KR20220088256A - Method of performing synchronization and frequency offset estimation based on simultaneous phase compensation of single training sequence and receiver performing the same - Google Patents

Abstract

In the synchronization and frequency offset estimation method, an input signal corresponding to a single training sequence is received. An auto-correlation function (ACF) is performed on an input signal to generate phase information and a phase index. A template signal for the sample index is generated based on at least one prestored look-up table (LUT), a phase index, and a frequency bandwidth and a sample index for the input signal. The power of the sample index is calculated by performing matched filtering on the input signal based on the template signal. Simultaneously determine the synchronization timing and frequency offset for the input signal based on the result of matched filtering.

Description

A method for estimating synchronization and frequency offset using real-time correction of a single training train and a receiver performing the same

The present invention relates to a semiconductor integrated circuit, and more particularly, to a method for estimating synchronization and frequency offset using a real-time correction technique of a single training train, and a receiver performing the method.

In a wireless communication system, it is important to have a strong communication signal. In particular, the largest possible signal-to-noise ratio (SNR) is required at the receiver. Likewise, increasing the SNR at the receiver increases the probability that frames are correctly received and reduces the amount of retransmission required from the source. Some methods to achieve better SNR at the receiver are to increase the transmit power, decrease the distance between the source and the receiver, and increase the antenna gain.

On the other hand, with the development and expansion of wireless communication standards, communication in a wider frequency bandwidth than before is required. For example, in the case of a wireless local area network (WLAN) system standard such as WiFi (Wireless Fidelity), a standard operating in a bandwidth of about 160 MHz or more has already been proposed, and various methods for improving communication performance and/or accuracy are available. is being studied

It is an object of the present invention to provide a synchronization and frequency offset estimation method capable of efficiently performing synchronization timing detection and frequency offset determination using a real-time correction technique of a single training sequence.

Another object of the present invention is to provide a receiver included in a wireless communication system and performing the above synchronization and frequency offset estimation method.

In order to achieve the above object, in the synchronization and frequency offset estimation method according to embodiments of the present invention, an input signal corresponding to a single training sequence is received. An auto-correlation function (ACF) is performed on the input signal to generate phase information and a phase index. A template signal for the sample index is generated based on at least one look-up table (LUT) stored in advance, the phase index, and a frequency bandwidth and sample index for the input signal. The power of the sample index is calculated by performing matched filtering on the input signal based on the template signal. A synchronization timing and a frequency offset for the input signal are simultaneously determined based on a result of the matched filtering.

In order to achieve the above another object, a receiver according to embodiments of the present invention includes a first operation unit, a template generation unit, and a second operation unit. The first operation unit receives an input signal corresponding to a single training sequence, and performs an auto-correlation function (ACF) on the input signal to generate phase information and a phase index. The template generator generates a template signal for the sample index based on at least one look-up table (LUT) stored in advance, the phase index, and a frequency bandwidth and sample index for the input signal. create The second calculator calculates the power of the sample index by performing matched filtering on the input signal based on the template signal, and a synchronization timing for the input signal based on a result of the matched filtering and a frequency offset are simultaneously determined.

In the synchronization and frequency offset estimation method and receiver according to the embodiments of the present invention as described above, synchronization timing and frequency offset may be simultaneously detected using only a single training sequence. At this time, in order to reduce computational complexity, a template signal (that is, a phase reflection template signal) is generated using a lookup table stored in advance, and synchronization timing and frequency offset are determined based on the result of performing matched filtering using the template signal. can be detected. Accordingly, while the amount of calculation/computation time is reduced, the detection accuracy is improved, and the performance of the receiver and the wireless communication system can be improved.

1 is a flowchart illustrating a synchronization and frequency offset estimation method according to embodiments of the present invention.
2 is a block diagram illustrating a receiver and a wireless communication system including the same according to embodiments of the present invention.
3 is a diagram for explaining operations of a receiver and a wireless communication system according to embodiments of the present invention.
4 and 5 are flowcharts illustrating an example of generating the phase information and the phase index of FIG. 1 .
6 and 7 are flowcharts illustrating an example of a step of generating a template signal of FIG. 1 .
8A and 8B are diagrams illustrating an example of a lookup table used to perform the operation of FIG. 7 .
9, 10, 11A, and 11B are diagrams for explaining the operation of FIG. 7 .
12, 13 and 14 are flowcharts illustrating an example of calculating the power of FIG. 1 and simultaneously determining a synchronization timing and a frequency offset.
15 is a block diagram illustrating an example of a first operation unit included in the receiver of FIG. 2 .
16 is a block diagram illustrating an example of a template generator included in the receiver of FIG. 2 .
17 is a block diagram illustrating an example of a second operation unit included in the receiver of FIG. 2 .
18, 19a, 19b, 20, 21a, 21b, 22a, and 22b are diagrams for explaining the operation of a receiver and a wireless communication system including the same according to embodiments of the present invention.
23 is a block diagram illustrating an electronic device in a network environment according to embodiments of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components are omitted.

1 is a flowchart illustrating a synchronization and frequency offset estimation method according to embodiments of the present invention.

Referring to FIG. 1 , a method for estimating synchronization and frequency offset according to embodiments of the present invention may be performed by a receiver receiving an input signal from a transmitter in a wireless communication system. The receiver and the specific structure of the wireless communication system including the same will be described later with reference to FIG. 2 and the like.

In the method for estimating synchronization and frequency offset according to embodiments of the present invention, an input signal (or a received signal) corresponding to a single training sequence is received (step S100 ). Unlike the conventional method of detecting the synchronization timing and frequency offset using two or more different training sequences, in embodiments of the present invention, the synchronization timing and frequency offset may be detected using only a single training sequence.

An auto-correlation function (ACF) is performed on the input signal to generate phase information and a phase index (step S200). For example, for frequency offset tracking and updating, the ACF may be performed by delaying the input signal to obtain the phase information, and the phase index for indicating the phase information may be calculated. Step S200 will be described later in detail with reference to FIGS. 4 and 5 .

Generates a template signal for the sample index based on at least one look-up table (LUT) stored in advance, the phase index, and a frequency bandwidth and sample index for the input signal do (step S300). The template signal is implemented in consideration of the phase index, and may be referred to as a phase index-based template signal or a phase reflection template signal. For example, in order to reduce computational complexity, the template signal may be generated using the lookup table, and may be implemented with a simplified ternary structure. Step S300 will be described later in detail with reference to FIGS. 6 to 11 .

Matched filtering is performed on the input signal based on the template signal to calculate the power of the sample index (step S400). A synchronization timing and a frequency offset for the input signal are simultaneously determined based on the result of the matched filtering (step S500). For example, the synchronization timing may be determined by performing a cross-correlation function (CCF) based on the input signal and the template signal. Steps S400 and S500 will be described later in detail with reference to FIGS. 12 to 14 .

Communication may be performed between the transmitter and the receiver included in the wireless communication system based on the synchronization timing and the frequency offset determined in step S500.

