KR102064657B1 - Method and apparatus for random access preamble generation - Google Patents

Abstract

A method and apparatus for generating a preamble are disclosed. Preamble generation method of each node (UE), (a) checking the available frequency bandwidth (bandwith); And (b) generating a preamble by mapping node identification information (ID) based on a linear frequency modulated (LFM) signal within the bandwidth in the presence of Doppler.

Description

Preamble generation method and apparatus therefor {Method and apparatus for random access preamble generation}

The present invention relates to a method and apparatus for generating a preamble in a high Doppler underwater communication, terrestrial (LTE communication), aeronautical (drone) communication system.

Over the last decade, underwater communications have become increasingly popular for commercial, scientific or military uses. The scope of underwater communications can be applied to a wide range of applications, from tactical surveillance systems to observations of living organisms. It has emerged as an essential element for the field. In particular, there has been a need for a communication technology that requires high data rates, such as environmental observation, security-related or real-time video, between unmanned submarines and sensors.

However, the acoustic wave, which is an underwater communication medium, has very difficult propagation characteristics, such as diffraction due to the reflection of the underwater medium or the beach, and the difference in temperature depth of water. Underwater acoustic waves propagate through multiple paths at very low speeds. In addition, low underwater propagation rates result in high Doppler transitions, resulting in changes in the underwater channel in the time and frequency axes. In addition, the attenuation of the underwater signal has a characteristic that changes depending on the moving distance and frequency. Therefore, underwater communication is limited to a relatively low frequency band, and bandwidth is also limited by the communication distance and the frequency band used.

For this reason, it is necessary to study the robust random access preamble in the presence of Doppler such as the underwater environment.

The present invention is to provide a method and apparatus for generating a preamble in an underwater communication, terrestrial (LTE) communication, aeronautical (drone) communication system in which high Doppler exists.

The present invention provides a method and apparatus for generating a preamble capable of generating a preamble based on an LFM signal.

According to one aspect of the present invention, there is provided a method of generating a preamble in an underwater communication, terrestrial (LTE) communication, aeronautical (drone) communication system in which high Doppler exists.

According to an embodiment of the present invention, a method of generating a preamble of each node (UE), the method comprising: (a) identifying an available frequency bandwidth; And (b) generating a preamble by mapping node identification information (ID) based on a linear frequency modulated (LFM) signal within the bandwidth in the presence of Doppler.

In step (b), a preamble may be generated by mapping each node identification information by changing a starting frequency, which is a frequency variation variable of the LFM signal, within the available frequency band.

The node identification information ID of step (b) may be mapped using the frequency sweep variable of the LFM signal.

By varying the frequency sweep variable of the LFM signal differently, each node identification information may be mapped to generate a preamble.

In order to avoid time ambiguity, a difference between time frequencies assigned to each node identification information is equal to or greater than the frequency sweep variable value and may be limited to less than half of the value obtained by subtracting the frequency sweep variable value from the bandwidth.

The LFM signal is calculated by the following equation,

는 주파수 스윕 변수를 나타내며, t는 시간을 나타내고,

는 심벌 주기를 나타낸다. Where f represents a frequency shift variable,

Represents the frequency sweep variable, t represents time,

Denotes a symbol period.

The preamble may be a random access preamble or a downlink preamble.

According to another aspect of the present invention, there is provided an apparatus for generating a preamble in an underwater communication, terrestrial (LTE) communication, aeronautical (drone) communication system in which high Doppler exists.

According to an embodiment of the present invention, an apparatus for generating a preamble of each node includes: a memory storing at least one instruction; And a processor interoperating with the memory to execute instructions stored in the memory, wherein the instructions executed by the processor include: checking an available frequency bandwidth; And generating a preamble by mapping node identification information (ID) based on a linear frequency modulated (LFM) signal within the bandwidth in the presence of Doppler. .

The generating of the preamble may generate a preamble by mapping each node identification information by changing a starting frequency, which is a frequency variation variable of the LFM signal, within the available frequency band.

The generating of the preamble may further use a frequency sweep variable of the LFM signal.

By providing a method and apparatus for generating a preamble according to an embodiment of the present invention, a preamble robust to a Doppler existence environment can be generated.

In addition, the present invention has the advantage that can be identified by mapping each node identification information based on the LFM signal.

와 f값에 따른 CTCF값을 나타낸 도면.
도 13은 본 발명의 일 실시예에 따른 CTCF의 상위 임계값과 최대값을 나타낸 도면.
도 14는 본 발명의 일 실시예에 따른 가능한 프리앰블의 개수를 나타낸 도면.
도 15는 본 발명의 일 실시예에 따른 프리앰블 생성 장치의 내부 구성을 개략적으로 도시한 도면.1 is a diagram illustrating a communication system configuration according to an embodiment of the present invention.
2 is a diagram illustrating frequency allocation of a communication system according to an embodiment of the present invention.
3 is a flowchart illustrating a preamble generation method according to an embodiment of the present invention.
4 illustrates a Fresnel integral value in accordance with an embodiment of the present invention.
5 is a view illustrating an LFM waveform according to an embodiment of the present invention.
6 is a view for explaining the instantaneous frequency of the LFM signal according to an embodiment of the present invention.
7 illustrates a spectrum of a preamble according to an embodiment of the present invention.
8 illustrates a contour line of a CTAF according to an embodiment of the present invention.
9 is a view showing a peak value and a time shift value of the CTAF according to an embodiment of the present invention.
10 is a view showing the spread of another CTAF in an embodiment of the present invention.
11 is a diagram showing simulation and analytical results of a CTCF value according to an embodiment of the present invention.
12 is according to an embodiment of the present invention.

