KR101232375B1 - Method for detecting satellite navigation received signal and apparatus thereof - Google Patents

Abstract

The present invention relates to a received signal detection method and an apparatus for detecting satellite navigation received signal performing the same.

According to the present invention, the correlation value obtained through parallel signal detection is selected by selecting cells whose threshold value is greater than or equal to a predetermined signal detection threshold value, and performing the time domain correlation to verify the correlation value. The cell that is greater than or equal to the predefined verification threshold is detected as the final signal.

In this way, the cells exceeding the threshold value are selected as a subset, and the correlation detection is performed by performing sequential correlation in the time domain for the extended period to improve the signal detection probability.

Parallel detection, threshold, time domain correlation, correlation

Description

Method for detecting received signal and apparatus for detecting satellite navigation using same

The present invention relates to a received signal detection method and an apparatus for detecting satellite navigation received signal performing the same. The present invention relates to an apparatus and a method for detecting a GNSS signal by performing parallel correlation in a global navigation satellite system (hereinafter referred to as 'GNSS') receiver.

The present invention is derived from a study conducted as part of the IT original technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development (Task Management No .: 2007-F-040-02, Task name: Indoor and outdoor continuous positioning technology development).

Global Navigation Satellite System (GNSS) receivers, such as Global Positioning System (GPS), Galileo, GLONASS, and Bayer's Navigation System (COMPASS), provide at least four pseudoranges (GNSS satellites and GNSS receivers). Distance and the position of the GNSS satellite.

The GNSS receiver estimates the arrival time by comparing signals from several GNSS satellites with demodulated signals generated internally in order to measure the distance between the satellite and the receiver. The process of calculating the arrival time from the GNSS satellite signal can be performed in various ways such as the thermal noise and oscillator error of the receiver, the Doppler shift due to the relative movement of the satellite and the receiver, and the interference between the PRN (Pseudo Random Number). It starts by detecting signals of visible satellites in the environment of error sources.

The GNSS signal detection method is a parallel search using a sequential search method that sequentially searches the received signals for each PRN of a GNSS satellite in the time domain and a method such as FFT-IFFT in the frequency domain. It can be classified into a method such as.

Correlators using sequential search are mainly used in hardware-based GNSS receivers. The correlator using parallel search is used as an efficient search method in software-based GNSS receivers because it provides correlation values for all search cells with one operation of time delay and frequency offset.

In the case of high signal attenuation, such as in high-rise buildings, tunnels, or indoors, high-sensitivity GNSS receivers use a coherent, non-coherent method to increase signal to noise ratio (SNR). The signal correlation value is integrated over several periods of the GNSS satellite PRN using a method or a mixing method.

The coherent method can obtain a larger SNR compared to the noncoherent method, but brings a very large increase in the frequency band to be searched.

In addition, the integration method using the coherent method is limited in the correlation period by the modulation of the PRN code by the navigation data or the modulation by the secondary code. In general, modulation symbols should always be matched to avoid integration when the sign is reversed.

If the modulation symbol is unknown, the coherent integration can be extended over multiple modulation symbols by calculating the sum of the correlation values for each combination of symbol values over an extended period and selecting the highest correlation value. . The number of modulation symbol combinations tested can be reduced to half by squared or by taking the absolute value and removing the sign of the correlation value.

The non-coherent integration of several cycles of the aforementioned coherent correlation matrix may increase the SNR but may be limited by the user's motion or local oscillator error.

The technical problem to be solved by the present invention is to provide a method and apparatus for detecting a weak GNSS signal using a verification procedure for the correlation result.

According to an embodiment of the present invention, a method for detecting a received signal is provided. According to a received signal detection method, a satellite navigation receiver detects a received signal through parallel correlation, and performs time-domain correlation by selecting cells whose correlation value obtained through parallel signal detection is equal to or greater than a predefined signal detection threshold value. Verifying the correlation value; And detecting a cell that is greater than or equal to a predefined verification threshold as the final received signal.

