KR101736162B1 - Modulation/Demodulation method for improving the survivability of Chirp Spread Spectrum wireless communication system - Google Patents

Abstract

The present invention relates to a modulation and demodulation technique, and more particularly, to a modulation and demodulation method for implementing survivability of wireless communication, capable of satisfying anti-jamming and low probability of detection at the same time. According to the present invention, the survivability of a wireless communication system can be increased by implementing an access method for increasing the survivability of communication in the same time-bandwidth product. The method includes the steps of: generating a modulation signal; considering a time-bandwidth product and a cross-correlation property in the modulation signal; analyzing anti-jamming performance; generating a jamming output signal; and generating a demodulation signal.

Description

[0001] The present invention relates to a modulating / demodulating method for improving the survivability of a CSS wireless communication system,

The present invention relates to a modulation and demodulation technique, and more particularly, to a modulation and demodulation method for realizing an increase in the survivability of a wireless communication that can simultaneously satisfy anti-jamming / low-jam detection.

A typical spread spectrum technique is exposed to various jamming and / or detection techniques and only increases the processing gain in order to increase the survivability of the communication. However, in order to increase processing gain, there is a disadvantage that the PN (pseudo-noise) chip speed, which is a spreading code, must be increased within the same data transmission rate.

In addition, since the actual spreading bandwidth is also limited, problems arise in terms of implementation.

Particularly, in a communication system which is currently aiming at high-speed transmission, a portion where a PN chip is generated at a speed higher than a data transmission speed is also problematic in that it is not economical.

만을 고려하여 항재밍/저피탐 성능을 높이려고 접근하고 있다는 문제점이 있다. In a CSS (Chirp Spread Spectrum) system, a time-bandwidth product

There is a problem in approaching to improve anti-jamming / low-fat performance.

1. Korean Registered Patent No. 10-1034949 (May 05, 2011) (Title of the invention: Performance analysis method of CSS system according to tone jamming signal) Method for analyzing bit error rate for partial band jamming environment in direct modulation-differential four-phase phase-shift keying system based on chirp signal spread spectrum method And its apparatus)

1. Jang, Won-Seok, "A Study on Optimum Receiver Demodulation Technique in Spread Spectrum Wireless Communication System" Dissertation (Ph.D.) Ajou University 2004 2. Kim, Baek Hyun et al., "Surveillance of Radio Communication System for Train Control", Proceedings of the KSRS Fall III Conference,

내에서 통신의 생존성을 증대시키기 위한 접근 방식을 구현하는 무선 통신 시스템의 생존성 증대를 위한 변복조 방법을 제공하는데 그 목적이 있다.The present invention has been proposed in order to solve the problem according to the above background art, and a time-bandwidth product (Time-Bandwidth Product)

And more particularly, to a method and apparatus for increasing the survivability of a wireless communication system implementing an approach for enhancing the survivability of communication within a wireless communication system.

Another object of the present invention is to provide a modulation / demodulation method that realizes an efficient anti-jamming / low-complexity technique considering cross-correlation between two different chirp signals.

내에서 통신의 생존성을 증대시키기 위한 접근 방식을 구현하는 무선 통신 시스템의 생존성 증대를 위한 변복조 방법을 제공한다.SUMMARY OF THE INVENTION In order to achieve the above-described object, the present invention provides a time-

The present invention provides a modulation and demodulation method for increasing the survivability of a wireless communication system implementing an approach for enhancing the survivability of communication within a wireless communication system.

The modulation / demodulation method includes:

A modulation and demodulation method for increasing the survivability of a chirp spread spectrum (CSS) wireless communication system having a transmitter and a receiver,

(a) modulating an input signal by the transmitter to generate a modulated signal;

(b) considering the time-bandwidth product and cross-correlation property of the modulated signal for the transmitter to increase the survivability of the modulated signal; And

(c) analyzing the anti-jamming performance of the transmitter using the time-of-band product and the cross-correlation property;

(d) generating a jamming output signal by applying the time-domain product and cross-correlation property to the transmitter; And

(e) demodulating the jamming output signal by the receiver to generate a demodulation signal.

