Chaotic Radio Pulses Research Articles

Experiments on Coherent Addition of Chaotic Radio Pulses in a Wireless Channel

The possibility of coherent addition of chaotic radio pulses in a wireless channel has been demonstrated experimentally. A method for obtaining chaotic radio pulses having an initial section with oscillations similar in shape is described. Chaotic radio pulses are generated and emitted by independent, structurally identical generators of chaotic oscillations, each of which is modulated by a sequence of video power pulses. It is shown that at the output of an antenna receiving signals from two emitters, coherent addition of chaotic radio pulses is observed.

Интервально-импульсная модуляция сверхширокополосных хаотических радиоимпульсов: теория и эксперимент

An approach to reduce the negative impact of multipath signal propagation (interpulse interference) in a wireless communication channel has been proposed. Pulse-interval modulation of chaotic radio pulses allows to increase the time interval between pulses without reducing the average bitrate. The possibility of using this method in ultra-wideband microwave channels with multipath propagation is demonstrated. The noise immunity of the AWGN channel has been studied. An experimental implementation of the method is described.

Experiments on Coherent Summation of Chaotic Radio Pulses in a Wireless Channel

Experiments on Coherent Summation of Chaotic Radio Pulses in a Wireless Channel

Measuring Received Signal Strength of UWB Chaotic Radio Pulses for Ranging and Positioning

The use of ultra-wideband (UWB) signals for local positioning is very attractive for practice, because such signals have the potential to provide centimeter precision. In this paper, we consider wireless ranging (distance measurement) and positioning, using one of the kinds of UWB signals, i.e., chaotic radio pulses, which are noise-like signals with no constant shape. The distance measurement is based on an assessment in the receiver of the power of UWB chaotic radio pulses emitted by the transmitter. A new method for estimating their power and its experimental implementation is proposed and described. Experimental layouts of the transmitter and receiver and the principles of their operation are described. To determine the main features of this method under real signal propagation conditions, full-scale indoor measurements were carried out, and statistical estimates of the accuracy were made. We present the results of experimental testing of the proposed approach for positioning the emitter relative to a system of anchors in an office space 6 × 6.5 m2 in the mode of measuring object coordinates on a line and on a plane. The mean absolute error (MAE) of distance measurement (1D) was 25 cm, and the root mean squared error (RMSE) was 39 cm. When positioning on a plane (2D), the MAE of coordinate estimation was 34 cm and the RMSE was 42 cm. The proposed distance measurement method is intended for use in wireless UWB transceivers used in wireless sensor networks.

Моделирование энергетического приемника для систем сверхширокополосной хаотической радиосвязи

The problem of modeling an energy receiver of ultra-wideband chaotic radio pulses for chaotic radio communications is studied. As is shown, a combination of numerical and analytical modeling completes the problem of calculating characteristics of ultra-wideband chaotic communication systems. On the one hand, the numerical method is effective for calculating receiving systems with short radio pulses, and with an increase in the duration of radio pulses Tp the rate of the method decreases proportionally, whereas technical requirements for the computing equipment increase proportionally, so the operation time increases faster than Tp. On the other hand, the accuracy of the analytical solution, which is insufficient in the case of short radio pulses, grows proportion-ally with an increase in the duration of the radio pulses. Thus, in this problem, the numerical and analytical methods ideally complement each other. It is shown that the accuracy of the approximate analytical solution for the optimal threshold and the error probability becomes sufficient for engineering calculations at the values of the number of freedom degrees (processing gain) of chaotic radio pulses B  200. The combination of numerical and analytical modeling methods can significantly simplify tiresome modelling of chaotic communication systems, for example, those that provide maximum range by increasing the signal length.

Эксперимент по генерации близких по форме сверхвысокочастотных хаотических радиоимпульсов

A method for generating chaotic radio pulses using an analog generator of chaotic oscillations is proposed. The method makes it possible to reproduce the pulse wave-form both by the same generator instance and by different instances of structurally identical generators. The pulse waveforms are controlled by the supply voltage of the generator. To prove the concept an experimental test-bed consisting of four identical generators of 100–500 MHz band has been developed. The proposed method can be applied both for coherent reception of chaotic UWB oscillations in the microwave band and for beamforming.

