Areej Munadel Kadhum; Ekhlas Kadum Hamza
Volume 21, Issue 2 , June 2021, , Page 59-69
Abstract
with the introduction of new standards at a fast pace, wireless communicationis experiencing great development and growth, thereby raising the level of demand forradio spectrum. The spectrum, however, is a limited resource and cannot be subdividedindefinitely to satisfy any use. As a result, spectrum ...
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with the introduction of new standards at a fast pace, wireless communicationis experiencing great development and growth, thereby raising the level of demand forradio spectrum. The spectrum, however, is a limited resource and cannot be subdividedindefinitely to satisfy any use. As a result, spectrum scarcity arises. This scarcityrepresents the main problem that faces the future of wireless networks. This scarcity isdue to the inefficient fixed spectrum allocation technique. The Dynamic Spectrum Access(DSA) is a successful solution to reduce the spectrum scarcity that wirelesscommunications currently face. DSA allows users without a spectrum license known asSecondary Users (SUs) to temporarily use the unused licensed spectrum. This workfocuses on analysis, and design of the Cognitive Radio (CR) system forOrthogonalFrequency Division Multiplexing modulation. The OFDM transceiver system has beenimplemented in the first stage using the Quadrature Phase Shift Keying (QPSK)modulation technique by Xilinx System Generator Inter-Symbol InterferenceSimulink(XSG) based on MATLAB. The second stage of the proposed system is to design energydetection of the OFDM transceiver. This system was analyzed under the Adaptive WhiteGaussian Noise (AWGN) channel based XSG. In this work, the energy detector is alsodesigned using the XSG ISE14.1 Simulink and obtained all the signals successfully.
Mohammed A. Hussein1; Ala'a. H. Ali; Ali K. Nahar3
Volume 21, Issue 1 , March 2021, , Page 16-30
Abstract
The technology has been growing rapidly in the form of portable wireless devices that can perform multiple functions to cope with the state-of-the-art technology and synchronization. A total device capacity must be increased to accommodate new wireless applications. This can be achieved by leveraging ...
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The technology has been growing rapidly in the form of portable wireless devices that can perform multiple functions to cope with the state-of-the-art technology and synchronization. A total device capacity must be increased to accommodate new wireless applications. This can be achieved by leveraging new technologies, with higher data rates. Spectrum pooling has gained immense popularity, with increased demand for frequency range and bandwidth availability constraints. Statistics suggest that much of the spectrum licensed is not used all the time. Because of the transmitter's nonlinearity nature, the large (peak to average power ratio (PAPR)) phenomenon is a drawback in orthogonal frequency division multiplexing (OFDM). Several hybrid approaches have recently been implemented to minimize PAPR's high value, at the expense of increasing the level of computational complexity in the system. In this paper, a new hybrid approach has been introduced in parallel to combine the selective mapping approach (SLM) with the partial transmit sequence (PTS) approach to improve the efficiency of PAPR reduction with lower numerical method complexity. The findings reveal that the OFDM systems with the proposed hybrid approach have better efficiency in terms of PAPR elimination, side-information, and computational complexity compared to current hybrid methods. Also, a hybrid approach proposed output could be maintained without degradation.
Ali Y. Fattah; Falah Hasan Abdul-Baqi
Volume 15, Issue 3 , December 2015, , Page 64-76
Abstract
Abstract –High-capacity and long-haul transmission technologies are indispensable
to develop cost-effective optical transport networks. Optical communication is rapidly
advancing toward 1-Tera bit per second (Tb/s) and beyond transport. As the available
bandwidth of Standard Single-Mode Fiber (SSMF) ...
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Abstract –High-capacity and long-haul transmission technologies are indispensable
to develop cost-effective optical transport networks. Optical communication is rapidly
advancing toward 1-Tera bit per second (Tb/s) and beyond transport. As the available
bandwidth of Standard Single-Mode Fiber (SSMF) is limited, high Spectral Efficiency
(SE) becomes an important issue. Coherent Optical Orthogonal Frequency-Division
Multiplexing (CO-OFDM) has become one of the promising candidates due to its high
SE and resilience to linear channel impairments such as Chromatic Dispersion (CD).
In this paper, based on Optisystem 11.0 software simulation platform, the performance
of a 1.6 Tb/s (16 x 100 Gb/s) PDM-CO-OFDM transmission system is investigated
invest by using QPSK modulation format and applying Polarization Interleaving
Scheme (PIS) over 1440 km with 2 b/s/Hz spectral efficiency.