Also, the step (b) may be characterized by considering cross-correlation of various chirp signal types.

(여기서, P_b는 BER(Bit Error Rate) 성능이고,

는 펄스 재밍의 듀티 사이클(Duty Cycle)이고,

는 Q-함수(function)이며,

는 신호의 에너지,

는 싱글 사이드(Single-Side) 재머의 재밍 전력 밀도이고,

는 처프 신호(Chirp)의 교차 상관(Cross-Correlation) 값을 의미한다)에 대해 처프 신호 기반 전송 기법에서 펄스 재밍에 대한 듀티 사이클(Duty Cycle) 및 처프 신호(Chirp) 사이에서 발생되는 교차 상관성 특성을 고려하여 펄스 재밍에 대한 항재밍 성능을 예측함으로써 이루어지는 것을 특징으로 할 수 있다.Further, in the step (c), the analysis on the anti-

(Where P _b is a bit error rate (BER) performance,

Is a duty cycle of pulse jamming,

Is a Q-function,

The energy of the signal,

Is the jamming power density of a single-side jammer,

Correlation between the duty cycle (Duty Cycle) for pulse jamming and the chirp signal (Chirp) in the chirp signal-based transmission scheme for the chirp signal (Chirp) Jamming performance for pulse jamming is considered in consideration of the jamming performance.

(P_b는 BER(Bit Error Rate) 성능이고,

는 Q-함수(function)이며,

는 신호의 에너지,

는 싱글 사이드(Single-Side) 재머의 재밍 전력 밀도이고, N₀는 잡음 전력 스펙트럼 밀도 (Noise Power Spectral Density),

는 처프 신호(Chirp)의 교차 상관(Cross-Correlation) 값을 의미한다)에 대해 처프 신호 기반 전송 기법에서 교차 상관성 특성을 고려하여 톤 재밍에 대한 항재밍 성능을 예측함으로써 이루어지는 것을 특징으로 할 수 있다.On the other hand, in the step (c), the analysis on the anti-

(P _b is a bit error rate (BER) performance,

Is a Q-function,

The energy of the signal,

Is the jamming power density of the single-side jammer, N ₀ is the noise power spectral density,

Jamming performance for tone jamming in consideration of the cross-correlation property in the chirp signal-based transmission scheme with respect to the chirp signal Chirp (which means a cross-correlation value of the chirp signal Chirp) .

Also, the chirp-based transmission scheme may be a CSS-BOK (Chirp Spread Spectrum-Binary Orthogonal Keying) transmission scheme.

On the other hand, the chirp-based transmission scheme may be a CSS-DM (Chirp Spread Spectrum-Direct Modulation) scheme.

Also, the chirp signal may be a different chirp signal having an orthogonal characteristic, and the transmitter may directly apply the different chirp signals.

On the other hand, the chirp signal may be a PN code for spread spectrum.

Also, as the time-bandwidth product increases, the cross-correlation characteristic decreases and the orthogonal characteristic increases.

In addition, the cross-correlation characteristic may be calculated using a multiple linear chirp (MLC) technique or a non-linear chirp technique.

내에서 통신의 생존성을 증대시키기 위한 접근 방식을 구현함으로써 무선 통신 시스템의 생존성을 증대할 수 있다.According to the present invention, the same Time-Bandwidth Product

It is possible to increase the survivability of the wireless communication system by implementing an approach to increase the survivability of the communication within the wireless communication system.

Another advantage of the present invention is that an efficient anti-jamming / low-fidelity technique that takes into account cross-correlation between two different chirp signals can be implemented.

Further, another advantage of the present invention is that the low-pass performance is excellent by considering cross-correlation rather than simply considering a time-bandwidth product.

