In this paper, a theoretical investigation was suggested to study underwater wireless optical communication (UWOC) system based on multiple input–multiple output (MIMO) technique. The modulation schemes such as RZ-OOK, NRZ-OOK, 32-PPM and 4-QAM applied under different coastal water types. MIMO technique enabled the system to transmit data rate with longer distance link. The performance of the proposed system examined by BER and data rate as a metrics. Several impairments such as the types of water by the attenuation of coastal water and the distance link were taken into account for the transmission of the optical signal to appreciate the reliability of the MIMO technique. The theoretical analysis shows the proposed of MIMO (4Tx/4Rx) technique get the better performance compared with the other techniques in terms of BER. When 32-PPM is applied as a modulation scheme. For the system with MIMO technique the maximum distance link arrive to 14.9 and 2.9 m for coastal water types JIC and J9C, respectively. While SISO (1Tx/1Rx) technique achieved the maximum distance link are 10 and 2.3 m for coastal water types JIC and J9C, respectively. Therefore, 32-PPM can outperform the other modulation schemes and consider the suitable option for obtaining a low BER with the best maximum distance link for LoS of MIMO technique.
The aim of the research is to examine the multiple intelligence test item selection based on Howard Gardner's MI model using the Generalized Partial Estimation Form, generalized intelligence. The researcher adopted the scale of multiple intelligences by Kardner, it consists of (102) items with eight sub-scales. The sample consisted of (550) students from Baghdad universities, Technology University, al-Mustansiriyah university, and Iraqi University for the academic year (2019/2020). It was verified assumptions theory response to a single (one-dimensional, local autonomy, the curve of individual characteristics, speed factor and application), and analysis of the data according to specimen partial appreciation of the generalized, and limits
... Show MoreThe employment of cognitive radio (CR) is critical to the successful development of wireless communications. In this field, especially when using the multiple input multiple output (MIMO) antenna technology, energy consumption is critical. If the principal user (PU) is present, developers can utilize the energy detecting approach to tell. The researchers employed two distinct phases to conduct their research: the intense and accurate sensing stages. After the furious sensing step was completed, the PU user was identified as having a maximum or minimal energy channel. There are two situations in which the proposed algorithm's performance is tested: channels for fading AWGN and Rayleigh. When the proposed methods' simulation results a
... Show MoreFree-Space Optical (FSO) can provide high-speed communications when the effect of turbulence is not serious. However, Space-Time-Block-Code (STBC) is a good candidate to mitigate this seriousness. This paper proposes a hybrid of an Optical Code Division Multiple Access (OCDMA) and STBC in FSO communication for last mile solutions, where access to remote areas is complicated. The main weakness effecting a FSO link is the atmospheric turbulence. The feasibility of employing STBC in OCDMA is to mitigate these effects. The current work evaluates the Bit-Error-Rate (BER) performance of OCDMA operating under the scintillation effect, where this effect can be described by the gamma-gamma model. The most obvious finding to emerge from the analysis
... Show MoreThe analytical study of optical bistability is concerned in a fully
optimized laser Fabry-Perot system. The related phenomena of
switching dynamics and optimization procedure are also included.
From the steady state of optical bistability equation can plot the
incident intensity versus the round trip phase shift (φ) for different
values of dark mistuning
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or finesse (F= 1, 5, 20,
100). In order to obtain different optical bistable loops. The inputoutput
characteristic for a nonlinear Fabry-Perot etalon of a different
values of finesse (F) and using different initial detuning (φ0) are used
in this rese
Massive multiple-input multiple-output (m-MIMO) is considered as an essential technique to meet the high data rate requirements of future sixth generation (6G) wireless communications networks. The vast majority of m-MIMO research has assumed that the channels are uncorrelated. However, this assumption seems highly idealistic. Therefore, this study investigates the m-MIMO performance when the channels are correlated and the base station employs different antenna array topologies, namely the uniform linear array (ULA) and uniform rectangular array (URA). In addition, this study develops analyses of the mean square error (MSE) and the regularized zero-forcing (RZF) precoder under imperfect channel state information (CSI) and a realist
... Show MoreAn optimization calculation is made to find the optimum properties of combined quadrupole lens which consists of electrostatic and magnetic lens. Both chromatic and spherical aberration coefficients are reduced to minimum values and the achromatic aberration is found for many cases. These calculations are achieved with the aid of transfer matrices method and using rectangular model of field distribution, where the path of charged-particles beam traversing the field has been determined by solving the trajectory equation of motion and then the optical properties for lens have been computed with the aid of the beam trajectory along the lens axis. The computations have been concentrated on determining the chromatic and spher
... Show MoreThis study aims to determine the effect of x-ray radiation resulting from solar flares in high-frequency radio wave communications through the ionosphere and to study the radio blackout events that occur over Iraq, located within (38,28) latitude, and (38,49) longitude. Using X-ray data during strong X flares and radio wave absorption data across the D ionosphere for 10 years from 2012 to 2021. The study concluded that there were 43 events of x-flare, most of which were during years of high solar activity. All of these flares produced X-rays that caused a radio blackout, R3 and only 13 events affected Iraq.