共查询到20条相似文献,搜索用时 8 毫秒
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通过引入满速率空时分组码方案, 该文给出一种满速率空时分组编码CDMA系统模型, 并针对现有空时编码CDMA系统过高的译码复杂度, 提出一种低复杂度的多用户接收方案。该方案在通过类似多用户检测方法有效抑制多用户干扰后, 充分利用空时分组码的复正交性来简化原有方案高译码复杂度。与原有指数性译码复杂度相比, 该方案有着线性复杂度, 而且与满分集空时分组编码CDMA系统相比, 可实现满速率、低复杂度和部分分集, 有着相对多的空间冗余信息, 从而级联信道编码后可有效弥补部分分集所带来的性能损失。仿真结果表明在相同系统容量和级联码的情况下, 所给系统比相应的满分集空时编码CDMA系统有着低的误比特率。 相似文献
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给出了一种新的线性空时多用户接收机的一般表达形式。对这种表达形式的分析表明,线性空时多用户接收机可以分解为4个级联部分,即匹配滤波、空域合并、多径合并和多用户检测器,并且前3个部分的运算仍是以单用户接收为基础的。仿真结果表明,这种结构分解可以有效降低线性空时多用户接收机的计算复杂度,加快自适应接收机的收敛速度,更利于实际系统应用。 相似文献
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卫星导航系统容易受到干扰,空时自适应处理在导航接收机抗干扰方面拥有明显的优势,即系统自由度显著提高,但是传统空时自适应处理应用于导航接收机抗干扰中却面临信号失真的难题。该文提出一种基于正交约束的导航接收机空时自适应处理方法。该方法从空时自适应处理的原理入手修改传统空时自适应处理优化的约束项,消除了不同时延信号对合成信号的影响,保证了空时自适应处理在有效抑制干扰的同时不影响导航信号的捕获和解码。理论分析和仿真结果表明,该方法能有效解决空时自适应处理中的导航信号失真问题。 相似文献
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ZHENG Sheng-hua XU Da-zhuan JIN Xue-ming 《中国电子科技》2007,5(1):33-37
The developments of the high speed analog to digital converters (ADC) and advanced digital signal processors (DSP) make the smart antenna with digital beamforming (DBF) a reality. In conventional M-elements array antenna system, each element has its own receiving channel and ADCs. In this paper, a novel smart antenna receiver with digital beamforming is proposed. The essential idea is to realize the digital beamforming receiver based on bandpass sampling of multiple distinct intermediate frequency (IF) signals. The proposed system reduces receiver hardware from M IF channels and 2M ADCs to one IF channel and one ADC using a heterodyne radio frequency (RF) circuitry and a multiple bandpass sampling digital receiver. In this scheme, the sampling rate of the ADC is much higher than the summation of the M times of the signal bandwidth. The local oscillator produces different local frequency for each RF channel The receiver architecture is presented in detail, and the simulation of bandpass sampling of multiple signals and digital down conversion to baseband is given. The principle analysis and simulation results indicate the effectiveness of the new proposed receiver. 相似文献
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通过对实际CDMA前向信道的分析,得出符合广义RAKE(G- RAKE)接收机的发射信号形式,证明了当多径相对时延非单位扩频码片时G -RAKE接收机多余分支的放置位置。对Matlab中simulink产生的CDMA前向信道信号进行仿真,结果显示了G- RAKE接收机良好的性能。 相似文献
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A beamspace-time (BT) RAKE receiver is proposed for multiple accessinterference (MAI) suppression and multipath diversity reception insectored wireless CDMA communications. The scheme involves three stages.First, a set of adaptive beamformers encompassing a prescribed angular sectoris constructed on an antenna array, each providing effective suppression ofout-of-sector MAI and reception of in-sector signal. Second, a set of adaptivecorrelators is attached to each beam to combat in-sector MAI. Finally, thebeamspace correlator output data are combined to capture the signal multipathscoherently.The above three-stage operation is performed in a blind mode inthat no training signal is needed. The only information required is the signature,timing and a rough estimate of the angle of arrival (AOA) of the desired signal. 相似文献
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实现智能天线技术需要解决的一项关键问题是通道失配的校正,已有的通道校正方法未考虑实际通道间存在处理时延差异。本文分析了一种盲校正方法的原理,仿真结果表明该方法在通道间存在时延差异的情况下已失效。进而,提出了一种改进的盲校正方法。结合DS—CDMA信号的特点,该方法首先补偿了各通道间的时延差异,并在此基础上结合原有的盲校正方法。仿真实验证明了它的有效性。 相似文献
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In this paper we propose a soft-output RAKE receiver for CDMA mobile terminals using low spreading factor and/or high-order modulation constellations for high data rates. Based on the outputs of theRAKE correlator fingers, the receiver produces symbol or bit metrics for soft decision decoding. The formulation of these metrics is derived analytically taking into account the multipath propagation, interfering users and channel estimation errors. Simulations show thata performance gain is achieved when low spreading factors or high-order modulation constellations are used. 相似文献
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CDMA系统反向信道RAKE接收的研究 总被引:1,自引:0,他引:1
本文研究了码分多址系统反向链路上的正交调制非相干RAKE接收机,介绍了接收机模型,并对最强径搜索、逐位输出软判量度、天线分集等问题进行了讨论,最终给出了相应的仿真结果。 相似文献
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An implementation of a reverse link receiver for IS-95 CDMA (Code-Division Multiple-Access) communications that applies decision feedback to the decoding of the received signal is presented. Decision feedback is used in order to improve BER performance by making use of additional information that conventional receiver designs generally ignore. Qualitative analysis and computer simulation of the hardware components of the proposed implementation shows that it can be built as a single integrated circuit using present day technology. The design presented here does not include the RF front-end of the receiver, does not consider the effects of multipath and fading on system performance, and assumes perfect power control. 相似文献