According to another embodiment of the present invention, an apparatus for detecting satellite navigation received signals is provided. According to an apparatus for detecting a satellite navigation signal, the apparatus for detecting a satellite navigation signal through parallel correlation includes performing time-domain correlation of cells whose correlation value obtained through parallel signal detection is equal to or greater than a predefined signal detection threshold value. A verification unit that verifies the correlation value; And a detector for detecting a cell that is greater than or equal to a predefined verification threshold as a final signal.

According to an embodiment of the present invention, a signal detection probability is increased at a given false alarm probability by adding a verification process for a correlation value to a signal detection process using parallel search in a GNSS receiver for receiving a weak GNSS signal. In addition, even when the correlation time is extended for a plurality of periods, the complexity of the related operation can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “… module”, “… block” described in the specification mean a unit that processes at least one function or operation, which means hardware or software or hardware and software. It can be implemented as a combination of.

Now, a method of detecting a received signal according to an embodiment of the present invention and an apparatus for detecting a satellite navigation received signal performing the same will be described in detail with reference to the accompanying drawings.

First, Figure 1 is a block diagram showing the configuration of a satellite navigation signal reception apparatus according to an embodiment of the present invention.

According to FIG. 1, the apparatus for detecting satellite navigation signal 100 detects a signal using a correlator using parallel search. Correlators using parallel search are efficient in software-based Global Navigation Satellite System (GNSS) receivers because they provide correlation values for all search cells in one operation with time delay and frequency offset. Used as a search method.

In this case, the satellite navigation signal detection apparatus 100 includes a selector 120, a verification unit 140, and a detection unit 160.

The selector 120 selects a verification candidate cell. That is, cells whose correlation value calculated by performing parallel correlation between the received signal and the reference signal are greater than or equal to a predefined signal detection threshold value are sorted according to the magnitude of the correlation value. The sorted cells are separated according to code delay and frequency bin to select a verification candidate cell for time domain correlation.

The verification unit 140 determines that there is no signal when the correlation value is less than the signal detection threshold. In addition, when the correlation value is greater than or equal to the signal detection threshold value, the selector 120 performs time domain correlation on the selected verification candidate cell to verify the correlation value. In this case, the verification unit 140 performs time-domain correlation by calculating a non-coherent integration value for the verification candidate cell.

The detector 160 detects a cell whose time domain correlation value verified by the verifier 140 is equal to or greater than a predetermined verification threshold value as a final signal. That is, the detection unit 160 outputs an error detection when the noncoherent integrated value calculated by the verification unit 140 is less than the verification threshold value. In addition, when the non-coherent integrated value is greater than or equal to the verification threshold, the detection unit 160 outputs a cell in which the non-coherent integrated value exceeds the verification threshold as a signal detection result.

Next, a detailed signal detection process of the satellite navigation signal reception apparatus 100 will be described in detail.

2 is a flowchart illustrating a method of detecting a received signal according to an embodiment of the present invention.

According to FIG. 2, the verification unit 140 of FIG. 1 stores the correlation matrix M _nc generated through the process of detecting the parallel signal (S101) (S103). That is, the verification unit 140 accumulates the coherent correlation value of the signal generated in the receiver and the actual received signal in a non-coherent manner for N periods by using a signal acquisition method using a general parallel search. Create a three-dimensional correlation matrix (M _nc ). In this case, the coherent correlation value includes a code delay, a frequency offset, and a modulation symbol delay.

In this case, when there is an actual Global Navigation Satellite System (GNSS) satellite signal corresponding to the signal generated inside the receiver, the correlation matrix M _nc is calculated as follows.

