Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems

Orthogonal Frequency Division Multiplexing (OFDM) is a form of a Frequency Division Multiplexing (FDM) scheme that is used in recent broadband wireless communication systems. The main advantage of OFDM systems is immunity against the fading phenomena caused by natural multipath environment. However...

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主要作者:	Mohammady, Somayeh
格式:	Thesis
語言:	English
出版:	2012
主題:	Frequency multipliers Wavelength division multiplexing
在線閱讀:	http://psasir.upm.edu.my/id/eprint/38550/1/FK%202012%2020R.pdf
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spelling	my-upm-ir.385502015-05-05T02:11:47Z Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems 2012-01 Mohammady, Somayeh Orthogonal Frequency Division Multiplexing (OFDM) is a form of a Frequency Division Multiplexing (FDM) scheme that is used in recent broadband wireless communication systems. The main advantage of OFDM systems is immunity against the fading phenomena caused by natural multipath environment. However, there is a major drawback of high Peak-to-Average Power Ratio (PAPR). Signal with high PAPR forces the Power Amplifier (PA) to work in its nonlinear region, which generates distortions. The PA has to be operated with back-off to avoid high PAPR, which decreases the power efficiency. To overcome the PAPR problem in OFDM systems, several techniques are introduced such as Conventional Selected Mapping (C-SLM) and Dummy Sequence Insertion (DSI). In C-SLM method, by increasing the number of Inverse Fast Fourier Transform (IFFT) blocks, the PAPR performance is enhanced at the expense of complexity and side information, which results in high cost and spectrum efficiency degradation. In DSI method, inserting the dummy signals degrades the spectrum efficiency and also exhibits data rate loss. In this thesis, two schemes have been proposed in order to reduce PAPR. The first proposed scheme is called DSI-SLM, which combines the modified dummy sequence of the DSI with the phase sequence of the SLM. As a result of applying this scheme, the PAPR performance is enhanced and the complexity is reduced compared to C-SLM. The second proposed method is named Optimum Phase Sequence with Dummy Sequence Insertion (OPS-DSI) that is designed to improve the DSI-SLM method in terms of complexity and side information. In OPS-DSI method, the optimum phase sequence is applied while only one IFFT is performed and the side information can be placed within the dummy signals. In order to demonstrate the feasibility of these methods in actual systems, the prototype of DSI-SLM and OPS-DSI methods are carried out in Field Programmable Gate Array (FPGA). The implementation results are comparable with simulation results. However,there is less than 0.1dB difference which is due to the constraints of the FPGA input and output bit resolutions. Finally, these methods are integrated with Digital Predistortion (DPD) and actual PA to represent an OFDM transmitter system. This results in Power Added Efficiency (PAE) enhancement by an average of 17%, which leads to less power consumption and prolonged battery life. This system is simulated based on IEEE 802.16e standard and the results are numerically analyzed and compared with various numbers of dummy signals and candidate signals. The DSI-SLM method reduces PAPR by 3.6dB. Almost 76% reduction in total complexity is also achieved compared to CSLM,meanwhile OPS-DSI method enhances PAPR performance by 4.2dB and total complexity reduction by 95%. Hence, OPS-DSI outperforms DSI-SLM in terms of PAPR and complexity. Their Bit Error Rates (BERs) are in acceptable range of 10-4 at Sb/Nb=14 dB. Frequency multipliers Wavelength division multiplexing 2012-01 Thesis http://psasir.upm.edu.my/id/eprint/38550/ http://psasir.upm.edu.my/id/eprint/38550/1/FK%202012%2020R.pdf application/pdf en public phd doctoral Universiti Putra Malaysia Frequency multipliers Wavelength division multiplexing
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English
topic	Frequency multipliers Wavelength division multiplexing
spellingShingle	Frequency multipliers Wavelength division multiplexing Mohammady, Somayeh Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
description	Orthogonal Frequency Division Multiplexing (OFDM) is a form of a Frequency Division Multiplexing (FDM) scheme that is used in recent broadband wireless communication systems. The main advantage of OFDM systems is immunity against the fading phenomena caused by natural multipath environment. However, there is a major drawback of high Peak-to-Average Power Ratio (PAPR). Signal with high PAPR forces the Power Amplifier (PA) to work in its nonlinear region, which generates distortions. The PA has to be operated with back-off to avoid high PAPR, which decreases the power efficiency. To overcome the PAPR problem in OFDM systems, several techniques are introduced such as Conventional Selected Mapping (C-SLM) and Dummy Sequence Insertion (DSI). In C-SLM method, by increasing the number of Inverse Fast Fourier Transform (IFFT) blocks, the PAPR performance is enhanced at the expense of complexity and side information, which results in high cost and spectrum efficiency degradation. In DSI method, inserting the dummy signals degrades the spectrum efficiency and also exhibits data rate loss. In this thesis, two schemes have been proposed in order to reduce PAPR. The first proposed scheme is called DSI-SLM, which combines the modified dummy sequence of the DSI with the phase sequence of the SLM. As a result of applying this scheme, the PAPR performance is enhanced and the complexity is reduced compared to C-SLM. The second proposed method is named Optimum Phase Sequence with Dummy Sequence Insertion (OPS-DSI) that is designed to improve the DSI-SLM method in terms of complexity and side information. In OPS-DSI method, the optimum phase sequence is applied while only one IFFT is performed and the side information can be placed within the dummy signals. In order to demonstrate the feasibility of these methods in actual systems, the prototype of DSI-SLM and OPS-DSI methods are carried out in Field Programmable Gate Array (FPGA). The implementation results are comparable with simulation results. However,there is less than 0.1dB difference which is due to the constraints of the FPGA input and output bit resolutions. Finally, these methods are integrated with Digital Predistortion (DPD) and actual PA to represent an OFDM transmitter system. This results in Power Added Efficiency (PAE) enhancement by an average of 17%, which leads to less power consumption and prolonged battery life. This system is simulated based on IEEE 802.16e standard and the results are numerically analyzed and compared with various numbers of dummy signals and candidate signals. The DSI-SLM method reduces PAPR by 3.6dB. Almost 76% reduction in total complexity is also achieved compared to CSLM,meanwhile OPS-DSI method enhances PAPR performance by 4.2dB and total complexity reduction by 95%. Hence, OPS-DSI outperforms DSI-SLM in terms of PAPR and complexity. Their Bit Error Rates (BERs) are in acceptable range of 10-4 at Sb/Nb=14 dB.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Mohammady, Somayeh
author_facet	Mohammady, Somayeh
author_sort	Mohammady, Somayeh
title	Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
title_short	Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
title_full	Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
title_fullStr	Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
title_full_unstemmed	Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
title_sort	peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems
granting_institution	Universiti Putra Malaysia
publishDate	2012
url	http://psasir.upm.edu.my/id/eprint/38550/1/FK%202012%2020R.pdf
_version_	1747811732922826752

Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems

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