KR101142787B1 - Method for transmitting sychronization signal and calculating correlation value thereof in wireless communication system - Google Patents

Abstract

The disclosed technology relates to a synchronization signal transmission method and a correlation value calculation method in a wireless communication system. Among the embodiments, a method of generating and transmitting a new sync signal from a sync signal group including a plurality of sync signals may include combining at least one of real and imaginary components of a sync signal belonging to the sync signal group. Generating a real component of the new sync signal; Generating an imaginary component of the new sync signal by combining at least one of real and imaginary components of the sync signal belonging to the sync signal group; And transmitting the generated new synchronization signal to the terminal. The new sync signal is a different signal from the sync signals belonging to the sync signal group.

Description

Synchronization signal transmission method and correlation value calculation method in wireless communication system {METHOD FOR TRANSMITTING SYCHRONIZATION SIGNAL AND CALCULATING CORRELATION VALUE THEREOF IN WIRELESS COMMUNICATION SYSTEM}

The disclosed technology relates to a synchronization signal transmission method and a correlation value calculation method in a wireless communication system.

Asynchronous wireless mobile communication systems such as Wideband Code Division Multiple Access (WCDMA) and Long Term Evolution-Advanced (LTE-Advanced) use different patterns of synchronization signals between base stations, thereby providing a base station of a terminal. It supports to perform division, cell selection and initial synchronization. For example, in the LTE-Advanced system, the base station periodically transmits a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) for cell selection and initial synchronization of the UE. Here, the number of patterns of PSS and SSS corresponds to 3 and 168, respectively.

Meanwhile, in recent wireless mobile communication systems including LTE-Advanced, application of heterogeneous network technology that adds and operates a low power node such as a femto cell in base station cell coverage is being considered. When a low power node such as a femtocell is installed and a heterogeneous network environment is implemented, a femto cluster environment in which a plurality of femtocells are concentrated may be formed.

An object of the present invention is to provide a synchronization signal transmission method and a correlation value calculation method in a wireless communication system.

In order to achieve the above technical problem, a first aspect of the disclosed technology is a method of generating and transmitting a new sync signal from a sync signal group including a plurality of sync signals, the real components of the sync signal belonging to the sync signal group and Combining at least one of the imaginary components to produce a real component of the new sync signal; Generating an imaginary component of the new sync signal by combining at least one of real and imaginary components of the sync signal belonging to the sync signal group; And transmitting the generated new synchronization signal to the terminal, wherein the new synchronization signal is a signal different from the synchronization signals belonging to the synchronization signal group.

In order to achieve the above technical problem, a second aspect of the disclosed technology is a method of calculating a correlation value between a new reference signal generated from a reference signal group including a plurality of reference signals and a received signal received from a base station by a terminal, Receiving, by the terminal, the received signal from the base station; Calculating a correlation value between a reference signal belonging to the reference signal group and the received signal by a plurality of correlators; Receiving a partial correlation value generated in the calculating of the correlation value from the plurality of correlators; And combining the provided partial correlation values to calculate a correlation value of the new reference signal and the received signal, wherein the new reference signal is a signal different from a reference signal included in the reference signal group. Provide a method.

According to a third aspect of the disclosed technology, a method of calculating a correlation value between a new reference signal generated from a reference signal group including a plurality of reference signals and a received signal received from a base station by a terminal, Receiving, by the terminal, the received signal from the base station; Generating a partial correlation value by a plurality of correlators, each of the correlators performing a correlation operation on different reference signals belonging to the reference signal group; And combining the generated partial correlation values to calculate a correlation value between the new reference signal and the received signal, wherein the new reference signal is a signal different from a reference signal included in the reference signal group. Provide a calculation method.

Embodiments of the disclosed technique may have effects that include the following advantages. It should be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, since the embodiments of the disclosed technology are not meant to include all such embodiments.

According to the disclosed technology, it is possible to prevent the pattern overlap phenomenon of the synchronization signal. Accordingly, pattern overlap of synchronization signals can be prevented from occurring in a femto cluster environment, and performance degradation of initial cell search, frequency synchronization, and timing synchronization algorithms of a terminal due to pattern overlap can be prevented.

