构建高扩展性的县级广电宽带数据网络

提出在县市级广电宽带数据网络的建设过程中,要着眼业务发展,突出高扩展性,构建基于标准、扩展灵活的主干网,实现网络建设的可持续性发展,并结合实际,从核心设备、端口、中继带宽、网络业务4个方面对扩展能力进行了阐述.     

WCDMA的MBMS技术

主要介绍了基于WCDMA的MBMS技术,给出了其网络架构和技术难点,并对其应用给无线网络带来的影响作了一定深度的探讨。     

现场直播技术问题探讨

就电视现场直播中如何保障安全播出、各路信号同步以及保证信号质量等问题进行探讨.同时就常用于直播信号传输的微波传输系统的多种不同使用场合及使用方法作一介绍.     

Secure Multi-Party Computation without Agreement

It has recently been shown that authenticated Byzantine agreement, in which more than a third of the parties are corrupted, cannot be securely realized under concurrent or parallel (stateless) composition. This result puts into question any usage of authenticated Byzantine agreement in a setting where many executions take place. In particular, this is true for the whole body of work of secure multi-party protocols in the case that a third or more of the parties are corrupted. This is because these protocols strongly rely on the extensive use of a broadcast channel, which is in turn realized using authenticated Byzantine agreement. We remark that it was accepted folklore that the use of a broadcast channel (or authenticated Byzantine agreement) is actually essential for achieving meaningful secure multi-party computation whenever a third or more of the parties are corrupted. In this paper we show that this folklore is false. We present a mild relaxation of the definition of secure computation allowing abort. Our new definition captures all the central security issues of secure computation, including privacy, correctness and independence of inputs. However, the novelty of the definition is in decoupling the issue of agreement from these issues. We then show that this relaxation suffices for achieving secure computation in a point-to-point network. That is, we show that secure multi-party computation for this definition can be achieved for any number of corrupted parties and without a broadcast channel (or trusted pre-processing phase as required for running authenticated Byzantine agreement). Furthermore, this is achieved by just replacing the broadcast channel in known protocols with a very simple and efficient echo-broadcast protocol. An important corollary of our result is the ability to obtain multi-party protocols that remain secure under composition, without assuming a broadcast channel.     

An efficient reliable broadcasting protocol for wireless mobile ad hoc networks

The mobile ad hoc network (MANET) has recently been recognized as an attractive network architecture for wireless communication. Reliable broadcast is an important operation in MANET (e.g., giving orders, searching routes, and notifying important signals). However, using a naive flooding to achieve reliable broadcasting may be very costly, causing a lot of contention, collision, and congestion, to which we refer as the broadcast storm problem. This paper proposes an efficient reliable broadcasting protocol by taking care of the potential broadcast storm problem that could occur in the medium-access level. Existing protocols are either unreliable, or reliable but based on a too costly approach. Our protocol differs from existing protocols by adopting a low-cost broadcast, which does not guarantee reliability, as a basic operation. The reliability is ensured by additional acknowledgement and handshaking. Simulation results do justify the efficiency of the proposed protocol.     

一种频率广播策略在短波组网中的应用

针对频率广播机制在短波组网中的弊端，比较了多种解决方案，提出了一种基于频率分时复用和反向动态唤醒的短波台站频率广播策略，为短波组网项目提供一种短波频率广播机制的实现方案。     

单点嵌入式广播监测系统设计研究

广播信号监测一直以来都很重要,掌握专业的监测技术来实现监测系统并满足五七三台日常监测需求就变得十分有意义.以往的监测系统核心监测点大都采用价格昂贵的专业测试仪器,从监测的角度看有一些价值浪费.探讨了广播信号监测的技术需求,在此基础上研究了如何高性价比地利用业已成熟的监测卡产品实现单点广播信号监测系统设计,并分析了整机性能指标.     

援津巴布韦高清电视转播车视音频系统介绍

本文介绍了我国援助津巴布韦国家电视台高清电视转播车视音频系统的设备选型、系统设计思路。津巴布韦国家电视台目前主要采用标清和模拟系统设备,我国援助的高清转播车,实现了高清、标清的充分兼容,系统可扩展,实用、灵活、安全性。视频系统具有强大的备份功能,包括切换台和矩阵的相互备份,主备调音台的应急备份及录像机的应急备份等。     

DVB-T工程实现中的高/中比特率固定接收

讨论了DVB-T标准的工程实现中,高比特率(20～27 Mbit/s)和中比特率(14～18 Mbit/s)两类固定接收的有关参数及其特点,并把它同ATSC标准和中国地面数字电视广播(DTTB)传输的国家标准作对比.初步分析表明:中国标准优于DVB-T.