FIG. 1 is a graph showing a general detection probability in a general AWGN (Additive White Gaussian Noise) environment.
2 is a diagram showing an example of a general wideband jamming signal.
3 is a diagram showing a spectrum of a general variety of tone jamming signals.
FIG. 4 is a graph showing a cross-correlation characteristic according to a time-bandwidth product.
5 is a conceptual diagram showing a general wireless communication system model.
FIG. 6 is a block diagram showing a detailed configuration of a radiometer configured in the interceptor 531 shown in FIG.
7 is a graph showing anti-jamming performance in a general wideband jamming environment.
8 is a graph illustrating anti-jamming performance in a broadband jamming environment according to an embodiment of the present invention.
9 to 12 are graphs illustrating anti-jamming performance in a pulse jamming environment according to an embodiment of the present invention.
13 to 16 are graphs showing anti-jamming performance in a tone jamming environment according to an embodiment of the present invention.
FIG. 17 is a graph showing an example of comparison of low-pass performance between an SLC (Single Linear Chirp) technique and an MLC (Multiple Linear Chirp) technique according to an embodiment of the present invention.
18 is a configuration block diagram of a modulation and demodulation system 1800 for increasing the survivability of a wireless communication system according to an embodiment of the present invention.
FIG. 19 is a block diagram of a modulation and demodulation system 1900 for increasing the survivability of a wireless communication system according to another embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a modulation and demodulation method for increasing the survivability of a wireless communication system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

의 성능은 다음 수학식으로 표현되며, 이론적인 값을 도시한 도면이 도 3이다.FIG. 1 is a graph showing a general detection probability in a general AWGN (Additive White Gaussian Noise) environment. Referring to FIG. 1, a general detection probability in an AWGN environment

Is expressed by the following equation, and FIG. 3 is a diagram showing a theoretical value.

는 오경보율 (Probability of False Alarm)로 일반적으로는 10^-6을 가정하며, SNR은 신호대 잡음비(signal to noise ratio)를 나타내고, Q 함수(Q-function)는 다음 수학식과 같이 정의된다.here,

Is a Probability of False Alarm, which is generally assumed to be 10 ^-6 , SNR denotes a signal to noise ratio, and a Q-function is defined by the following equation.

Where x is the starting point of the integration and e is the exponential function.

내에 전체 전력이

인 AWGN(Additive White Gaussian Noise) 형태로 존재한다. 다음 수학식은 광대역 재밍 환경에서 일반적인 DSSS(Direct Sequence Spread Spectrum) 시스템의 이론적인 BER(Bit Error Rate) 성능을 나타낸 것이다.2 is a diagram showing an example of a general wideband jamming signal. Referring to FIG. 2, broadband jamming refers to a method of jamming an arbitrary frequency that simultaneously covers all frequency bands through broadband modulation. As shown in FIG. 2,

Full power within

In the form of Additive White Gaussian Noise (AWGN). The following equation shows the theoretical bit error rate (BER) performance of a conventional Direct Sequence Spread Spectrum (DSSS) system in a broadband jamming environment.

Where E _b is the energy of the signal, and N _j is the jamming power density of the single-side jammer.

는 중심 주파수,

는 확산 대역폭 (Hz),

는 확산 대역폭 내의 재밍 전력을 나타낸다.2,

The center frequency,

Is the spreading bandwidth (Hz),

Represents the jamming power within the spread bandwidth.

이 항재밍 성능에 영향을 미치는데

가 짧을수록 한 심벌에 여러 개의 재밍 신호가 간섭을 일으키게 되어 항재밍 성능이 저하된다. On the other hand, pulse jamming is a technique of applying jamming by generating a strong pulse for a short time using a characteristic in which a short signal in the time domain appears widely in the frequency domain. In a pulse jamming environment, a duty cycle of a pulse per unit time

This affects jamming performance

The jamming performance of several jamming signals is interfered with one symbol.

일 때 광대역 재밍과 동일한 BER 성능을 보인다.In general, anti-jamming schemes for pulse jamming are based on coding and interleaving. The following equation shows the theoretical BER (Bit Error Rate) performance of a general DS / BPSK (Binary Phase Shift Keying) system in a pulse jamming situation,

, It shows the same BER performance as broadband jamming.

는 단위 시간 당 펄스의 듀티 사이클을 나타낸다.here,

Represents the duty cycle of the pulse per unit time.

3 is a diagram showing a spectrum of a general variety of tone jamming signals. Referring to FIG. 3, in a manner of jamming with one or several tones, it is represented by the following equation.

