优先队列控制模型参数优化

文献[1]中提出了一种新交换结构模型──优先队列控制（PQC）模型．本文主要讨论如何设定该模型的参数，这是一个二指标的多目标优化问题首先，本文假设两类到达业务分别为两个相互竞争的局中人，进而将这个多目标优化问题转化为一个合作对策问题来求解；然后，运用Kuhn-Tucker条件求出效用空间和Pareto边界，再用一类协商规则解得一组使得全局能具有较好满意程度的理性解；最后给出了一些数值计算的例子进行说明     

相干光通信系统中的偏振控制技术

在相干光通信系统中,接收端的输入信号和本机振荡信号的偏振状态(SOP)必须相匹配,否则不但难以达到应有的接收灵敏度,甚至还可能劣于直接检测系统。对于目前普遍使用的单模光纤,由于其SOP转移特性是随时间和其它环境条件的影响而变化,因此必须对接收端的输入信号或本机振荡信号的SOP进行实时控制,以确保系统的性能指标。本文介绍了目前国际上常用的几种偏振控制技术,重点放在无限循环控制(Endless Control)和电光集成器件运。用Poincare球面表示法,任何一种偏振控制器的SOP转移特性都可以看作是代表SOP的点在Poincare球面上的旋转过渡。     

利用标准数字信道传输的混沌保密通信系统

研究了基于Rossler系统的主动-被动混沌调制保密通信系统,利用标准数字信道传输发送信号。仿真结果表明,当采样保持的频率达到一定大小时,只需8位量化就可实现保密通信,且只要信道噪声的信噪比高于14dB则恢复的信号失真较小。     

一种适合多媒体处理的新型芯片

介绍ＭＭＸ技术的基本内容及带有ＭＭＸ技术的微处理器，以ＭＭＸ技术在视频会议系统上的应用为例，侧重分析ＭＭＸ技术给多媒体与通信应用带来的性能改善，并对ＭＭＸ技术的应用及发展前景进行探讨。     

Prediction of rain effects on earth-space communication links operating in the 10 to 35 GHZ frequency range

This paper reviews the effects of precipitation on earth-space communication links operating the 10 to 35 GHz frequency range. Emphasis is on the quantitative prediction of rain attenuation and depolarization. Discussions centre on the models developed at Virginia Tech. Comments on other models are included as well as literature references to key works. Also included is the system level modelling for dual polarized communication systems with techniques for calculating antenna and propagation medium effects. Simple models for the calculation of average annual attenuation and cross-polarization discrimination (XPD) are presented. Calculation of worst month statistics are also presented.     

Quantum phase transition in the generalized single-mode superradiant model

In this paper we reveal a zero-temperature quantum phase transition for the single-mode superradiant model with the form A² from the normal to superradiant phase by mean of the Holstein-Primakoff transformation. In the thermodynamic limit, in which the numbers of atoms becomes infinite, the ground state energy and corresponding wavefunctions of both the normal and superradiant phases are obtained and therefore the scaling behavior near the critical transition point is derived.     

铁路旅客列车无线公用电话应用技术

据不完全统计,全国铁路每年有超过10亿人/次的客运流量,铁路列车作为运输旅客的载体蕴藏着一个潜在的、亟待开发的巨大通信市场。开发这个市场,为旅客在出行途中提供商用级的电信服务,一直是铁道部领导重视以及中国铁通探讨和研究的课题。本文对无线公用电话在旅客列车上的成功应用进行了深入研究。     

实值循环ESPRIT算法

为了降低循环ESPRIT算法的计算复杂度,提出了一种实值循环ESPRIT算法,通过构造了循环自相关矩阵的数据模型,使其具有厄尔米特特性,将复数自相关矩阵映射成实值矩阵,通过实值分解降低了计算量,而且具有信号选择特性。由于空间平滑技术的引入,较好地解决了多径传播环境中信号高度相关问题。仿真实验结果证明,与循环ESPRIT算法相比,该算法适应多径传播环境,具有计算量小和性能好等特点。     

Trellis-coded dpsk with multiple-symbol viterbi decoding over mobile satellite channel at K and L bands

Mobile satellite communication systems at K_a/K band (30/20 GHz) are attractive because of their large bandwidth availability and potentiality to support smaller earth-stations and satellite antennas compared with L-band (1·6/1·5 GHz) systems. In this paper, multiple-symbol Viterbi decoding and dual-space equal-gain diversity reception for trellis-coded differential M-ary phase-shift-keying (DPSK) modulation are investigated as two mitigation techniques for severe channel impairments expected from a land mobile satellite communication channel at K band and, for comparison purposes, at L band. The multiple-symbol Viterbi decoder (MSVD) is a modified Viterbi decoder with inputs from multiple differential detectors. The channel is modelled as Rayleigh distributed multipath fading with a lognormally distributed line-of-sight (LOS) component due to shadowing. Four trellis-coded modulation (TCM) schemes are studied. The dependency of the system performance improvement on the decoder structure, the TCM scheme, and the system RF frequency band is presented.     

下一代移动通信中的空时编码技术

为了满足下一代移动通信的要求，提出一种结合分集发送、调制和编码的空时编码技术。为此介绍了空时码的原理以及空时分层编码、空时栅格编码和空时分组编码的编译码方案，以及分析了空时编码在IMT-2000、OFDM等下一代移动通信系统中的应用前景等。