CTCF values according to and f values.
13 illustrates the upper threshold and the maximum value of the CTCF according to an embodiment of the present invention.
14 illustrates the number of possible preambles in accordance with one embodiment of the present invention.
FIG. 15 schematically illustrates an internal configuration of a preamble generating device according to an embodiment of the present invention. FIG.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. In this specification, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or some steps It should be construed that it may not be included or may further include additional components or steps. In addition, the terms "... unit", "module", etc. described in the specification mean a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software. .

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

1 is a diagram illustrating a communication system configuration according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating frequency allocation of a communication system according to an embodiment of the present invention.

In the present specification, in order to facilitate understanding and explanation, it will be assumed that the communication system is a system applied in an underwater environment, and will be described based on this. However, it is obvious that the communication system according to the exemplary embodiment of the present invention may be equally applicable not only to the underwater environment but also to the ground (car) environment or the aviation (drone) environment.

Referring to FIG. 1, the communication system 100 includes a controller 110, a base station 115, and a sensor node 120. The communication system 100 is composed of two links, a first link Link 1 and a second link Link 2, as shown in Fig. 1. Here, the first link Link 1 is a wireless backbone link. backbone link) and connects the base station 115 located in the water with the controller 110 or the buoy on the water surface. The second link 2 connects the base station 115 and the plurality of sensor nodes 120 to each other. Connect.

2 illustrates an example of a frequency band allocated to each link. In FIG. 2, different frequency bands are used for the first link Link 1 and the second link Link 2 to avoid mutual interference. It is assumed that each link has a frequency division duplex (FDD) that divides uplink and downlink communications into frequency bands.

Referring to FIG. 2, the first link Link 1 includes one downlink and three uplinks, and a frequency band lower than that of the second link Link 2 is allocated, and the lowest link assigned to the first link is assigned. The band may be allocated to the downlink common to all base stations.

The second link Link 2 is allocated to a terminal requiring a higher transmission amount than the first link Link 1. The second link Link 2 includes one downlink and four uplinks. The second link also allocates the lowest frequency band among the frequency bands allocated in the second link, like the first link, to the downlink, and UL0, the lowest frequency band of the uplink, is a far-end terminal and UL3, the highest frequency band, is short It is assumed that each is allocated for the terminal.

In the present specification, the downlink means communication from the base station to the sensor node, and the uplink means communication from the sensor node to the base station.

General functions of the controller 110, the base station 115, and the sensor node 120 constituting the communication system 100 are already apparent to those skilled in the art, and are not related to the main subject matter of the present invention. It will be omitted.

Due to the nature of the underwater environment, the sensor node 120 may be moved instead of being fixed at a predetermined position according to the influence of algae or the characteristics of the sensor node itself. Accordingly, when data is received from the plurality of sensor nodes at the base station 115 or the controller 110, a method for identifying each sensor node is needed.

The communication system 100 according to an embodiment of the present invention assumes a Doppler-based, cellular-based communication system, and randomly identifies each sensor node when data is transmitted from a plurality of sensor nodes. A method of transmitting an access preamble will be described.

와 f값에 따른 CTCF값을 나타낸 도면이고, 도 13은 본 발명의 일 실시예에 따른 CTCF의 상위 임계값과 최대값을 나타낸 도면이며, 도 14는 본 발명의 일 실시예에 따른 가능한 프리앰블의 개수를 나타낸 도면이다. 3 is a flowchart illustrating a preamble generation method according to an embodiment of the present invention, FIG. 4 is a diagram showing a Fresnel integral value according to an embodiment of the present invention, and FIG. 5 is an LFM according to an embodiment of the present invention. 6 is a diagram illustrating waveforms, and FIG. 6 is a diagram illustrating instantaneous frequencies of LFM signals according to an embodiment of the present invention, and FIG. 7 is a diagram illustrating a spectrum of a preamble according to an embodiment of the present invention. 8 is a view showing the contour of the CTAF according to an embodiment of the present invention, Figure 9 is a view showing a peak value and a time shift value of the CTAF according to an embodiment of the present invention, Figure 10 FIG. 11 is a diagram illustrating diffusion of CTAF according to an embodiment of the present invention, and FIG. 11 is a diagram showing simulation and analytical results of CTCF values according to an embodiment of the present invention, and FIG. 12 is according to an embodiment of the present invention.