In the conventional method of detecting synchronization timing and frequency offset using two types of training sequences, first, coarse synchronization timing and frequency offset are detected using one training sequence, and then the other training sequence is detected. was used to detect fine synchronization timing and frequency offset. In this case, there are problems such as a decrease in detection accuracy or an increase in the amount of calculation/operation time.

In the synchronization and frequency offset estimation method according to embodiments of the present invention, synchronization timing and frequency offset may be simultaneously detected using only a single training sequence. At this time, in order to reduce computational complexity, a template signal (that is, a phase reflection template signal) is generated using a lookup table stored in advance, and synchronization timing and frequency offset are determined based on the result of performing matched filtering using the template signal. can be detected. Accordingly, while the amount of calculation/computation time is reduced, the detection accuracy is improved, and the performance of the receiver and the wireless communication system operating based thereon can be improved.

2 is a block diagram illustrating a receiver and a wireless communication system including the same according to embodiments of the present invention.

Referring to FIG. 2 , the wireless communication system 10 includes a transmitter 100 and a receiver 200 . The transmitter 100 may be referred to as an access point (AP), and the receiver 200 may be referred to as a station (STA).

In one embodiment, the wireless communication system 10 may be a wireless local area network (WLAN)-based wireless communication system. For example, the wireless communication system 10 may be a wireless communication system based on WiFi (Wireless Fidelity). For example, the WLAN system may be implemented based on the IEEE 802.11ac or IEEE 802.11ax standard, or may be implemented based on the next standard, the IEEE 802.11be standard.

In a WLAN system, communication may be performed between the transmitter 100 and the receiver 200 in an Orthogonal Frequency Division Multiplexing (OFDM) scheme. The OFDM scheme is a wideband modulation scheme in which a frequency bandwidth allocated for a communication session is divided into a plurality of narrowband frequency subbands. Each of the narrowband frequency subbands includes a radio frequency (RF) sub-carrier. and each sub-carrier may be mathematically orthogonal to an RF sub-carrier included in each of the other sub-channels.

In the OFDM scheme, data to be transmitted is first converted into a complex symbol in the form of M-ary QAM (M-ary quadrature amplitude modulation), and a complex symbol sequence that is a sequence of complex symbols is serially and parallelized. After converting to a plurality of parallel complex symbols through serial-to-parallel conversion, a multi-carrier modulation method in which each of the parallel complex symbols is square-wave shaped and sub-carrier-modulated can be In the multi-carrier modulation scheme, a frequency interval between sub-carriers may be set so that all sub-carrier modulated parallel complex symbols are orthogonal to each other. Accordingly, the OFDM scheme allows the spectrum of each subcarrier to overlap without interference with other carriers due to the orthogonality of the subcarriers, and divides the frequency bandwidth into a plurality of orthogonal subbands to achieve high data transmission rates and very efficient bandwidth usage. It may be possible.

In a WLAN system in which communication is performed in the OFDM scheme, when synchronization timing and frequency offset for an input signal are accurately and efficiently detected at the beginning of an operation, the performance of the system may be improved.

Hereinafter, operations of the wireless communication system 10 and the receiver 200 according to embodiments of the present invention will be described with a focus on the operation of detecting the synchronization timing and frequency offset for the input signal at the beginning of the operation. However, the present invention is not limited thereto, and the wireless communication system 10 may perform normal signal transmission based on the detected synchronization timing and frequency offset after detecting the synchronization timing and frequency offset.

The transmitter 100 transmits a signal SIG for detection of synchronization timing and frequency offset. For example, the signal SIG is provided in the form of a packet, and may correspond to a single training sequence.

The transmitter 100 may include a plurality of antennas (or transmit antennas) 101 . The transmitter 100 may output a signal SIG using the plurality of antennas 101 .

The receiver 200 receives an input signal ISIG corresponding to the signal SIG through a channel from the transmitter 100, performs ACF on the input signal to generate phase information and a phase index PIDX, A template signal (TEM) for a sample index (SIDX) based on at least one stored lookup table, a phase index (PIDX), and a frequency bandwidth and a sample index for the input signal (ISIG) (eg, SIDX in FIG. 3 ) ) and performing matched filtering on the input signal (ISIG) based on the template signal (TEM) to calculate the power for the sample index (SIDX), and based on the result of the matched filtering, matched filtering on the input signal (ISIG) Simultaneously determine the synchronization timing (SYNC) and frequency offset (FO) for

The receiver 200 includes a first operation unit 210 , a template generation unit 220 , and a second operation unit 230 . The receiver 200 may further include a plurality of antennas (or reception antennas) 201 .

The receiver 200 may receive the input signal ISIG from the transmitter 100 through the channel using the plurality of antennas 201 . Although not shown in detail, the channel (eg, a radio channel) may be formed between the plurality of antennas 101 of the transmitter 100 and the plurality of antennas 201 of the receiver 200 .

The first operation unit 210 receives the input signal ISIG, performs ACF on the input signal ISIG, and generates the phase information and the phase index PIDX. In other words, the first operation unit 210 may perform steps S100 and S200 of FIG. 1 .

The template generator 220 generates a template signal TEM for the sample index SIDX based on the lookup table, the phase index PIDX, the frequency bandwidth, and the sample index SIDX. In other words, the template generator 220 may perform step S300 of FIG. 1 .

The second calculating unit 230 calculates the power of the sample index SIDX by performing matched filtering on the input signal ISIG based on the template signal TEM, and based on the result of the matched filtering, the input signal ( Simultaneously determine the synchronization timing (SYNC) and frequency offset (FO) for the ISIG). In other words, the second operation unit 230 may perform steps S400 and S500 of FIG. 1 .

A detailed configuration of the first calculating unit 210 , the template generating unit 220 , and the second calculating unit 230 will be described later in detail with reference to FIGS. 15 to 17 .

According to embodiments of the present invention, the ACF of the input signal ISIG corresponding to the training sequence is calculated and updated to track the phase information of the corresponding sample timing (ie, the sample index SIDX), The phase index PIDX is determined from the phase information corresponding to the sample timing of the input signal ISIG, the template signal TEM having a ternary structure is constructed, and the synchronization timing is obtained from the matched filtering result using the template signal TEM. (SYNC) is detected, and a frequency offset (FO) can be calculated from the phase information corresponding to the synchronization timing (SYNC). In this case, there is no additional delay and frequency response distortion due to filtering by using a template signal (TEM) containing segmented band information in the frequency domain, and the accuracy of synchronization timing (SYNC) and frequency offset (FO) can be improved. have. In addition, by using only a single training sequence, it can be applied to various standards having a single or more training sequence, and in a standard including two or more training sequences, such as WLAN, it may be possible to improve accuracy by iterative operation.

3 is a diagram for explaining operations of a receiver and a wireless communication system according to embodiments of the present invention.

Referring to FIG. 3 , sampling, ACF, template signal generation, and CCF may be performed while periodically setting a sample index (SIDX) for an input signal (ISIG) received by the receiver 200 and corresponding to a single training sequence. . For example, the input signal ISIG may be an OFDM signal, and the input signal ISIG may include a plurality of OFDM symbols. For example, sampling of the input signal ISIG may be performed N _M (N _M is a natural number equal to or greater than 2) times.

