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林云峰  雷霞  刘皓 《中国集成电路》2009,18(8):38-43,19
Turbo迭代均衡技术与OFDM相结合能够有效提高系统的抗干扰、抗衰落性能,从而提高系统的通信质量和容量。以往的研究大多是从Turbo均衡的算法的角度上进行研究和改进,本文以OFDM系统的Turbo均衡链路为基础,从工程实现的角度对系统实现的整体架构进行改进,并在TI C6416T DSP上进行了仿真验证。仿真结果表明,本文提出的Turbo均衡链路的实现方式能有效提高系统的实现性能,增加Turbo迭代的次数和效果。  相似文献
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连续相位调制(CPM)由于其相位连续和恒包络,可以使用低成本的非线性功率放大器,且CPM信号有近于1的峰均功率比,在放大器处产生的能量消耗小,从而解决协同系统中移动终端的成本和能量受限问题。本文针对平坦衰落信道下的CPM协同通信系统,研究了可表征系统容量下界的对称信息率(SIR)。分析和数值结果表明,协同CPM系统与单入单出CPM系统相比,能获得更大的信道容量,同时还拥有更低的中断概率。进一步地,以最大化系统遍历容量为目标,在考虑路径损耗的条件下,对系统的最优中继位置问题进行了讨论。分析和数值结果表明,对比中继位置在对称中点的系统,最优中继位置系统的信道容量获得明显提升。进一步,研究了信道估计误差和SNR估计误差对CPM协同通信系统的容量的影响。  相似文献
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近年来,我校“移动通信系统”课程组大力推进多层、多模和开放式实践教学的建设,依托国家重点实验室,深化教学改革,强化了实践模式设计.我们最终在构筑国际一流的实践教学平台,建立“移动通信系统”课程实践教学体系以及建设国际化教师队伍等方面都取得了一定的成果.  相似文献
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目的:研究氨基酮戊酸(5-aminolevulinic acid,5-ALA)光动力疗法(photodynamic therapy)(ALA-PDT)对铜绿假单胞菌的杀灭作用。方法:以铜绿假单胞菌标准菌株ATCC27853为研究对象,采用ALA为光敏剂,用630nm的红光为光源,按不同的浓度剂量组合分为6组,用细菌涂板法观察细菌浓度,同时利用氯仿萃取法测定照射后48小时的绿脓毒素;结果:仅有光敏剂实验组与对照组(无ALA,无红光)细菌量相比,对铜绿假单胞菌无杀灭作用,仅有红光照射(90J/cm2×40分钟)组有轻度杀菌作用,抑制率为18.9%,而ALA与红光组合的三个ALA-PDT实验组对铜绿假单胞菌均有不同程度的杀菌作用(10nMALA+90J/cm2红光×20分钟组的抑制率为82.0%,20nMALA+90J/cm2红光×20分钟组的抑制率为96.4%,而20nMALA+90J/cm2红光×40分钟组抑制率为100%),ALA-PDT对铜绿假单胞菌的杀灭作用随ALA浓度增高和红光能量增高作用加强;绿脓毒素的量在光动力治疗组也有明显下降,随剂量增加明显下降。结论:ALA-PDT对体外培养的铜绿假单胞菌ATCC27853具有明确的杀灭作用,能减少绿脓毒素分泌,且与剂量相关。  相似文献
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This paper deals with Carrier frequency offset (CFO) estimation for Multiple-input multiple-output (MIMO) systems. A Rayleigh fiat-fading channel model is considered and spatial correlation among channels corresponding to different pairs of transmit and receive antennas is taken into account. A Data-aided (DA) Maximum likelihood (ML)CFO estimator based on the marginal likeli- hood function is proposed. It can exploit spatial diversity and make use of the knowledge of spatial correlation by averaging the conditional likelihood function over all realizations of the channel. The Cramer-Rao bound (CRB) for the problem is derived as a benchmark. Simulation results are given to illustrate the performance of the pro- posed estimator. It is shown that its performance is close to the CRB at high Signal-to-noise ratio (SNR) region and improved with decrease of the spatial correlation and in- crease of the number of receive antennas.  相似文献
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限幅技术常用于正交频分复用系统中以抑制高峰值平均功率比,为抑制限幅造成的带内失真和带外辐射,可以在接收端进行限幅噪声的迭代估计和对消。该文提出对限幅带来的非线性失真进行迭代估计和对消的效果要比仅对限幅噪声进行估计对消好。前者在理想情况下能完全恢复出发端未限幅前的信号,但后者将始终受到由限幅带来的信号衰减的影响。理论分析和仿真结果验证了该结论及性能,同时数字结果表明,该算法能有效改进系统性能。在归一化限幅门限为1.2时,只通过一次迭代就能提高2dB。  相似文献
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A novel vertical interconnect scheme between highly integrated multilayer low temperature co-fired ceramic (LTCC) modules has been proposed in this paper. Substrate integrated waveguide (SIW) is manufactured in LTCC substrate and microwave solder-less connector based on the fuzz button technology is used to realize reliable and effective interconnection. The proposed scheme makes use of double current probes to transfer energy between two substrates. Two forms of this interconnect are demonstrated, and simulated bandwidth more than 30% by using 15dB return-loss reference, insertion loss is less than 0.5dB over the passband.  相似文献
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This paper presents the design and fabrication of a highly integrated Low Temperature Co-fired Ceramic (LTCC) receiver front-end module. This LTCC module is a dual channel receiver module, works at Ka-band, and fabricated including six Ferro A6M dielectric layers and five metal layers, contains eight embedded resistors and eight MMICs. All MMICs are mounted into pre-making cavities on the top surface of the LTCC substrate. Three slot coupled waveguide-to-microstrip transitions are integrated at LTCC substrate to realize RF and LO signal input. The developed module is highly integrated and reliable, which has a compact size of 58 × 50 × 22 mm3 (including the metal cavity). Each channel of the receiver has the noise figure of less than 9 dB and the gain of more than 24 dB at Ka-band.  相似文献
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