Тенденции развития сверхширокополосных прямохаотических средств связи

The report discusses the development trends in the development of ultra-wideband wire-less communications based on chaotic signals. For the first time, direct chaotic communications were proposed in 2000 as a way to use noise-like (chaotic) signals for communication systems. The idea was to generate information-carrying signals directly in the region of radio or microwave frequencies where transmission takes place, and to modulate and demodulate these signals there without resorting to frequency transfer operations. In the basic version of the scheme, chaotic radio pulses were used as an information carrier, which made it possible to use “on-off” modulation and modulation of the positions of chaotic radio pulses. An envelope detector matched with the transmitted signal was used as a receiver. Another variant of the direct chaotic system is the recently proposed relative transmission scheme based on chaotic radio pulses. The report examines the characteristics and specifics of both schemes when used in ultra-wideband wire-less communication in the centimeter and decimeter wavelength ranges.

Modulation, Shaping and Replicability of UWB Chaotic Radiopulses for Wireless Sensor Applications.

A modulation method is proposed for generating identical UWB chaotic radio pulses using an analog generator of chaotic oscillations. The problem is on the edge of two contradicting requirements: (1) theoretical ability to produce a huge number of various-shape signals, because of high sensitivity to the initial conditions of the generator; (2) the necessity to reproduce oscillations of the same shape both in the receiver and in the transmitter for the implementation of coherent methods of signal processing. The considered method allows us to resolve this contradiction. A single-transistor chaotic oscillator with single power supply and frequency range 100 to 500 MHz is proposed. A mathematical model of the generator (a system of ODEs) was derived. A method of generating chaotic radio pulses with a reproducible shape that could be varied in a manner that is controlled and natural for UWB radio by means of changing the supply voltage of the chaotic oscillator is shown. The mathematical model of the generator is simulated numerically and proves the proposed ideas. The shaping and the replicability of UWB pulses was experimentally proven in an analog domain on a testbed with four instances of the chaotic generator.

Statistical Characteristics of Differential Communication Scheme Based on Chaotic Radio Pulses

The aim of this paper is to analyze statistical characteristics of the new differential communication scheme based on chaotic radio pulses in the presence of additive white noise (Gaussian) and using various distributions of instantaneous values of the chaotic signal. The characteristic feature of the presented scheme is the usage of significantly shorter time delays compared to the classical differential chaotic shift keying (DCSK) scheme. In order to investigate noise immunity of the direct chaotic differential communication (DC2) scheme, numerical statistical simulation is performed in terms of the bit error probability (BER) of the transmitted information. Then, the results of this simulation are compared to the results of analytical research. It is shown that due to the inherent internal noises of the scheme, the bit error probability (BER) for arbitrarily large values of the ratio of the signal energy to the Gaussian noise spectral density (Eb/N0) is higher than 10−3 for the values of processing gain K < 30 for any distribution of instantaneous values of the chaotic signal. With the increase of the K values, there is a rapid decrease in BER in a system with a channel without white noise. Numeric simulation is performed, which verifies and clarifies the analytical estimates obtained earlier regarding the bit error probabilities as functions of processing gain and ratio of the signal energy to the Gaussian noise spectral density. The minimum values of Eb/N0 are obtained, which provide necessary error probabilities with the processing gain set. It is shown that with a high processing gain (K > 30), the communication scheme considered here operates effectively both in a channel without fluctuation noises and in a channel with additive white Gaussian noise. The statistical characteristics of the proposed scheme do not depend on the choice of a particular distribution of instantaneous values of the chaotic signal. Taking into account that the scheme uses short delays, which do not depend on the processing gain of the used signal and are easily implemented, for example, on fragments of a high-frequency cable, the results obtained show good prospects for its implementation in a physical experiment.

Filtering and Detection of Ultra-Wideband Chaotic Radio Pulses with a Matched Frequency-Selective Circuit

An approach is proposed to the filtering of an additive mixture of ultra-wideband chaotic signals and white Gaussian noise, in order to retrieve the useful signal in the receiver. The role of the filter is performed by a passive frequency-selective circuit, identical to the one involved in the formation of oscillations in the chaos generator. A mathematical model of a modulating chaos generator, detecting and receiving a sequence of ultra-wideband chaotic radio pulses in a noisy channel is designed. For the receiver of sequences of symbols encoded by chaotic radio pulses with 2- and 4-position modulation, the bit error ratio as a function of the noise level and the pulse duration is estimated numerically.

