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OFDM快时变信道下的相位旋转调制技术 总被引:1,自引:0,他引:1
由于发射端和接收端振荡器之间的频率偏差以及无线信道的时变性,OFDM系统各个子载波之间的正交性将会被破坏,从而产生载波间干扰(ICI)。该文利用发送端的多天线分集,提出了一种新型的相位旋转调制技术。它通过在频域对不同发送天线上的发送信号进行不同角度的旋转,使接收端等效信道频域响应产生的载波间干扰最小,达到抑制载波间干扰的作用。实验证明,这种新型的相位旋转调制技术不会改变OFDM系统的发送功率,能够在不占用额外系统带宽的情况下有效地消除快时变信道环境下系统的载波间干扰,达到较好的误码率性能。 相似文献
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为了有效地抑制OFDM系统载频间干扰(ICI),提出一种并行干扰消除的迭代检测算法。基于检测信号的信干噪比最大化的准则,通过对接收信号进行判决、重构、干扰抵消处理,建立了ICI抑制的迭代检测算法,给出了信号检测流程。通过对时变信道的分析,研究了时变信道中归一化频偏对系统陛能的影响,给出了性能仿真结果。仿真结果表明所建议的算法可有效地利用时变信道的时间分集特性来提高系统性能,计算复杂度从O(N^3)降低到O(N)。 相似文献
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高移动环境下利用无线信号空域特征实现OFDM系统的ICI消除 总被引:1,自引:0,他引:1
高移动性正交频分复用(OFDM)系统受多普勒扩展影响产生严重的子载波间干扰(ICI)。根据实际场景中无线信号的空域传播特征,采用WINNER II信道模型建模无线信道,提出利用阵列天线作为接收天线从空域角度消除ICI。该方法利用波达方向估计和波束形成网络对接收信号进行分离,并对分离后的各路信号分别做多普勒频偏补偿,最后将各路处理后的信号进行最大比合并获得多波束分集增益。仿真结果表明,所提方法可有效减小ICI和误码率平台,较处理前可获得5~7 dB的信干比增益。 相似文献
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为了最大程度地利用资源和减小电磁干扰,无人机平台的雷达通信一体化设计有着尤为重要的意义。正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)信号具有较高的频谱利用率、较强的抗干扰性能、易于数字化处理等优点,在雷达通信一体化系统备受关注。然而,OFDM信号在雷达和通信系统中对多普勒频偏较为敏感,针对多普勒频偏引起的子载波间干扰(Inter-Carrier Interference,ICI)问题,本文设计出一种RS-OFDM雷达通信一体化信号,并提出一种ICI抑制的信号处理算法,其中基于多普勒估计和校正实现OFDM的无ICI处理。仿真结果表明:所提方法在目标成像性能上优于传统方法,且对多普勒频偏具有较强的鲁棒性,而且并无明显增加计算复杂度。 相似文献
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针对高速移动环境下多普勒频偏造成移动信道的快衰落和正交频分复用OFDM系统中子载波间干扰(ICI)问题,本文给出了OFDM系统中的多种ICI干扰消除技术。 相似文献
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OFDM系统相位噪声的Huber ML抑制方法 总被引:1,自引:0,他引:1
OFDM系统对相位噪声(PHN)非常敏感,由其引起的子载波相位旋转和载波间干扰(ICI)会严重恶化系统性能。该文提出了一种新的OFDM接收机PHN估计和抑制方法,利用判决数据采用Huber ML估计方法对PHN引起的ICI分量进行迭代估计,将估计的ICI系数变换到时域来校正每个样点的相位误差,从而达到抑制PHN的目的。与传统的基于判决的估计方法相比,该方法对判决的错误传播具有鲁棒性,可进一步提高ICI抑制性能。对算法在AWGN和多径信道环境下的仿真结果表明所提方法对PHN引起的ICI有较好的抑制性能。 相似文献
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Generalized frequency-division multiplexing (GFDM) is a candidate waveform for the fifth generation (5G) wireless communication systems. However, the carrier frequency offset (CFO) causing synchronization problem is very important for GFDM system. In this paper, we propose a turbo receiver with channel estimation, equalization and CFO compensation for MIMO (multiple input multiple output) GFDM system with index modulation (IM). So far, no related researches exist. This paper proposes a novel receiver to solve CFO compensation with two-path transmission and proposes a modified phase rotated conjugate cancellation (PRCC) algorithm for the receiver. On the other hand, GFDM with index modulation (GFDM-IM) can achieve better performance and lower peak-to-average power ratio (PAPR) than those of GFDM by using active index subcarrier. To reduce the system complexity, the log-likelihood ratio (LLR) criteria is also employed to search which subcarrier is active. Moreover, the Kalman filter is employed to trace the time-varying channels. The initial channel estimation is performed by the sparse pilot signals. In the simulations, we compare the proposed receiver with several existing schemes in different time-varying channels and modulations. The proposed scheme outperforms the existing schemes. 相似文献
