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该文提出了两种适用于宽带单载波多用户MIMO-CDMA系统下行链路的分数间隔空频均衡接收方案,并进行了理论推导。第1种接收方案采用分数间隔空频均衡器对MIMO频率选择性衰落信道进行均衡,从而恢复了扩频码的正交性,减小了码间干扰和共道干扰。第2种方案在假设接收端已知各用户扩频码的前提下,将分数间隔空频均衡器与频域并行干扰消除器结合,能够进一步消除天线间干扰,提高系统性能。仿真结果表明,这两种分数间隔空频均衡接收方案都比传统的频域均衡接收方案在性能上有很大的提高,并且复杂度也比较低。 相似文献
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ABSTRACT In all mines the operating costs depend largely on the type and size of the mining equipment. While a standard equipment is most often selected for small mines, considerable savings may be realized if the use of the continuous mining equipment is investigated. To facilitate such investigations, the paper describes the suitable continuous mining equipment, and discusses the mining methods applicable in small mines. 相似文献
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S. W. Cheung A. H. Aghvami 《International Journal of Satellite Communications and Networking》1989,7(5):413-423
This paper investigates the effects of additive white Gaussian noise (AWGN), adjacent-channel interference (ACI) and co-channel interference (CCI) combined with flat fading on the performance of bandlimited 16-ary differentially encoded quadrature amplitude modulation (16-ary DEQAM) signalling transmitted through a non-linear high-power amplifier (HPA). It is assumed that the HPA exhibits both AM-AM and AM–PM conversion distortions. This situation may be applied to the up-link or down-link of a regenerative satellite system where the HPA is the earth-station travelling-wave tube (TWT) or the on-board TWTA, respectively. The signal-to-noise ratio (SNR) degradations at a specific bit error rate (BER) are evaluated by means of a series of computer simulation tests for various values of channel roll-off factor α (channel bandwidth) and different degrees of output backoff (OBO) of the HPA in the presence of various combinations of the channel impairments. It is shown that by employing a baseband or RF predistortion technique for the HPA and selecting the best arrangement of channel roll-off factor, OBO value of the HPA and channel spacing, a good performance can be achieved regarding the most efficient use of bandwidth together with a minimum SNR degradation due to the presence of channel impairments. Thus, the use of 16-ary DEQAM for satellite communications is feasible in the near future. 相似文献
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Shu‐Han Liao Chien‐Ching Chiu Min‐Hui Ho Chun‐Liang Liu 《International Journal of Communication Systems》2010,23(12):1600-1612
In this paper, the channel capacity of multiple‐input multiple‐output ultra‐wideband (MIMO‐UWB) systems with single co‐channel interference (CCI) is calculated. A ray‐tracing approach is used to calculate the wanted channel frequency response, and the channel frequency response is further used to calculate the corresponding channel capacity. By the ray‐tracing approach, two different antenna arrays are applied to our simulation to observe whether MIMO can reduce CCI. Also the effects caused by the two antenna arrays for the desired system and CCI are quantified. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Anxue Zhang Lei Wang Chen Guo Yansheng Jiang 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(10):1067-1072
TEM horn antenna with constant characteristic impedance (CCI TEM horn antenna) is a widely used ultra-wideband (UWB) antenna.
Considering the peak-to-peak value of the axial electric field (Vpp), how to design such antenna’s characteristic impedance (Z
c) has not been involved in previous research. The relationship between Vpp and antenna aperture as well as characteristic impedance is numerical analyzed. The simulation and experimental results show
that the optimal aperture is existed to maximize Vpp when the antenna’s length is fixed at the axis. More over, Vpp of the antenna with optimal aperture reaches the maximum value when the characteristic impedance is 280 ohm. 相似文献
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异构无线网络干扰对齐技术研究 总被引:1,自引:0,他引:1
由于宏蜂窝和微蜂窝所构建的异构网络可以大幅提高网络的容量而成为未来移动通信的发展趋势,但是微蜂窝的引入增加了异构网中小区的数量,使得小区间同道干扰更加突出,成为限制异构网容量的主要因素,因此,需要研究有效的干扰抑制技术以增强网络性能。近年提出的干扰对齐技术能够获得干扰网络的最大自由度并可达其最优容量。为此研究了基于低秩干扰空间的多小区干扰对齐技术,然后将其推广到异构无线网络,提出了优化的异构网络干扰对齐方案。仿真结果表明,优化后的干扰对齐技术能够有效提高网络容量并降低实现复杂度。 相似文献
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本文提出一种基于压缩感知的同频干扰下长期演进系统信道估计方法。与现有方法不同,本文将干扰和噪声区别对待,利用干扰信号结构建立该系统下多小区信道估计模型(MCCE)。由于无线信道在宽带系统下表现出较为明显的稀疏特性,本文将压缩感知技术应用于上述模型,通过求解新的感知矩阵,并利用多输入多输出信道共有非零支撑集的特性,提出了适用于长期演进系统的联合改进子空间追踪算法(J-MSP),解决了上述模型下字典矩阵列相关度较高的问题;由于所提模型中含有未知的干扰符号,因此还需解决信道和干扰符号的联合估计。仿真结果和分析表明,本文方法在干扰与本小区同步时相比单小区信道估计方法性能显著提升,异步时与最大似然算法性能相当,同时也适用于无干扰场景。 相似文献
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It is well known that orthogonal frequency division multiplexing (OFDM) is sensitive to carrier frequency offset (CFO) and suffers from a high peak‐to‐average ratio. In addition, the performance of OFDM is severely affected by strong co‐channel interference and strong narrowband interference. To mitigate the limitations of OFDM, we propose a new multi‐carrier transceiver based on frequency‐shift filter. A frequency‐shift filter can separate spectrally overlapping sub‐carrier signals by exploiting the spectral correlation inherent in the cyclostationary modulated signals. To increase spectral efficiency, we increase the percentage of spectral overlap between two adjacent sub‐channels. We derive an upper bound and a lower bound on the bit error rate performance of the proposed multi‐carrier transceiver in additive white Gaussian noise channel and frequency‐nonselective Rayleigh fading channel, respectively. Compared with OFDM, our simulation results show that the proposed multi‐carrier transceiver is much less sensitive to CFO and has a lower peak‐to‐average ratio; moreover, without any additional interference suppression technique, the proposed transceiver has the advantage of being able to mitigate strong co‐channel interference with CFO from the intended multi‐carrier signal and mitigate strong narrowband interference in additive white Gaussian noise channel and in Rayleigh fading channel in which a large CFO between the transmitted signal and the received signal often occurs. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献