: 상관값,

: 변조 심볼 에지,

: 코드 지연,

: 주파수 빈,

은

시간동안 수신한 신호의 평균 진폭,

는 변조 심볼 불일치에 의해 발생하는 신호손실,

는 GNSS 위성의 PRN 코드에 대한 자기상관함수,

은

시간동안의 평균 코드페이즈 불일치,

는

시간동안의 평균 주파수 불일치,

는 반송파 위상에 대한 오차,

와

는 In-phase와 Quadrature 신호에 대한 잡음이다. 또한, ix 는 1 또는 2와 같은 값으로 다르게 설정할 수 있다.here,

: Correlation value,

: Modulation symbol edge,

: Code delay,

Frequency bin,

silver

Average amplitude of the received signal over time,

Signal loss caused by modulation symbol mismatch,

Is the autocorrelation function for the PRN code of the GNSS satellite,

silver

Mean code phase mismatch over time,

The

Mean frequency mismatch over time,

Is the error with respect to the carrier phase,

Wow

Is the noise for the in-phase and quadrature signals. In addition, ix may be set differently to a value such as 1 or 2.

In this case, the average of the correlation loss with respect to the offset of the symbol edge can be expressed as follows.

는 심볼주기의 개수이고,

는 심볼의 옵셋이며,

는 심볼의 주기이다.here,

Is the number of symbol periods,

Is the offset of the symbol,

Is the period of the symbol.

In a received signal having a low signal to noise ratio (SNR), noise may generate a plurality of cells that exceed a signal detection threshold.

), 주파수 빈(

), 변조 심볼에지(

)에 대한 상관값(

)이 저장된다. In the three-dimensional matrix (M _nc ) calculated by the above equations, the code delay (

), Frequency bin (

), Modulation symbol edge (

Correlation value for

) Is stored.

)이 신호 검출 임계값(Th^D) 이상인지를 판단한다(S105). At this time, the verification unit 140 stores the stored correlation value (

) Is determined whether the signal detection threshold (Th ^D ) or more (S105).

)이 없는 경우, 검출부(도 1의 160)는 신호 없음(Signal Absence)으로 선언한다(S107). As a result of the determination, the correlation value greater than or equal to the signal detection threshold Th ^D (

), The detector (160 in FIG. 1) declares a signal absent (Signal Absence) (S107).

)이 존재하는 경우, 선택부(도 1의 120)가 상관값 검증을 위한 후보 셀을 선택하여 저장한다(S109).As a result of the determination, the correlation value greater than or equal to the signal detection threshold Th ^D (

), The selection unit 120 of FIG. 1 selects and stores a candidate cell for correlation value verification (S109).

The verification unit 140 generates an internal demodulated signal using information of each cell included in the candidate cell and performs correlation in the time domain (S111). Correlation in the time domain is as follows.

), 주파수 빈(

)의 정보는 후보 셀의 검증을 위하여 수신기 내부의 복조 신호와의 매칭에 사용된다. Code delay for each group of candidate cells (

), Frequency bin (

) Information is used to match the demodulated signal inside the receiver for verification of the candidate cell.

개 샘플에 대한 연속된

개 블록의 코히어런트 상관값이 계산된다.Through the equation below

Consecutive for samples

Coherent correlation values of the blocks are calculated.

는 심볼주기(

)에서 심볼에지 지연의 개수이고,

는 심볼에지 지연간의 샘플의 개수이다.

는 수 신기의 샘플 주기이다.

는 1부터

까지이고,

은 수신신호의 벡터이다.here,

Is the symbol period (

) Is the number of symbol edge delays,

Is the number of samples between symbol edge delays.

Is the sample period of the receiver.

From 1

Until

Is the vector of the received signal.

)는 현재 셀 그룹에서 선택된 각각의 심볼에지(

)에 대하여 아래 수학식과 같이 계산된다.In addition, the coherent integration value (

) Represents each symbol edge (

) Is calculated as in the following equation.

이고,

과

은 각각 실수와 허수에 대한 연산을 의미한다.Where I is from 1

ego,

and

Are operations on real and imaginary numbers, respectively.