는 톤의 개수, t는 시간,

는 톤의 크기, 는 톤의 주파수,

는 톤의 위상을 의미한다.here,

Is the number of tones, t is the time,

The size of the tone, Is the frequency of the tone,

Means the phase of the tone.

The anti-jamming scheme for tone jamming is a method of lowering the occupied bandwidth ratio of jamming through spread spectrum. The anti-jamming performance is improved as the spreading bandwidth is increased. The following equation shows the BER performance of the DS / BPSK system for tone jamming.

Where N ₀ represents the noise power spectral density.

FIG. 4 is a graph showing a cross-correlation characteristic according to a time-bandwidth product. Referring to FIG. 4, techniques for improving survivability of a wireless communication signal that can cope with a jamming and detection technique for a friend group's signal include Direct Sequence Spread Spectrum (DSSS), Frequency Hopping Spread Spectrum (FHSS) Spread Spectrum) technique.

를 설명한다. Time-Bandwidth Product

는 CSS 시스템에서 사용되는 용어로, 일반적인 DSSS와 FHSS에서의 처리 이득(Processing Gain)과 동일한 개념으로 사용된다. Here, in the embodiment of the present invention, a time-bandwidth product (CSS)

. Time-Bandwidth Product

Is a term used in the CSS system. It is used in the same concept as the processing gain in general DSSS and FHSS.

은 처프 신호 지속기간(Chirp Duration)으로 단위는 초(s)이고,

는 처프 신호 대역폭(Chirp Bandwidth)으로 단위는 헤르츠(Hz)가 된다. 즉, 처프 신호(Chirp) 신호를 이용하여 확산하고자 하는 대역폭을 의미한다. 따라서, 시간 대역폭(Time-Bandwidth Product)

가 높을수록 항재밍/저피탐 성능 또한 높아질 것으로 예상할 수 있다. 다음 수학식은 시간 대역폭 곱(Time-Bandwidth Product)

에 따른 일반적인 CSS 시스템의 교차 상관성(Cross-Correlation) 특성을 표현한 것이다.here

Is the chirp duration, expressed in seconds,

Is a chirp bandwidth (unit: hertz (Hz)). That is, it means a bandwidth to be spread using a chirp signal. Thus, the time-bandwidth product

It can be expected that the anti-jamming / anti-jamming performance will also increase. The following equation is the time-bandwidth product:

And the cross-correlation characteristics of a typical CSS system according to the present invention.

는 시간 대역폭 곱을 나타내며,

와

에 대한 두 개의 적분은 Fresnel's 적분으로 다음 수학식과 같다.here,

Represents the time-bandwidth product,

Wow

The two integrals for Fresnel's integral are as follows.

이 1

이고, 처프 신호 대역폭(Chirp Bandwidth)

가 50MHz 일 때의 결과이다. 도 4의 결과를 분석하면 시간 대역폭 곱(Time-Bandwidth Product)

가 커질수록 교차 상관성(Cross-Correlation) 특성이 줄어들게 되므로 항재밍/저피탐 특성을 높일 수 있다는 것을 의미한다.FIG. 4 shows the result of Equation (7). The chirp duration (Chirp Duration)

This 1

, The chirp bandwidth (chirp bandwidth)

Is 50 MHz. Analysis of the results of FIG. 4 reveals that the Time-Bandwidth Product

The cross-correlation characteristics are reduced, which means that the anti-jamming / low-fatigue characteristic can be enhanced.

5 is a conceptual diagram showing a general wireless communication system model 500. FIG. 5 illustrates a wireless communication system model 500 in an electronic warfare wherein the wireless communication system 500 includes a transmitter 510, a transmitter antenna 511, a friendly receiver 520, The first antenna 532-1, the second antenna 532-1, and the like. In addition, an enemy group receiver 530 is configured with an interceptor 531 for intercepting a signal, a jammer 532 for jamming, and the like.