Specifically, sampling is performed on the input signal ISIG at a first time point to obtain a first sampling value, and at this time, a first sample index (“0”) for the first sampling value is obtained, and the first sample index (“0”) is obtained. ACF, template signal generation, and CCF for 1 sampling value can be performed. Thereafter, sampling is performed on the input signal ISIG at a second time point that has elapsed by the sampling interval TS from the first time point to obtain a second sampling value, and a second sample index with respect to the second sampling value (“1”) is obtained, and ACF, template signal generation, and CCF for the second sampling value may be performed. A third sampling value is obtained by sampling the input signal ISIG at a third time point that has elapsed by the sampling interval TS from the second time point, and a third sample index ("2" for the third sampling value) "), and ACF, template signal generation, and CCF for the third sampling value may be performed.

Similarly, the (n+1)th sampling value is obtained by sampling the input signal ISIG at the (n+1)th time point, and the (n+)th sampling value is 1) A sample index (“n”) is obtained, and ACF, template signal generation, and CCF may be performed on the (n+1)th sampling value. Sampling the input signal (ISIG) is performed at the N _M th time point to obtain an N _M th sampling value, and an N _{M th} sample index ("N _M -1") for the N _M th sampling value is obtained, ACF, template signal generation, and CCF may be performed on the N _Mth sampling value.

In an embodiment, the N _M value may be determined based on the number of a plurality of sub-carriers present in one OFDM symbol. For example, the value of N _M may be greater than or equal to the number of the plurality of subcarriers.

In an embodiment, the sampling interval TS may be set to about 4 ms, but the present invention may not be limited thereto.

In relation to signal modeling, in general, an OFDM signal transmitted in the OFDM scheme may use a training sequence that repeats a specific unit band in the frequency domain in order to have a PN (pseudo noise) characteristic in the time domain. If an arbitrary unit band training sequence of length Nsub having PN characteristics in both the time and frequency domains is defined as X _Nsub (k) in the frequency domain, then A(t), which is the ACF value for X _Nsub (k), is It can be obtained as in Equation 1].

[Equation 1]

If a wideband or wideband signal sequence formed by repeating a plurality of X _Nsub (k) is defined as x _{sub (n) in the time domain, x sub (} n) is expressed as [Equation 2] below, , a(n), which is an ACF value for x _sub (n), may be obtained as in [Equation 3] below.

[Equation 2]

[Equation 3]

ACF is also called serial correlation, and represents the correlation between a specific signal and a delayed signal. That is, it represents the similarity between the observed values as a function of time delay between the observed values. ACF is a mathematical tool for finding repeating patterns, such as identifying the presence of periodic signals obscured by noise or missing fundamental frequencies in harmonic frequency signals. ACF is being used in signal processing to analyze a set of values or functions, such as time domain signals.

은 하기의 [수학식 7]과 같이 표현될 수 있다.A wideband signal including X _Nsub (k) in an arbitrary unit band position index b is defined as follows [Equation 4], [Equation 5] and [Equation 6], CCF result

can be expressed as in [Equation 7] below.

[Equation 4]

[Equation 5]

[Equation 6]

[Equation 7]

In signal processing, CCF represents a measure of the similarity of two series as a function of displacement relative to each other. Also called sliding dot product or sliding inner-product, it is commonly used to search for short, known features in long signals, for example in pattern recognition, single particle analysis, electron tomography, averaging, encryption analysis, etc. CCF can be similar to the convolution of two functions.

은 하기의 [수학식 8]을 만족할 수 있다.Also, by Parseval's theorem between the time domain and the frequency domain,

may satisfy the following [Equation 8].

[Equation 8]

Based on the above-mentioned contents, the training sequence using the wide band may be defined as the sum of x _N,b (n) as shown in [Equation 9] below.

[Equation 9]

For any received signal (or input signal) including x _{N, {B}} (n), a relationship such as the following [Equation 10] is established with respect to the reference signal x _{N, b} (n), and this characteristic is Various applications, such as synchronization timing and unit band detection, may be possible.

[Equation 10]

In particular, a(0), which is the CCF value, is composed of a complex conjugate multiplication operation without a delay time, so that the same calculation as the matched filtering for several reference signals can be performed.

On the other hand, most communication standards can provide a training sequence that is repeated in the time domain to estimate the frequency offset. If an arbitrary training sequence of length N repeated at intervals of N samples is defined as x _N (n), x _N (n) may satisfy [Equation 11] below.

[Equation 11]

If the frequency offset between the transmission and reception systems is f _o , the phase change φ(n) in the time domain may be expressed as in [Equation 12] below.

[Equation 12]

은 하기의 [수학식 15]와 같이 획득될 수 있다.Ignoring other channel distortion, the received signals y _N (n) and y _N (nN) are expressed as in [Equation 13] and [Equation 14] below, and the ACF value for this is

can be obtained as in [Equation 15] below.

[Equation 13]

[Equation 14]

[Equation 15]

의 각도 측정을 통해 해당 샘플의 주파수 오프셋에 의한 위상 변화를 계산할 수 있다.Here, γ is a scale value having an arbitrary positive number, and is a complex value as shown in [Equation 16] below.

By measuring the angle of , the phase change due to the frequency offset of the corresponding sample can be calculated.

[Equation 16]

The matched filtering result of the received signal y _N (n) corresponding to the training sequence and the corresponding reference signal x _N (n) may be expressed as [Equation 17] below.

[Equation 17]

If the reference signal x _P (n) reflecting the phase information is defined as in Equation 18 below, a new matched filtering result can be expressed as in Equation 19 below.

[Equation 18]

[Equation 19]

이며 w(n)=0인 경우에 최대 값을 가질 수 있다.The matched filtering result has a maximum value when the delay index n = 0, and is generally as shown in [Equation 20] below

and can have a maximum value when w(n) = 0.

[Equation 20]

Embodiments of the present invention may be implemented based on the above-described signal modeling method and matched filtering method reflecting phase information.

4 and 5 are flowcharts illustrating an example of generating the phase information and the phase index of FIG. 1 .

1, 3 and 4, in generating the phase information and the phase index (step S200), the first sampling value corresponding to a first sample index (“0”) and obtained at the first time point Based on the phase information (eg, delta phase) may be measured (step S201). A first phase index corresponding to the first sampling value and a first sample index (“0”) may be generated based on the phase information measured in step S201 (step S202).

Thereafter, the phase information may be measured and updated based on the second sampling value corresponding to the second sample index (“1”) and obtained at the second time point (step S204). A second phase index corresponding to the second sampling value and the second sample index (“1”) may be generated based on the phase information measured in step S204 (step S205).

Thereafter, the phase information may be measured and updated based on the N _M th sampling value corresponding to the N _M th sample index (“N _M −1”) and obtained at the N _M th time (step S207). . An N _M th phase index corresponding to the N _{M th} sampling value and the N _{M th} sample index (“N _M −1”) may be generated based on the phase information measured in step S207 (step S208).

