SFBC MIMO-OFDM系统中基于无边带信息降低峰均功率比的研究

发布时间：2018-04-15 05:25

本文选题：多输入多输出 + 正交频分复用　；参考：《华中科技大学》2014年硕士论文

【摘要】：多输入多输出（MIMO）技术通过使用多根发送天线和接收天线，利用空间分集来提高系统的容量和频谱利用率。另一方面，，正交频分复用（OFDM）能够有效地对抗频率选择性衰落。因此，将MIMO和OFDM两项技术相结合构成MIMO-OFDM系统，能够同时提高无线通信系统的容量和传输可靠性。但是MIMO-OFDM系统同OFDM系统一样，存在非常严重的峰均功率比问题。本文提出两种无需发送边带信息的方法来降低基于空频分组编码（SFBC）的MIMO-OFDM系统中的峰均功率比（PAPR）。提出的第一种方法是载波预留方法，我们设计载波预留方法中的原始峰值抵消信号时，同时考虑两根发射天线上的信号，能够在不破坏SFBC的结构的情况下，大幅度降低两根天线上OFDM信号的PAPR。仿真结果证实我们提出的方法能够很好地降低SFBC MIMO-OFDM系统的PAPR和比特误码率（BER）。我们提出的第二个方法是无需发送边带信息的选择性映射（SLM）方法。在这个方法里，我们利用MIMO-OFDM系统中的小部分的空闲子载波，将这些空闲子载波的位置同SLM方法的相位旋转因子的序号联系起来。在接收端，通过检测预留子载波的位置，确定使用的是哪一组相位旋转因子，从而避免发送额外的边带信息。仿真结果显示，提出的SLM方法降低PAPR的性能与传统的SLM方法相同，在信道条件较好的情况下，我们提出来的SLM方法能够在不发送任何边带信息的情况下，取得和传统SLM方法边带信息完美恢复时相同的BER性能。
[Abstract]:Multiple input multiple output (MIMO) technology uses multiple transmit and receive antennas to improve the system capacity and spectral efficiency by using spatial diversity.On the other hand, OFDM (orthogonal Frequency Division Multiplexing) can effectively combat frequency selective fading.Therefore, combining MIMO and OFDM to form MIMO-OFDM system can improve the capacity and transmission reliability of wireless communication system at the same time.But MIMO-OFDM system, like OFDM system, has very serious PAPR problem.In this paper, two methods are proposed to reduce the peak-to-average power ratio (PAPR) of MIMO-OFDM systems based on space-frequency block coding (SFBCs) without sending sideband information.The first method proposed is carrier reservation. When we design the original peak cancellation signal in the carrier reservation method, we consider the signals on two transmit antennas at the same time, which can not destroy the structure of SFBC.The PAPR of OFDM signal on two antennas is greatly reduced.The simulation results show that the proposed method can effectively reduce the PAPR and bit error rate (BER) of SFBC MIMO-OFDM system.The second method we propose is the selective mapping (SLM) method without sending sideband information.In this method, the position of these free subcarriers is associated with the ordinal number of the phase rotation factor of the SLM method using a small number of free subcarriers in the MIMO-OFDM system.At the receiving end, the position of the reserved subcarrier is detected to determine which set of phase rotation factors are used, thus avoiding the transmission of additional sideband information.The simulation results show that the proposed SLM method can reduce the performance of PAPR the same as the traditional SLM method. In the case of better channel conditions, the proposed SLM method can send no sideband information.Obtain the same BER performance as the traditional SLM method when the sideband information is recovered perfectly.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN919.3

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