And CTCF values according to the f value, FIG. 13 is a view showing the upper threshold value and the maximum value of the CTCF according to an embodiment of the present invention, Figure 14 is a view of possible preambles according to an embodiment of the present invention It is a figure which showed the number.

In operation 310, the preamble generating apparatus 300 checks the available bandwidth.

In operation 315, the preamble generating apparatus 300 generates a random access preamble by mapping node identification information ID based on a linear frequency modulated (LFM) signal within a bandwidth when performing random access in an environment where Doppler exists.

In the present specification, for convenience of understanding and explanation, the following description will focus on generating a random access preamble. However, the preamble generating apparatus 300 according to an embodiment of the present invention may be equally applicable to the case of generating the downlink preamble based on the LFM signal. Therefore, in the following description, assuming that a random access preamble is generated and described based on this, it should be extended and interpreted as a case of generating a downlink preamble.

This will be described in more detail below.

The random access preamble according to an embodiment of the present invention can be applied in an LTE environment in which a Doppler environment exists.

The random access preamble according to an embodiment of the present invention is generated based on a linear frequency modulated (LFM) signal which is not sensitive to Doppler. The random access preamble according to an embodiment of the present invention may generate a random access preamble by mapping node identification information (ID, hereinafter referred to as node ID) based on the LFM signal.

랜덤 엑세스 프리앰블 신호는 시간축에서 수학식 1과 같이 나타낼 수 있다. Symbol period for node c

The random access preamble signal may be represented by Equation 1 on the time axis.

는 주파수 스윕 변수(frequency sweeping parameter)를 나타낸다. Here, BW represents bandwidth. In addition, f represents a frequency shift parameter,

Denotes a frequency sweeping parameter.

및

는 수학식 2와 같은 구형파로 나타낼 수 있다.Basic LFM signal,

And

May be represented by a square wave as shown in Equation 2.

는 위상을 나타내며, t는 시간을 나타낸다. here,

Represents phase and t represents time.

The characteristics of the basic LFM signal can be summarized as in Equation 3.

는 음(-), 영(0)과 양(+)의

값에 대해 각각 -1, 0, 1값을 가지는 시그넘 함수를 나타내며,

이다.here,

Is negative, zero and positive

Represents a signum function with -1, 0, and 1 value for each value,

to be.

In addition, the integral used for LFM signal analysis may be defined as shown in Equation 4.

는 각각 정규화 프레넬(Fresnel) 적분으로 정의된 사인(sine) Fresnel 적분과 코사인(cosine) Fresnel) 적분을 나타낸다. 정규화 Fresnel 적분은 수학식 5와 같이 정의될 수 있다.here,

Denotes a sine Fresnel integral and a cosine Fresnel integral defined by normalized Fresnel integration, respectively. Normalization Fresnel integration may be defined as in Equation 5.

로 수렴하는 것을 알 수 있다. 4 is a graph showing a Fresnel integral value of a 10 second period at a sampling rate (4 KHz) near the origin (0). As shown in Figure 4, the maximum value is 0.8948 for sine, 0.9775 for cosine, 30 seconds or more in the case of sine and cosine at infinity

It can be seen that the convergence.

That is, as shown in Equation 6, the LFM signal has a characteristic that the instantaneous frequency is constantly increased in the symbol period.

5 is a conceptual diagram of an LMF signal based on Equation 6. As shown in FIG. 5, the LFM signal has a waveform that is linearly modulated.

Based on the characteristics of the LFM signal, in an embodiment of the present invention, a random access preamble may be generated by mapping the node ID to at least one of a frequency shift parameter and a frequency sweeping parameter of the LFM signal.

값의 변화에 따라 도시한 도면이다. 수학식 6에서 보여지는 바와 같이,

는

일 때 원점을 지나는 직선이고,

는 원점을 지나지 않는 직선인 것을 알 수 있다. 또한, 직선의 기울기는

값에 따라 변하는 것을 알 수 있다. 도 6의 (b)에서 보여지는 바와 같이, 순간 주파수는 f값만큼 변하는 것을 알 수 있다. 즉,

이면 순간 주파수는 위로 1KHz만큼 증가하는 것을 알 수 있다. 또한, 전제 주파수는 대역폭 4KHz내에서 존재한다. FIG. 6 shows the instantaneous frequency given in Equation 6 at f and 4KHz bandwidth.

The figure shows the change of a value. As shown in equation (6),

Is

Is a straight line through the origin,

It can be seen that is a straight line that does not pass the origin. Also, the slope of the straight line

You can see that it changes according to the value. As shown in FIG. 6 (b), it can be seen that the instantaneous frequency changes by f value. In other words,

We can see that the instantaneous frequency increases by 1KHz. In addition, the premise frequency exists within the bandwidth 4KHz.

와

값에 따른 랜덤 엑세스 프리앰블의 스펙트럼은 수학식 7과 같이 Fresnel 적분 형태로 표현할 수 있다. Using the characteristics of Equations 3 and 4

Wow

The spectrum of the random access preamble according to the value may be expressed in the form of Fresnel integration as shown in Equation (7).

와

는 수학식 8과 같다. here,

Wow

Is the same as Equation 8.

