一种实用的多数据库量子信息检索协议

针对目前量子私有信息检索不能适用与云存储的多数据库问题,基于现在成熟的量子密钥分发方法,提出了一种适合在多数据库环境下,实用的量子私有信息检索协议。对于不同大小的数据库,协议可通过调节参数θ和k,在保证数据库安全及用户隐私的情况下,完成信息的检索。性能分析结果表明,协议的通信复杂度低,检索成功率高、易于实施。     

Optimal filtering and control for wireless networked closed-loop control systems

This article studies the optimal filtering and control for wireless networked control systems (WNCSs). In WNCSs, packets may be lost in both control and feedback channels and user datagram protocol is usually used to improve the performance of the real-time control. Relevant literature indicates that the conventional optimal filtering for such a system cannot be applied in practice due to the complex calculation with Gaussian mixtures. This paper proposes a novel scheme to realize the optimal filtering and the linear quadratic Gaussian control for WNCSs, in which the controlled node performs a local estimation and the remote-control node performs the final estimation and control, and a synchronization of two estimators is guaranteed by a communication mechanism. An optimal filtering algorithm is developed, the stability condition of the filtering error covariance is obtained, optimal finite-horizon and infinite-horizon control are derived, and the stability of the closed-loop control system is proved. Numerical simulations show the validity and feasibility of the theoretical results.     

多带OFDM-UWB系统峰均功率比降低方法研究

针对多带OFDM—UWB信号存在高峰均功率比的问题，提出了利用扩展与交织降低系统信号峰均功率比的方法。该方法通过对传输数据进行正交扩展与交织，使得进入多载波调制的数据趋于高斯分布，减小了传输数据自相关函数的旁瓣峰值，降低了OFDM-UWB信号的峰均功率比。由于采用正交矩阵进行扩展，扩展前后的数据传输速率保持不变。仿真结果表明，扩展与交织可以有效地降低信号峰均功率比2-5dB左右。同时该方法还具有抗窄带干扰的鲁棒性。     

数字集群通信在我国的使用和发展前景

介绍了数字集群的技术性能和在国外的发展概况，叙述了数字集群通信在我国的使用和发展前景。     

无线通信的跨层优化

传统的OSI分层结构无法适应无线网络环境，随着越来越多无线应用的出现，人们提出了跨层设计，其主要内容就是通过在协议栈的各层之间（主要是应用层、传输层、网络层、链路层和物理层）传递特定的信息，使协议栈能够根据无线环境的变化来实现对资源的自适应优化配置，从而更有效的利用无线网络资源，提高系统的性能。     

GPRS技术在SCADA系统中的实现与应用

GPRS是一种构建于GSM移动网络之上的通信新技术，可以提供中低速率的数据通信能力，本文介绍了GPRS的技术规范和特点，并提出了该技术在SCADA(即数据采集与监视控制)系统中的应用，给出相应的系统结构与软硬件设计要点，说明了其广泛的应用领域与前景。     

HART通信协议在汽油机速度测量和监控方面的应用

首先介绍了HART通信协议及他的优点，然后介绍了HART通信协议在汽油机测速方面的软件实现。该软件主要采用目前流行的VB编程语言。可设计出界面友好、功能强大的测量和监控软件。     

Wireless video streaming with TCP and simultaneous MAC packet transmission (SMPT)

Video streaming is expected to account for a large portion of the traffic in future networks, including wireless networks. It is widely accepted that the user datagram protocol (UDP) is the preferred transport protocol for video streaming and that the transmission control protocol (TCP) is unsuitable for streaming. The widespread use of UDP, however, has a number of drawbacks, such as unfairness and possible congestion collapse, which are avoided by TCP. In this paper we investigate the use of TCP as the transport layer protocol for streaming video in a multi‐code CDMA cellular wireless system. Our approach is to stabilize the TCP throughput over the wireless links by employing a recently developed simultaneous MAC packet transmission (SMPT) approach at the link layer. We study the capacity, i.e. the number of customers per cell, and the quality of service for streaming video in the uplink direction. Our extensive simulations indicate that streaming over TCP in conjunction with SMPT gives good performance for video encoded in a closed loop, i.e. with rate control. We have also found that TCP is unsuitable (even in conjunction with SMPT) for streaming the more variable open‐loop encoded video. Copyright © 2004 John Wiley & Sons, Ltd.     

一种基于混沌渐近同步的数字保密通信方法

根据驱动－响应混沌同步原理，提出了一种基于混沌渐近同步的数字保密通信方法。通过设计对发射信号进行多级单值非线性变换，使得通过预测法的攻击完全失效，因而这种通信方法具有较高的抗破译能力。理论分析和数值模拟结果证实了本方法的正确性与有效性。     

光纤通信在天波超视距雷达中的应用

天波超视距雷达是低空防御系统中一种有效的预警手段。通过采用光纤传输技术，利用其信息传输容量大，速度快，频带宽，抗干扰能力强，线路损耗低。易于施工等特点，实现全相参雷达的信息传输和系统控制，具有优良的保密性，稳定性、抗干扰性和抗摧毁能力。