Wavelet methods with discrete cosine transform for peak-to-average power ratio and bit error rate reduction in orthogonal frequency division multiplexing systems / Lim Yong Liang
OFDM telah digunakan dalam rangkaian tanpa wayar, talian pelanggan digital (DSL)
pengaksesan Laman Sesawang, 4G komunikasi mudah alih, televisyen digital dan siaran
audio. Kadar bit yang tinggi semasa penghantaran isyarat, kecekapan spektrum yang
tinggi dan saluran frekuensi pemudaran yang teguh merupakan kelebihan untuk aplikasi
OFDM. Kelemahan dalam sistem OFDM ialah PAPR yang tinggi. Ia menyebabkan
kemerosotan penghantaran isyarat. Dua objektif telah dinyatakan dalam projek ini.
Objektif yang pertama adalah untuk membuat kajian tentang konsep teknik Wavelet dan
transformasi kosinus diskret pada OFDM dan kesannya. Objektif yang kedua ialah untuk
melaksanakan kaedah penambahbaikan Wavelet dengan DCT. Projek ini dibahagikan
kepada empat peringkat iaitu: memahami konsep OFDM dan PAPR, pelaksanaan
algoritma serta mencapai keputusan simulasi dan menganalisasi keputusan simulasi.
Keputusan simulasi menunjukkan pelaksanaan kaedah penambahbaikan Wavelet dengan
DCT dapat mengurangkan PAPR kepada kira-kira 5.111dB untuk 1024 sub-pembawa
isyarat dengan skema modulasi QPS dengan 35%. Di samping itu, BER juga dikira bagi
semua skema modulasi untuk mengkaji prestasi sistem dengan perbandingan antara
nombor bit yang diterima dengan nombor bit yang dihantar. DCT-precoded Wavelet
mencapai kemajuan BER 30% manakala DCT- Wavelet mencapai kemajuan BER 34%
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Orthogonal Frequency Division Multiplexing (OFDM) is nowadays applied in wireless
networks, Digital Subscriber Line Internet Access, 4G mobile communications, digital
television and audio broadcasting. This system has been widely used in high data rate
wireless communications systems. High transmission bit rate, high spectral efficiency and
robustness to frequency fading channels are the benefit for the application of OFDM.
However, there is a major drawback in OFDM systems which is high Peak-to-Average
Power Ratio (PAPR). High PAPR will reduce the performance of OFDM. Several
techniques has been proposed to reduce PAPR. In this study, two objectives are identified.
The first objective is to implement the improved PAPR reduction technique based on DCT
on wavelet method. Then, the second objective is to analyze the performance of the
proposed method based on PAPR and BER. This study is divided into four stages,
understand the concept of OFDM implementation of algorithm, obtaining results and
analyzing the simulation results. The simulation results show that improved method of
DCT wavelet can reduce PAPR to about 5.111dB (35% PAPR reduction improvement)
for 1024 subcarriers by using 64-QAM modulation scheme. Besides that, the Bit Error
Rate is calculated to investigate the performance of the system by comparing the number
of bits received in errors and the number of bits transmitted. DCT-precoded Wavelet gives
30% of improvement of BER whereas DCT-Wavelet gives 34% of improvement of BER
Wavelet methods with discrete cosine transform for peak-to-average power ratio and bit error rate reduction in orthogonal frequency division multiplexing systems / Lim Yong Liang
Wavelet methods with discrete cosine transform for peak-to-average power ratio and bit error rate reduction in orthogonal frequency division multiplexing systems_Lim Yong Liang _E3_2019_MYMY