Analytical Model of an Energy Detector for Ultra-Wideband Chaotic Communications

For the ultra-wideband chaotic radio pulses an analytical model of an energy detector is designed and closed-form expressions for the optimal threshold and the detection probabilities are derived. The analytical solution is compared with the results of the numerical simulation. The model proves to be well-suited for the chaotic radio pulses with large base B (or processing gain, or the number of freedom degrees), namely, B ≥ 100. Potential applications areas of the proposed model are ultra-wideband communications with chaotic pulse carriers, e.g., ultra-wideband systems of 802.15.x standards, and multi-element chaotic communication systems.

Experimental Investigation of a Relative Transmission Scheme on Chaotic Radio Pulses

The practical feasibility of a wireless relative transmission scheme based on chaotic radio pulses is demonstrated. New components necessary for the implementation of this scheme have been developed. A prototype of a transmission system in the frequency range of 200–500 MHz was created on which experiments were carried out on the transmission of binary information. The measurement results correspond to the previously obtained theoretical and computational estimates on the main properties and characteristics of a new transmission scheme that uses dynamic chaos as an information carrier.

Experimental Investigation of a Relative Transmission Scheme on Chaotic Radio Pulses

Experimental Investigation of a Relative Transmission Scheme on Chaotic Radio Pulses

Introduction to the statistical theory of differential communication based on chaotic signals

The purpose of this paper is to analyse the statistical characteristics of a Direct Chaotic Differentially Coherent communication scheme based on chaotic radio pulses in a communication channel with additive white Gaussian noise, where the chaotic signal is given by different instantaneous distributions. Methods. To achieve this goal, numerical modelling of the noise immunity of Direct Chaotic Differentially Coherent communication is conducted and compared with the results of analytical research. Results. The regularities associated with the use of chaotic signals with various statistical distributions of instantaneous values were studied. The minimum values of energy per bit to white Gaussian noise power spectral density ratio were obtained, providing the required error probabilities. Conclusion. It is shown that the proposed system works efficiently at high values of processing gain, and as the processing gain increases, the dependence of noise immunity on the specific statistical distribution of the chaotic signal is levelled out.

Experimental implementation of differentially coherent wireless communication scheme based on chaotic radio pulses

The possibility of practical implementation of differentially coherent wireless communication scheme based on chaotic radio pulses has been experimentally proven. For this purpose a prototype of that communication scheme was created in the frequency range of 200-500 MHz for binary information transmission and experiments were carried out with it. The obtained results fully confirm the previously developed theoretical principles of scheme functioning and its main properties. Keywords: dynamic chaos, ultra-wideband signals, differentially coherent information transmission, correlation reception.

Multiple Access in Relative Information Transmission Systems with Chaotic Radio Pulses

Multiple Access in Relative Information Transmission Systems with Chaotic Radio Pulses

Мультимедийные сенсорные сети на основе сверхширокополосных хаотических радиоимпульсов

The fast direction in information and communication systems of the wireless sensor network is discussed. Special attention was paid to ultra-wideband wireless sensor networks, which use chaotic radio pulses as information carriers for communication between sensor nodes. The creation of such systems became possible after many years of research on the creation and management of chaos in electronic systems. The requirements for transceivers for transmitting multimedia data in wireless sensor networks and the characteristics of existing systems are considered. The prospects of using ultra-wideband wireless systems based on direct chaotic data transmission in multimedia sensor networks are analyzed.

Detection of Chaotic Radio Pulses Using an Ensemble of Envelope Detectors

In this paper, we study the possibility of detecting ultrawideband chaotic radio pulses using an ensemble of incoherent receivers based on envelope detectors. An analytical expression for the reception error probability as a function of the signal-to-noise ratio at the input of the envelope detector is obtained. The sensitivity of radio pulse detection (in terms of the signal-to-noise ratio) is shown to improve in proportion to the number of detectors.

Измерение мощности сверхширокополосного хаотического сигнала для решения задач определения расстояния и позиционирования

A method increasing the accuracy of distance measurements using an ultra-wideband chaotic radio pulses, intended for application in wireless sensor networks is proposed. It was shown that the relative error of distance measurement in the experimental test bench is within 5-9%.

Обнаружение хаотических радиоимпульсов с помощью ансамбля детекторов огибающих

Detection of ultrawideband chaotic radio pulses with ensemble of noncoherent receivers based on envelope detectors is investigated. Analytical solution is derived for the detection error probability as a function of signal-to-noise ratio at the detector input. The sensitivity of the radio pulse detection (by signal-to-noise ratio) is shown to increase in proportion to the number of detectors.