1 is a diagram illustrating a process of performing initial cell search and timing synchronization using PSS of an LTE-Advanced system.
2 is a diagram for describing a subcarrier allocation structure of a PSS.
3 is a diagram for explaining a low power node being discussed in the heterogeneous network technology of LTE-Advanced.
4 is a diagram for describing a PSS pattern overlapping phenomenon occurring in an environment where three femtocells are adjacent to each other.
5 is a view for explaining a method of generating a synchronization signal according to an embodiment of the disclosed technology.
6 is a diagram for describing a method of calculating a correlation value of a synchronization signal generated according to an embodiment of the disclosed technology.
7 is a flowchart illustrating a method of generating a new synchronization signal and calculating a correlation value according to an embodiment of the disclosed technology.
FIG. 8 is a table listing cross-correlation outputs between a real part, an imaginary part, and a pattern of five patterns generated according to an embodiment of the disclosed technology.
9 is a graph illustrating autocorrelation patterns of three types of PSSs and patterns generated according to one embodiment of the disclosed technology.
10 is a table showing a maximum peak to maximum adjacent peak ratio for each pattern.
11 is a graph illustrating a detection error probability of a synchronization algorithm for each pattern type according to a signal to noise power ratio (SNR) when a differential correlation technique is applied.
12 illustrates the probability of detection error of the coarse synchronization algorithm for each pattern type according to SNR when applying the partial correlation technique.

The description of the disclosed technique is merely an example for structural or functional explanation and the scope of the disclosed technology should not be construed as being limited by the embodiments described in the text. That is, the embodiments may be variously modified and may have various forms, and thus the scope of the disclosed technology should be understood to include equivalents capable of realizing the technical idea.

Meanwhile, the meaning of the terms described in the present application should be understood as follows.

The terms " first ", " second ", and the like are used to distinguish one element from another and should not be limited by these terms. For example, the first component may be named a second component, and similarly, the second component may also be named a first component.

When a component is referred to as being "connected" to another component, it should be understood that there may be other components in between, although it may be directly connected to the other component. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions describing the relationship between the components, such as "between" and "immediately between" or "neighboring to" and "directly neighboring to", should be interpreted as well.

Singular expressions should be understood to include plural expressions unless the context clearly indicates otherwise, and terms such as "include" or "have" refer to features, numbers, steps, operations, components, parts, or parts thereof described. It is to be understood that the combination is intended to be present, but not to exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof.

Each step may occur differently from the stated order unless the context clearly dictates the specific order. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed technology belongs, unless otherwise defined. Terms defined in commonly used dictionaries should be interpreted to be consistent with meaning in the context of the relevant art and can not be construed as having ideal or overly formal meaning unless expressly defined in the present application.

1 is a diagram illustrating a process of performing initial cell search and timing synchronization using PSS of an LTE-Advanced system. Asynchronous wireless mobile communication systems, such as WCDMA and LTE-Advanced, support synchronization of base stations, cell selection, and initial synchronization of terminals by using different patterns of synchronization signals between base stations. Referring to FIG. 1, a process of performing initial cell search and synchronization of a terminal will be described, taking the case of the LTE-Advanced system as an example. Initial cell search is a process of determining whether a frame transmitted from a base station is received and a start position by using three types of PSSs assigned to each cell, and determining a cell ID of the received PSS. The received signal is correlated with three other reference signals according to cell ID during a 5 ms period. Three types of PSS signals allocated to each cell are used as the reference signal, and the reference signal enables the cell ID of the received signal to be determined based on a correlation value with the received signal. The reference signal may be represented by another name such as a reference signal. The correlation calculation process of the received signal r [n] and the reference signal s [n] can be expressed by Equation 1.

는 고속푸리에변환(Fast Fourier Transform, FFT) 크기를 의미하며, n은 시간 영역 샘플의 인덱스를 의미한다.

