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121.
在正交频分复用(OFDM)系统中,相干解调比差分解调有3 dB的增益,所以一般采用相干解调.为获得准确的信道信息,就需采用基于导频辅助(PSA)的信道估计方法.而在移动多径信道中,时变性致使子载波之间不再严格正交,从而造成子载波间干扰(ICI),影响信道估计性能.对此文中提出了1种基于ICI自消除的新型OFDM信道估计... 相似文献
122.
This paper studies the frequency offset correction technique which can be applied in optical OFDM systems. Through theoretical analysis and computer simulations, we can observe that our proposed scheme named pilot self-coding (PSC) has a distinct influence for rectifying the frequency offset, which could mitigate the OFDM performance deterioration because of inter-carrier interference and common phase error. The main approach is to assign a pilot subcarrier before data subcarriers and copy this subcarrier sequence to the symmetric side. The simulation results verify that our proposed PSC is indeed effective against the high degree of frequency offset. 相似文献
123.
ICI reduction in OFDM systems by using improved sinc power pulse 总被引:2,自引:0,他引:2
In this paper, we propose a new pulse shape to reduce the average ICI power of OFDM systems. Numerical and simulation results show that the proposed pulse is superior to the conventional pulse shapes in terms of ICI power reduction, SIR and BER performance. 相似文献
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在快衰落时变信道中,正交频分复用(OFDM:Orthogonal Frequency Division Multiplexing)系统子载波间的正交性会遭到破坏,由此引起的载波间干扰(ici:Inter-Carrier Interferellce)会对系统性能带来很大的影响。本文提出了一种利用时域线性模型的信道估计算法,利用随时间线性变化的模型描述信道。仿真结果表明,本算法能够有效地消除载波间干扰,降低系统的BER。与类似算法相比,当系统的BER性能相同时,算法复杂度大大的降低。 相似文献
126.
KaziTakpaya 《电子科学学刊(英文版)》2003,20(5):371-377
A robust interference canceller for Multi-Carrier Code Division Multiple Access (MC-CDMA) using Orthogonal Frequency Division Multiplexing (OFDM) in Rayleigh fading is proposed. This interference canceller is robust in the sense that it cancels Inter-Carriers Interference (ICI) and is suitable for use in dispersive channels. To come up the effects of the slgnal dispersion, Doppler shifts and delay spreads on the performance of MC-CDMA systems over mobile fading channels, this interference canceller exploits the merit of the orthogonal signaling and pilot signals to evaluate the channel parameters. This interface canceller is well suited to work in iterative turbo interference cancellation. 相似文献
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Adaptive subcarrier bandwidth and power in OFDM‐based cognitive radio systems for high mobility applications
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OFDM‐based cognitive radio systems are spectrally flexible and efficient, but they are vulnerable to intercarrier interference (ICI), especially in high mobility environments. High mobility of the terminal causes large Doppler frequency spread resulting in serious ICI. Such ICI severely degrades the system performance, which is ignored in the existing resource allocation of OFDM‐based cognitive radio systems. In this paper, an adaptive subcarrier bandwidth along with power allocation problem in OFDM‐based cognitive radio systems for high mobility applications is investigated. This adaptive subcarrier bandwidth method should choose the suitable subcarrier bandwidth not only to balance the tradeoff between ICI and intersymbol interference but also to be large enough to tolerate an amount of Doppler frequency spread but less than the coherence bandwidth. The power budget and interference to primary users caused by cognitive radio users are imposed for primary users' protection. With these constraints, a joint optimization algorithm of subcarrier bandwidth and power allocation is proposed to maximize the bandwidth efficiency of OFDM‐based cognitive radio systems in such conditions. Numerical simulation results show that the proposed algorithm could maximize the system bandwidth efficiency and balance this tradeoff while satisfying the constraints. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
130.
相位噪声也能引起信道间干扰( ICI) ,本文系统的分析了采用ICI自消除方案前后相位噪声对OFDM系统的影响,得出了载波干扰比和信噪比的近似计算公式,在AWGN信道上仿真了系统的误码性能。从仿真结果看,ICI自消除的方案能够显著提高系统的载波干扰比和误码率 相似文献