Chaotic Radio Pulses Research Articles

Multimedia sensor networks based on ultrawideband chaotic radio pulses

The requirements to transceivers, which are intended for multimedia data transmission in wireless sensor networks, and existing system characteristics are discussed. Ultrawideband wireless systems based on direct chaotic data transmission are analyzed to reveal the prospects of their application to multimedia sensor networks. The results obtained during experimental studies into video data-flow transfer, which are performed in the point-to-point mode with the use of radio relaying and through-wall transmission, are presented.

Demodulation of chaotic signals with the use of a reference chaos generator

A new circuit of incoherent reception is proposed for communication systems using chaotic radio pulses as a medium. The analysis of the circuit is performed and its workability and efficiency as a receiver of chaotic radio pulses is demonstrated.

Separation of chaotic signals during their incoherent reception using a reference chaos generator

A new scheme of incoherent reception of chaotic radio pulses using a reference chaos generator is described. Analysis of the proposed scheme confirms its performance and efficiency. The scheme exhibits selectivity and can be used for separating pulses generated by several sources.

Propagation of ultrawideband chaotic radio pulses through the slits of metal surfaces

The leakage of ultrawideband (UWB) chaotic radio pulses through the defects (holes, slits, cracks, etc.) of metal surfaces-an urgent problem arising from their application as information carriers in wireless sensor networks-is investigated. Experiments with UWB chaotic radio pulses leaking from the slits of metal surfaces are described, and the experimental results are analyzed. The signal attenuation has been estimated when chaotic radio signals propagate through slits of different size.

Determination of the difference between the arrival times of a chaotic radio pulse at two receivers based on the cross-correlation of of the pulse envelopes

The problem of positioning with the use of ultra-wideband chaotic radio pulses is considered. A method for determination of the difference of signal arrival times based on the cross-correlation function of the envelope of chaotic radio pulses is proposed and studied. It is demonstrated that this method provides an error of estimation of the difference of signal arrival times that is inverse proportional to the frequency band of the radio-pulse envelope. It is found that the noise stability of the method is improved with as the suration of the chaotic radio pulse increases.

Noise immunity of the wireless communications scheme based on ultrawideband chaotic radio pulses in multipath channels

The problem of determining the noise immunity of wireless data transmission based on ultrawide-band (UWB) chaotic radio pulses in the multipath channel with white noise is substantiated. The results have been calculated via numerical simulation using the multipath channel models describing UWB signal propagation in rooms of different classes at distances as long as several tens of meters. The direct chaotic communications method is shown to have the noise immunity high enough to employ this scheme in practical wireless applications where information is transmitted under severe conditions of multipath propagation. In this case, the ultimate data transfer rates are found to 25 Mb/s.

Compensation of a narrowband interference in an ultrawideband communication system based on chaotic radio pulses

The influence of narrowband signals on incoherent reception of ultrawideband chaotic radio pulses in direct chaotic communication (DCC) system is considered. A method for compensating the influence of narrowband signals on the characteristics of this system after incoherent reception of chaotic radio pulses is proposed. The proposed solution enables one to compensate a narrowband signal, preserving the possibility to determine chaotic radio pulses at corresponding time positions. The dependence of the probability of an error per bit on the spreading ratio of chaotic radio pulses is established.

Amplification of chaotic pulses in a multipath environment

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.

A nonautonomous generator of chaotic radio pulses

Digital simulation methods (ADS package) and an experimental model are used to demonstrate that a train of chaotic radio pulses may be generated under the effect of a chaotic periodic signal on a nonlinear dynamic system generating chaotic oscillations in the range 300–600 MHz. The system’s modulation characteristics are studied.

A train of chaotic pulses generated by a dynamic system driven by an external (periodic) force

The possibility of generating chaotic radio pulses by applying an external signal to a dynamic system is studied. The system is represented by a mathematical model of a chaos generator with 2.5 degrees of freedom where a bipolar transistor is used as an active element. Application of a periodic external signal to such a system is shown to enable generation of a train of chaotic pulses. The duration of chaotic pulses and the frequency of their repetition can be varied in a broad range by selecting the signal’s frequency and the direct bias voltage (transistor’s operation point).

UWB direct chaotic communication technology

In this letter, an ultra-wideband (UWB) direct chaotic communication technology is proposed. Based on this system, a 2-GHz wide chaotic signal is directly generated into the lower band of the UWB spectrum, i.e., 3.1-5.1 GHz. The information component is modulated by the chaotic signal based on the chaotic-on-off keying modulation scheme which results in a series of chaotic radio pulses. At the receiver, a simple noncoherent envelope detector is used as an energy collector. Various system design parameters and tradeoffs are discussed in the letter in order to meet the low-complexity, low-power consumption, and low-cost requirements while still compliant with the Federal Communications Commission UWB regulation. The average power consumptions for various operating data rates and the technical feasibilities of implementing the above system as low-cost integrated circuit are also addressed. Additionally, the system performance in both additive white Gaussian noise (AWGN) channel and various types of multipath channels are provided in order to further demonstrate the capability of the proposed system.

Experiments on Direct Chaotic Communications in Microwave Band

We discuss a concept of Direct Chaotic Communications (DCC) that is based on the following ideas: (1) chaotic oscillator generates signals directly in a specified microwave band; (2) information component is put in the chaotic signal by means of formation of an appropriate stream of chaotic radio pulses; (3) envelope detection is used. The principle of communications is confirmed experimentally in microwave band. Transmission rates up to 100 Mbps are demonstrated.