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.
Dhafer R. Zaghar; Hadeel N. Abdullah; Ikhlas M. Farhan
Volume 20, Issue 1 , January 2020, , Page 40-52
Abstract
The study and evaluation of digital communication systems in low signal-to-noise power ratio (LSNR) environments is a hot and important topic due to its wide contemporary applications. This review is an attempt to focus on the most distinctive vital parameters required in the analysis and design of such ...
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The study and evaluation of digital communication systems in low signal-to-noise power ratio (LSNR) environments is a hot and important topic due to its wide contemporary applications. This review is an attempt to focus on the most distinctive vital parameters required in the analysis and design of such systems. It includes a brief literature survey for many algorithms, techniques, methodologies, and mitigations that have been used to overcome the high noise problem encountered in these systems in order to guarantee reliable communication. Amongst these topics, the study reviews the most widely utilized modulation techniques in LSNR communication systems such as the On-Off Keying (OOK) and binary PSK schemes. The capacity for both AWGN and wireless fading channels is also discussed along with a clarification of the minimum limits in these types of channels.On the other hand, some important and recommended detection and estimation techniques for low power communication systems are briefly covered. This unified study has additionally discussed spectral efficiency and bit energy trade-off within the low-power, and broadband systems, and different limitations are stated clearly. Finally, the survey throughout this paper recommends some significant techniques that can be used in the analysis and design of successful communication systems in LSNR regimes.
Salah Al-iesawi; Maha Abd Rajab; Ahmed I. A
Volume 15, Issue 1 , April 2015, , Page 80-99
Abstract
Abstract – This paper demonstrates the effect of color image transmission through AWGN channel using binary phase shift key modulation (BPSK) system and transmission of compressed color image through AWGN. On the other hand, the transmission consumes a large amount of channel and needs the processing, ...
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Abstract – This paper demonstrates the effect of color image transmission through AWGN channel using binary phase shift key modulation (BPSK) system and transmission of compressed color image through AWGN. On the other hand, the transmission consumes a large amount of channel and needs the processing, therefore utilizes compression techniques to reduce the size of the original color image to facilitate the transmission compressed color image through AWGN and to obtain the channel optimization. In this paper, a simple hybrid lossy color image compression transmission through AWGN using convolutional coding with Viterbi decoding system is proposed. It is based on combining effective techniques, started by wavelet transform that decompose the image signal followed by polynomial approximation model of linear based to compress approximation image band. The error caused by applying polynomial approximation is coded using bit plane slice coding, whereas the absolute moment block truncation coding exploited to coded the detail sub bands. Then, the compressed information encoded using LZW, run length coding and Huffman coding techniques, the compressed information is entered to the channel coding to coded the information using convolutional coding and modulation using BPSK to transmit through channel and added AWGN, the received signal is demodulated and decoded using Viterbi decoding, the result compressed data passed to source decoding to reconstruct the compressed image. The test results indicated that the proposed system can produce a balance between the compression performance and preserving the image quality, and also simulations results observed that with increase in signal to noise ratio (SNR) values the bit error rate (BER) values decrease.