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BER performance of differential detection severely degrades with carrier frequency drift. The authors propose a baseband processing frequency-drift-compensation (FDC) scheme that estimates the phase rotation of the differential detector output expressed in complex form and multiplies the complex conjugate of the estimate to cancel the phase rotation. 16 kbit/s QDPSK transmission experiments using a simulated Rayleigh fading channel show that a carrier frequency drift of up to about 3/64 times the bit rate can be tolerated with the use of the proposed baseband FDC.<> 相似文献
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研究了相位共轭信号在长距离无中继传输系统中的抗非线性效应的性能。通过构建相应的仿真系统,对比分析了单偏振信号与相位共轭信号的性能差异。仿真结果表明,对于无中继传输系统,相位共轭信号的色散预补偿与有中继传输系统有所差别。在传输信号为32-GBaud的QPSK、传输距离为330km以及后向泵浦设置为0.8W的情况下,当前向泵浦为0.4,0.6以及0.8W时,相较于单偏振传输信号,相位共轭信号的BER性能均可提高2dB以上。此外,相对于单偏振信号,相位共轭信号的传输距离约提升10%。 相似文献
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介绍了一种阵列信号频分复用毫米波传输技术.采用分组二次上变频频谱装配频分复用和解复用技术,实现多路阵列信号在一条宽带毫米波链路上进行双向传输.通过设计控制和幅相校正技术保证了阵列信号分量间的良好幅相一致性.完成了30路阵列信号传输设备研制并进行了测试,结果证明了技术方案的可行性.该技术可以应用到多路阵列信号的毫米波传输... 相似文献
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针对微波光子链路在实际应用中信号相位受光纤温度变化产生的波动,利用检波器矢量和原理检测微波信号的相位偏差量,并设计了信息处理模块控制可调谐电移相器进行精准的相位补偿,实现微波信号的相位稳定传送。在理论模型的基础上,实验测试了温度变化对微波光链路相位的影响,并构造了微波稳相光传输系统,使用25 km的标准单模光纤传输10 GHz微波信号,对系统输出信号进行了长时间测量,相位波动稳定控制在±2°以内,实验结果验证了该方案的可行性。 相似文献
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Xinchun Wu Jinxiang Wang Zhigang Mao Jianwei Zhang 《Circuits, Systems, and Signal Processing》2010,29(3):499-514
The interleaved partitioning partial transmit sequence (IP-PTS) scheme is an attractive technique for peak-to-average power
ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems. But the PAPR performance of IP-PTS is
inferior to that of the adjacent partitioning PTS (AP-PTS) scheme because the candidates generated in IP-PTS are not fully
independent. This paper analyzes the independence of candidates in IP-PTS in detail and finds the effective phase factor vectors.
In order to improve the PAPR performance of IP-PTS, a conjugate IP-PTS (C-IP-PTS) scheme is proposed. By performing the conjugate
operations on some sub-blocks, the number of candidates is increased. Because of the conjugate property of the discrete Fourier
transform (DFT), the additional inverse DFT can be avoided. By optimizing the conjugate sequence, the complexity can be further
lowered. Simulation results show that C-IP-PTS can obtain better PAPR performance compared with AP-PTS; moreover, the computational
complexity of C-IP-PTS is not high. 相似文献
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Conjugate ESPRIT (C-SPRIT) 总被引:5,自引:0,他引:5
In this paper, we present an algorithm to estimate the direction of the arrival angles (DOAs) from noncoherent one-dimensional (1-D) signal sources such as binary phase shift keying (BPSK) and M-ary amplitude shift keying (MASK). The proposed algorithm can provide a more precise DOA estimation and can detect more signals than well-known classical subspace-methods MUSIC and ESPRIT for the 1-D signals. The complexity is the same as that of ESPRIT since the proposed algorithm uses the same array geometry and subarray processing that ESPRIT does. The main differences between the proposed algorithm and the ESPRIT algorithm are as follows: 1) the number of overlapping array elements between two subarrays is equal to M in the proposed algorithm, while in ESPRIT the maximum number of overlapping elements is M-1, where M denotes the total number of array elements, and 2) the proposed algorithm employs the conjugate of rotation matrix (CRM) /spl Phi//sup */ while ESPRIT uses /spl Phi/ with no conjugate for the second subarray geometry. 相似文献