1, 4, and 5, FIG. 5 shows a specific example of generating one phase information and one phase index. For convenience, the operation of FIG. 5 will be described based on the case in which steps S201 and S202 of FIG. 4 are performed.

In generating the phase information and the phase index (step S200), quantization may be performed on the input signal (ISIG of FIGS. 2 and 3) (step S210). For example, quantization to a certain level may be performed to reduce computational complexity. For example, quantization may be performed on the first sampling value obtained from the input signal ISIG.

The ACF may be performed on the quantized input signal (step S220). For example, the ACF operation may be performed based on a delay time suitable for the structure of the training sequence.

An arctangent (ATAN) function may be performed on the input signal on which the ACF has been performed (step S230). The phase information may be measured and tracked based on the input signal on which the ATAN function is performed (step S240). For example, the phase information may be measured from the result of the ACF operation having a complex form, and infinite impulse response (IIR) filtering may be performed to measure, track, and update the phase information.

A phase index (PIDX of FIG. 2 ) for generating a template signal (TEM of FIG. 2 ) may be generated based on the phase information (step S250 ). For example, the first phase index corresponding to the first sampling value and the first sample index (“0”) may be generated.

The phase index PIDX may be a value corresponding to the phase information. For example, the phase information may have any real value of -π or more and π or less (or 0 or more and 2π or less), and the corresponding phase index (PIDX) is 0 or more (K-1) (K is 2 or more natural number) and may have any integer value of or less. K may indicate a range of phase information.

As described above, by performing steps S210, S220, S230, S240 and S250 of FIG. 5, steps S201 and S202 of FIG. 4 may be performed, steps S204 and S205 of FIG. 4, and steps S207 and S208 of FIG. This can be done similarly.

6 and 7 are flowcharts illustrating an example of a step of generating a template signal of FIG. 1 .

1, 3, 4 and 6, in generating the template signal for the sample index (step S300), the at least one lookup table, a first sample index (“0”), and the first phase Based on the index and the frequency bandwidth for the input signal ISIG, a first sample index (“0”) and a first template signal for the first phase index may be generated (step S301 ).

Then, based on the lookup table, a second sample index (“1”), the second phase index and the frequency bandwidth, a second sample index (“1”) and a second template for the second phase index A signal can be generated (step S304).

Then, based on the lookup table, the N _Mth sample index (“N _M −1”), the N _M th phase index and the frequency bandwidth, the N _{M th} sample index (“N _M −1”) and the An N _M th template signal for the N _{M th} phase index may be generated (step S307).

1, 6, and 7, FIG. 7 shows a specific example of generating one template signal. For convenience, the operation of FIG. 7 will be described based on the case in which step S301 of FIG. 6 is performed.

In generating the template signal (step S300), a reference template signal may be obtained from a first lookup table based on the frequency bandwidth and the sample index (SIDX of FIG. 3) (step S310). For example, the frequency bandwidth and sample index SIDX may be obtained from the input signal (ISIG of FIGS. 2 and 3 ) without a separate operation. For example, the reference template signal may be an initial or basic template signal without phase reflection. For example, the first lookup table may include information on the reference template signal to which the phase is not reflected.

Based on the frequency bandwidth and the sample index SIDX, a plurality of reference values may be obtained from a second lookup table different from the first lookup table (step S320). For example, the second lookup table may include step size information according to a phase change corresponding to the phase information. The plurality of reference values may be used to generate a shift index for converting the reference template signal into a template signal (TEM of FIG. 2 ).

A first direction determination signal may be generated based on the sample index SIDX (step S330). A second direction determination signal may be generated based on the sample index (SIDX), the phase index (PIDX of FIG. 2 ), and the plurality of reference values (step S340 ). A template signal TEM may be obtained based on the reference template signal, the first direction determination signal, and the second direction determination signal (step S350).

As will be described later with reference to FIG. 9 , a template signal TEM is generated by phase rotating or phase shifting the reference template signal based on the phase information, and for this purpose, the directionality of the phase may be determined. According to embodiments of the present invention, the directionality of the phase may be determined by performing the two operations of steps S330 and S340. The operation of step S330 may be referred to as a primary direction determination operation (or a primary sign direction determination operation), and the operation of step S340 may be referred to as a secondary direction determination operation (or a secondary code direction determination operation).

8A and 8B are diagrams illustrating an example of a lookup table used to perform the operation of FIG. 7 .

Referring to FIG. 8A , an example of the first lookup table used in step S310 of FIG. 7 is shown.

The reference template signal corresponds to a complex value and may include a reference real number part TEM_REF_RE and a reference imaginary number part TEM_REF_IM. The first lookup table may include information on the sample index SIDX and corresponding reference real part TEM_REF_RE and reference imaginary part TEM_REF_IM.

For example, when the value of the sample index SIDX is “0”, based on the first lookup table, T _RE (0) and T _IM (0) are reference real parts included in the reference template signal, respectively. (TEM_REF_RE) and the reference imaginary part (TEM_REF_IM). Similarly, when the value of the sample index SIDX is “1”, T _RE ( 1 ) and T _IM ( 1 ) may be obtained as a reference real part (TEM_REF_RE) and a reference imaginary part (TEM_REF_IM), respectively. . When the value of the sample index SIDX is “n”, T _RE (n) and T _IM (n) may be obtained as a reference real part TEM_REF_RE and a reference imaginary part TEM_REF_IM, respectively. When the value of the sample index SIDX is "N _M -1", T _RE (N _M -1) and T _IM (N _M -1) are the reference real part (TEM_REF_RE) and the reference imaginary part (TEM_REF_IM), respectively. can be obtained with

The reference real part TEM_REF_RE and the reference imaginary part TEM_REF_IM may each have a value corresponding to one of +1, 0, and -1. In addition, when the phase index PIDX is determined, the reference template signal including the reference real part TEM_REF_RE and the reference imaginary part TEM_REF_IM is rotated according to the phase index PIDX to be converted into a template signal TEM. .

Meanwhile, similarly to the reference template signal, the template signal TEM also corresponds to a complex value, and includes an output real part and an output imaginary part, wherein the output real part and the output imaginary part are +1, 0, and -1, respectively. It can have a value corresponding to one.

Referring to FIG. 8B , an example of the second lookup table used in step S320 of FIG. 7 is shown.

The second lookup table may include information on the sample index SIDX and corresponding reference values P_STEP_RE1, P_STEP_RE2, P_STEP_IM1, and P_STEP_IM2.

