共查询到17条相似文献,搜索用时 109 毫秒
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多输入多输出频分复用技术是将OFDM与MIMO技术相结合的无线通信系统,也具有OFDM系统存在的峰均比较高的问题。分析了MIMO-OFDM系统模型及PAPR问题,在次优PTS算法的基础上,提出了迭代限幅PTS联合算法。该算法先将MIMO-OFDM信号经过迭代PTS算法进行处理,然后再将其经过限幅处理进一步降低系统的PAPR。最后在自适应PTS算法的基础上进行了改进,仿真结果表明系统复杂度和PAPR性能有所降低,但可以通过调整门限来提高性能。 相似文献
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多输入多输出正交频分复用(MIMO-OFDM)可以提高系统在频率选择性衰落信道的传输性能.与OFDM系统一样,MIMO-OFDM系统也存在高峰值平均功率比(PAPR)的问题.为此,提出了一种降低空时分组编码MIMO-OFDM系统PAPR的正交部分传输序列算法,运用这种算法,利用傅里叶变换的性质,通过调整空时编码与基带正交调制的顺序,对两天线发射端,可以降低算法近一半的复杂度,且可以减少一半的边信息.利用高功率放大器的非线性模型,得到了瑞利衰落信道下PAPR降低后系统的误码率性能.仿真结果证明了该方法的有效性. 相似文献
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OFDM技术能有效解决塑料光纤(POF)信道中频率选择性衰落及码间干扰等问题。这里在POF通信中引入OFDM技术,建立OOFDM通信模型,分析了高峰均比(PAPR)对POF系统的影响。提出采用脉冲整形技术改变原始数据相位和幅度的分布来抑制PAPR,通过仿真分析了不同基带调制方式对PAPR抑制性能影响,并与几种常见PAPR抑制方法进行比较,最后对模型的整体性能进行仿真。仿真结果表明该技术计算复杂度较小,效率比其他方法高很多,结合QPSK信号调制,降低峰均比效果明显,能有效降低BER值,提高信号质量。 相似文献
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第四代移动通信系统计划以正交频分复用(OFDM)为核心技术提供增值服务,在宽带领域的应用有很大的潜力。在正交频分复用(OFDM)系统中,对频率偏移敏感和峰均比相对较大是OFDM系统要解决的两个很重要的问题。针对针对正交频分复用(OFDM)技术具有较高的峰均功率比(PAPR)的缺点,分析了PTS算法降低OFDM系统PAPR的原理,并对其性能进行了仿真分析,仿真结果验证了算法的有效性。 相似文献
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正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)非常适合高速通信系统,但存在高峰均功率比(PAPR)的问题。对OFDM系统中如何降低PARR的问题进行了研究,讨论了降低PAPR的主要方法,重点分析了选择性映射法(SLM),并在此基础上提出了一种基于预编码矩阵的改进算法,最后通过matlab进行了算法仿真,仿真结果表明,改进算法在使得OFDM系统在降低峰均功率比的性能上得到了进一步的改善。 相似文献
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峰均功率比(PAPR)问题是OFDM系统的主要缺陷之一,在光OFDM系统中,由于调制器、D/A转换器、功率放大器和光纤的非线性,高峰均功率比的信号将会产生严重畸变,对系统的性能造成较大的影响。介绍了降低OFDM系统PAPR的主要方法,包括信号预畸变技术、编码技术和概率类技术,并对星座图扩展(ACE)方法和脉冲成形(PS)方法进行了仿真分析,讨论了各自的优缺点及改进的空间。 相似文献
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Bashir Reza Karimi Mojtaba Beheshti Mohammad Javad Omidi 《Wireless Personal Communications》2014,79(3):1925-1940
Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is a promising solution for next generation wireless communications, due to high bandwidth efficiency, resistance to RF interference, and robustness to multipath fading. A major drawback of OFDM is its high peak-to-average power ratio (PAPR) which results in non-linearities in the output signal. In this paper, two methods based on spatial/temporal processing are proposed to reduce the PAPR of MIMO-OFDM systems. These methods divide the OFDM block at each transmit antenna into some subblocks. Then, spatial and temporal processing in the form of circular shifting or interleaving are applied to generate different candidate sequences. Finally, for each transmit antenna the candidate sequence with the lowest PAPR is chosen for transmission. Compared to the conventional PAPR reduction schemes such as ordinary partial transmit sequences (O-PTS), the proposed methods require lower computational complexity and have superior PAPR reduction performance. 相似文献
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Multiple-Input Multiple-Output (MIMO) communications are frequently employed to improve the transmitted data rate and the link quality. Index modulated orthogonal frequency division multiplexing (OFDM-IM) improves the error rate performance and the peak-to-average power ratio (PAPR) compared with those of the conventional OFDM system due to the activation of partial subcarriers. The MIMO OFDM-IM can transmit additional information bits via the indices of active subcarriers. Also, in order to reduce the transmission power of the OFDM system, the MIMO OFDM-IM scheme can be employed to approach the demanded data transmission rate and the error rate performance. Multiple-input multiple-output orthogonal frequency division multiplexing index modulation (MIMO-OFDM-IM) is an effective multicarrier transmission scheme and can be proposed as an alternative to conventional MIMO-OFDM system. In this scheme, OFDM-IM is combined with MIMO transmission to take the benefits of these two techniques. In this paper, we propose a joint channel estimation and turbo equalisation receiver for MIMO-OFDM-IM system. Some simulation examples are given to demonstrate the effectiveness of the proposed receiver. 相似文献
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Xiaodong Zhu 《Wireless Personal Communications》2012,65(2):335-346
Clipping is a simple scheme to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Further, it can be extended to space-time block coding (STBC) multiple-input multiple-output (MIMO) OFDM systems for the PAPR reduction. In the conventional clipping schemes for STBC MIMO-OFDM systems, the input symbols are first encoded and then clipped. In this paper, a new scheme is proposed, where the clipping operation is performed before space-time block coding. We theoretically prove that the proposed scheme has better bit-error rate (BER) performance while maintaining the same PAPR reduction as the conventional schemes. Additionally, we derive the symbol-error rate (SER) and BER expressions for the new scheme over multipath fading channels. The simulation results show a good match with our analysis. 相似文献
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STBC MIMO-OFDM peak-to-average power ratio reduction by cross-antenna rotation and inversion 总被引:2,自引:0,他引:2
Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has become a promising candidate for high performance 4G broadband wireless communications. However, like OFDM, one main disadvantage of MIMO-OFDM is that the signals transmitted on different antennas might exhibit a prohibitively large peak-to-average power ratio (PAPR). We will show that the PAPR reduction for MIMO-OFDM needs a more efficient solution than applying existing schemes for OFDM systems separately on each antenna. Further, we suggest a scheme of cross-antenna rotation and inversion (CARI), which utilizes additional degrees of freedom by employing multiple antennas. Two suboptimal schemes, termed successive suboptimal CARI (SS-CARI) and random suboptimal (RS-CARI) show significant performance advantages and lower computational complexity compared to the concurrent selective mapping (SLM) scheme proposed in Y. -L. Lee et al. (2003). 相似文献
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多输入多输出正交频分复用(MIMO-OFDM)系统已成为第四代无线通信的关键技术之一,而系统所产生的高峰均功率比(PAPR)信号是限制MIMO-OFDM技术实用化的主要障碍。针对此,对MIMO-OFDM系统中现有的几种降低PAPR的传统及改进算法进行了详细介绍,并描述了改进算法相对于传统算法的主要优点。 相似文献