는 s[n]의 공액 복소를 나타낸다. 수학식 1과 같은 상관 출력에 대하여, 단말은 임계값을 넘는 출력 중 최대값을 갖는 신호를 cell ID로 판단하며 셀 접속을 수행한다. 또한, 단말은 수학식 2와 같이 상관 출력의 최대값이 검출되는 위치

를 추정하여 해당 위치를 기준으로 프레임 동기를 수행한다.In Equation 1

Is the fast Fourier transform (FFT) size, and n is the index of the time-domain sample.

Represents a conjugate complex of s [n]. For the correlation output as shown in Equation 1, the terminal determines the signal having the maximum value among the outputs exceeding the threshold value as the cell ID and performs cell access. In addition, the terminal is the position where the maximum value of the correlation output is detected, as shown in equation (2)

The frame synchronization is performed based on the corresponding position by estimating.

In this case, three types of PSS signals used as reference signals are composed of Zadoff Chu (ZC) sequences having root indexes of 25, 29, and 34, respectively, based on direct current (DC) subcarriers in the frequency domain. It is allocated to 63 subcarriers. The ZC sequence is a type of the conventional CAZAC sequence and has excellent characteristics of Peak-to-Average Power Ratio (PAPR) and autocorrelation. Accordingly, the ZC sequence has been applied as a reference signal for synchronization in various systems such as SC-FDE (Ultra Wide Band), UWB (Ultra Wide Band) as well as orthogonal frequency division multiplexing. When the root index is represented by d, a ZC sequence having a length of 63 is defined as in Equation 3.

라 할 때 이와 같은 할당 구조는 수학식 4와 같이 나타낼 수 있다.2 is a diagram for describing a subcarrier allocation structure of a PSS. Referring to FIG. 2, a 63 length ZC sequence of Equation 3 is allocated to 63 subcarriers based on a DC index, and 0 is assigned to a DC index. DC index

In this case, such an allocation structure may be represented as in Equation 4.

The time-domain PSS signal is defined as an Inverse Fourier Transform (IFFT) output for the frequency-domain PSS signal of Equation 4, which can be expressed as Equation 5.

The base station transmits a time domain PSS signal to the terminal to perform synchronization with the terminal. Meanwhile, recent wireless mobile communication systems consider application of heterogeneous network technology in which various low power nodes are added and operated in base station cell coverage.

3 is a diagram for explaining a low power node being discussed in the heterogeneous network technology of LTE-Advanced. Examples of low power nodes include a hot zone cell 310, a relay node 320, a femto cell 330, and the like. The hot zone cell 310 is a node installed by a network operator for the purpose of ensuring sufficient performance in a densely populated area, and is also referred to as a pico cell. Hot zone cell 310 has a wired interface with a base station. The relay node 320 is a node installed by a network operator for cell coverage expansion and shadow area elimination, and has a radio interface with an eNB (evolved NodeB). The femto cell 330 is an indoor low-power node that serves only a specific closed subscriber group (CSG) and is installed, operated, and operated mainly by an individual. Whether the base station interface of the femto cell 330 is wired or wireless has not been determined on the LTE-Advanced standard yet.

As a low power node such as a femtocell 330 is installed to implement a heterogeneous network environment, a femto cluster environment in which a plurality of femtocells are concentrated may be formed. In a femto cluster environment in which a plurality of femtocells are adjacent, overlapping of a synchronization signal pattern for cell selection and initial synchronization of a terminal may occur. In particular, in the case of the LTE-Advanced PSS, it is expected that the pattern overlapping phenomenon using the same pattern of synchronization signal between adjacent nodes will occur more frequently.