For example, when the value of the sample index SIDX is “0”, S _RE (0,0), S _RE (0,1), S _IM (0,0) based on the second lookup table and S _IM (0,1) may be obtained as reference values P_STEP_RE1, P_STEP_RE2, P_STEP_IM1, and P_STEP_IM2, respectively. Similarly, when the value of the sample index (SIDX) is "1", S _RE (1,0), S _RE (1,1), S _IM (1,0), and S _IM (1,1) These may be obtained as reference values P_STEP_RE1, P_STEP_RE2, P_STEP_IM1, and P_STEP_IM2, respectively. When the value of the sample index (SIDX) is “n”, S _RE (n,0), S _RE (n,1), S _IM (n,0), and S _IM (n,1) are the reference values, respectively. (P_STEP_RE1, P_STEP_RE2, P_STEP_IM1, P_STEP_IM2). When the value of the sample index (SIDX) is "N _M -1", S _RE (N _M -1,0), S _RE (N _M -1,1), S _IM (N _M -1,0) and S _IM (N _M −1n,1) may be obtained as reference values P_STEP_RE1, P_STEP_RE2, P_STEP_IM1, P_STEP_IM2, respectively.

Calculating the template signal (TEM) in real time can be a very complex process. Even if the template signal TEM is obtained using the lookup table, it may be difficult to implement all possible cases as the lookup table. According to embodiments of the present invention, using the first and second lookup tables having a relatively simple structure, the template signal (TEM), which is the final template signal in which the phase is reflected, is obtained through a simple indexing process from a minimum reference signal set. By reorganizing, it is possible to reduce computational complexity and the size of the lookup table.

9, 10, 11A, and 11B are diagrams for explaining the operation of FIG. 7 .

9 and 10 , the reference template signal TEM_REF and the final template signal to which the phase is reflected, that is, the template signal TEM are shown.

The reference template signal TEM_REF and the template signal TEM may be respectively disposed on a complex number plane. As shown in the left side of FIG. 9 , the template signal TEM may be generated by phase-shifting the reference template signal TEM_REF based on the phase information. At this time, as shown on the right side of FIG. 9 , the reference template signal TEM_REF and the template signal TEM are mapped on ternary lattice coordinates formed on a complex plane, respectively, to reduce computational complexity. can The template signal TEM may be obtained by moving the reference template signal TEM_REF on the ternary grid coordinates based on the phase index PIDX.

As described above with reference to FIG. 8A , the reference template signal TEM_REF includes a reference real part TEM_REF_RE and a reference imaginary part TEM_REF_IM, and the reference template signal TEM_REF is mapped onto the ternary grid coordinates. The reference real part TEM_REF_RE and the reference imaginary part TEM_REF_IM may each have a value corresponding to one of +1, 0, and -1. In other words, the reference template signal TEM_REF may be determined as one of nine complex values shown in FIG. 10 .

The reference template signal TEM_REF is rotated based on the phase index PIDX. At this time, according to the ternary characteristic, the reference real part (TEM_REF_RE) and the reference imaginary part (TEM_REF_IM) are "1" -> "0" - It can have a certain conversion order, such as >"-1"->"0"->"1"->"0"->... In this case, when the value of the reference real part TEM_REF_RE or the reference imaginary part TEM_REF_IM is "1" or "-1", when the shift index is determined, the output real part or the The output imaginary part may be determined according to the conversion order. When the value of the reference real part TEM_REF_RE or the reference imaginary part TEM_REF_IM is "0", the output real part or the output imaginary part part according to the conversion order, and the reference real part TEM_REF_RE and the reference imaginary part (TEM_REF_RE) and the reference imaginary part ( TEM_REF_IM) may be determined according to cross-check.

For example, when the value of the reference real part TEM_REF_RE is "1" and the real part shift index for the reference real part TEM_REF_RE is "1", the output real part is from "1" to "1" according to the conversion order. It may be determined as “0” shifted by one. When the value of the reference imaginary part TEM_REF_IM is "-1" and the imaginary part shift index for the reference imaginary part TEM_REF_IM is "2", the output imaginary part is from "-1" to 2 according to the conversion order. It may be determined as shifted “1”. When the value of the reference real part TEM_REF_RE is "0" and the real part shift index is "1", the output real part may be determined to be "1" or "-1" according to the conversion order, and the This may require cross-checking.

As described above, in order to determine the output real part and the output imaginary part included in the template signal TEM, as described above with reference to FIG. 7 , a second step including the primary direction determining operation and the secondary direction determining operation operation may be performed.

Specifically, the first direction determination signal generated in step S330 of FIG. 7 may be obtained based on the following [Equation 21].

[Equation 21]

In Equation 21, D(n) may represent the first direction determination signal, and n may represent a sample index SIDX. For convenience of operation, D(n) is expressed as an imaginary value. The sample index SIDX has a range greater than or equal to 0 and less than N (N is a natural number equal to or greater than 2), and N may indicate the length of the template signal TEM. For example, it may be N=N _M -1.

In addition, the second direction determining signal generated in step S340 of FIG. 7 includes the real part shift index and the imaginary part shift index, and the real part shift index and the imaginary part shift index are the following [Equation 22] ] and [Equation 23].

[Equation 22]

[Equation 23]

In [Equation 22] and [Equation 23], SHIFT _RE (k, n) is the real part shift index, SHIFT _IM (k, n) is the imaginary part shift index, and k is the phase index (PIDX) , S _RE (n,0), S _RE (n,1), S _IM (n,0), and S _IM (n,1) may represent a plurality of reference values (P_STEP_RE1, P_STEP_RE2, P_STEP_IM1, P_STEP_IM2). .

Finally, the output real part and the output imaginary part included in the template signal TEM generated in step S350 of FIG. 7 are based on the following [Equation 24], [Equation 25] and [Equation 26] can be obtained.

[Equation 24]

[Equation 25]

[Equation 26]

In the above [Equation 24], [Equation 25] and [Equation 26], T _P,RE (k,n) is the output real part, T _P,IM (k,n) is the output imaginary part , T _RE (n) is a reference real part (TEM_REF_RE), T _IM (n) is a reference imaginary part (TEM_REF_IM), RE{.} is a real part acquisition function, and IM{.} is an imaginary part acquisition function. .

11A and 11B, the first and second lookup tables of FIGS. 8A and 8B, the ternary grid coordinate mapping method described above with reference to FIGS. 9 and 10, and [Equation 21] to [Mathematics A process of converting a reference template signal into a template signal is exemplified based on Equation 26]. In the example of FIGS. 11A and 11B , n<2/N, k=150, and K=256.

In the example of FIG. 11A , when T _RE (n) = 1 and T _IM (n) = -1, the reference template signal TEM_REF1 can be mapped onto the ternary lattice coordinates on the complex plane as shown. have. When n<2/N, D(n)=j may be. If S _RE (n,0)=120 and S _RE (n,1)=180, then S _RE (n,0)<k<S _RE (n,1), so SHIFT _RE (k,n) =1. In the case where S _IM (n,0)=70 and S _IM (n,1)=120, S _IM (n,1)<k, thus SHIFT _IM (k,n)=2 may be. Finally, T _P,RE (k,n)=0 and T _P,IM (k,n)=1 is obtained, so that the template signal TEM1 is on the ternary lattice coordinates on the complex plane as shown can be mapped.

