In the context of spectrum surveillance, a method to recover the code of spread spectrum signal is presented, whereas the receiver has no knowledge of the transmitter’s spreading sequence. The approach is based on a genetic algorithm (GA), which is forced to model the received signal. Genetic algorithms (GAs) are well known for their robustness in solving complex optimization problems. Experime...

Code Division Multiple Access (CDMA) is probably the most interesting multiple access method provided by spread spectrum technology. CDMA refers to a multiple access method in which the individual terminals use spreadspectrum techniques and occupy the entire spectrum whenever they transmit. This paper focuses on direct-sequence spread-spectrum principles (processing gain, spreading, de-spreadin...

This paper considers proposing the mathematical model and simulation mode of inter-satellite channel based on the reliability of inter-satellite communication system. The Monte Carlo method is adopted to develop the spread spectrum communication system of two consumers. In order to reduce the bit errors of inter-satellite communication, both spread spectrum communication technology and channel ...

In this paper, we introduce the slow frequency hopping (SFH) technique to the multicarrier (MC) code-division multiple-access (CDMA) systems for overlay situations. Using lower chip rate, which results in a narrower spectrum for each carrier and hopping the signal in frequency, the MC direct sequence (DS)/SFH system achieves better performance than the MC DS CDMA system in most cases, especiall...

Anomalous advection-diffusion in two-dimensional semiconductor systems with coexisting energetic and structural disorder is described in the framework of a generalized model of multiple trapping on a comb-like structure. The basic equations of the model contain fractional-order derivatives. To validate the model, we compare analytical solutions with results of a Monte Carlo simulation of phonon...

We present a new approach to the problem of alternating signs for fermionic many body Monte Carlo simulations. We demonstrate that the exchange of identical fermions is typically short-ranged even when the underlying physics is dominated by long distance correlations. We show that the exchange process has a maximum characteristic range of √ 2(1− f)βh lattice sites, where β is the inverse temper...

The finite temperature phase transition in the SU(2) Higgs model at a Higgs boson mass MH ≃ 34 GeV is studied in numerical simulations on four-dimensional lattices with time-like extensions up to Lt = 5. The effects of the finite volume and finite lattice spacing on masses and couplings are studied in detail. The errors due to uncertainties in the critical hopping parameter are estimated. The t...

A multi-species generalization of the Asymmetric Simple Exclusion Process (ASEP) has been considered in the presence of a single impurity on a ring. The model describes particles hopping in one direction with stochastic dynamics and hard core exclusion condition. The ordinary particles hop forward with their characteristic hopping rates and fast particles can overtake slow ones with a relative ...

We use a one-dimensional step model to study quantitatively the growth of step bunches on Si~111! surfaces induced by a direct heating current. Parameters in the model are fixed from experimental measurements near 900 °C under the assumption that there is local mass transport through surface diffusion and that step motion is limited by the attachment rate of adatoms to step edges. The direct he...

Structural optimization for heteronuclear clusters consisting of one alkali-metal ion and of up to 79 neutral rare gas atoms has been carried out. The basin-hopping Monte Carlo minimization method of Wales and Doye is used. Rare gas atoms interact with the Lennard–Jones potential, whereas the interaction between a neutral atom and an ion impurity is given by the Mason–Schamp potential. Starting...