56 research outputs found
Interference reduction using one-third ICI-SC subcarrier mapping scheme in STFBC MIMO-OFDMA system / Hanis Adiba Mohamad
No full textNowadays, the demand for multimedia wireless communication is growing extremely at a rapid pace and this trend is expected to continue in the future. The primary challenge is the demand for multimedia services accessed by many simultaneous users. A prominent example of this trend is orthogonal frequency division multiple access (OFDMA) technology. In addition, multiple input multiple output - orthogonal frequency division multiple access (MIMO-OFDMA) is combined to promote the benefits of simplicity, high performance system and exploitation of the multipath diversity which increases data rates and link reliability. Even though the OFDMA concept is simple in its basic principle, the design of a practical OFDMA system is far from being a trivial task. OFDMA is extremely sensitive to timing errors and carrier frequency offsets (FO) between the incoming waveform and the local references used for signal demodulation
The effect of different crossing angles on similarity and stability of target spectra in forward scattering micro radar (FSMR) using graphical user interface (GUI) / Hanis Adiba Mohamad
Get PDFThis project highlights the simulation by using MATLAB to identify the effect of different crossing angles on target spectra in Forward Scattering Micro Radar (FSMR) for ground target detection. The main objective is to model and compare the target signatures of moving ground target without the presence of clutter and other external factors that might affect the signals in actual radar sites. FSMR operates at low carrier frequencies within the VHF and UHF bands using omnidirectional antennas. Ability to detect small and stealth target, the use of distributed FSR sensors network that can offers number of interesting features such as detection and classification of target even at low frequency, small and light weight. This makes FSMR an interesting topic to learn about. The algorithm is developed based on Fourier transform for features transformation from time domain signal to power spectrum density. Besides that, new software in producing the target signatures is developed by using Graphical User Interface (GUI) in MATLAB which can be used as a learning material in universities. Therefore, by completing this project with novel features will definitely give a lot of benefit to radar development generally
The effect of different crossing angles on similarity and stability of target spectra in Forward Scattering Micro Radar (FSMR) using graphical user interface (GUI) / Hanis Adiba Mohamad
Get PDFThis paper investigates the effect of different crossing angles of target spectra in Forward Scattering Micro Radar (FSMR). Target modeling and simulation signals have been executed using MATLAB Software to evaluate the performance of ground based Forward Scattering Radar (FSR) with omnidirectional antennas that operates at a low frequency bands (VHF and UHF). The obtained results show the effect of different crossing angles to the target spectra
Interference reduction using MMSE-DFE Equalizer with One-Third ICI-SC STFBC for MIMO-OFDMA System
No full textOrthogonal frequency division multiple access (OFDMA) allows simultaneous low data rate transmission for several users. However, as one symbol interferes with subsequent symbol, it will produce a phenomenon called intersymbol interference (ISI) which has similar effect as noise and thus making the communication less reliable. Besides that, Doppler spread due to channel time-variation destroys the orthogonality in OFDMA system and degrade the system performance with intercarrier interference (ICI). In order to solve this issue, minimum mean square error-decision feedback equalizer (MMSE-DFE) with one-third (ICI-SC) subcarrier mapping method using space-time-frequency block codes (STFBC) is proposed. The objective is to minimize both ISI and ICI effects by evaluating pairwise error probability (PEP) and bit error rate (BER) performances. From the simulation results, MMSE-DFE with one-third ICI-SC technique shows the best result for MIMO-OFDMA system with 25% improvement of PEP and 4.8% improvement of BER
MIMO-OFDMA subcarrier mapping improvement by using quarter ICI-SC with STFBC technique
No full textMany wireless communication systems rely on Orthogonal Frequency Division Multiple Access (OFDMA) to guarantee reliable transmission and better performance. However, the orthogonality of the subcarriers has been destroyed by frequency offset (FO) and thus leads to inter-carrier interference (ICI) which reduces the system performance. In order to overcome this problem, quarter ICI self-cancellation (ICI-SC) subcarrier mapping scheme using data allocation in space-time-frequency block codes (STFBC) for MIMO-OFDMA system is proposed. The technique is then evaluated through Pairwise Error Probability (PEP) and Bit Error Rate (BER) performance. From the results, proposed quarter ICI-SC subcarrier mapping scheme technique with STFBC shows the best result for MIMO-OFDMA system
CIR performace of one-third ICI-SC subcarrier mapping technique with STFBC in MIMO-OFDMA system
No full textIn multiple input multiple output (MIMO) with orthogonal frequency division multiple access (OFDMA) system, intercarrier interference (ICI) is one of the major drawback in the system. This is due to the orthogonality of the subcarrier which has been destroyed by frequency offset (FO) and thus degrades the system performance. In order to overcome this problem, one-third intercarrier interference self-cancellation (ICI-SC) subcarrier mapping method with space time frequency block codes (STFBC) is proposed. Average power desired (APD) signal, ICI and carrier to interference ratio (CIR) are derived theoretically and the proposed signal is analyzed with other previous methods. As a result, it is proven that by choosing the suitable subcarrier mapping with ICI-SC method, MIMO-OFDMA system performance which affected by FO can be improved with maximum diversity order
Enhancement of pairwise error probability performance in MIMO-OFDMA system using one-third ICI-SC subcarrier mapping technique with STFBC
No full textDevelopment of knowledge in records management by using bibliometric analysis on records management journal / Kamarul Azwan Azman, Mohd Nizam Yunus and Hanis Diyana Kamarudin
Get PDFA bibliometric analysis of 235 articles published in Records Management Journal's 15 years of publication, ranging from 1994-2009 was carried out. The range of articles published per volume is between 9 and 17. Most papers (80%) are single authored or 187 authors out of a total of 235 authors. Elizabeth Shepherd, the most prolific author contributed 7 papers. 174 (59.2%) of the authors are geographically affiliated to United Kingdom. The most productive institution/organization is University of Northumbria, United Kingdom with 24 out of 187 authors. Subject analysis indicates that "Systems Design and Implementation" outnumbered other subjects with 15.8% (37) out of total of 235 articles. Most of the cited publications (97.7%) are in English Language. The majority of articles are research papers contributing 78 articles (33.2%)
MIMO OFDMA receiver optimization using APA adaptive filter based in MMSE-DFE equalizer with diversity techniques
No full textBER and PAPR analysis of MIMO OFDMA and SCFDMA system using different diversity techniques
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