의 크기의 근사값은 스테이셔너리 위상 원리(Principle of Stationary Phase, PSP)에 근거하여 수학식 9와 같이 주어질 수 있다.In equation (7)

An approximation of the size of may be given by Equation 9 based on the Principle of Stationary Phase (PSP).

와

값에 따른 랜덤 엑세스 프리앰블의 스펙트럼을 나타낸 것이다. 도 7의 (a)는

일 경우에 Fresnel 적분과 PSP에 의한 결과를 비교한 것이다. 도 10에서 Fresnel 적분에 의한 값은 PSP로부터 구해진 상수 값 -39dB (

KHz)와 -42dB (

KHz) 근처에서 변화함을 볼 수 있다. 도 7(a)에서 각 랜덤 엑세스 프리앰블의 스펙트럼은 각각 서로 다른 대역폭을 가지며, PSP 방법을 통하여 간편하게 LFM의 스펙트럼의 근사값을 구할 수 있음을 알 수 있다. 도 7(b)에서는 랜덤 엑세스 프리앰블의 스펙트럼의 중심이

만큼 이동함을 볼 수 있다. 또한 수학식 9에서

값은 스펙트럼의 대역폭에는 영향을 미치지 않으며, 스펙트럼의 크기에만 영향을 미침을 알 수 있다.

값이 커짐에 따라 스펙트럼의 대역폭이 증가하며,

값은 스펙트럼의 대역폭과 크기 모두에 영향을 미치지 않으며, 단지 스펙트럼의 중심 주파수만을 이동시킨다. 주파수를 주어진 주파수 대역폭 내에 제한 시키려면

값은 (13)에 주어진 값으로 제한된다.7 is

Wow

It shows the spectrum of the random access preamble according to the value. (A) of FIG.

In this case, the result of Fresnel integration and PSP is compared. In FIG. 10, the value obtained by the Fresnel integration is a constant value -39 dB (

KHz) and -42dB (

You can see the change near KHz). In FIG. 7A, the spectrum of each random access preamble has a different bandwidth, and it can be seen that an approximation of the spectrum of the LFM can be easily obtained through the PSP method. In FIG. 7B, the center of the spectrum of the random access preamble is

As far as you can see. Also in Equation 9

It can be seen that the value does not affect the bandwidth of the spectrum, only the size of the spectrum.

As the value increases, the bandwidth of the spectrum increases.

The value does not affect both the bandwidth and the magnitude of the spectrum, but only shifts the center frequency of the spectrum. To limit the frequency within a given frequency bandwidth

The value is limited to the value given in (13).

값과

값에 제한을 가하게 된다. Since the random access preamble is defined on the continuous time axis, the correlation characteristics of the random access preamble will also be analyzed on the continuous time axis. In one embodiment of the present invention, the continuous time autocorrelation function (CTAF) is defined as a general uncertainty function (AF). CTAF is a function of time delay and Doppler transition. The effect of Doppler on CTAF values is consequently possible

Value and

It will limit the value.

는 수식 전개의 편이상 생략되었다. CTAF는 수학식 10과 같이 나타낼 수 있다. In Equation 10, the change in CTAF due to the Doppler effect will be described. Subscript in Equation 10

Has been omitted for more than one expansion of the equation. CTAF may be expressed as in Equation 10.

. 수학식 10은 수학식 3을 이용하여 얻을 수 있다. 수학식 10에서,

의 크기는

에 영향을 받지 낳으나

,

와

에는 영향을 받는다. 본 발명의 일 실시예에서는 심벌 길이

는 적당한 값으로 고정하기로 한다. 도플러에 관한 안정도는 수학식 10의 최대값에 좌우될 수 있다. 수학식 10의 피크 값에 따라 랜덤 엑세스 프리앰블의 탐색 가능성이 결정되는데, 그 값은 도플러 환경 에서도 유지되어야 한다.

일 경우에 수학식 10은 폭

인 펄스 함수의 AF과 동일하며, 시간 지연에 따라 이동하는 삼각파 형태가 된다. 도플러 축에서는 그 크기는

Hz 단위로 영점이 생길만큼 급격하게 감소한다.

일 때는 기울어진 모양의 삼각파 형태를 가진다. 도 8은

msce,

Hz 경우의 수학식 8의 값을 등고선(contour) 형태로 나타낸 것이다. In equation (10)

. Equation 10 may be obtained using Equation 3. In Equation 10,

The size of

Unaffected by

,

Wow

Is affected. In one embodiment of the invention the symbol length

Is fixed to an appropriate value. Stability with respect to Doppler may depend on the maximum value of equation (10). The peak value of Equation 10 determines the searchability of the random access preamble, which must be maintained in the Doppler environment.

Equation 10 is

It is the same as the AF of the in-pulse function, and forms a triangular wave moving with time delay. On the Doppler axis,

Decrease rapidly enough to produce a zero point in Hz.

Has a slanted triangular wave shape. 8 is

msce,

Equation 8 in the case of Hz is shown in the contour (contour) form.