4 is a diagram for describing a PSS pattern overlapping phenomenon occurring in an environment where three femtocells are adjacent to each other. In the case where three or more femtocells are concentrated, the UE should be able to distinguish four or more nodes, including a base station, for smooth cell search. However, since the current number of PSS patterns in the LTE-Advanced standard is three, if three or more femtocells are concentrated, at least two nodes of four nodes use the same PSS pattern. Referring to FIG. 4, although femtocell 1, femtocell 2, and femtocell 3 use different PSS patterns, it can be seen that the PSS patterns of the base station and femtocell 2 collide with each other. That is, in an environment in which more femtocells are concentrated than the number of PSS patterns, pattern overlap occurs. When the pattern overlap phenomenon occurs, performance degradation of initial cell search, frequency synchronization, and timing synchronization algorithms of the UE occurs.

5 is a view for explaining a method of generating a synchronization signal according to an embodiment of the disclosed technology. The disclosed technique may prevent the synchronization signal pattern overlapping phenomenon that may occur in the heterogeneous network environment described with reference to FIG. 4. The synchronization signal overlap phenomenon may cause degradation of cell ID detection performance, frequency, and timing synchronization performance of the terminal. In order to prevent overlapping of the synchronization signal pattern, the disclosed technology generates a new synchronization signal for the femtocell through a combination of real and imaginary parts of the existing synchronization signal pattern. When generating a new synchronization signal according to the disclosed technology, there is an advantage that a correlation value for a new synchronization signal can be calculated through a combination of values calculated in a correlator mounted on an existing terminal. Therefore, even if a new synchronization signal is used, no increase in hardware is required. In FIG. 5, a PSS signal pattern generation of LTE-Advanced is described as an example, but is not limited thereto. The disclosed technology may be equally applied to SSS generation of the same system and synchronization signal generation of another system.

및 34인 패턴

이 수학식 6과 같은 관계를 가진다.The new sync signal generating method according to the disclosed technology combines the real and imaginary components of the existing sync signal pattern to generate the real and imaginary components of the new sync signal. Combining real and imaginary components herein may include linear operations of the real and imaginary components. That is, an operation of adding or subtracting real and imaginary components to each other, or adding or subtracting or changing the magnitudes of the real and imaginary components may be included. In case of LTE-Advanced, the root index is 29 out of 3 patterns of PSS

And 34-person pattern

This equation has the same relationship as in (6).

의 실수 성분 및 허수 성분로부터

의 실수 성분 및 허수 성분을 유도할 수 있다. 따라서, 개시된 기술을 LTE-Advanced에 적용하는 경우는

및

의 실수 성분 및 허수 성분만을 고려해도 된다. 이러한 경우, 조합 가능한 신호 성분은 다음의 수학식 7과 같이 8개가 있다.Due to the characteristics such as

From real and imaginary components of

The real and imaginary components of can be derived. Therefore, when applying the disclosed technology to LTE-Advanced

And

Only the real and imaginary components of may be considered. In this case, there are eight signal components that can be combined as shown in Equation 7 below.

A new sync signal can be generated by combining the eight signal components of Equation 7 to form a new real component and an imaginary component.

과 29인 패턴

을 기초로 새로운 PSS 동기 신호 패턴

을 생성한다. 도 5의

의 실수 성분은

의 실수 성분과

의 허수 성분을 더하여 생성되며,

의 허수 성분은

의 허수 성분과

의 실수 성분을 반전한 것을 더하여 생성된다. 수학식 8은 도 5에 도시된 바와 같이 생성된 새로운 동기 신호를 수학식 7에서 정의한 8개 신호의 조합으로 나타낸 것이다.In FIG. 5, a pattern having a root index of 25 among PSS patterns of LTE-Advanced

And 29-person pattern

PSS sync signal pattern based on

. Of FIG. 5

Real ingredients of

Real ingredients of

Is created by adding the imaginary components of

The imaginary component of

With the imaginary component of

It is created by adding the inverse of the real component of. Equation 8 shows the new synchronization signal generated as shown in FIG. 5 as a combination of eight signals defined in Equation 7.

은 새로운 동기 신호의 부반송파 별 평균 전력이 기존 패턴과 동일한 값을 가지도록 하는 전력 표준화 상수이다.
here

Is a power standardization constant such that the average power of each subcarrier of the new synchronization signal has the same value as the existing pattern.

