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首页> 外文学位 >Nonlinear transform approach to the reduction of peak-to-average power ratio in orthogonal frequency division multiplexing (OFDM) systems.
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Nonlinear transform approach to the reduction of peak-to-average power ratio in orthogonal frequency division multiplexing (OFDM) systems.

机译：降低正交频分复用（OFDM）系统中峰均功率比的非线性变换方法。

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摘要

The design of modulation technique for wireless data communications in mobile radio channels is important implementation issue due the dispersive and time-variant nature of the channel. In recent years, the interest in multicarrier modulation for wireless transmission has been increased. In general multicarrier schemes, the transmitted data is split into a number of parallel data streams, each one used to modulate a separate subcarrier. An attractive approach to multicarrier modulation is Orthogonal Frequency Division Multiplexing (OFDM). OFDM offers advantages in transmission over (severe) multipath channels so that there is an increased interest in applying OFDM in high-data rate mobile or portable data transmission.The transmit signal in OFDMsystem has a high Peak-to-Average Power Ratio (PAPR) and therefore both the Digital-to-Analog Converter (DAC) and the Power Amplifier (PA) require high dynamic range to perform accurately, otherwise the signal is distorted and hence Bit Error Rate (BER) performance degradation occurs. On the other hand, the battery life in mobile communication is an important key concept in the system design. The PA is driven at high bias voltage levels in order to achieve power efficiency, therefore, it is the main part which requires the most energy as far as the power consumption is concerned. Besides, for signals with large PAPR as in OFDM system, BER performance can be severely degraded by the nonlinear distortion of the PA. As a result, the reduction in PAPR in OFDM system is desirable in order to obtain power efficiency and increase BER performance.In this research, a novel nonlinear sliding norm transforms (SNTs) are developed to reduce the PAPR of the OFDM transmit signal. These are Absolute Norm Sliding Transform, Maximum Norm Sliding Transform, and L 2-by-3 Norm Transform. The simulation results showed that the proposed transforms provide different PAPR reduction based on different modulation levels of QAM. The SNTs exploit the sliding norm of the signal to reduce PAPR. It is shown that the proposed method reduces PAPR of the OFDM signal and thus increases efficiency of power amplifier, increases system performance by reducing in-band and out-of-band distortions. The key novelty of the transforms can briefly be summarized that they are nonlinear, reversible and fast transforms, applicable independently of the signal constellation and mapping on subcarriers, and reduce PAPR at low computational complexity. The transforms can adjust the PAPR reduction by only changing value of parameter alpha and this value can be used by transmitter and receiver as a convention it does not have to be transmitted.Theoretical and performance analysis of the proposed SNTs in terms of PAPR reduction and BER are given for different values of the parameter alpha of the proposed SNTs. In the simulation, the system is IEEE 802.11a Wireless LAN PHY Layer with Memoryless Rapp Model Power Amplifier with different IBO (Input Backoff). The proposed transforms are suitable for OFDM based wireless communication systems such as IEEE 802.11a, g, 802.16e, Multi-band OFDM, DVB/DAB, and HiperLAN/2.
机译：由于信道的分散性和时变性，用于移动无线电信道中的无线数据通信的调制技术的设计是重要的实现问题。近年来，对于用于无线传输的多载波调制的兴趣已经增加。在一般的多载波方案中，传输的数据被分成多个并行数据流，每个并行数据流用于调制单独的子载波。多载波调制的一种有吸引力的方法是正交频分复用（OFDM）。 OFDM在（严重）多径信道上的传输具有优势，因此越来越有兴趣将OFDM应用在高数据速率移动或便携式数据传输中.OFDM系统中的发射信号具有很高的峰均功率比（PAPR）因此，数模转换器（DAC）和功率放大器（PA）都需要高动态范围才能准确执行，否则信号会失真，从而导致误码率（BER）性能下降。另一方面，移动通信中的电池寿命是系统设计中的重要关键概念。为了实现功率效率，PA以高偏置电压电平驱动，因此，就功耗而言，它是需要最多能量的主要部分。此外，对于OFDM系统中具有大PAPR的信号，由于PA的非线性失真会严重降低BER性能。因此，为了降低功率效率并提高BER性能，希望降低OFDM系统的PAPR。在本研究中，开发了一种新颖的非线性滑动范数变换（SNT）以降低OFDM发送信号的PAPR。这些是绝对范数滑动变换，最大范数滑动变换和L 2×3范数变换。仿真结果表明，所提出的变换基于不同的QAM调制级别提供了不同的PAPR降低。 SNT利用信号的滑动范数来降低PAPR。结果表明，所提出的方法降低了OFDM信号的PAPR，从而提高了功率放大器的效率，通过减少带内和带外失真来提高系统性能。可以简单地概括一下这些变换的关键新颖之处，它们是非线性，可逆和快速变换，可独立于信号星座图和子载波映射而使用，并以低计算复杂度降低了PAPR。这些变换可以通过仅改变参数alpha的值来调整PAPR降低，并且该值可以作为发送方和接收方使用，而不必传输该约定。从PAPR降低和BER方面对建议的SNT进行理论和性能分析给出了建议的SNT的参数alpha的不同值。在仿真中，系统是具有不同IBO（输入回退）的无记忆Rapp模型功率放大器的IEEE 802.11a无线LAN PHY层。提出的变换适用于基于OFDM的无线通信系统，例如IEEE 802.11a，g，802.16e，多频带OFDM，DVB / DAB和HiperLAN / 2。

著录项

  • 作者

    Dursun, Serkan.;

  • 作者单位

    The University of Texas at San Antonio.;

  • 授予单位 The University of Texas at San Antonio.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 96 p.
  • 总页数 96
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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