generates n detection results using the input signal. The n detection results are input to the co-determinator 530, and the co-determinator 530 uses the n detection results to determine a final determination result (H ^f _{1). or 0} ) The algorithm used by the co-determinator 530 to generate a final determination result is as described with reference to FIGS. 7 and 8.

The present invention improves the reliability of spectrum detection by using time delay, which is a base technology for the secondary user using CR technology to reliably use the spectrum of the main user. Furthermore, if only a simple time delay is additionally considered, a reliable spectrum detection can be achieved by adding only a detector without increasing the complexity.

Claims (10)

antenna; A first detector receiving a signal from the antenna to generate a first detection result; A first time delayer receiving the signal from the antenna and time delaying the signal; A second detector for generating a second detection result from the output of the first time delay; A second time delayer for time delaying the output signal of the first time delayer; A third detector for generating a third detection result from the output of the second time delay unit; And And a co-determiner for receiving the first to third detection results and generating a final judgment result. The method of claim 1, And each of the first to third detection results is an analog value representing energy of a signal. The method of claim 1, Each of the first to third detection results is 1 if a signal is detected and 0 if the signal is not detected. The method of claim 2, The co-determinator compares an average value of the first to third detection results with a preset threshold value, and if the average value is greater than the threshold value, determines the final determination result as the presence of a signal, and the average value is the threshold value. And a value of less than the value, determines the final result of the determination as the absence of a signal. The method of claim 3, wherein The co-determiner obtains the number of detections of the signal among the first to third detection results, and if the number of detections is equal to or larger than the determination coefficient K, determines the final determination result as the presence of the signal, and the detection number is the Spectrum detection apparatus for determining the final determination result in the absence of the signal if less than the determination coefficient K. delete delete delete delete delete

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