6 is a diagram for describing a method of calculating a correlation value of a synchronization signal generated according to an embodiment of the disclosed technology. In general, for the cell search of the terminal, as many correlators as the number of patterns of the sync signal are used, and if the number of patterns of the sync signal is increased, an additional correlator is required to be installed in the terminal. However, in the case of a new synchronization signal generated according to the disclosed technology, it is possible to obtain a correlation output of a new synchronization signal by combining values calculated in a correlator mounted on an existing terminal without adding a separate correlator.

When a new sync signal generated as in Equation 8 is transmitted, the correlation value thereof is as shown in Equation 9.

및

은 루트 인덱스가 25인 PSS로부터 파생된 신호이며,

및

은 루트 인덱스가 29인 PSS로부터 파생된 신호이다. 수학식 9의 상관 값은 수학식 10과 같이 정리할 수 있다.Referring to Equation 7,

And

Is a signal derived from the PSS with a root index of 25,

And

Is a signal derived from the PSS whose root index is 29. The correlation value of Equation 9 can be summarized as in Equation 10.

에 대한 상관 연산을 수행하는 상관기 이고, PSS #1 correlator는 기존의 동기 신호

에 대한 상관 연산을 수행하는 상관기이다. 도 6을 참조하면, 수학식 10의 상관 값은 기존의 상관기 PSS #0 correlator 및 PSS #1 correlator의 내부 연산에서 생성되는 값들의 조합으로 얻어질 수 있음을 확인할 수 있다. 본 명세서에서는 기존의 상관기의 내부 연산에서 생성되는 값을 부분 상관 값으로 정의한다. 예컨대, 수신 신호 r[n]과 기존의 기준 신호 S[n]과의 상관 연산 시에 생성되는 Re{r[n]}Re{s[n]}, Re{r[n]}Im{s[n]}, Im{r[n]}Re{s[n]}, Im{r[n]}Im{s[n]}이 부분 상관 값에 포함된다. 보다 구체적으로, 수학식 10의 각 항과 도 6에서 생성되는 부분 상관 값과의 관계를 살펴보면, 수학식 10의 (1) 항은 도 6의 610에서 연산되는 값, 수학식 10의 (2) 항은 도 6의 620에서 연산되는 값, 수학식 10의 (3) 항은 도 6의 630에서 연산되는 값, 수학식 10의 (4) 항은 도 6의 640에서 연산되는 값을 부호 반전한 값, 수학식 10의 (5) 항은 도 6의 680에서 연산되는 값, 수학식 10의 (6) 항은 도 6의 670에서 연산되는 값을 부호 반전한 값, 수학식 10의 (7) 항은 도 6의 660에서 연산되는 값, 수학식 10의 (8) 항은 도 6의 650에서 연산되는 값과 같다.The PSS # 0 correlator of Figure 6 is a conventional synchronization signal

Correlator that performs a correlation operation on the PSS # 1 correlator is a conventional synchronization signal

Correlator that performs a correlation operation on. Referring to FIG. 6, it can be seen that the correlation value of Equation 10 may be obtained by a combination of values generated by internal operations of the existing correlator PSS # 0 correlator and PSS # 1 correlator. In this specification, a value generated by an internal operation of an existing correlator is defined as a partial correlation value. For example, Re {r [n]} Re {s [n]} and Re {r [n]} Im {s generated during correlation between the received signal r [n] and the existing reference signal S [n]. [n]}, Im {r [n]} Re {s [n]}, and Im {r [n]} Im {s [n]} are included in the partial correlation value. More specifically, referring to the relationship between each term in Equation 10 and the partial correlation value generated in FIG. 6, the term (1) in Equation 10 is a value calculated at 610 in FIG. 6, and (2) in Equation 10. The term is a value calculated at 620 of FIG. 6, the term (3) of Equation 10 is the value calculated at 630 of FIG. 6, and the term (4) of Equation 10 is the sign inverted the value calculated at 640 of FIG. Value, Equation (10) of Equation 10 is a value calculated at 680 of FIG. 6, Equation (10) of Equation 10 sign-inverted the value calculated at 670 of FIG. 6, Equation (10) The term is a value calculated at 660 of FIG. 6, and the term (8) of Equation 10 is the same as the value calculated at 650 of FIG. 6.

