Search

Efficient and precise location of emission sources in an urbanized environment is very important in electronic warfare. Therefore, unmanned aerial vehicles (UAVs) are increasingly used for such tasks. In this paper, we present the cooperation of several UAVs creating a wireless sensor network (WSN) that locates the emission source. In the proposed WSN, the location is based on spectrum sensing and the signal Doppler frequency method. The paper presents the concept of the system. Simulation studies are used to assess the efficiency of the cooperative WSN. In this case, the location effectiveness for the WSN is compared to the single UAV., Comment: 6 pages, 6 figures

This paper presents using bit error rate (BER) measurements to evaluate operation correctness of traffic (input-output) interfaces in modem of very small aperture terminal (VSAT). Such functional tests are carried out, for example, when purchasing communication equipment for armed forces. Generally, available standards do not describe measurement procedures in this area. In this case, accredited laboratories should develop dedicated assessment methodologies. In this paper, we show the methodology for the VSAT modems, which is based on the BER measurements., Comment: 5 pages, 5 figures, 2 tables

Emerging telecommunication technologies like 5G, green communications, and massive MIMO contribute to the use of directional antennas and beamforming. For this reason, modern propagation models should consider directional antennas with different beam widths, gains and radiation pattern directions. Most of the available propagation models are based on omnidirectional or isotropic antennas. A proposition to solve this problem is an empirical path loss model that considers the different types of antennas. This model assumes that the transmitting and receiving antenna beams are directing each other. In this paper, we propose modifying this model by determining attenuation for any direction of the antenna patterns. For this aim, the multi-elliptic channel model is used., Comment: 4 pages, 7 figures

An issue of the parameter selection in various branches of a multi-antenna receiver system determines its effectiveness. A significant effect on these parameters are correlation properties of received signals. In this paper, the assessment of the signal correlation properties for different environmental conditions is presented. The obtained results showed that depending on the receiver speed, the adaptive selection of the delays in the different RAKE receiver branches provide minimization of the correlation between the signals. Particularly low levels of the signal correlation could be obtained in complex propagation environments such as urban and bad urban., Comment: 4 pages, 5 figures

Most propagation models do not consider the influence of antenna patterns on the parameters and characteristics of received signals. This assumption is equivalent to the use of isotropic or omnidirectional antennas in these models. Empirical measurement results indicate that the radiation pattern, gain and direction of directional antennas significantly influence on properties of the received signal. This fact shows that consideration the directional antennas in propagation models is very important especially in the context of emerging telecommunication technologies such as beamforming or massive MIMO. The purpose of this paper is to present the modeling method of power angular spectrum and direction of antenna patterns in a multipath propagation environment., Comment: 5 pages, 7 figures

Angular dispersion is the effect of a multi-path propagation observed in received signals. An assessment of this phenomenon is particularly important from the viewpoint of emerging fifth generation (5G) communication systems. In these systems, using the beam-forming and massive multiple-input multiple-output antenna arrays are planned. This phenomenon also has a negative impact on direction finding and older generation communication systems used in an urban environment. In this paper, we present the angular dispersion evaluation for various propagation environments based on simulation studies. This analysis is carried out for different environment types defined in the 3GPP standard model for a selected frequency. In this case, the angular spread is determinated based on the power angular spectrum. This parameter is the basis for the influence evaluation of the propagation environment on the received signal angular dispersion., Comment: 5 pages, 10 figures, 3 tables

In an urban environment, a multipath propagation is one of the basic phenomena affecting a quality of received signals. This causes dispersions in time and angular domains. Basic parameters describing these dispersions are the rms delay spread and rms angle spread, respectively. The delay spread is related to a frequency of the transmitted signal and the nature of the propagation environment. In this paper, we show a mutual relationship between the time and angular dispersions in the received signal. The obtained simulation results present a comparison of the described dispersions for two different frequencies. In this case, the multi-elliptical propagation model and standard model developed by 3GPP are the basis for the simulation analysis of new communication system solutions., Comment: 5 pages, 8 figures

An angular distribution of received signals has a significant impact on their spectral and correlational properties. Most of angular dispersion models do not consider antenna patterns. The developed procedure for determining the propagation path parameters enables a wide range of assessment of the impact of the propagation environment on the received signal properties. In contrast to the other models, this procedure is based on a geometrical structure, which parameters are defined on the basis of power delay profile or spectrum This modeling method allows also the power radiation pattern (PRP) of the transmitting antenna. The aim of the paper is to present the influence of the transmitter antenna PRP on the scattering propagation paths that arrive at the receiver. This analysis is realized on the basis of simulations studies using the developed procedure. Presented in this paper procedure maps the effects of propagation phenomena that predominate in an azimuth plane., Comment: 5 pages, 8 figures

A method to evaluate the statistical properties of the reception angle seen at the input receiver that considers the receiving antenna pattern is presented. In particular, the impact of the direction and beamwidth of the antenna pattern on distribution of the reception angle is shown on the basis of 3D simulation studies. The obtained results show significant differences between distributions of angle of arrival and angle of reception. This means that the presented new method allows assessing the impact of the receiving antenna pattern on the correlation and spectral characteristics at the receiver input in simulation studies of wireless channel. The use of this method also provides an opportunity for analysis of a co-existence between small cells and wireless backhaul, what is currently a significant problem in designing 5G networks., Comment: 6 pages, 7 figures

This paper focuses on assessing the limitations in the direction-finding process of radio sources with directional antennas in an urbanized environment, demonstrating how signal source antenna parameters, such as beamwidth and maximum radiation direction affect bearing accuracy in non-line-of-sight (NLOS) conditions. These evaluations are based on simulation studies, which use measurement-tested signal processing procedures. These procedures are based on a multi-elliptical propagation model, the geometry of which is related to the environment by the power delay profile or spectrum. The probability density function of the angle of arrival for different parameters of the transmitting antenna is the simulation result. This characteristic allows assessing the effect of the signal source antenna parameters on bearing error. The obtained results are the basis for practical correction bearing error and these show the possibility of improving the efficiency of the radio source location in the urbanized environment., Comment: 24 pages, 16 figures, 3 tables; Accepted in International Journal of Microwave and Wireless Technologies (from Cambridge University Press)