OFDM系统中降低PAPR技术的研究

【作者】 陈琳；

【导师】 郭振民；

【作者基本信息】 扬州大学 ， 计算机应用技术， 2004， 硕士

【摘要】 正交频分复用(OFDM)是一种特殊的多载波传输技术。它可以有效地对抗多径衰落，能够以很高的频谱利用率来实现高速数据传输。但是目前OFDM系统还有很多关键问题没有解决，如对频偏敏感、高峰均功率比，这限制了OFDM技术的广泛应用。本论文主要围绕降低OFDM系统中峰均功率比(PAPR)展开研究，利用MATLAB软件完成了对所有研究内容的仿真：并结合数字信号处理(DSP)芯片，在代码编译集成开发环境(CCS IDE)中，对基带OFDM信号的功率谱进行了硬件仿真。 论文首先详细分析了基于离散傅立叶变换的OFDM系统原理、关键技术及其优缺点。然后，给出了峰均功率比的定义和分布，并总结了目前国内外降低PAPR的多种技术。其次，对信号扰码技术中的选择映射(SLM)法和部分选择序列(PTS)法进行了全面的研究与比较。对于基于Newman相位序列的选择映射法，通过仿真分析发现，PAPR性能的改善效果不如理论上的良好，该算法在实际应用中还有改进之处。对于基于线性分组码标准阵列的选择映射法，提出了用[16，11]扩展汉明码标准阵列来降低峰均功率比的具体算法，并通过蒙特卡罗仿真，证明了该算法可以有效地降低PAPR。再次，对于编码技术，提出了一种基于格雷互补序列和雷德密勒码降低峰均功率比的详细的编译码方案。采用此分组码不仅能够抑制OFDM符号的PAPR，而且还能实现前向纠错。论文的最后部分，结合TI公司的TMS320C5402数字信号处理芯片，对OFDM系统的基带调制进行了CCS仿真。初步探讨了利用实时数据交换(RTDX)技术，将数据传输到DSP目标系统进行实时处理的硬件实现平台。更多还原

【Abstract】 Orthogonal frequency division multiplexing (OFDM) is a special multicarrier transmission technology. It can strongly combat multi-path delay and transmit high-rate data with high bandwidth efficiency. However, many key problems of an OFDM system have not been solved yet, such as sensitivity of frequency offset and high peak-to-average power ratio (PAPR), which limit OFDM’s wide applications. This thesis mainly focuses on the techniques of PAPR reduction, and obtains some results by MATLAB simulations. And then under the Code Composer Studio Integrated Development Environment (CCS IDE), it performs hardware simulations of baseband OFDM signal’s power spectrum with Digital Signal Processor (DSP).Firstly, the principle of DFT-based OFDM system, its key techniques, advantages and disadvantages of OFDM technology are analyzed in this thesis. Secondly, the definition and distribution of PAPR are introduced, and various techniques on reducing the PAPR are summarized. Thirdly, signal scrambling techniques are analyzed, including Selective Mapping (SLM) and Partial Transmit Sequences (PTS). For SLM using Newman phase sequences, the PAPR curve with simulation is not patch on the theoretical curve, and further improvement is needed in actual application for this scheme. Here a specific scheme is proposed to reduce the PAPR by using the standardarrays of [16,11] extended hamming code. With Monte Carlo simulation, the effect onPAPR reduction of this scheme is testified. Fourthly, a coding scheme based on Golay Complementary Sequences and Reed-Muller codes is proposed to reduce the PAPR. This scheme can control the PAPR of OFDM signal, and have forward error correction capability. In the last part, CCS simulation of OFDM system baseband modulation is performed with TI’s TMS320C5402 Digtal Signal Processor. And then a hardware platform of data realtime processing is designed for transmitting data to DSP target system with realtime data exchange (RTDX) technique.更多还原