By such association, a correlation value of Equation 10 may be obtained by a combination of values calculated in an existing correlator. In addition, in the case where the synchronization signal is generated through a combination of other types in addition to the example of the combination of the synchronization signal, for example, a correlation value may be obtained through a similar process.

,

,

인 세가지 PSS 신호일 수 있다. 7 is a flowchart illustrating a method of generating a new synchronization signal and calculating a correlation value according to an embodiment of the disclosed technology. Parts described with reference to FIGS. 5 to 6 may be equally applicable to the present embodiment, and thus description thereof will be omitted. A method of generating and transmitting a new sync signal from a sync signal group including a plurality of sync signals will be described with reference to FIG. 7. The sync signal group may include, for example, a primary synchronization signal (PSS) signal group of LTE-Advanced, and the sync signal belonging to the sync signal group may be

,

,

It may be three PSS signals.

일 수 있다.In step S710, the base station combines at least one of the real and imaginary components of the sync signal belonging to the sync signal group to generate a real component of the new sync signal. According to an embodiment, the real component of the new synchronization signal may be generated through a linear operation on the at least one component. In step S720, the base station combines at least one of real and imaginary components of the sync signal belonging to the sync signal group to generate an imaginary component of the new sync signal. According to an embodiment, the imaginary component of the new sync signal may be generated through a linear operation on the at least one component. The new sync signal is a different signal from the sync signals belonging to the sync signal group. For example, the new synchronization signal is expressed by Equation 8

Can be.

,

,

인 세가지 PSS 신호일 수 있다. 새로이 생성된 기준 신호는 수학식 8의

일 수 있다. In step S730, the base station transmits the generated new synchronization signal to the terminal. The transmitted sync signal calculates a correlation value with the reference signal and is used to synchronize the terminal with the corresponding cell. In this embodiment, a new reference signal generated from a reference signal group including a plurality of reference signals is used to calculate the correlation value. The new reference signal is a signal different from the reference signal included in the reference signal group. For example, the new reference signal may be represented by a combination of real and imaginary components of the reference signals belonging to the reference signal group. Like the synchronization signal group, the reference signal group may include a primary synchronization signal (PSS) signal group of LTE-Advanced, and the reference signal belonging to the reference signal group

,

,

It may be three PSS signals. The newly generated reference signal is represented by Equation 8

Can be.

In operation S740, a plurality of correlators included in the terminal calculate a correlation value between the reference signal belonging to the reference signal group and the received signal. Each of the correlators generates a partial correlation value in the course of performing a correlation operation. In operation S750, the terminal combines the partial correlation values to calculate a correlation value between the new reference signal and the received signal. In this case, the correlation value may be calculated, for example, as described in Equation 9 or 10. The terminal may calculate a correlation value of Equation 9 or 10 by adding or subtracting the partial correlation value.

)에 대하여 산출된 각각의 상관 값 중 최대 값을 갖는

신호와 주파수 동기를 수행할 수 있다. 또한, 단말은 상기 주파수 동기를 수행하는

신호에 대하여, 수학식 2과 같이 상관 값이 최대가 되는 위치(

)를 추정하여 상기 위치를 기준으로 프레임 동기를 수행할 수 있다.
In step S760, the terminal performs synchronization with the base station based on the calculated correlation value. According to an embodiment, the terminal may transmit a plurality of different new synchronization signals (S750).

With the maximum value of each correlation value calculated for

Frequency synchronization with the signal can be performed. In addition, the terminal performs the frequency synchronization

With respect to the signal, as shown in Equation 2, the position where the correlation value is maximum (

) Can be estimated to perform frame synchronization based on the position.