와

의 값에 따라 변화한다. CTAF의 최대값의 크기와 타임 쉬프트는 수학식 11 및 수학식 12와 같이 나타낼 수 있다.The maximum value of CTAF is an important variable

Wow

It depends on the value of. The magnitude and time shift of the maximum value of the CTAF may be represented by Equations 11 and 12.

값 (0,12,30)에 따른 피크 값을

도메인에, 서로 다른 세 개의

값 (05, 2, 4)에 따른 피크 값을

도메인에 도시한 것이다. 또, 도 9의 (c)와 (d)는 동일한 조건에서 타임 쉬프트 값을 도시한 것이다. 도 9의 (a)와 (c) 에서

일 경우에는 피크값과 타임 쉬프트 값이 변화하지 않으며, 도플러가 존재할 때는 두 값이 모두 변화함을 알 수 있다. 도 9의 (a)와 (c) 에서

,

Hz일 때 피크 값은 0.2에 이르며, 타임 쉬프트 값의 최대치는 480 샘플에 이른다. 샘플링 레이트 4 KHz를 가정하면 480 샘플은 1500m 음파의 속도에서 180 미터의 오차를 유발한다. 적은 타이밍 에러가 있는 환경에서 탐색 확률을 높이려면, 피크 값은 크게 타임 쉬프트 값은 작게 하는

의 값을 선택하여야 한다. 9 illustrates values of Equations 9 and 10. FIG. (A) and (b) of FIG. 9 are three different

The peak value according to the value (0,12,30)

In the domain, three different

The peak value according to the value (05, 2, 4)

It is shown in the domain. 9C and 9D show time shift values under the same conditions. In Figures 9 (a) and (c)

In this case, the peak value and the time shift value do not change, and when Doppler is present, both values change. In Figures 9 (a) and (c)

,

At Hz, the peak value reaches 0.2 and the maximum value of the time shift value reaches 480 samples. Assuming a sampling rate of 4 KHz, 480 samples cause 180 meters of error at a speed of 1500 m sound waves. To increase the probability of searching in environments with low timing errors, increase the peak value to decrease the time shift value.

The value of should be selected.

값을 적어도 0.5 KHz로 유지할 수 있다. 도 9 (b)에서 최소 피크 값은 4 kHz의

값에서는 매 8 Hz의 도플러마다 0.6366, 2 kHz의

값에서는 매 4 Hz의 도플러마다 0.8918, 0.5 kHz의

값에서는 50 Hz의 도플러에서는 0.91이다. 반면에 도 9의 (d)에서 타임 쉬프트 값은 반대의 특성을 갖는다. 즉, 0.5 kHz의

값에서의 타임 쉬프트 값은 4 또는 2kHz의

값에서의 그것보다 빠르게 증가한다. 50 Hz의 도플러에서 타임 쉬프트 값은 0.5, 2, 4의

값에서 각각 50, 12와 6 샘플이다. 또한 피크 값은 모든 도플러 값에 대해 0.6보다 크다. 또한 큰 값의

를 가지는 LFM 신호는 날카로운 CTAF 형상을 가진다. 수학식 10의 CTAF의 크기는 구형파 함수인

의 곱으로 주어지는 sinc 함수,

이다. 이 경우에 타임 쉬프트 값의 근사값을 수학식 13과 같이 구할 수 있다. In one embodiment of the present invention

The value can be kept at least 0.5 KHz. In Figure 9 (b) the minimum peak value is 4 kHz

Values are 0.6366 and 2 kHz for every 8 Hz Doppler

Value of 0.8918, 0.5 kHz for every 4 Hz Doppler

The value is 0.91 at 50 Hz Doppler. On the other hand, in FIG. 9D, the time shift value has the opposite characteristic. Ie 0.5 kHz

The time shift value in the value is 4 or 2 kHz

Increment faster than that in the value. At 50 Hz Doppler, the time shift values are 0.5, 2, and 4

The values are 50, 12 and 6 samples respectively. The peak value is also greater than 0.6 for all Doppler values. Also of great value

The LFM signal with has a sharp CTAF shape. The magnitude of CTAF in Equation 10 is a square wave function

Sinc function given by the product of

to be. In this case, an approximation of the time shift value can be obtained as shown in Equation 13.

값이 샘플링 레이트에 근접할 때 수학식 13의 근사값은 참값에서 멀어진다.Also

When the value is close to the sampling rate, the approximation of Equation 13 is far from the true value.

값의 변화에 따른 스프레드(spread)의 변화를 도시한 것이다.

값이 커질수록 스프레드는 적어짐을 알 수 있으며, 적은 스프레드는 타이밍 추정의 정확도를 높인다. 이상적인 시퀀스는 하나의 피크를 가지며 그 외에서는 0인 상관값을 갖는 것이다. CTAF의 대략적인 첫 번째 영점의 값은 수학식 10의 sinc 함수로부터 구할 수 있다. 값의 정확도는 샘플링 타임의 차이에 따라 달라지는데, 샘플링 레이트가 높을수록 정확하다. 첫 번째 영점은 수학식 14와 같이 주어진다. The degree of dispersion of autocorrelation values can be defined as the interval between the first zero and the maximum peak value, which greatly affects the accuracy of timing and distance measurements. (D) of FIG.

