The ultrawideband communication facilities where chaotic radio pulses are used as an information carrier are considered. As perspective applications of such systems the wireless sensor networks are discussed.

The problem of positioning using UWB chaotic radio pulses is considered. Differential time of arrival method based on cross-correlation function of chaotic radio pulse envelope signals is proposed and investigated. It is shown that the proposed approach provides accurate estimation of time difference of arrival, proportional to the envelope signal frequency bandwidth. Immunity of the proposed method to noise increases with the duration of chaotic radio pulse.

The effect of multipath amplification in the communication system with chaotic radio pulses has been investigated. For 3-10 GHz range the effect develops from the pulse length 20 nsec. The estimates show multipath gain from 4 to 13-14 dB depending on propagation conditions. Multipath amplification substantially improves performance of chaotic communication systems.

The use of phase locked loops (PLLs) gives the opportunity to develop wideband chaotic oscillator with manipulated spectrum (electronic switching of frequency bands, electronic control of spectrum width). This paper contains results on numerical study of mathematical model of PLL and results of modeling with the use of specialized electronic design software. Considered models take into account peculiarities of modern components of phase locked loops (pulse phase discriminators, frequency dividers). Analysis of these models approves the possibility of control of spectrum width and possibility of electronic shifting of spectrum of chaotic phase-modulated signals in wide frequency range. Shift of the frequency range is obtained by means of changing coefficients of frequency dividers in phase locked loop. Additional control of the loop gain allows keeping the same dynamic properties of chaotic frequency modulation during spectrum shifting. As an example we have modeled generator of phase chaos with spectrum width about 500 MHz and ability of spectrum steering in the range 3-5 GHz.

The problem of generation of ultrawideband phase-chaotic signal in microwave band by the phase-locked loop is considered. Mathematical simulation of the third order phase-locked loop taking into account realistic characteristics of the phase detector, frequency dividers and voltage controlled oscillator is carried out. Simulations allow to estimate parameter's values of the experimental phase-locked loop testbed to be operated in chaotic mode. Based on the obtained numerical results and standard electronic elements the phase-locked loop testbed generating UWB phase-chaotic signal with even power spectrum in 700-1300 MHz band was developed and experimentally tested.

The problem of obtaining ultrawideband phase chaos in the decimeter band with the use of a phase-locked loop is considered. The mathematical simulation of a third-order phase-locked loop is performed with account for the real characteristics of the phase detector, the signal frequency divider in the phase-locked loop, and the voltage-controlled oscillator. This simulation allows determination of the parameters of a prototype of a phase-locked loop operating in the chaotic generation mode. Based on the obtained results and available circuit technology, a prototype of a phase-locked loop generating ultrawideband phase-chaotic oscillations with a uniform power spectrum in a frequency range from 700 to 1300 MHz is developed and tested.

Рассмотрено интенсивно развивающееся направление в области беспроводной сверхширокополосной связи. Описаны разработанные в ИРЭ РАН сверхширокополосные прямохаотические приемопередатчики двух типов и продемонстрировано их применение в беспроводных сенсорных сетях.

An actively advancing branch of wireless ultrawideband communications is considered. Direct chaotic transceivers of two types are described. The transceivers were developed at the Institute of Radio Engineering and Electronics, Russian Academy of Sciences. Application of these transceivers in wireless sensor networks is demonstrated.

The characteristics of ultrawideband communications systems using chaotic RF pulses and operating in a multipath environment are considered. It is shown that, under certain conditions imposed on the pulse duration and on the guard time intervals between the pulses, the signal propagating in this environment is amplified with respect to the signal propagating in free space. It is found that this multipath-amplification effect may result in a considerable increase in the communication range. The characteristics of an ultrawideband communications system using chaotic radio pulses are compared to the characteristics of a communications system using ultrashort pulses under the conditions of a multipath environment.

Basic ideas and concepts underlying the technology of ultrawideband wireless direct-chaos communications are presented. The factors of crucial importance for the development of this communications platform are considered. The models for the origin of chaos in different frequency bands are discussed. Effects of multipath propagation on ultrawideband chaotic signals are analyzed. The results of the experimental study of direct-chaos transmitters/receivers are presented.

Изложены основные идеи и принципы технологии сверхширокополосной беспроводной прямохаотической связи. Рассмотрена совокупность вопросов, оказывающих решающее влияние на развитие этой коммуникационной платформы. Обсуждаются модели источников хаоса в различных частотных диапазонах. Проведен анализ влияния многолучевого распространения сверхширокополосных хаотических сигналов. Приведены результаты экспериментального исследования прямохаотических приемопередатчиков.