The synchronization signal generation technique according to the disclosed technique may generate various kinds of new synchronization signals according to how the eight signal components of Equation 7 are combined to form a real component and an imaginary component. However, in order for the newly generated signal to be realistically applied, the newly generated synchronization signal needs to satisfy the following condition. The first condition is that the correlation between the three existing types of PSS should be sufficiently low. The second condition is that the cross-correlation between new sync signals generated through the sync signal generation method according to the disclosed technique should also be low enough. The third condition is that when the same timing synchronization algorithm is applied, when a new synchronization signal is used, a performance similar or better than that when timing synchronization is performed using three existing PSSs is required. The fourth condition is that when the same frequency synchronization algorithm is applied, performance similar to or superior to that of performing frequency synchronization using three types of existing PSSs should be shown. 8 to 12 show results of an experiment for checking whether a new synchronization signal satisfies the four conditions.

FIG. 8 is a table listing cross-correlation outputs between a real part, an imaginary part, and a pattern of five patterns generated according to an embodiment of the disclosed technology. In order to confirm whether the first condition and the second condition are satisfied, cross-correlation comparison is performed at on-time positions between three existing PSSs and five patterns generated by the method according to the disclosed technology. It was. The allowable numerical value of the cross-correlation applied for evaluating the excellence of the pattern was defined as about 0.2 considering the cross-correlation between the existing patterns within 0.2. The newly generated five patterns disclosed in FIG. 8 are stable at about 0.2 in both the correlations with the three existing PSSs and the correlations with the other newly generated patterns. Therefore, it can be seen that the five patterns of FIG. 8 satisfy the first condition and the second condition.

9 is a graph illustrating autocorrelation patterns of three types of PSSs and patterns generated according to one embodiment of the disclosed technology. In order to confirm that the newly generated pattern satisfies the third condition, the maximum peak vs. maximum side peak for the autocorrelation output of each of the three existing PSSs and the five newly generated patterns Rate comparisons were performed. Referring to FIG. 9, it can be seen that the autocorrelation pattern appears in a similar form regardless of the type of the synchronization signal. In addition, referring to FIG. 9, it can be seen that the maximum peak occurs at the on-time position at which the sample index is 0, while the maximum adjacent peak occurs immediately before or after the maximum peak.

10 is a table showing a maximum peak to maximum adjacent peak ratio for each pattern. In general, the greater the difference between the maximum peak and the maximum adjacent peak, the easier it is to detect the on-time point, which results in better performance during timing synchronization. Referring to FIG. 10, the three types of PSSs have a maximum peak-to-maximum adjacent peak ratio of about 0.4 and a similar value for a pattern generated according to an embodiment of the disclosed technology. have. Therefore, the timing synchronization using the pattern generated according to the disclosed technology can be expected to show similar performance as the case of the three existing types of PSS. That is, it can be seen that five newly generated patterns satisfy the third condition.

11 is a graph illustrating a detection error probability of a synchronization algorithm for each pattern type according to a signal to noise power ratio (SNR) when a differential correlation technique is applied. In order to confirm whether the fourth condition is satisfied, the approximate frequency synchronization performance of each of the three existing PSSs and the newly generated five patterns was verified. Simulation for performance verification was carried out through the COST207 TU model, which is a channel environment modeling the urban environment. FFT size NFFT = 128, carrier frequency 2.6GHz, bandwidth 1.25MHz, mobile speed 60km / h, normalized frequency offset 1.25 were used as the simulation parameters. The frequency synchronization algorithm employs the differential correlation technique, which is generally known as the best in the frequency selective channel environment, and the partial correlation technique, which is known to be most suitable for the LTE-Advanced system. As a performance evaluation method, the detection error probability for each algorithm was compared. The detection error probability means a probability that the integer frequency offset value estimated through the coarse synchronization algorithm does not match the actual integer offset value generated.

Since the differential correlation technique and the partial correlation technique generally correspond to well-known approximate frequency offset estimation techniques, only the estimation process will be briefly described below using mathematical equations. The differential correlation technique uses the correlation between the differentially correlated received signal and the PSS reference signal. When the frequency-domain received signal is R (k) and the frequency-domain PSS reference signal is S (k), the estimation process can be expressed by Equation (11).

