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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myupmir.3855020150505T02:11:47Z Peak to average power ratio reduction based on optimum phase sequence in orthogonal frequency division multiplexing systems 201201 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 PeaktoAverage 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 backoff 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 (CSLM) and Dummy Sequence Insertion (DSI). In CSLM 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 DSISLM, 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 CSLM. The second proposed method is named Optimum Phase Sequence with Dummy Sequence Insertion (OPSDSI) that is designed to improve the DSISLM method in terms of complexity and side information. In OPSDSI 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 DSISLM and OPSDSI 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 DSISLM method reduces PAPR by 3.6dB. Almost 76% reduction in total complexity is also achieved compared to CSLM,meanwhile OPSDSI method enhances PAPR performance by 4.2dB and total complexity reduction by 95%. Hence, OPSDSI outperforms DSISLM in terms of PAPR and complexity. Their Bit Error Rates (BERs) are in acceptable range of 104 at Sb/Nb=14 dB. Frequency multipliers Wavelength division multiplexing 201201 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 
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Universiti Putra Malaysia 
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PSAS Institutional Repository 
language 
English 
topic 
Frequency multipliers Wavelength division multiplexing 
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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 PeaktoAverage 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 backoff 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 (CSLM) and Dummy Sequence Insertion (DSI). In CSLM 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 DSISLM, 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 CSLM. The second proposed method is named Optimum Phase Sequence with Dummy Sequence Insertion (OPSDSI) that is designed to improve the DSISLM method in terms of complexity and side information. In OPSDSI 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 DSISLM and OPSDSI 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 DSISLM method reduces PAPR
by 3.6dB. Almost 76% reduction in total complexity is also achieved compared to CSLM,meanwhile OPSDSI method enhances PAPR performance by 4.2dB and total complexity reduction by 95%. Hence, OPSDSI outperforms DSISLM in terms of
PAPR and complexity. Their Bit Error Rates (BERs) are in acceptable range of 104 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 