In the example of FIG. 11B , when T _RE (n)=0 and T _IM (n)=1, the reference template signal TEM_REF2 may be mapped onto the ternary grid coordinates on the complex plane as shown. . Similar to that described above with reference to FIG. 11A , D(n)=j, SHIFT _RE (k,n)=1, SHIFT _IM (k,n)=2, and finally T _P,RE (k,n) =-1 and obtained as T _P,IM (k,n)=-1, thus the template signal TEM2 can be mapped onto the ternary lattice coordinates on the complex plane as shown.

In other words, in the example of FIGS. 11A and 11B , the template signals TEM1 and TEM2 may be generated by phase-shifting the reference template signals TEM_REF1 and TEM_REF2, respectively, based on the phase index k. The template signals TEM1 and TEM2 may correspond to the reference signal x _P (n) reflecting the phase information described above with reference to Equations 18 to 20 above.

12, 13 and 14 are flowcharts illustrating an example of calculating the power of FIG. 1 and simultaneously determining a synchronization timing and a frequency offset.

1, 3, and 12, in calculating the power for the sample index (step S400), the first power for the first sample index (“0”) may be calculated (step S401). Thereafter, the second power for the second sample index (“1”) may be calculated (step S404). Thereafter, the N _M th power for the N _M th sample index (“N _M −1”) may be calculated (step S407).

1, 3, 12 and 13, in simultaneously determining the synchronization timing and the frequency offset for the input signal (step S500), first to Nth powers based on the first to N _M powers One of the N _M sample indices ("0", "1", ..., "N _M -1") may be selected (step S501). A timing corresponding to the selected sample index may be determined as the synchronization timing (step S504). An offset corresponding to the selected sample index may be determined as the frequency offset (step S507).

In an embodiment, the power corresponding to the selected sample index may have the largest value among the first to _N -th powers.

1 and 14 , a specific example of selecting a sample index having the maximum power and determining a synchronization timing and a frequency offset based thereon is shown.

In calculating the power (step S400) and simultaneously determining the synchronization timing and the frequency offset (step S500), a power calculation and selection operation for the i-th sample index may be performed.

Specifically, i=0 may be set at the beginning of the operation (step S410), and the i-th power PWR(i) for the i-th sample index may be calculated (step S420). For example, the power calculation is performed by performing wideband matched filtering using the phase reflection template signal TEM, and CCF may be performed at this time.

When the i-th power (PWR(i)) calculated in step S420 is greater than the maximum power (PWR_PEAK) (step S430: Yes), the maximum power (PWR_PEAK) is updated to the i-th power (PWR(i)), The maximum power index PEAK_IDX corresponding to the maximum power PWR_PEAK may be updated to the value i (step S510). When the ith power PWR(i) is less than or equal to the maximum power PWR_PEAK (step S430: NO), step S510 may be omitted.

When the value of i is smaller than N _M −1 (step S440: No), the value of i is increased by 1 (step S450), and steps S420, S430, and S510 may be repeated.

When the value of i is equal to N _M −1 (step S440: Yes), that is, when all of the first to N _M powers for the first to N _M sample indices are calculated, the maximum power (PWR_PEAK) ) may be determined as the synchronization timing index SYNC_IDX corresponding to the synchronization timing SYNC (step S520). Also, an offset FO (PEAK_IDX) corresponding to the maximum power index PEAK_IDX may be determined as the final frequency offset FO_FINE (step S530).

15 is a block diagram illustrating an example of a first operation unit included in the receiver of FIG. 2 .

Referring to FIG. 15 , the first operation unit 210 may include a quantization unit 211 , an ACF unit 213 , an ATAN unit 215 , a phase update unit 217 , and a phase index generation unit 219 . .

The quantization unit 211 may quantize the input signal ISIG. In other words, the quantization unit 211 may perform step S210 of FIG. 5 .

The ACF unit 213 may perform the ACF on the quantized input signal ISIG_Q. In other words, the ACF unit 213 may perform step S220 of FIG. 5 .

The ATAN unit 215 may perform an ATAN function on the input signal ISIG_ACF on which the ACF has been performed. In other words, the ATAN unit 215 may perform step S230 of FIG. 5 .

The phase updater 217 may measure and track the phase information PI based on the input signal ISIG_ATAN on which the ATAN function is performed. In other words, the phase updater 217 may perform step S240 of FIG. 5 .

The phase index generator 219 may generate a phase index PIDX based on the phase information. In other words, the phase index generator 219 may perform step S250 of FIG. 5 .

16 is a block diagram illustrating an example of a template generator included in the receiver of FIG. 2 .

Referring to FIG. 16 , the template generator 220 includes a first lookup table 221 , a second lookup table 223 , a first determiner 225 , a second determiner 227 , and a third determiner ( 229) may be included.

The first lookup table 221 may store the reference template signal TEM_REF and output the reference template signal TEM_REF based on the frequency bandwidth BW and the sample index SIDX. In other words, step S310 of FIG. 7 may be performed based on the first lookup table 221 .

The second lookup table 223 is different from the first lookup table 221 , and stores a plurality of reference values RV, and a plurality of reference values RV based on the frequency bandwidth BW and the sample index SIDX. can be printed out. In other words, step S320 of FIG. 7 may be performed based on the second lookup table 223 .

In an embodiment, the sizes of the first lookup table 221 and the second lookup table 223 may be proportional to the frequency bandwidth (BW).

The first determiner 225 may generate the first direction determination signal DDS1 based on the sample index SIDX. In other words, the first determiner 225 may perform step S330 of FIG. 7 .

The second determiner 227 may generate the second direction determination signal DDS2 based on the sample index SIDX, the phase index PIDX, and the plurality of reference values RV. In other words, the second determiner 227 may perform step S340 of FIG. 7 .

The third determiner 229 may output the template signal TEM based on the reference template signal TEM_REF, the first direction determination signal DDS1 , and the second direction determination signal DDS2 . In other words, the third determiner 229 may perform step S350 of FIG. 7 .

17 is a block diagram illustrating an example of a second operation unit included in the receiver of FIG. 2 .

Referring to FIG. 17 , the second operation unit 230 may include a matched filtering unit 231 and a detection unit 233 .

The matched filtering unit 231 may calculate the power PWR of the input signal ISIG based on the input signal ISIG and the template signal TEM. For example, the matched filtering unit 231 may calculate the first to N _M th powers with respect to the first to N _M th sample indices included in the input signal ISIG. In other words, the matched filtering unit 231 may perform steps S401, S404, and S407 of FIG. 12 and steps S420 of FIG. 14 .

According to an embodiment, the quantized input signal ISIG_Q may be provided to the matched filtering unit 231 instead of the input signal ISIG.

The detection unit 233 selects one of the first to N _{M th} sample indexes based on the first to N _M th powers, and determines a timing corresponding to the selected sample index as a synchronization timing (SYNC), , an offset corresponding to the selected sample index may be determined as a frequency offset (FO). In other words, the detector 233 may perform steps S501, S504, and S507 of FIG. 13 and steps S520 and S530 of FIG. 14 .

18, 19a, 19b, 20, 21a, 21b, 22a, and 22b are diagrams for explaining the operation of a receiver and a wireless communication system including the same according to embodiments of the present invention.

