移动IP综述

论述了移动IP的概念和发展过程，分析了国内外对移动IP研究的重点问题及其方法，对移动IP的发展方向进行了归纳和总结，并提出了有关用的问题。     

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。     

基于实值分解技术的Unitary Cyclic ESPRIT算法

针对多径传播环境中的信号到来方向估计问题,提出了一种基于实值分解技术的Unitary Cyclic ESPRIT算法,通过重新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,较好地解决了多径传播环境中信号高度相关问题,通过实值分解降低了计算量,而且具有信号选择特性.仿真实验结果证明,与Cyclic 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.     

Class-Based Packet Scheduling to Improve QoS for IP Video

An important issue for video transmission over IP networks is the preservation of perceived video quality despite packet loss. Packet loss can be detrimental to compressed video. However, reducing packet loss to a very low level is difficult with current techniques. Furthermore, even a very low objective loss probability can still seriously distort perceived video quality. This paper presents a packet scheduling scheme at a router which addresses the loss issues of networked video. Experiments using real video data show that the proposed scheme can significantly improve the visual quality of video and network efficiency. Moreover, it can provide different classes of videos with different levels of loss guarantees, while maintaining service fairness among the same class of videos.     

Managing logical channel configurations in complex satellite architectures

As a result of the increased switching complexity of many communications satellites, often transponders are available with a variety of configuration options offering flexibility in power, bandwidth, and coverage. Many of these configurations share resources that prevent them from being simultaneously active, making it a challenge to understand and manage the satellite capacity inventory. In this paper we define the logical channel configuration (LCC) as an unambiguous unit of the inventory and present a novel method of modelling the interdependencies between these LCCs using linear algebra. In particular, a projector matrix is defined which can be used to update the activation state of all LCCs when the state of one or more of these is changed. As a result, a number of valid LCC scenarios can be easily generated and evaluated for optimal use of the satellite resources. Copyright © 2005 John Wiley & Sons, Ltd.     

Improved Analysis of Co-Channel Interference in Cellular Communications Systems

1 Introduction The performance analysis of co-channel interferenceincellular systems has been actively researched in the lastfewyears , due to the rapid deployment and success ofsuch systems , and because of the scarce bandwidthwhich calls for very careful design tools in order to uti-lizeit most efficiently.Signal transmission over a mobilechannel often suffers fromshadowing effect ,causing byobstacles in the radio propagation, such as the build-ings .In a cellular mobile system,the problemis…     

Two‐layer LMDS system architecture: DAVIC‐based approach and analysis

Despite the growing interest for LMDS systems there have been only a few commercial implementations until now especially outside of the U.S.A. The use of hierarchical structure through two‐layer networking has been even rarer. In many cases LMDS systems have strong advantages against their competitors to cover the last mile. In this article, we review and analyze the standards currently available and describe the European two‐layer trial system developed in 1996–2000. We show why further development towards IP based LMDS is useful in the future. Most of our recommendations are based on results derived from the European Union supported research project CABSINET. It had the aim of demonstrating the viability of a 40 GHz cellular digital television system with a return channel to offer interactive services. Two systems were tested: a line of sight link using QPSK, and a non‐line of sight with COFDM modulation scheme. In the RF‐subsystems, the greatest difficulty of any viable LMDS system is to obtain a moderately low price for the user receiver, while fulfilling the hard OFDM requirements in terms of phase noise, stability and spectrum restrictions. Several options have been studied in order to design the subsystems with the smallest cost. This paper will present the architectures of the transmitters, nomadic terminals, and the design of the IF/RF subsystems for both types of modulations. The discussion is focused on system engineering and selections required in order to build a full two‐layer LMDS system. Copyright © 2002 John Wiley & Sons, Ltd.     

七号信令在现代通信中的应用

七号信令是国际标准化公共信道信令，介绍了七号信令的网络结构和功能结构，及其在公用电话网(PSTN)／综合业务数据网(ISDN)、移动通信网和智能网中的应用。随着现代通信网的快速发展，七号信令有必要引入高速信令链路以解决网络拥塞问题，同时对第三代移动通信系统将影响到现有七号信令的网络结构与协议，七号信令也要与下一代IP网络的融合，以实现电信网与下一代网络体系的互通等问题进行了进一步探讨。     

CDMA通信中的空—时MRC和MMSE处理

本文针对两种不同的空－时数据结构,研究了直序扩频码分多址（DS－CDMA）通信中的最大比合并（MRC）和最小均方误差（MMSE）空0－时Rake滤波技术,分析了空－时数据结构对空－时MRC和MMSE Rake接收机完成性能的影响,并通过计算机对两种空－时数据结构空的空－时接收机的完成性能进行了比较。     

与偏振无关的双向2×2光纤光开关

本文提出了新颖的与偏振无关全光 2× 2光纤光开关结构 ,采用自由空间光互连模块 ,能够实现 2× 2与偏振无关的双向光纤光开关直通和交换功能。以此为基础 ,提出了新的全光 4× 4光纤光开关的光学实现方法。该光开关具有光学元件少、结构紧凑、易于光学装配等特点