In an embodiment of the present invention, it is assumed that an enemy receiver (Unintended Receiver) 530 detects a signal transmitted from a friendly transmitter 510 to an associated receiver 520. [

In an actual electronic warfare environment, an interceptor 531 in the enemy's receiver 530 is used to generate a first signal (e. G., A signal < / RTI > The presence of the < / RTI >

The Low Probability of Detection technique is a technique for reducing the probability that a signal is detected at the interceptor 531. Since the technique can improve the anti-jamming performance, the anti-jamming / We need modulation and demodulation techniques to increase the survivability of wireless communication.

FIG. 6 is a block diagram showing a detailed configuration of a radiometer configured in the interceptor 531 shown in FIG. Referring to FIG. 6, a radiometer includes a first antenna 531-1 for receiving a signal, a bandpass filter 610 for filtering the signal, a square function for processing the filtered signal using a square function A squaring function unit 620, an integrator 630 for integrating a signal, and a comparator 640 for comparing signals.

It is assumed that this radiometer can detect wideband signals and detect all types of spread spectrum signals. Therefore, an energy detection technique using a radiometer is generally used.

는 다음 수학식과 같이 표현된다.The energy of the received signal detected by the radiometer

Is expressed by the following equation.

Where r is the received signal and T is the sampling time of the integrator.

시간에서 발생되는 에너지의 양을 임계치 (Threshold)

와 비교하여 신호의 존재 유무를 탐지하게 된다.Thus, the Radiometer

The amount of energy generated in the time is defined as a threshold (Threshold)

The presence of the signal is detected.

뿐만이 아니라 서로 다른 두 개의 처프 신호(Chirp) 사이에서 발생되는 교차 상관성(Cross-Correlation)도 고려한다. In an embodiment of the present invention, a conventional Time-Bandwidth Product (CSI) is an approach for increasing the viability of a chirp spread spectrum (CSI) based wireless communication system.

In addition, cross-correlation between two different chirp signals is also considered.

To design the system, the theoretical performance of each transmission technique is required. For this purpose, we first derive the theoretical values for various anti-jamming performance, and compare the CSS-BOK (Chirp Spread Spectrum-Binary Orthogonal Keying) transmission technique and the CSS-DM (Chirp Spread Spectrum-direct modulation) Simulation experiments were performed. There are several techniques considering cross-correlation, such as multiple linear chirp (MLC) and non-linear chirp techniques.

In one embodiment of the present invention, an MLC technique is considered as a technique considering cross-correlation, and a single linear chirp that considers only TmBw without consideration of a separate cross-correlation Signal (Single Linear Chirp) and anti - jamming / low - pass performance.

을 고려한 광대역 재밍에 대한 CSS-BOK 시스템의 항재밍 성능(P_AJ)은 다음 수학식과 같이 표현할 수 있다. In terms of anti-jamming, the anti-jamming performance for broadband jamming is the same as the transmission performance in a general AWGN (Additive White Gaussian Noise) environment. Therefore, the cross-correlation characteristic

The anti-jamming performance (P _AJ ) of the CSS-BOK system for broadband jamming can be expressed as the following equation.

는 Q-함수(function)이며,

는 신호의 에너지,

는 싱글 사이드(Single-Side) 재머의 재밍 전력 밀도를 의미한다.here,

Is a Q-function,

The energy of the signal,

Means the jamming power density of a single-side jammer.

를 고려한 이론적인 결과와 동일한 것을 확인할 수 있다.7 is a graph showing anti-jamming performance in a general wideband jamming environment. In particular, FIG. 7 compares transmission performance results of a general SLC technique that does not consider cross-correlation and a general DS / BPSK (Direct Sequence Binary Phase Shift Keying). 7, the CSS-DM scheme has the same performance as the DS / BPSK scheme, the CSS-BOK scheme has a cross-correlation coefficient of SLC,

The results are the same as the theoretical results.

8 is a graph illustrating anti-jamming performance in a broadband jamming environment according to an embodiment of the present invention. In particular, FIG. 8 compares transmission performance results of the CSS technique and the MLC technique.

