An improved selective mapping (SLM) technique for peak to average power ratio (PAPR) reduction in orthogonal frequency division multplexing (OFDM) system

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Date
2017-06
Authors
Fatin Qurratu Ainii Binti Abdul Rahman
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Orthogonal Frequency Division Multiplexing (OFDM) is the most popular modulation method that has been implemented in high speed wireless communication. This due to its reliability to communicate over fading channels, high spectral efficiency, robustness against multipath propagation, simple to be implemented, and simple equalizer. Unfortunately, major disadvantage of OFDM is Peak to Average Power Ratio (PAPR). By having high PAPR, the performance of signal transmission reduces. Therefore, there are variety of techniques being proposed in reducing PAPR. Selected mapping (SLM) is the best PAPR technique in reducing PAPR due to its ability to gives the lowest PAPR result, flexibility to work with arbitrary number of subcarriers and distortion less scheme in reducing PAPR. In this thesis, the methods that has been proposed in order to improve the SLM technique in reducing PAPR is the combination of Discrete Cosine Transform (DCT) with SLM. The DCT transform is used to reduce the autocorrelation of the input sequence in order to reduce the PAPR. SLM is applied after DCT transform. The obtained result of PAPR is based on the type of modulation and the number of subcarrier used. In addition, as the number of subcarriers increase, the PAPR value also increases. For 64 QAM, it gives more reduction of PAPR value compared to 16 QAM. The result by the application of SLM with DCT in OFDM system is better than application of SLM without DCT.
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