The change in spread according to the value change is shown.

It can be seen that the larger the value, the smaller the spread, and the smaller the spread, the higher the timing estimation accuracy. An ideal sequence would have one peak and otherwise have a correlation value of zero. The approximate first zero value of CTAF can be obtained from the sinc function of Equation 10. The accuracy of the value depends on the difference in sampling time, the higher the sampling rate the more accurate. The first zero is given by Equation 14.

은 0.5, 1과 3 KHz의

값에서는 각각 8.1323, 4.0325와 1.3369이 된다. In equation (14)

0.5, 1 and 3 kHz

The values are 8.1323, 4.0325 and 1.3369, respectively.

KHz의 경우에는 근사값이 차이가 많음을 볼 수 있는데, 이 현상은 샘플링 시간 차이 때문에 발생한다. 이 연구에서 샘플링 레이트는 4 KHz이다. In Figure 10

In the case of KHz, the approximation is much different, which is caused by the sampling time difference. In this study, the sampling rate is 4 KHz.

The continuous time cross correlation function (CTCF) may be defined as Equation 15 in a similar sense.

일 때는 수학식 15는 수학식 16과 같이 나타낼 수 있다.

In Equation 15, Equation 15 may be expressed as Equation 16.

로 대치한 함수와 유사한 형태를 가진다. 타임 쉬프트,

와 그에 대응하는

에서의 피크 값

는 대략적으로 수학식 17과 같이 주어질 수 있다. In Equation 15, CTAF has a Fresnel integral form. In Equation 16, CTAF is a variable of the sinc function.

It has a form similar to a function replaced by. Time Shift,

And the corresponding

Peak value at

May be approximately given by Equation 17.

와

와

값에 따라 비례하여 증가한다. In Equation 17, the time shift value is a linear approximation. That is, the time shift value

Wow

Wow

It increases in proportion to the value.

일 때의 모의 실험 결과와, 수학식 15와 수학식 16의 분석을 통한 결과를 나타낸 그래프이다. 도 11에서 두 결과가 잘 일치함을 볼 수 있다. 수학식 15의 계산에서 Fresnel 적분의 값은 도 4에 주어진 수치 값을 계산하여 사용하였다. 도 11의 (a)에서

가 50인 경우 상호 상관값은 최대 피크 값의 50%인 0.5까지 이르는 것을 알 수 있다. 도 11의 (b)에서는

와

를 모두 0으로 하였으며, 제로 타임에서 최대 상관값을 얻음을 알 수 있다. 11 is

It is a graph showing the results of the simulation when and the results of the analysis of equations (15) and (16). It can be seen from Fig. 11 that the two results agree well. In the calculation of Equation 15, the value of Fresnel integration was used by calculating the numerical value given in FIG. In Figure 11 (a)

When 50 is the cross-correlation value it can be seen that reaches to 0.5, 50% of the maximum peak value. In Figure 11 (b)

Wow

Are all 0, and it can be seen that the maximum correlation value is obtained at zero time.

와

값의 변화에 따른 샘플된 CTCF의 값을 보여준다. 여기서

KHz,

Hz이다. 도 12의 (a)는 세 개의

값 (0.55, 2와 1)에 따른 수학식 16의 결과를 나타낸다. 여기서

값이 증가하면 상호 상관값이 감소하는 것을 알 수 있다. 도 12의 (b)에는 최대 피크 외에 두 개의 큰 피크를 보이는데, 첫 번째는

Hz(

Hz) 두 번째는

Hz(

Hz)에서 나타나는 것을 알 수 있다. 이 두 피크는

Hz인 랜덤 엑세스 프리앰블에 대해 상관을 할 경우에 시간 추정의 모호성(ambiguity)이 발생한다. 도 12의 (b)의 피크 값과 그에 대응하는 타임 쉬프트 값은 수학식 17에 의해 예측이 가능하다. 이 시간 모호성을 피하려면

의 값은 수학식 18과 같이 제한하여 해결할 수 있다.12 is

Wow

Show the value of the sampled CTCF as the value changes. here

KHz,

Hz. 12 (a) shows three

The result of Equation 16 according to the values (0.55, 2 and 1) is shown. here

It can be seen that as the value increases, the cross correlation value decreases. 12 (b) shows two large peaks in addition to the maximum peak.

Hz (

Hz) The second one

Hz (

Hz). These two peaks

The ambiguity of time estimation occurs when correlating for a random access preamble of Hz. The peak value of FIG. 12B and the corresponding time shift value can be predicted by Equation 17. FIG. To avoid this time ambiguity

The value of can be solved by limiting it as in Equation 18.