를 고려한 MLC(Multiple Linear Chirp)의 성능이 Cross-Correlation Coefficient

를 고려하지 않은 SLC 기법의 성능보다 향상된 것을 확인하였다. 특히 CSS-BOK 계열에서는 업-MLC(Up-MLC) 기법의 성능이 SLC 기법보다 BER 10^-4에서 약 1dB 정도 향상된 것을 확인할 수 있고, 업/다운-MLC(Up/Down-MLC)의 경우에는 약 2.5dB 정도 향상된 것을 확인할 수 있다. 그리고, 수학식 10의 이론적인 항재밍 성능과 모의실험 성능이 동일한 것을 확인할 수 있다.The CSS-DM series has the same performance as the DS / BPSK scheme, the CSS-BOK series has the cross-correlation coefficient,

The performance of MLC (Multiple Linear Chirp) considering Cross-Correlation Coefficient

The performance of the SLC method without consideration of the SLC technique is improved. In particular, in the CSS-BOK system, the performance of the up-MLC scheme is improved by about 1 dB at the BER 10 ^-4 compared with the SLC scheme. In the case of the up / down-MLC scheme It can be confirmed that it is improved by about 2.5 dB. It can be confirmed that the theoretical anti-jamming performance and the simulation performance of Equation (10) are the same.

Next, the anti-jamming performance for pulse jamming will be described. The anti-jamming performance of the CSS-BOK scheme for pulse jamming can be expressed mathematically as Equation (4) and Equation (10) as follows.

는 펄스 재밍의 듀티 사이클(Duty Cycle)이고,

는 처프 신호(Chirp)의 교차 상관 계수(Cross-Correlation Coefficient)를 의미한다.(여기서 Cross-correlation은 물리적인 특성에 해당되며, Cross-correlation Coefficient는 물리적인 특성에 해당하는 값을 의미한다.)here,

Is a duty cycle of pulse jamming,

Means the cross-correlation coefficient of the chirp (Chirp) (where the cross-correlation corresponds to a physical characteristic and the cross-correlation coefficient means a value corresponding to a physical characteristic).

이 1, 0.5, 0.1, 0.01일때 각각의 항재밍 성능의 비교 결과를 보여주는 그래프가 각각 도 9 내지 도 12에 도시된다.9 to 12 are graphs illustrating anti-jamming performance in a pulse jamming environment according to an embodiment of the present invention. 9 to 12, there are shown comparison results of anti-jamming performance for pulse jamming of the SLC technique and the MLC technique. Duty cycle of pulse jamming

9 to 12 are graphs showing the results of comparison of the anti-jamming performance at 1, 0.5, 0.1, and 0.01, respectively.

가 증가하여도 성능에 제한이 발생되는 것을 확인할 수 있다. 이것은 펄스 재밍의 특성 상 펄스 재밍의 Duty Cycle

가 작아지면,

가 작아지기 때문에 발생되는 현상이다. CSS-DM 계열의 성능은 Chirp 신호가 PN 코드로 사용되었기 때문에 일반적인 DS/BPSK의 항재밍 성능과 동일한 것을 확인할 수 있다. When it is as short as 0.01

It can be seen that the performance is limited. This is because of the characteristics of pulse jamming, the pulse jamming duty cycle

Lt; / RTI >

Is small. Since the Chirp signal is used as a PN code, the performance of the CSS-DM series can be confirmed to be the same as the anti-jamming performance of a general DS / BPSK.

를 고려한 MLC 기법의 항재밍 성능이 SLC 기법보다 Duty Cycle

이 짧을 상황에서도 우수한 것을 확인할 수 있다. 그리고 수학식 11의 이론적인 성능과 동일함을 볼 수 있다.However, the CSS-BOK series has cross-correlation characteristics

The anti-jamming performance of the MLC scheme considering the Duty Cycle

It can be confirmed that this method is excellent even in a short time. And the theoretical performance of Equation (11) can be seen.

Meanwhile, the anti-jamming performance of tone-jamming can be expressed as Equation (6) and Equation (10) as follows.

