Reduction of Peak-to-Average Power Ratio in OFDM and OFDM-CDMA System

• Main Authors: Shin-Ying Liaung, 梁新潁
• Other Authors: Eric S. Li
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/70964040313421487005

碩士 === 國立暨南國際大學 === 電機工程學系 === 91 === Multicarrier communication has been employed for wire-line communications and has been adapted for use in the future wireless local area network. The term multicarrier modulation includes a number of transmission schemes whose main characteristic is the decomposition of any wideband channel into a set of independent narrowband channels. With this family, the most commonly used schemes are Orthogonal Frequency Division Multiplexing (OFDM) and OFDM-CDMA (Code Division Multiple access), which are based on the Discrete Fourier Transform, resulting in an implementable, high performance structure. Due to its robustness against multipath fading with certain implementation advantage over single-carrier system, coded OFDM has become a popular technique in various high-speed wireless data transmission system. One of the main implementation disadvantages of OFDM and OFDM-CDMA is the high peak-to-average power ratio (PAPR) of the transmitted signals. In this paper, we proposed a technique that combines block code modulation (BCM) with Golay complementary sequence to reduce the peak to average power ratio (PAPR) in OFDM system. And we proposed a reduced algorithm to find optimum Walsh-Hadamard code sets which can maintain almost the minimum peak to average power ratio in OFDM-CDMA system.