일 경우에만 성립하는데, 그렇지 않은 경우에는 오직 한 개의

만이 가능하며 그에 대응하는 하나의 랜덤 엑세스 프리앰블만을 생성할 수 있다. 예로,

와

가 모두 0.5 KHz일 때는 7개의 랜덤 액세스 프리앰블 (

)의 생성이 가능하며, 이 경우에는 모호성이 발생하지 않는다. 그러나 대역폭이 제한되어 있으므로 작은 상관값을 가지는 랜덤 엑세스 프리앰블을 다수 생성하기 위하여는

의 값을 적절하게 선택하여야 한다. 랜덤 엑세스 프리앰블의 개수에 관하여 보다 자세한 분석을 하기 위하여 CTCF 값의 상위 임계값 (upper bound)을 살펴본다.

와

를 각각 싸인형 Fresnel 적분과 코싸인형 Fresnel 적분의 최대값이라 하면, 수학식 19와 같은 관계식을 얻을 수 있다. The condition of Equation 18 is

Only if, otherwise only one

Only one and only one random access preamble can be generated. For example,

Wow

Are 7 random access preambles

) Can be created, in which case no ambiguity occurs. However, because bandwidth is limited, in order to generate a large number of random access preambles having a small correlation value,

The value of should be chosen appropriately. For a more detailed analysis of the number of random access preambles, we look at the upper bound of the CTCF value.

Wow

If the maximum value of the signed Fresnel integral and the cosine Fresnel integral, respectively, can be obtained as shown in equation (19).

In Equation 19, the upper threshold of the CTCF is given as follows.

,

이다. 수학식 20에서 상위 임계값은

나

값의 함수가 아님으로 CTCF 값 또한

나

값의 영향이 최소임을 짐작할 수 있다. 그러나 심벌 길이

와,

와

값의 차이는 큰 영향을 미친다. 즉,

의 값이 커질수록 상위 임계값은 작아진다. 가능한 주파수 스윕 변수의 범위는 CTAF 의 특성이 좋은 양수 부분과 음수 부분의 합집합이다. 즉,

이다. 여기서

이고

이며,

는 타임 쉬프트, 최대 크기와 스프레드 측면에서 가장 좋은 CTAF를 제공하는 가장 작은 값이다. From FIG. 4

,

to be. In Equation 20, the upper threshold is

I

Not a function of value, so the CTCF value

I

It can be assumed that the influence of the value is minimal. But symbol length

Wow,

Wow

The difference in values has a big impact. In other words,

The larger the value of, the smaller the upper threshold. The range of possible frequency sweep variables is the union of the positive and negative portions of the CTAF, which have good characteristics. In other words,

to be. here

ego

Is,

Is the smallest value that provides the best CTAF in terms of time shift, maximum size and spread.

으로 주어지는 CTCF의 최대값을 보여준다. 여기서

는 0.5 KHz이고,

는 임의의 적절한 값이고,

는

의 값을 변화시켜 얻어진다. 상위 임계값은

와

이 증가함에 따라 감소하는 것을 알 수 있다. 또한, CTCF의 최대값은 상위 임계값보다 작으며,

와

이 증가함에 따라 감소한다. 또한 최대값과 상위 임계값은

=0에 대하여 대칭인 것을 알 수 있다. 도 13의 (a)에서

가 양수일 때는

,

는 집합

의 원소이다.

가 음수일 때는

,

는 집합

의 원소이다. 도 13의 (b)는 도 13의 (a)에서 양의 부분만을 도시한 것이다. 도 13의 (c) 및 (d)는

를 각각

KHz와

KHz로 설정하여 위와는 반대로 설정한다. 다시 말해,

가 양수일 때는

KHz,

이고,

가 음수일 때는

,

이다. 도 13의 (a), (b) 및 (c)로부터 CTCF의 최대값은 항상 상위 임계값보다 작다. 그러나 도 13의 (d)에서 보듯이

의 값이 동작 대역폭에 근접할 때에는 그 반대 현상이 발생한다. 그러나 최대값이 상위 임계값보다 많이 크지는 않다. 심벌 길이가 125ms일 경우에 최대값이 7.7% 더 크다. 그러므로 CTCF의 관점에서

에 관한 수학식 1의 조건은 성립한다. 13 is the upper threshold value of Equation 20

Shows the maximum CTCF given by. here

Is 0.5 KHz,

Is any suitable value,

Is

It is obtained by changing the value of. The upper threshold is

Wow

It can be seen that as the increase increases. In addition, the maximum value of the CTCF is less than the upper threshold,

Wow

It decreases as it increases. Also, the maximum and upper thresholds

It can be seen that it is symmetric about = 0. In Figure 13 (a)

Is positive

,

Set

Is an element of.

Is negative

,

Set

Is an element of. FIG. 13B shows only the positive part in FIG. 13A. (C) and (d) of FIG.

Each

KHz and

Set KHz to the opposite of the above. In other words,

Is positive

KHz,

ego,

Is negative

,

to be. From Figs. 13A, 13B and 13C, the maximum value of the CTCF is always smaller than the upper threshold value. However, as shown in Fig. 13D

The opposite occurs when is close to the operating bandwidth. However, the maximum is not much greater than the upper threshold. The maximum value is 7.7% larger when the symbol length is 125ms. Therefore in terms of CTCF

The condition of Equation 1 in relation to holds.