의 크기가 큰 경우에는

가 커져도 항재밍 성능에 제한이 발생되는 것을 확인할 수 있다. CSS-DM 계열의 성능은 펄스 재밍의 항재밍 성능과 동일하게 일반적인 DS/BPSK 변조 기법의 항재밍 성능과 동일한 것을 확인할 수 있다. 그러나, CSS-BOK 계열은 Cross-Correlation

를 고려한 MLC 기법에서 항재밍 성능이 향상된 것을 확인할 수 있다. 그리고 수학식 12의 이론적인 성능과 동일함을 볼 수 있다.13 to 16 show comparison results of anti-jamming performance for tone jamming of the SLC technique and the MLC technique. Characteristics of tone jamming

Is large

It can be seen that the anti-jamming performance is limited. The performance of the CSS-DM series is the same as the anti-jamming performance of the pulse jamming, which is the same as the anti-jamming performance of the general DS / BPSK modulation technique. The CSS-BOK series, however,

The anti-jamming performance is improved in the MLC method considering the above-mentioned case. And the theoretical performance of Equation (12).

가 20dB, SLC 기법은 27dB, 그리고 교차 상관성(Cross-Correlation)을 고려한 기법 중 하나인 업-MLC(Up-MLC) 기법은 31dB, 또 다른 MLC 기법 중에 하나인 업/다운-MLC(Up/Down-MLC) 기법은 35dB에서 100% 탐지가 되는 것을 볼 수 있다. 17 is a graph illustrating an example of comparison of the low-pass performance of the SLC (Single Linear Chirp) technique and the MLC (Multiple Linear Chirp) technique according to an embodiment of the present invention. Referring to FIG. 17, a typical DS / BPSK scheme

(Up-MLC) technique, which is one of techniques considering cross-correlation, is 31 dB, and up / down-MLC (Up / Down) -MLC) technique is 100% detection at 35dB.

As a result, the low - pass performance of the MLC scheme is improved by about 11 ~ 15dB compared to the conventional DS / BPSK scheme and by about 4 ~ 8dB over the SLC scheme. This can be interpreted as a result of the fact that the energy of the MLC signal in the band of the considered bandpass filter is smaller than that of the other techniques. As a result, more receiving power is required to obtain the same detection rate from the enemy's point of view, and in the case of a friend, it improves the performance of the low-pitched detection within the same time bandwidth.

Therefore, as mentioned in the embodiment of the present invention, it is verified that the performance of the technique considering the cross-correlation is superior to that of the technique considering only the time-bandwidth product.

18 is a configuration block diagram of a modulation and demodulation system 1800 for increasing the survivability of a wireless communication system according to an embodiment of the present invention. Referring to FIG. 18, there is shown a transceiver structure of an anti-jamming / anti-jamming system based on a CSS-BOK (Bi-Orthogonal Keying) transmission scheme considering cross-correlation.

The correlation unit 1810 performs a function of considering cross-correlation.

The first chirp signal portion 1820-1 and the second chirp signal portion 1820-2 are configured to transmit data to be transmitted on the basis of the cross correlation considered by the correlation portion 1810 to different chirp signals Chirp) signal.

The switching unit 1830 performs a function of selecting the first chirp signal unit 1820-1 or the second chirp signal unit 1820-2.

The jamming unit 1840 performs a function of generating a jamming output signal y (t) by adding the jamming signal to the first chirp signal or the second chirp signal x (t).

A demodulator 1850 demodulates the jamming output signal to generate a demodulated signal.

The first and second integrators 1860-1 and 1860-2 integrate the demodulation signal to generate a final output signal.

The determining unit 1870 performs a function of determining a signal to be transmitted using the final output signal.

In addition, the modulation and demodulation system 1800 shown in FIG. 18 is a technique of directly modulating and demodulating using different chirp signals having orthogonal characteristics.

FIG. 19 is a block diagram of a modulation and demodulation system 1900 for increasing the survivability of a wireless communication system according to another embodiment of the present invention. Referring to FIG. 19, a modulation / demodulation system 1900 shows a transceiver structure of an anti-jamming / low-complexity system based on a CSS-DM (Direct Modulation) transmission scheme considering cross-correlation characteristics.

