| Title | Research and Implementation of Techniques for Peak-to-Average Power Ratio Reduction in OFDM Systems |
| Abstract | Orthogonal Frequency Division Multiplexing (OFDM)is an effective transmission scheme to realizing high-rate data transmission thanks to its intrinsic robustness to multi-path fading, high spectral efficiency,and its characteristic of combating inter symbol interference(ISI). Recently OFDM is being considered as one of the key technologies in the next generation broadband wireless communication systems. However, the OFDM system has the drawback of high peak-to-average power ratio (PAPR).High PAPR may cause signal distortion, spectrum spread and system performance degradation. This dissertation explores the question of Peak-to-Average Power Ratio in OFDM systems primarily.Firstly, the principle of OFDM systems, its key techniques, advantages and disadvantages of OFDM technology are analyzed in this thesis .The definition and distribution of PAPR are introduced and the influences on the system performances by high PAPR were analyzed based on the model of high power amplifier. Various techniques on reducing the PAPR are researched. And the advantages and disadvantages of these techniques are analyzed and summarized.Secondly, a segmented linear companding transform method is proposed to fit the FPGA hardware implementation. Its performance is approached to the traditional no-linear companding transform but it greatly reduces the system’s complexity. Emulation and practical results shows the implementation scheme has a high practical value in OFDM system.Thirdly, clipping method to reduce the PAPR is implemented by FPGA hardware. We oversample each OFDM block by padding the original input with zeros and taking a twice longer IFFT. It reduces the band-in noise effectively. The practical result shows the implementation scheme has good effect.At last, a new method for reducing the PAPR of OFDM signal is proposed via constellation optimization. This method reduce the PAPR by changing the amplitude of constellation, choosing proper amplitude changing factor and adjusting the constellation position .The changing factor is acquired by solving an optimization problem. No change in receiver structure is required; no band-in noise and no spectrum spread; it can reduce the PAPR greatly with a little influence on the system bit error rate. |
| Category | Radio |
| Keywords | Constellation Optimization, FPGA, OFDM, PAPR, Segmented Linear Companding Transform, |
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| Pages | 107 |
| Price | US$80.00 |
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Research and Implementation of Techniques for Peak-to-Average Power Ratio Reduction in OFDM Systems
Billy HU, Ph.D
E-Mail:itpaper@hotmail.com
TEL:1-888-786-998A