The number of random access preambles that can be generated is given by Equation 21.

의 값은 도 13이나 수학식 18에 주어진 상위 임계값으로부터 수학식 22와 같이 정의될 수 있다.From the stomach

The value of may be defined as in Equation 22 from the upper threshold given in Equation 13 or Equation 18.

값에 따라

의 함수로 도시한 것이다.

가 증가할 때, 랜덤 엑세스 프리앰블의 수는 감소하는 것을 알 수 있다. 최저 랜덤 엑세스 프리앰블의 수는 4이다. 도 13의 (b)에서 최대 상호 상관값은 가 0.5 KHz, 심벌 길이가 125ms, 25ms, and 50ms 인 경우 각각 16%, 11%와 7.5%이다. 이 경우 랜덤 엑세스 프리앰블의 수는 약 16이다. 만약 수학식 18과 수학식 1에서

KHz,

로 설정하면 랜덤 엑세스 프리앰블의 수는 8개가 증가한다. 첫 6 개의 랜덤 엑세스 프리앰블은

KHz,

KHz로 설정하여 생성하고, 두 번째 두 개의 RAP는

,

KHz에서 생성한다. 결과적으로

KHz에서 총 24 랜덤 엑세스 프리앰블을 생성할 수 있다. The number of Equation 21 does not consider the number of random access preambles generated in the frequency shift axis. 14 shows the number of random access preambles of Equation 21

According to the value

It is shown as a function of.

As can be seen, the number of random access preambles decreases. The number of lowest random access preambles is four. In FIG. 13B, the maximum cross-correlation values are 16%, 11%, and 7.5% when 0.5 KHz and symbol lengths of 125 ms, 25 ms, and 50 ms, respectively. In this case, the number of random access preambles is about 16. If in Equation 18 and Equation 1

KHz,

If set to 8, the number of random access preambles is increased. The first six random access preambles

KHz,

Is set to KHz, and the second two RAPs

,

Generate at KHz. As a result

A total of 24 random access preambles can be generated at KHz.

FIG. 15 is a diagram schematically illustrating an internal configuration of a preamble generating device according to an embodiment of the present invention.

Referring to FIG. 15, the preamble generating apparatus 300 according to an embodiment of the present invention includes a memory 1510 and a processor 1515.

The memory 1510 stores at least one instruction.

The processor 1515 is interlocked with the memory 1510 and is a means for executing instructions stored in the memory 1510.

As described with reference to FIGS. 3 to 14, the instructions executed by the processor 1515 may generate a random access preamble by differently mapping node identification information ID based on the LFM signal. This will be the same as described with reference to FIGS. 3 to 14, and thus redundant descriptions thereof will be omitted.

In addition, embodiments of the present invention can be implemented in the form of program instructions that can be executed by various computer means may be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks such as floppy disks. Examples of program instructions such as magneto-optical, ROM, RAM, flash memory, etc. may be executed by a computer using an interpreter as well as machine code such as produced by a compiler. Contains high-level language codes. The hardware device described above may be configured to operate as one or more software modules to perform the operations of one embodiment of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help the overall understanding of the present invention, the present invention is not limited to the above embodiments, Various modifications and variations can be made by those skilled in the art to which the present invention pertains. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

300: preamble generating device
1510: memory
1515: processor

Claims (11)

In the preamble generation method of each node (UE),
(a) identifying available frequency bandwidths; And
(b) generating a preamble by mapping node identification information (ID) based on a linear frequency modulated (LFM) signal within the bandwidth in the presence of Doppler,
In step (b),
And generating a preamble by mapping identification information of each node by changing a starting frequency, which is a frequency variation variable of the LFM signal, within the available frequency band.

delete According to claim 1,
Node identification information (ID) of step (b),
And generating a frequency sweep variable of the LFM signal.
The method of claim 3, wherein
And generating a preamble by mapping identification information of each node by differently changing frequency sweep variables of the LFM signal.
The method of claim 3, wherein
The difference between frequencies assigned to each node identification information to avoid time ambiguity is equal to or greater than the frequency sweep variable value and is limited to less than half of the value obtained by subtracting the frequency sweep variable value from the bandwidth.
delete According to claim 1,
The preamble is a preamble generation method, characterized in that the random access preamble or downlink preamble.
A computer-readable recording medium having recorded thereon a program code for performing the method according to claim 1.
In the preamble generating device of each node (UE),
A memory for storing at least one instruction; And
Includes a processor to execute instructions stored in the memory in conjunction with the memory,
Instructions executed by the processor are:
(a) identifying available frequency bandwidths; And
(b) generating random access preamble by mapping node identification information (ID) based on a linear frequency modulated (LFM) signal within the bandwidth when performing random access in an environment where Doppler exists;
In step (b),
And generating a preamble by mapping identification information of each node by changing a starting frequency, which is a frequency variation variable of the LFM signal, within the available frequency band.
delete The method of claim 9,
Generating the preamble,
And a frequency sweep variable of the LFM signal.

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