19, the modulation / demodulation system 1900 includes a modulator 1920 that modulates bitstream data d (t) to generate a binary phase shift keying (BPKS) signal s (t) jamming unit for summing the chirp signal (c _k (t)), the diffuser 1930 is applied to produce a first chirp signal x (t) of, the jamming signal (J (t)) to the chirp signal x (t) ( A despreader 1950 for applying the chirp signal c _k (t) to the received signal y (t) to which the jamming signal J (t) is added to generate the second chirp signal r (t) A demodulator 1960 for demodulating the second chirp signal r (t) to generate a demodulation signal, an integrator 1970 for generating a final output signal by integrating the demodulation signal, a correlation unit 1910, A correlation unit 1910 for generating a signal, a determination unit 1980 for determining a signal received through a binary hypothesis test using the final output signal of the integrator, and the like. And it may be configured.

In addition, the modulation / demodulation system 1900 shown in FIG. 19 is a technique applicable to various modulation because the Chirp signal plays a role of PN (pseudo-noise) code for spread spectrum.

500: Wireless communication system model
510: Transmitter 511: Transmitter antenna
520: Friendly receiver 521: Friendly receiver antenna
530: enemy receiver 531: interceptor
531-1: First antenna 532: Jammer
532-1: Second antenna
1810, 1910:
1820-1 and 1820-2: first and second chirp signal sections
1830:
1840, 1940: Jamming
1850: Demodulator
1860-1, 1860-2: first and second integrators
1870:
1920: Demodulator
1930: Diffuser 1950: Despreader
1970: Integrator 1980: Decision Department

Claims (10)

A modulation and demodulation method for increasing the survivability of a chirp spread spectrum (CSS) wireless communication system having a transmitter and a receiver,
(a) modulating an input signal by the transmitter to generate a modulated signal;
(b) considering the time-bandwidth product and cross-correlation property of the modulated signal for the transmitter to increase the survivability of the modulated signal; And
(c) analyzing the anti-jamming performance of the transmitter using the time-of-band product and the cross-correlation property;
(d) generating a jamming output signal by applying the time-domain product and cross-correlation property to the transmitter; And
(e) demodulating the jamming output signal by the receiver to generate a demodulated signal;
And transmitting the modulated data to the CSS wireless communication system.
The method according to claim 1,
Wherein the step (b) considers cross-correlation of various chirp signal types. The method according to claim 1,
In the step (c), the analysis on the anti-

(Where P _b is a bit error rate (BER) performance,

Is a duty cycle of pulse jamming,

Is a Q-function,

The energy of the signal,

Is the jamming power density of a single-side jammer,

Correlation between the duty cycle (Duty Cycle) for pulse jamming and the chirp signal (Chirp) in the chirp signal-based transmission scheme for the chirp signal (Chirp) Jamming performance for pulse jamming in consideration of the jamming performance of the CSS wireless communication system.
The method according to claim 1,
In the step (c), the analysis on the anti-

(P _b is a bit error rate (BER) performance,

Is a Q-function,

The energy of the signal,

Is the jamming power density of the single-side jammer, N ₀ is the noise power spectral density,

Based on the cross-correlation property in the chirp signal-based transmission scheme, for the anti-jamming performance for the tone jamming, with respect to the chirp signal (Chirp) (Cross-Correlation Coefficient) A modulating and demodulating method for increasing the survivability of a wireless communication system.
The method of claim 3,
Wherein the chirp signal-based transmission scheme is a CSS-BOK (Chirp Spread Spectrum-Binary Orthogonal Keying) transmission scheme.
5. The method of claim 4,
Wherein the chirp signal-based transmission scheme is a CSS-DM (Chirp Spread Spectrum-Direct Modulation) scheme.
6. The method of claim 5,
Wherein the chirp signal is a different chirp signal having an orthogonal characteristic and the transmitter directly applies the different chirp signal.
The method according to claim 6,
Wherein the chirp signal serves as a PN code for spread spectrum transmission.
The method according to claim 1,
Wherein the cross-correlation property is lowered and the orthogonal property is increased as the time-bandwidth product is increased.
The method according to claim 1,
Wherein the cross-correlation characteristic is calculated using a multiple linear chirp (MLC) technique or a non-linear chirp technique. .

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