주기에 대한 코히어런트 적산을 위하여,

범위에서 각 코히어런트 주기(

)에 걸쳐 변조 부호를 일치시키기 위하여 심볼의 조합에 대한 추정이 필요하다. 코히어런트 상관주기에 대한 전체 부호는

연산에 의해 제거되므로

와

상관값에 대한

개의 심볼조합이 가능하다. Symbol unknown

For coherent integration of the cycle,

Each coherent period in the range (

Estimation of the combination of symbols is needed to match the modulation code over < RTI ID = 0.0 > The full sign of the coherent correlation period is

Is removed by operation

Wow

For the correlation

Symbol combinations are possible.

에 대한 코히어런트 상관은 아래 수학식과 같이 계산된다. Symbol combination

The coherent correlation for is calculated by the following equation.

는 심볼조합을 평가하기 위한 변조 패턴이다. 가장 큰 상관값을 갖는 심볼조합을 선택하고 논코히어런트 적산

을 다음과 같이 계산한다.here,

Is a modulation pattern for evaluating symbol combination. Select the symbol combination with the largest correlation and noncoherent integration

Calculate as

)는 미리 정의된 검증 임계값(

)과 비교한다(S113). As such, the verification unit 140 performs noncoherent integration of all cells included in the verification candidate cell. And the verification unit 140 is a result of the non-coherent integration (

) Is the predefined validation threshold (

(S113).

)가 검증 임계값(

)을 초과하지 않는 경우 즉 검증 임계값(

)을 초과하는 셀이 없는 경우, 검출부(160)는 오류검출(False Alarm)을 선언한다(S115). At this time, the result of the non-coherent integration (

) Is the validation threshold (

Does not exceed, that is, the verification threshold (

If there is no cell larger than), the detector 160 declares a false alarm (S115).

)가 검증 임계값(

) 이상인 경우, 검출부(160)는 신호존재('Signal Presence)를 선언한다(S117).However, as a result of noncoherent integration (

) Is the validation threshold (

), The detector 160 declares a signal presence ('Signal Presence') (S117).

)을 초과하는 셀이 하나인 경우, 그 셀은 최종 후보셀로서 선택된다. At this time, the verification threshold (

If there is more than one cell, the cell is selected as the final candidate cell.

)을 초과하는 경우, 논코히어런트 측정값은

와 같다. 그리고 최대 상관값을 갖는 즉,

가 최대인 셀이 신호 검출 결과로 출력된다. In addition, the verification threshold (

), The noncoherent measurement is

Same as And having the maximum correlation

The cell with the maximum is output as the signal detection result.

Here, step S109 will be described in more detail. 3 is a flowchart illustrating a candidate cell selection process according to an embodiment of the present invention.

)의 크기에 따라 내림차순으로 정렬한다(S201). According to FIG. 3, the selector 120 of FIG. 1 correlates each cell in the three-dimensional correlation matrix M _nc stored in step S101 of FIG. 2.

In descending order according to the size of (S201).

) 이상의 상관값(

)을 가진 셀들을 검색(S203)하여 VCCListtemp에 저장한다(S205). And the selector 120 is a signal detection threshold (

) Or greater than

Cells are stored (S203) and stored in the VCCListtemp (S205).

)을 갖는 셀에 대하여 코드지연(

), 주파수 빈(

), 심볼 에지(

), 상관값(

) 및 그룹 넘버(

)를 저장한 목록이다. VCCList에 저장된 정보들은 시간 영역에서 상관을 수행할 때, 복조 신호를 생성하기 위한 정보로 사용된다. VCCListtemp는 임시 VCCList이다. Here, VCCList is a correlation value (above the signal detection threshold Th ^D )

Code delay for cells with

), Frequency bin (

), Symbol edge (

), The correlation value (

) And group number (

) Is a saved list. The information stored in the VCCList is used as information for generating a demodulated signal when performing correlation in the time domain. VCCListtemp is a temporary VCCList.

