On co-channel and adjacent channel interference mitigation in cognitive radio networks

Cognitive radio (CR) is an emerging wireless communications paradigm of sharing spectrum among licensed (or, primary) and unlicensed (or, CR) users. In CR networks, interference mitigation is crucial not only for primary user protection, but also for the quality of service of CR user themselves. In this paper, we consider the problem of interference mitigation via channel assignment and power allocation for CR users. A cross-layer optimization framework for minimizing both co-channel and adjacent channel interference is developed; the latter has been shown to have considerable impact in practical systems. Cooperative spectrum sensing, opportunistic spectrum access, channel assignment, and power allocation are considered in the problem formulation. We propose a reformulation–linearization technique (RLT) based centralized algorithm, as well as a distributed greedy algorithm that uses local information for near-optimal solutions. Both algorithms are evaluated with simulations and are shown quite effective for mitigating both types of interference and achieving high CR network capacity.     

基于Welch算法的SAW传感器测量系统

声表面波(SAW)传感器性能卓越,能满足恶劣环境的测量需求。针对测量过程中干扰源淹没回波信号的问题,研究了Welch算法在复杂环境下对提升回波信号检测精度的估计方法,设计了基于SAW温度传感器的温度测量系统,验证了算法在功率谱估计中的性能。测量系统包括发射及接收链路,实现了激励源的发射、回波信号的接收与处理及温度解算等功能。搭建温升实验平台,在20℃~110℃的温度范围通过该系统对高精度数显加热台进行温度测试。测试结果表明,相较于加热台设定温度,实际温度测量误差控制在2.4%以下,系统可靠性高且具有较好的测量效果。     

数字阵列雷达并行信号处理算法及实现

在某型号数字阵列雷达信号处理机的研制过程中,针对多波束、多任务下实时运算的难题,基于分布式多DSP处理器平台研究了数字阵列雷达的并行算法实现,采用多通道并行和通道内流水并行的处理方案进行算法分配和映射,成功完成了系统设计。实验结果表明,该系统具有较好的实时性、并行性和可扩展性。     

Design of Large-aperture and Wide-band Optical Lens

The design of a large-aperture and wide-band optical lens for camera is presented. By utilizing the atmospheric window of infrared light, clear images can be achieved in the dark or poor visibility conditions. To use near-infrared and visible light to obtain images, the charge coupled device(CCD) is adopted as the image sensor of the lens with the center wavelength of 880 nm, which operates at the wavelength range from 400 nm to 1 000 nm. After calculating the parameters of optical lens, Sunnah type is selected as the initial structure. Through the optimization of optical design software ZEMAX, the lens obtains an excellent imaging performance. The modulation transfer function(MTF) can be more than 0.3 at the spatial frequency of 110 lp/mm, and the maximum distortion can be less than 0.1%.     

粒子群算法优化神经网络结构的研究

针对BP神经网络初始权阈值确定的随机性和隐含层节点数的不确定性,通过利用十进制粒子群优化算法（DePSO）和二进制粒子群优化算法（BiPSO）,同时优化神经网络的初始权阈值和结构。通过粒子群优化算法首先确定一个较好的搜索空间,然后在这个解空间里利用BP算法对网络进行训练和学习,搜索出最优解。通过函数拟合数值实验对该模型来进行训练和测试,相比其他算法,该模型可以获得较高的预测精度,结果表明该方法是可行的。     

基于迭代滤波盲复原算法的水下图像噪声去除

摘要：图像复原的目的是从观测到的退化图像重建原始图像,维纳滤波与约束去卷积滤波是比较常采用的复原方法。在未知降质函数的情况下,直接运用维纳滤波和约束去卷积滤波有一定困难。针对此提出以维纳滤波与约束去卷积滤波为模型的迭代滤波盲复原算法对水下图像进行去噪。实验证明,该方法获得了比较理想的复原效果。     

一种改进的IMMPF目标跟踪算法

对多运动模型的目标进行跟踪,通常采用传统的交互式多模型粒子滤波算法。但是,该算法存在一些缺陷和不足。为此,提出了一种新的基于变速率模型和遗传算法的IMMPF目标跟踪算法。针对IMMPF算法对目标进行跟踪时可能出现的未知可变转弯速率,采用了一种更恰当的可变速率目标模型;对于IMMPF算法中的粒子多样性丧失问题,则将进化理论中的遗传算法引入到目标跟踪算法中,对采样进行优化,增加了采样粒子的多样性,使采样向后验分布取值较大的区域移动。仿真结果表明,提出的算法能更好的适应目标的机动运动,同时明显减少所需的采样数,取得了更好的跟踪性能。     

Tunnel transition mechanism support all types of NAT users

Through the analied of current tunneling mechanism,a more efficient and applicable tunneling mechanism called TrNAT based on TSP to face different scenarios was proposed.Optimization of the communications between NAT users was achieved with ideology of MIPv6.Then,Shim6 was utilized to realize route redundancy and also improved the route aggregation of 6 to 4 tunnel.Finally,TrNAT tunneling mechanism was implemented on Linux kernel and validated by experiments.     

RSA加密算法及其改进算法的研究和实现

首先利用RSA加密算法对数据进行加密和解密,实现了数据的安全传输;然后针对RSA加密算法时间开销大和算法设计复杂的缺点,提出基于乘同余对称特性的SMM算法。通过对该改进RSA加密算法的实现发现加密运算速度明显提高且算法更简单,从而证明了本文所提改进算法的有效性。     

基于改进BP算法的中间视合成方法

本文提出了一种新颖的基于改进BP算法的中间视合成方法。方法中首先改进了BP(Belief Propagation)算法来提高视差估计的正确率,然后在视图插值中设计了新的插值策略,在区域分类的基础上有针对地进行中间视合成。实验结果表明,采用本文提出的中间视合成方法可以获得具有很好视觉效果的虚拟视图。