Referring to FIG. 18 , synchronization timing detection accuracy is shown when embodiments of the present invention are applied to an additive white Gaussian noise (AWGN) channel and a fading channel. It can be seen that good results are shown in the general operating area.

19A and 19B, the AWGN channel and the fading channel according to the signal-to-noise ratio (SNR) of the result estimated from the received signal having the frequency offset distortion of about 20ppm (=100kHz) in the transmission frequency band of about 5GHz (For example, CH D) shows the comparison results. According to the characteristics of the OFDM-based communication system, the accuracy of the estimated frequency offset value may be affected by the synchronization timing detection accuracy.

Referring to FIG. 20 , the accuracy distribution of the estimated frequency offset is shown according to an error range. Although the frequency offset accuracy is degraded in the low SRN region, it is within the target SNR and may not significantly affect the actual reception performance. In the SNR region of about 10dB or more, it can provide accuracy within about 90% reference tolerance.

Referring to FIGS. 21A and 21B , detailed operations are shown when embodiments of the present invention are applied. A frequency offset (FO) is tracked like a thin solid line according to a sample index of the received signal, and a result (ie, power) of matched filtering in which phase information of the corresponding frequency offset is reflected may be estimated together with a thick solid line. 21A shows the measurement process and results for a frequency offset of about 0 ppm (ie, AWGN channel) in the about 5 GHz band, and FIG. 21B shows the measurement process and results for a frequency offset of about 20 ppm (ie, fading channel) in about 5 GHz band The result is shown, and the detection of the actually applied frequency offset value from the maximum value of the matched filter is shown.

22A and 22B, synchronization timing accuracy according to the measurement of the maximum value from matched filtering is shown. Each situation of the AWGN channel and the fading channel is assumed, and it can be seen that the performance difference according to the SNR is not large.

23 is a block diagram illustrating an electronic device in a network environment according to embodiments of the present invention.

Referring to FIG. 23 , in the network environment 300 , the electronic device 301 communicates with the electronic device 302 through a first network 398 (eg, short-range wireless communication), or a second network 399 ( It may communicate with the electronic device 304 or the server 308 via (eg, remote wireless communication). In one embodiment, electronic device 301 may communicate with electronic device 304 via server 308 . In one embodiment, electronic device 301 includes processor 320 , memory 330 , input device 350 , sound output device 355 , display device 360 , audio module 370 , and sensor module 376 . ), interface 377 , haptic module 379 , camera module 380 , power management module 388 , battery 389 , communication module 390 , subscriber identification module 396 , and antenna module 397 . may include According to an embodiment, at least one of the components (eg, the display device 360 or the camera module 380 ) may be omitted or another component may be added to the electronic device 301 . Depending on the embodiment, for example, as in the case of a sensor module 376 (eg, a fingerprint sensor, an iris sensor, or an illumination sensor) embedded in a display device 360 (eg, a display), some Components may be integrated and implemented.

The processor 320 may, for example, run software (eg, a program 340 ) to execute at least one other component (eg, a hardware or software component) of the electronic device 301 connected to the processor 320 . It can control and perform various data processing and operations. The processor 320 loads and processes a command or data received from another component (eg, the sensor module 376 or the communication module 390 ) into a volatile memory 332 , and results data may be stored in a non-volatile memory 334 . In one embodiment, the processor 320 operates independently of the main processor 321 (eg, a central processing unit (CPU) or application processor (AP)), and additionally or alternatively , using a lower power than the main processor 321, or the auxiliary processor 323 specialized for a specified function (eg, a graphic processing unit (GPU), an image signal processor (ISP), a sensor hub processor) (sensor hub processor), or a communication processor (CP, communication processor). Here, the auxiliary processor 323 may be operated separately from or embedded in the main processor 321 .

In this case, the auxiliary processor 323, for example, while the main processor 321 is in an inactive (eg, sleep (sleep)) state on behalf of the main processor 321, or the main processor ( While the 321 is in an active (eg, application execution) state, at least one of the components of the electronic device 301 (eg, the display device 360 , a sensor together with the main processor 321 ) It may control at least some of the functions or states associated with module 376 , or communication module 390 . In one embodiment, coprocessor 323 (eg, image signal processor or communication processor) may be implemented as some component of another functionally related component (eg, camera module 380 or communication module 390). can

The memory 330 may include various data used by at least one component (eg, the processor 320 or the sensor module 376 ) of the electronic device 301 , for example, software (eg, a program 340 ). ) and input data or output data for commands related thereto. The memory 330 may include a volatile memory 332 or a non-volatile memory 334 .

The program 340 is software stored in the memory 330 , and may include, for example, an operating system (OS) 342 , middleware 344 , or an application 346 .

The input device 350 may receive a command or data to be used by a component (eg, the processor 320 ) of the electronic device 301 from the outside (eg, a user) of the electronic device 301 . For example, the input device 350 may include a microphone, a mouse, a keyboard, or a digital pen (eg, a stylus pen).

The sound output device 355 may output a sound signal to the outside of the electronic device 301 . For example, the sound output device 355 may include a speaker used for general purposes such as multimedia playback or recording playback, and a receiver used exclusively for receiving calls. In one embodiment, the receiver may be formed integrally or separately from the speaker.

The display device 360 may visually provide information to a user of the electronic device 301 . For example, the display device 360 may include a display, a hologram device, or a projector and a control circuit for controlling the device. In one embodiment, the display device 360 includes touch circuitry configured to detect a touch, or sensor circuitry configured to measure the intensity of a force caused by the touch (eg, a pressure sensor). can do.

The audio module 370 may interactively convert a sound and an electrical signal. In an embodiment, the audio module 370 obtains a sound through the input device 350 , or an external electronic device (eg, an electronic device) connected to the sound output device 355 , or the electronic device 301 by wire or wirelessly. A sound may be output through the device 302 (eg, a speaker or headphones).

The sensor module 376 may generate an electrical signal or data value corresponding to an internal operating state (eg, power or temperature) of the electronic device 301 or an external environmental state. The sensor module 376 may include, for example, a gesture sensor, a gyro sensor, a barometer sensor, a magnetic sensor, an acceleration sensor, and a grip sensor. sensor), proximity sensor, color sensor (eg, RGB (red, green, blue) sensor), IR (infrared) sensor, medical sensor, biometric sensor, temperature sensor sensor), a humidity sensor, or an illuminance sensor.

The interface 377 may support a designated protocol that may be connected to an external electronic device (eg, the electronic device 302 ) in a wired or wireless manner. In an embodiment, the interface 377 may include a high definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface.

The connection terminal 378 is a connector capable of physically connecting the electronic device 301 and an external electronic device (eg, the electronic device 302 ), for example, an HDMI connector, a USB connector, or an SD card connector. , or an audio connector (eg, a headphone connector).

The haptic module 379 may convert an electrical signal into a mechanical stimulus (eg, vibration or movement) or an electrical stimulus that the user can perceive through tactile or kinesthetic sense. For example, the haptic module 379 may include a motor, a piezoelectric element, an electrical stimulation device, or the like.