), 주파수 빈(

)에 따라 그룹핑한다(S207). 즉 동일한 코드지연(

), 주파수 빈(

)에 따라 셀들을 분리한다.The selector 120 decodes the cells stored in step S205 (

), Frequency bin (

Grouping according to (S207). The same code delay (

), Frequency bin (

To separate the cells.

In operation S209, the selector 120 determines whether the number NumGrps grouped in step S207 is greater than or equal to a predetermined maximum group number NumGrpsMax.

In this case, when the grouping number NumGrps is greater than or equal to a predetermined maximum number of groups NumGrpsMax, the selecting unit 120 selects only the maximum number of groups NumGrpsMax from the cells included in the stored VCCListtemp in step S205 (S211).

However, when the grouping number NumGrps is not greater than the predetermined maximum group number NumGrpsMax, the selector 120 selects all cells included in the stored VCCListtemp in step S205 (S213).

The selector 120 stores the cell selected in step S211 or step S213 in the VCCList (S215).

)에 대한 검증을 수행함으로써 신호 검출 확률을 개선한다. 신호 검출 확률의 개선은 도 4 및 도 5를 통해 확인할 수 있다. As described above, the cells exceeding the threshold are selected as a subset, and sequential correlation is performed in the time domain with respect to the extended period so that the correlation value (

We improve the signal detection probability by performing The improvement of the signal detection probability can be confirmed through FIGS. 4 and 5.

4 and 5 are graphs showing a signal detection probability comparison according to an embodiment of the present invention.

4 and 5, the horizontal axis of the graph is False Alarm Probability. The vertical axis of the graph is detection probability.

4 is a signal detection probability graph according to the first embodiment of the present invention. When CNR (Carrier to Noise Ratio) is 20 dB-Hz, signal detection between the conventional detection method and the detection method according to the embodiment of the present invention is performed. Represent a probability comparison.

5 is a signal detection probability graph according to a second embodiment of the present invention, and shows a signal detection probability comparison between a conventional detection method and a detection method according to an embodiment of the present invention when CNR = 18dB-Hz.

4 and 5, it can be seen that the detection probability is much higher than the conventional detection method according to the embodiment of the present invention. That is, the detection performance of weak signals received with noise is further improved.

The embodiment of the present invention is not implemented only through the above-described apparatus and / or method, but may be implemented through a program or a recording medium on which the program is recorded, which realizes a function corresponding to the configuration of the embodiment of the present invention. Such an implementation can be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a block diagram showing the configuration of a satellite navigation signal reception apparatus according to an embodiment of the present invention.

2 is a flowchart illustrating a method of detecting a received signal according to an embodiment of the present invention.

3 is a flowchart illustrating a candidate cell selection process according to an embodiment of the present invention.

4 is a graph illustrating a comparison of signal detection probabilities according to the first embodiment of the present invention.

5 is a graph illustrating a signal detection probability comparison according to a second embodiment of the present invention.

Claims (13)

