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Title:	New sub-carrier allocation scheme using generalized interleaved frequency division multiple access in LTE-Advanced systems
Authors:	Mohamed Melood A. Abdased (P59744)
Supervisor:	Mahmod Ismail, Prof. Dr.
Keywords:	Long-Term Evolution (Telecommunications) Multiple access protocols (Computer network protocols) Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	1-Mar-2019
Description:	The Fourth Generation Long Term Evolution (LTE) and LTE-Advanced (LTE-A) standards utilizes the Single Carrier Frequency Division Multiple Access (SC-FDMA) for uplink instead of the Orthogonal Frequency Division Multiple Access as in downlink by virtue of its superior Peak to Average Power Ratio (PAPR) performance. SC-FDMA comprises two variations that are based on subcarrier allocation methods: Localized FDMA (LFDMA) and Distributed Frequency Division Multiple Access (DFDMA). The Interleaved FDMA (IFDMA) is a special case of GIFDMA that uses non-contiguous subcarrier in contrast to LFDMA that utilizes adjacent subcarrier. Both LFDMA and IFDMA subcarrier mappings significantly reduce PAPR at the expense of high time complexity, and therefore are not suitable for practical implementation. Moreover, improper selection of interleave degree could diminish the performance of Bit-Error-Rate (BER) and sacrifice them in terms of user and frequency diversity. The main objective of the thesis is to propose a new subcarrier allocation or mapping scheme using Generalized Interleaved Frequency Division Multiple Access (GIFDMA) in the LTE/LTE-A. Firstly, GIFDMA is proposed by integrating and making the transition between LFDMA/IFDMA schemes seamless based on interleaving level, thereby significantly enhancing subcarrier mapping. A new generalized mathematical formulation is derived as a controlling parameter. Secondly, the performance of PAPR reduction scheme is simulated and investigated using DFT-spreading techniques under various GIFDMA parameter settings such as roll-off factor, number of subcarriers, modulation technique, and FFT/IFFT size. Thirdly, in order to reduce the time complexity and heuristic correlation between interleave level and roll-off factors for fast PAPR estimates, a Multilayer Perceptron Artificial Neural Network (MLP-ANN) and Random Forest (RF) algorithms are introduced. Results of the simulation show that the PAPR of GIFDMA signal decreased by about 1.5 dB in comparison to the original LFDMA signal when the rolloff factor was increased to unity. The SNR of GIFDMA decreased by approximately 2 dB for the LFDMA/IFDMA while the value of BER remains at 10-6 dB. Finally, when the MLP-ANN and RF algorithms were executed, the execution time decreased from 0.15 to 0.018 to seconds and 0.03 to 0.01 seconds respectively in comparison to that of the original GIFDMA which increased from 12.5 to 27.5 seconds when the roll-off factor was varied from unity to zero. The correlation between the interleave level and roll-off factors for a fast PAPR is 0.75.,Ph.D.
Pages:	116
Call Number:	TK5103.48325.A233 2019 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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