互联网面向连接的解决方案

本文针对当前互联网络面临的三大问题,论述了采用面向连接的技术的必要性.文章随后分析了互联网"控制与转发分离"以及新一代网络中使用面向连接技术的相关进展,在肯定这些架构的先进性的同时,指出了它们继续保留无连接服务的缺点.文章在上述架构的基础上建议了一个完全面向连接的互联网架构,并着重论述了这一架构在遏制远程的黑客攻击与病毒投放方面的有效性.     

基于TOA/TD0A的Ad hoc网络无线定位研究

基于802.11b协议,该文针对Ad hoc网络的特点,探讨适合Ad hoc网络的定位方案.用TOA法获得定位中需要的时间测量值,从而得到各信标台的距离差;并对所得信息进行分解、综合,用TDOA法得到移动台的位置估计.这在多点定位时降低了矩阵的阶数,加快了运算速度.在此基础上,用适合于运动对象的扩展Kalman滤波算法对位置估计进行了优化,使得定位精度更加准确.     

基于Berlekamp-Justesen码的压缩感知确定性测量矩阵的构造

确定性测量矩阵构造是近期压缩感知领域的一个重要研究问题。该文基于Berlekamp-Justesen(B-J)码,构造了两类确定性测量矩阵。首先,给出一类相关性渐近最优的稀疏测量矩阵,从而保证其具有较好的限定等距性(RIP)。接着,构造一类确定性复测量矩阵,这类矩阵可以通过删除部分行列使其大小灵活变化。第1类矩阵具有很高的稀疏性,第2类则是基于循环矩阵,因此它们的存储开销较小,编码和重构复杂度也相对较低。仿真结果表明,这两类矩阵常常有优于或相当于现有的随机和确定性测量矩阵的重建性能。     

基于W61PC的短波数字信号分析

本文首先介绍了数字信号的特征参数、常用的短波数字通信体制和W61PC分析信号流程,对典型短波数字信号进行识别,结合实验数据,分析了W61PC对不同信噪比数字信号的识别能力。     

On constructions of algebraic space-time codes with AM-PSK constellations satisfying rate-diversity tradeoff

Constructions of space-time codes having amplitude-modulated phase-shift keying (AM-PSK) constellations are presented in this paper. The first construction, termed p-radii construction, is obtained by extending Hammons' dyadic dual-radii construction to the cases when the size of the constellation is a power of a prime p, p ges 2. The resultant code is optimal with respect to the rate-diversity tradeoff and has an AM-PSK constellation with signal points distributed over p- concentric circles in the complex plane, i.e., there are p radii. Also contained in this paper is the identification of rich classes of nontrivial subset-subcodes of the newly constructed space-time codes and it is shown that these subset-subcodes are again, all optimal. Finally, a new generalization of the super-unified construction by Hammons is presented. It is shown that codes obtained from several previously known constructions are subset-subcodes of the one derived from this generalized construction     

Low-temperature conductance measurements of surface states in HfO2–Si structures with different gate materials

Metal-oxide-semiconductor capacitors based on HfO₂ gate stack with different metal and metal compound gates (Al, TiN, NiSi and NiAlN) are compared to study the effect of the gate electrode material on the trap density at the insulator–semiconductor interface.C–V and G–ω measurements were made in the frequency range from 1 kHz to 1 MHz in the temperature range 180–300 K. From the maximum of the plot G/ω vs. ln(ω) the density of interface states was calculated, and from its position on the frequency axis the trap cross-section was found. Reducing temperature makes it possible to decrease leakage current through the dielectric and to investigate the states located closer to the band edge.The structures under study were shown to contain significant interface trap densities located near the valence band edge (around 2×10¹¹ cm⁻²eV⁻¹ for Al and up to (3.5–5.5)×10¹² cm⁻² eV⁻¹ for other gate materials). The peak in the surface state distribution is situated at 0.18 eV above the valence band edge for Al electrode. The capture cross-section is 5.8×10⁻¹⁷ cm² at 200 K for Al–HfO₂–Si structure.     

多智能体系统中的任务分配蚁群优化算法

Task allocation is a key issue of agent cooperation mechanism in Multi-Agent Systems. The important features of an agent system such as the latency of the network infrastructure, dynamic topology, and node heterogeneity impose new challenges on the task allocation in Multi-Agent environments. Based on the traditional parallel computing task allocation method and Ant Colony Opti-mization (ACO), a novel task allocation method named Collection Path Ant Colony Optimization (CPACO) is proposed to achieve global optimization and reduce processing time. The existing problems of ACO are ana-lyzed; CPACO overcomes such problems by modifying the heuristic function and the up-date strategy in the Ant-Cycle Model and es-tablishing a three- dimensional path phero-mone storage space. The experimental results show that CPACO consumed only 10.3% of the time taken by the Global Search Algorithm and exhibited better performance than the Forward Optimal Heuristic Algorithm.     

IP传输技术优化卫星传输CDMA数据探讨

中国电信大量使用卫星传输技术传输应急基站信号,为降低数据配置复杂度,提高卫星带宽使用效率,应急基站可以应用IP技术传输3G信号。本文探讨了在中国电信主流卫星调制解调器和应急基站E1接口之间应用IP传输技术,简化了数据配置的方法,并在中国电信上海卫星地面站开展验证测试,实地验证了IP传输技术的应用效果。     

A code-pattern-driven digital background calibration technique for SAR ADCs

The article presents the buck converter for the application on headlights of vehicle with chip-level design. The LED components are used as for lighting source, which near/far lights are controlled with high-current switching circuit in the chip. The level-shift circuit and its current driver is proposed to control the input of high-voltage power MOS. The bypass method is presented to reduce the transient time as load current changes suddenly. The input voltage widely ranges from 8 to 21 V while keeping a stable output voltage with 6 V. The chip current can output from 20 to 1500 mA with excellent regulation. This chip had been implemented with TSMC0.25 µm HV- process, and the size of the circuit layout is about 8.6 mm², where includes power switch and far/near lighting switches. Measurements show that peak efficiency can achieve 86.3%. The power regulation is excellent, where the load regulation is only 0.3%, and the line regulation is only 0.5%.