The camera module 380 may capture still images and moving images. In one embodiment, the camera module 380 may include one or more lenses, image sensors, image signal processors, or flashes.

The power management module 388 is a module for managing power supplied to the electronic device 301 , and may be configured as, for example, at least a part of a power management integrated circuit (PMIC).

The battery 389 is a device for supplying power to at least one component of the electronic device 301 and may include, for example, a non-rechargeable primary cell, a rechargeable secondary cell, or a fuel cell. can

The communication module 390 establishes a wired or wireless communication channel between the electronic device 301 and an external electronic device (eg, the electronic device 302 , the electronic device 304 , or the server 308 ), and establishes the established communication channel. It can support performing communication through The communication module 390 may include one or more communication processors that support wired communication or wireless communication, operated independently of the processor 320 (eg, an application processor). In one embodiment, the communication module 390 may include a wireless communication module 392 (eg, a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module 394 (eg: including a local area network (LAN) communication module, or a power line communication module, and among them, the first network 398 (eg, Bluetooth, Wi-Fi direct, or infrared data association (IrDA)) using a corresponding communication module. may communicate with the external electronic device through a local area communication network) or the second network 399 (eg, a cellular network, the Internet, or a telecommunication network such as a computer network (eg, a LAN or wide area network (WAN)). . The above-described various types of communication modules 390 may be implemented as one component (eg, one chip) or as multiple components (eg, multiple chips) separated from each other. The wireless communication module 392 uses user information (eg, international mobile subscriber identity (IMSI)) stored in the subscriber identification module 396 within a communication network such as the first network 398 or the second network 399 . It is possible to distinguish and authenticate the electronic device 301 .

In one embodiment, the wireless communication module 392 included in the communication module 390 includes a transmitter and a receiver included in a wireless communication system according to embodiments of the present invention, and to perform a synchronization and frequency offset estimation method can be implemented. For example, a wireless communication module 392 included in the electronic device 301 and a wireless communication module (not shown) included in the electronic device 304 include the transmitter 100 and the receiver 200 of FIG. 2 , respectively. and the second network 399 formed between the electronic devices 301 and 304 may correspond to a channel between the transmitter 100 and the receiver 200 . The receiver 200 included in the electronic device 301 may communicate with the transmitter 100 included in the electronic device 304 , in which case synchronization and frequency offset estimation method according to embodiments of the present invention at the beginning of operation can be performed. Similarly, the receiver 200 included in the electronic device 304 may communicate with the transmitter 100 included in the electronic device 301 , wherein, at the beginning of operation, synchronization and A frequency offset estimation method may be performed.

The antenna module 397 may receive a signal or power from the outside of the electronic device 301 (eg, an external electronic device), or may transmit a signal or power to the outside (eg, an external electronic device). In one embodiment, the antenna module 397 may include a radiating element made of a conductive material or an antenna including a conductive pattern formed in or on a substrate (eg, a PCB). In one embodiment, the antenna module 397 may include a plurality of antennas. In this case, at least one antenna suitable for a communication method used in a communication network, such as the first network 398 or the second network 399 , is, for example, from a plurality of antennas to the communication module 390 (eg, wireless may be selected by the communication module 392. The signal or power may then be transmitted or received between the communication module 390 and the external electronic device via the selected at least one antenna. In one embodiment, the antenna module As a part of the 397 , components other than the radiating component (eg, a radio frequency integrated circuit (RFIC)) may be additionally formed.

Embodiments of the present invention may be usefully used in various WLAN-based communication devices and systems and any electronic devices and systems including the same. For example, embodiments of the present invention are PC (Personal Computer), notebook (laptop), cell phone (cellular), smart phone (smart phone), MP3 player, PDA (Personal Digital Assistant), PMP (Portable Multimedia Player), Digital TV, digital camera, portable game console, navigation device, wearable device, Internet of Things (IoT) device, Internet of Everything (IoE) device, e-book ), virtual reality (VR) devices, augmented reality (AR) devices, and electronic systems such as drones.

Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. you will understand that you can

Claims (10)

receiving an input signal corresponding to a single training sequence;
generating phase information and a phase index by performing an auto-correlation function (ACF) on the input signal;
generating a template signal for the sample index based on at least one prestored look-up table (LUT), the phase index, and a frequency bandwidth and a sample index for the input signal;
calculating power for the sample index by performing matched filtering on the input signal based on the template signal; and
and simultaneously determining a synchronization timing and a frequency offset for the input signal based on a result of the matched filtering. The method of claim 1, wherein generating the template signal for the sample index comprises:
obtaining a reference template signal from a first lookup table based on the frequency bandwidth and the sample index;
obtaining a plurality of reference values from a second lookup table different from the first lookup table based on the frequency bandwidth and the sample index;
generating a first direction determination signal based on the sample index;
generating a second direction determination signal based on the sample index, the phase index, and the plurality of reference values; and
and obtaining the template signal based on the reference template signal, the first direction determination signal, and the second direction determination signal. 3. The method of claim 2,
The method for estimating synchronization and frequency offset, characterized in that the reference template signal and the template signal are each mapped on a ternary lattice coordinate formed on a complex number plane. 4. The method of claim 3,
The method for estimating synchronization and frequency offset, characterized in that the template signal is obtained by moving the reference template signal on the ternary grid coordinates based on the phase index. 4. The method of claim 3,
The reference template signal includes a reference real number part and an imaginary number part, and the template signal includes an output real part and an output imaginary part,
The reference real part, the reference imaginary part, the output real part, and the output imaginary part each have a value corresponding to one of +1, 0, and -1. The method of claim 1,
The input signal includes first to N _M th sample indices (N _M is a natural number greater than or equal to 2),
Calculating the power for the sample index comprises:
and calculating first to N _M th powers for the first to N _{M th} sample indices. 7. The method of claim 6, wherein simultaneously determining the synchronization timing and the frequency offset for the input signal comprises:
selecting one of the first to N _Mth sample indices based on the first to N _Mth powers;
determining a timing corresponding to the selected sample index as the synchronization timing; and
and determining an offset corresponding to the selected sample index as the frequency offset. 8. The method of claim 7,
The method of claim 1, wherein the power corresponding to the selected sample index has the largest value among the first to N- _th powers. The method of claim 1, wherein the generating of the phase information and the phase index comprises:
performing quantization on the input signal;
performing the ACF on the quantized input signal;
performing an arctangent (ATAN) function on the input signal on which the ACF has been performed;
measuring and tracking the phase information based on the input signal on which the ATAN function is performed; and
and generating the phase index based on the phase information. a first operation unit for receiving an input signal corresponding to a single training sequence, and performing an auto-correlation function (ACF) on the input signal to generate phase information and a phase index;
Template generation for generating a template signal for the sample index based on at least one pre-stored look-up table (LUT), the phase index, and a frequency bandwidth and sample index for the input signal wealth; and
The power for the sample index is calculated by performing matched filtering on the input signal based on the template signal, and the synchronization timing and frequency offset for the input signal are simultaneously determined based on the result of the matched filtering. A receiver including a second calculating unit for determining.

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