개 부반송파 단위의 블록으로 나누어 상관을 취하는 방법으로 추정 과정은 수학식 12와 같다. In addition, partial correlation technique

A method of estimating a correlation by dividing a block into individual subcarrier units is shown in Equation 12.

When the differential correlation technique is applied, the pattern having the root index of 25 among the three existing PSSs has the worst probability of detection error, while the five newly generated patterns according to the exemplary embodiment of the disclosed technique show better performance. can confirm.

12 shows the probability of detection error of the coarse synchronization algorithm for each pattern type according to SNR when the partial correlation technique is applied. Referring to FIG. 12, when the partial correlation technique is applied, a pattern having a root index of 34 among the three existing PSSs has the worst detection error probability, while all five newly generated patterns through the disclosed technique have superior performance. You can see that. When the results of FIGS. 11 and 12 are combined, the five newly generated patterns satisfy the fourth condition.

While the system and apparatus disclosed herein have been described with reference to the embodiments shown in the drawings for purposes of clarity of understanding, they are illustrative only and various modifications and equivalent embodiments can be made by those skilled in the art. I will understand that. Accordingly, the true scope of protection of the disclosed technology should be determined by the appended claims.

Claims (11)

In the method of generating and transmitting a new sync signal from a sync signal group comprising a plurality of sync signals,
Combining at least one of real and imaginary components of a sync signal belonging to the sync signal group to generate a real component of the new sync signal;
Generating an imaginary component of the new sync signal by combining at least one of real and imaginary components of the sync signal belonging to the sync signal group; And
Transmitting the generated new synchronization signal to a terminal;
The new sync signal is a different signal from the sync signals belonging to the sync signal group,
Generating the real component comprises generating a real component of a new sync signal through a linear operation on the at least one component,
Generating an imaginary component comprises generating an imaginary component of a new synchronization signal through a linear operation on the at least one component. delete The method of claim 1, wherein the synchronization signal group includes a primary synchronization signal (PSS) signal group of LTE-Advanced. The method of claim 1, wherein the synchronization signal is obtained based on a Zadoff Chu (ZC) sequence. A method for calculating a correlation value between a new reference signal generated from a reference signal group including a plurality of reference signals and a received signal received by a terminal from a base station,
Receiving, by the terminal, the received signal from the base station;
Calculating a correlation value between a reference signal belonging to the reference signal group and the received signal by a plurality of correlators;
Receiving a partial correlation value generated in the calculating of the correlation value from the plurality of correlators; And
Combining the provided partial correlation values to calculate a correlation value of the new reference signal and the received signal,
And the new reference signal is a signal different from a reference signal included in the reference signal group. 6. The method of claim 5, wherein the new reference signal can be represented by a combination of real and imaginary components of reference signals belonging to the reference signal group. The method of claim 5, wherein the partial correlation value,

(here,

Is a received signal, and s [n] represents a reference signal belonging to the reference signal group). The method of claim 5,
And performing synchronization with the base station based on the calculated correlation value. The method of claim 5,
The calculating of the correlation value may include a plurality of different new reference signals.

about,

(here,

Is the received signal,

Is

Calculating the respective correlation values according to the conjugate complex of
And performing frequency synchronization with the new reference signal having the maximum value among the calculated correlation values. 10. The method of claim 9,
The performing of the synchronization may include: for a new reference signal having a maximum value among the respective correlation values,

, Where the correlation value is maximum (

Estimating) and performing frame synchronization based on the position. A method for calculating a correlation value between a new reference signal generated from a reference signal group including a plurality of reference signals and a received signal received by a terminal from a base station,
Receiving, by the terminal, the received signal from the base station;
Generating a partial correlation value by a plurality of correlators, each of the correlators performing a correlation operation on different reference signals belonging to the reference signal group; And
Combining the generated partial correlation values to calculate a correlation value between the new reference signal and the received signal,
And the new reference signal is a signal different from a reference signal included in the reference signal group.

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