Abstract:Despite the numerous advantages, microstrip patch antennas suffer from narrow bandwidth which is approximately within 3-6% of the central frequency, one of the efficient methods used for the enhancement of MSPA
Abstract: Microwave link is one of several transmission media in modern telecommunications networks; it provides reliable data transfer in a wide variety of systems such as GSM, WLL, televisions and many other applications that need data transfer with reliable transfer rate and bandwidth. This thesis studies the point-to-point, line-of-sight microwave links design and the effective parameters on link performance. It presents the diffraction losses due to obstacles within the first Fresnel zone of a link.
Abstract: The ground stations all over the world have grown in the last 60 years as a part of satellite to earth link systems. One of the important applications for the ground station is to receive the space images acquired by remote sensing satellites. These images are widely used for an applications in the field of cartography, geology, oceanography or intelligence, etc.In this thesis, a proposal of a ground station design configuration that satisfies the needs and requirements of Iraqi users is presented.
Abstract: A major source of impairments in Orthogonal Frequency Division Multiplexing (OFDM) wireless communication systems is the imbalance between the real part (Inphase (I)) and the imaginary part (Quadrature (Q)) of the complex signal. This thesis addresses problem theoretically and introduces a blind estimation algorithm to estimate and then compensate the I/Q imbalance. The preformance of a direct-conversion receiver implemented in OFDM systems is analyzed in the presence of I/Q imbalance. Two types of imbalance (mismatch) between the I-and Q-branches are considered here.
Abstract: The digital video coding is a rapidly evolving field. Although its applications are numerous (from TV broadcasting to video conference), bit rate reduction is always needed .This has led to intensive efforts toward effective video compression techniques. In this work an adaptive codec scheme of H.263 standard that depends on transform coding (DCT) and quantization process in compression is proposed. In addition motion estimation search algorithms were used to estimate the predictive frames.
Abstract: An omni-directional antenna for telemetry, tracking and command (TT&C) com- munications is required for spin-stabilized geostationary satellites whether in the launching phase or once in orbit. The need for a despun platform can even be reduced by implementing a conformal microstrip antenna array °ush mounted on the cylindrical surface of the satellite for that purpose. The analysis and design of this kind of antennas is quite complicated and a powerful simulation software proves indispensable to achieve this goal.
Abstract: This thesis deals with design and analysis of both fullband and subband adaptive filters and compared between them with applications in real speech. . The Normalized Least Mean Square (NLMS) algorithm has been used to make control an adaptive filter. In fullband adaptive filter the system shows slow convergence time compared with subband adaptive filter with lower signal to noise ratio is gave about 0.00003 noise reduction with (S/N) = 3.24 dB according to woman voice and gave 0.000015 with (S/N) =3.68 dB according to man voice when both tested with real speech.
Abstract: Performance and flexibility of mobile radio systems essentially depend on the choice of the multiple access scheme. The novel Multicarrier Code Division Multiple Access (MC-CDMA) scheme which is the topic of this thesis is a promising alternative to conventional FDMA, TDMA, and CDMA schemes. With MC-CDMA, each data modulated chip of the user specific spreading code is mapped onto a separate subcarrier, so that the chips of the spreading code and, hence, the data symbol is transmitted in parallel on multiple subcarriers which introduces frequency diversity.
Abstract: Exponential growth of mobile communications, radio links and wireless networks has increased interest in many topics in radio propagation. Much effort is now devoted to refine radio propagation path-loss models for urban, suburban, and other environments together with substantiation by field data. The objective for the system designer is to provide sufficient clearance of the obstacle without appreciable transmission loss due to the obstacle. The degree of intersection between the obstacle and the first Fresnel zone gives a good measure of obstruction loss.
Abstract: In an attempt to keep flexibility of a programmable solution and the efficiency of dedicated solution, Field Programmable Gate Arrays (FPGAs) are beginning to emerge as a viable option. In this view, FPGAs are an attractive option for implementing digital communication systems for reasons of performance, power consumption, and reconfigurability. This work examines techniques for developing, modeling and generating FPGA implementation of QPSK modem. Amongst the more complex and demanding tasks performed in high data rate wireless communication system is synchronization.