A satellite navigation receiver detects a received signal through parallel correlation, Verifying the correlation value by performing time-domain correlation by selecting cells whose correlation value obtained through parallel signal detection is equal to or greater than a predefined signal detection threshold value; And Detecting a cell that is greater than or equal to a predefined verification threshold as a final received signal; The verifying step, By performing parallel correlation between a received signal and a reference signal, cells whose correlation value is greater than or equal to a predefined signal detection threshold are sorted according to the magnitude of the correlation value, and the sorted cells are separated according to code delay and Doppler frequency. Receiving signal detection method for selecting a verification candidate cell for the time domain correlation; The method of claim 1, The verifying step, Calculating the correlation value by performing parallel correlation between a received signal and a reference signal; Determining that there is no signal when the correlation value is less than the signal detection threshold value; Selecting a verification candidate cell when the correlation value is greater than or equal to the signal detection threshold value; And Performing time domain correlation on the verification candidate cell Received signal detection method comprising a. 3. The method of claim 2, Wherein the selecting comprises: Sorting cells having a correlation value greater than or equal to the signal detection threshold according to the magnitude of the correlation value; Grouping the sorted cells according to a code delay and a Doppler frequency; Determining whether the number of groupings is greater than or equal to a predefined maximum grouping number; If the number of groupings is greater than or equal to, selecting the grouped cells as the verification candidate cells by the maximum number of groupings; And Selecting all grouped cells as verification candidate cells if less than the maximum grouping number Received signal detection method comprising a. The method according to claim 2 or 3, The performing of the time domain correlation may include: Calculating a coherent correlation value for the estimated symbol combination for the verification candidate cell; And Calculating a non-coherent integrated value by selecting a symbol combination having the largest coherent correlation value Received signal detection method comprising a. 5. The method of claim 4, The detecting step, Comparing the noncoherent integration value with the predefined verification threshold; Outputting error detection when the noncoherent integration value is less than the verification threshold value; And If the non-coherent integrated value is greater than or equal to the verification threshold value, outputting a cell whose non-coherent integrated value is greater than or equal to the verification threshold value as a signal detection result; Received signal detection method comprising a. The method of claim 5, The outputting of the signal detection result may include: If there is one cell whose noncoherent integration value is greater than or equal to the verification threshold value, outputting a cell greater than or equal to the verification threshold value as a signal detection result; And Outputting a cell having a maximum sum of a correlation value obtained through the parallel signal detection and the non-coherent integrated value as a signal detection result when a plurality of cells whose non-coherent integrated value is greater than or equal to the verification threshold value are obtained. Received signal detection method comprising a. delete An apparatus for detecting a satellite navigation received signal through parallel correlation, A verification unit for verifying the correlation value by performing time-domain correlation of cells whose correlation value obtained through parallel signal detection is greater than or equal to a predefined signal detection threshold value; A detector for detecting a cell that is greater than or equal to a predetermined verification threshold as a final signal; And By performing parallel correlation between a received signal and a reference signal, cells whose correlation value is greater than or equal to a predefined signal detection threshold are sorted according to the magnitude of the correlation value, and the sorted cells are separated according to code delay and Doppler frequency. A selection unit for selecting a verification candidate cell for the time domain correlation and providing the detection candidate cell to the detection unit; Satellite navigation signal reception apparatus comprising a. 9. The method of claim 8, Wherein the selection unit comprises: Group the sorted cells into cells having the same code delay and Doppler frequency, and if the number of groupings is greater than or equal to the predefined maximum grouping number, select the grouped cells as the maximum number of verifying candidate cells, and if the grouping number is less than the maximum grouping number, A satellite navigation signal detection apparatus for selecting all cells as verification candidate cells. 10. The method according to claim 8 or 9, Wherein the verifying unit comprises: And determining that there is no signal when the correlation value is less than the signal detection threshold value, and performing time domain correlation on the verification candidate cell when the correlation value is greater than or equal to the signal detection threshold value. The method of claim 10, Wherein the verifying unit comprises: And calculating a coherent correlation value for the estimated symbol combination for the verification candidate cell, selecting a symbol combination having the largest coherent correlation value, and calculating a noncoherent integrated value. 12. The method of claim 11, The detection unit, Error detection is output when the noncoherent integration value is less than the verification threshold value, and when the noncoherent integration value is greater than or equal to the verification threshold value, a cell whose noncoherent integration value is greater than or equal to the verification threshold value is a signal detection result. Satellite navigation reception signal detection device for outputting. The method of claim 12, The detection unit, When there is one cell whose noncoherent integration value is greater than or equal to the verification threshold value, the cell outputting a cell that is greater than or equal to the verification threshold value as a signal detection result and when the number of cells whose noncoherent integration value is greater than or equal to the verification threshold value is parallel A satellite navigation signal detection apparatus for outputting a cell having a maximum sum of a correlation value obtained through signal detection and the noncoherent integrated value as a signal detection result.

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