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Báo cáo hóa học: " Peak-to-Average-Power-Ratio (PAPR) reduction in WiMAX and OFDM/A systems"
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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Peak-to-Average-Power-Ratio (PAPR) reduction in WiMAX and OFDM/A systems | Khademi et al. EURASIP Journal on Advances in Signal Processing 2011 2011 38 http asp.eurasipjournals.eom content 2011 1 38 o EURASIP Journal on Advances in Signal Processing a SpringerOpen Journal RESEARCH Open Access Peak-to-Average-Power-Ratio PAPR reduction in WiMAX and OFDM A systems Seyran Khademi1 Thomas Svantesson2 Mats Viberg1 and Thomas Eriksson1 Abstract A peak to average power ratio PAPR reduction method is proposed that exploits the precoding or beamforming mode in WiMAX. The method is applicable to any OFDM A systems that implements beamforming using dedicated pilots which use the same beamforming antenna weights for both pilots and data. Beamforming performance depends on the relative phase shift between antennas but is unaffected by a phase shift common to all antennas. PAPR on the other hand changes with a common phase shift and this paper exploits that property. An effective optimization technique based on sequential quadratic programming is proposed to compute the common phase shift. The proposed technique has several advantages compared with traditional PAPR reduction techniques in that it does not require any side-information and has no effect on power and bit-error-rate while providing better PAPR reduction performance than most other methods. Keywords WiMAX OFDM PTS PAPR reduction phase optimization sequential quadratic programing 1. Introduction Many recent wide-band digital communication systems use a multi-carrier technology known as orthogonal-frequency-division-multiplexing OFDM where the band is divided into many narrow-band channels. A key benefit of OFDM is that it can be efficiently implemented using the fast-fourier-transform FFT and that the receiver structure becomes simple since each channel or sub-carrier can be treated as narrow-band instead of a more complicated wide-band channel. Orthogonal-frequency-division-multi-access OFDMA is a similar technique but the bands can be occupied by different users. Although OFDM and OFDMA .