NACR: A New Adaptive Channel Reservation in Cellular Communication Systems

Future Personal Communication Networks (PCN) will employ microcells and picocells to support a higher capacity, thus increasing the frequency of handoff calls. Forced call terminations due to handoff call blocking are generally more objectionable than new call blocking. The proposed guard channel schemes for radio channel allocation in cellular networks reduce handoff call blocking probability at the expense of increases in new call blocking probability by giving resource access priority to handoff calls over new calls in call admission control. Under uniform traffic assumptions, it has been shown that a fixed number of guard channels leads to good performance results. In a more realistic system, non-uniform traffic conditions should be considered. In this case, the achieved call blocking probability may deviate significantly from the desired objective. In this paper, we propose a new adaptive guard channel scheme: New Adaptive Channel Reservation (NACR). In NACR, for a given period of time, a given number of channels are guarded in each cell for handoff traffic. An approximate analytical model of NACR is presented. Tabu search method has been implemented in order to optimize the grade of service. Discrete event simulations of NACR were run. The effectiveness of the proposed method is emphasized on a complex configuration.     

面向大规模认知诊断的DINA模型快速计算方法研究

在教育教学的过程中,如何诊断学生的知识水平是一个重要的问题.传统方法大多由教师根据学生的表现和成绩进行人工判断,存在效率低、主观性强的问题,且难以做到针对大量学生的个性化诊断.近年来,认知诊断模型中的DINA模型被广泛应用于诊断学生个性化知识掌握程度.然而传统DINA模型大多基于小样本数据,当面对在线教育带来的大规模数据处理需求时,存在收敛速度慢的问题,难以实际应用.针对DINA模型计算时间过长的问题,本文首先给出了DINA模型的收敛性证明,并提出了三种能够加速DINA求解的算法：（1）增量算法,它将学生数据划分为多个学生块,每次迭代只访问其中一个学生块;（2）最大熵方法,它只访问在极大化模型熵的过程中影响较大的学生数据;（3）基于前两者的混合方法.最后,本文通过真实数据和模拟数据上的实验,分析证明了三种方法均能在保证DINA模型有效性的情况下,达到几倍至几十倍的加速效果,有效地改善了DINA模型的计算效率.     

QoE-aware video distribution mechanism in FiWi

The mismatch of transmission ability causes the discontinuous transmission of video services in fiber-wireless access network,aimed at this problem,an QoE-aware video distribution mechanism was proposed.According to the structural characteristics of fiber-wireless access network,link state information and scalable video coding structure was considered,a QoE evaluation mode was established,and the particle swarm optimization algorithm was used to select optimal video transmission rate.Then the node transmission capacity and the node matching degree was analyzed,transmission path for the services was selected,so as to ensure the reliable transmission of services.The results show that the proposed mechanism can effectively improve the utilization rate of network resources and reduce network congestion while improving the quality of the user experience.     

压缩感知重构算法研究

压缩感知技术突破了奈奎斯特准则的局限性,在图像处理方面有着广泛的应用。在精典TV重构算法的基础上通过对测量矩阵与迭代过程加以改进,以测量值基本逆变换(IY)作为迭代初值的IY-TV重构算法;TV算法有利于去除信号的中噪声,在迭代过程中与IY变换图像差值相联合重建原始信号。测量矩阵直接影响图像的重构质量,设计与该算法相适应的测量矩阵以提取更多的基本信息。实验表明,该算法可以在较低采样率时,同样重构出较高的图像质量。     

差分吸收光谱测量中LED光源恒温控制的实现

提出了一种差分光学吸收光谱（DOAS）测量中LED光源的恒温控制方法。采用半导体制冷片作为控温元件来控制LED温度,应用PID算法动态调节半导体制冷片的工作电流,实现了DOAS测量过程中LED光源的温度恒定。介绍了恒温控制系统的硬件设计和软件流程,并对控温效果和LED谱的稳定性进行了测试。测试结果表明,提出的恒温控制方法能有效克服环境温度变化对LED光源温度的影响,温度控制精度达到了±0.1℃。在相同的测试条件下与无恒温相比,具有恒温功能的LED光源剩余噪声明显偏低,进一步验证了设计方案的可行性。     

SiGe HBT工艺宽带功率放大器

A novel broadband power amplifier fabricated in 0.13 m SiGe HBT technology is realized.The pseudo-differential structure is proposed to avoid the influence of the bonding wire due to the AC virtual ground created at the common emitter node.A compensated matching technique is adopted in interstage matching to expand bandwidth.A multi-stage broadband matching technique is used in an input/output matching network to offer broadband impedance matching,which ensures maximum power transfer.An adaptive bias circuit could improve linearity and efficiency in wide output power level.With 2.5 V power supply,the measured results achieve 96% 3-dB bandwidth(517-1470 MHz),27.2 dB power gain,26.9 dBm maximum output power,19.7 dBm output 1 dB compression point,and 26.7% power added efficiency.     

智能天线技术在移动通信中的应用

智能天线采用空分复用技术,利用信号在传播方向上的差异,将同频率、同时隙的信号从空域区分开来。它可以成倍的扩展通信容量,并和其它复用技术相结合,最大限度的利用有限的频谱资源;可以有效地克服移动通信中由于复杂的地形、建筑物结构等对电波传播的影响,以及时延扩展、多径衰落、共信道干扰等产生的不利影响;能有效地扩大信号覆盖范围,降低系统建设成本;还能进行紧急呼叫定位,并提供更高的定位精度,可开发更多的增值业务。因此其在各种移动通信系统中得到了广泛的应用。     

前视红外舰船图像的模糊分割算法研究

由分析海面舰船及其背景红外辐射特性入手，对前视海面舰船红外图像提出了一种新的自适应阈值张弛模糊分割算法，对目标进行图像分割．对本文提出的算法用实际红外图像进行仿真实验，取得令人满意的效果．表明本算法是可行和实用的．     

误差通道建模误差对多误差LMS算法性能的影响

本文证明了，在多通道自适应宽带有源噪声控制中，由于误差通道建模误差的存在，多误差LMS算法是条件收敛的，并推导了保证算法收敛的条件，还证明了，算法收敛后，得到自适应滤波器权值一般只是理论上最优值的有偏估计，计算机仿真结果验证了所得结论．     

An Simple Enumeration of All Minimal Cutsets of an All-Terminal Graph

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