基于TCP/IP的数字语音会议系统设计

文中以TCP/IP协议作为通信链路层协议,设计了终端-服务器模式的数字语音会议以及同声传译系统方案。给出了系统终端及中央控制单元的硬件结构原理设计,以及系统通信流程设计。该系统可实现多方数字语音会议以及实时同声传译。     

工业手持终端的通信设计

该通信方案以工业手持终端现场应用为背景,针对传统以太网在工业通信中实时性差的问题,提出了一种发送心跳包,建立socket长连接的方法,由此来减少通信过程中频繁建立和关闭连接所消耗的时间。运用XMPP协议实现轻量级、简单实用的消息推送组件,可以进行服务端消息推送从而代替了传统的客户端轮询机制,缩短了响应时间,提高了整个系统的实时性。     

XMPP协议在移动设备管理中的应用

针对企业敏感数据可能存在的泄露隐患以及目前解决方案的不足,提出一种基于XMPP协议的移动设备管理方法,搭建了消息推送服务器,绕开Google服务器,直接由服务端通过XMPP协议向移动设备终端推送消息,实现对移动设备的控制。     

异构无线网络可控匿名漫游认证协议

分析传统的匿名漫游认证协议,指出其存在匿名不可控和通信时延较大的不足,针对上述问题,本文提出异构无线网络可控匿名漫游认证协议,远程网络认证服务器基于1轮消息交互即可完成对移动终端的身份合法性验证;并且当移动终端发生恶意操作时,家乡网络认证服务器可协助远程网络认证服务器撤销移动终端的身份匿名性.本文协议在实现匿名认证的同时,有效防止恶意行为的发生,且其通信时延较小.安全性证明表明本文协议在CK安全模型中是可证安全的.     

基于CMMB技术的户外电子屏广告推送系统

基于CMMB技术的户外电子屏广告推送系统,能够利用CMMB的广播通道进行广告内容的实时或准实时推送,并且实现对广告播放策略方面的远程控制。本系统可以应用于室外电子广告屏、楼宇卖场广告终端、车载移动电视终端等场景下的广告推送,实现广告终端上的内容远程更换及控制,从而可以节约广告运营所投入的维护成本。     

云计算环境中支持隐私保护的数字版权保护方案简

针对云计算环境中数字内容安全和用户隐私保护的需求,提出了一种云计算环境中支持隐私保护的数字版权保护方案。设计了云计算环境中数字内容版权全生命周期保护和用户隐私保护的框架,包括系统初始化、内容加密、许可授权和内容解密4个主要协议;采用基于属性基加密和加法同态加密算法的内容加密密钥保护和分发机制,保证内容加密密钥的安全性;允许用户匿名向云服务提供商订购内容和申请授权,保护用户的隐私,并且防止云服务提供商、授权服务器和密钥服务器等收集用户使用习惯等敏感信息。与现有的云计算环境中数字版权保护方案相比,该方案在保护内容安全和用户隐私的同时,支持灵活的访问控制,并且支持在线和超级分发应用模式,在云计算环境中具有较好的实用性。     

终端协议一致性测试系统编解码器研究

编解码器是基于TTCN-3(测试和测试控制表示法版本3)的协议一致性测试系统必不可缺的组成部分,用来对TTCN-3数据和被测系统数据转换。针对通信终端协议种类多,协议消息结构复杂,终端测试系统总体架构类似等特点,提出一种基于数据类型的通用编解码器实现方案,适用于不同通信协议的终端测试系统。实践表明,该方案可行并能提高编解码器开发效率。     

基于ARM 9的数字处罚管理网络智能终端

介绍一种基于ARM 9的数字处罚管理网络终端。该设备读取个人识别射频卡中的个人识别信息,并通过GPRS通用分组无线业务网络在远程服务器端数据库中查询匹配,之后操作人员通过液晶触摸屏幕录入处罚信息,系统自动生成罚单,确认后采集违规人员指纹签名信息及现场图片证据一并上传服务器端数据库备份。该设备配合个人识别射频卡和服务器数据库可构成一套先进的数字处罚管理网络方案。同时,该系统也提供了服务器端与终端间的信息查询方案和语音通信方案。     

一种利用TURN穿越对称型NAT方案的设计与实现

针对在IP上承载语音和视频的协议的控制通道/媒体通道无法穿越对称NlAT与公网进行互通的问题,设计并完成基于SIP协议上采用TURN技术的一种穿越对称NAT的方案:利用TURN服务器的中转,TURN客户端穿越对称NAT,与外部主机进行正常通信;与STUN结合,既可以穿越所有类型的NAT,又可降低TURN服务器的负载.提供该模块的封装接口,易于移植到其他类型的终端上.本方案已成功应用于基于嵌入式Linux平台的VoIP网关中.     

智能资源分配协议的分析与实现

服务器集群是大规模流媒体点播系统中的关键技术。这种方案中，通常由一个集群控制服务器控制多个流媒体服务器。为了有效地控制流媒体服务器，必须在集群控制服务器与流媒体服务器之间建立一种有效的通信机制。本提出一种集群控制服务器与流媒体服务器之间的高效通信协议IRDP，并分析了该协议所采用的均衡策略，通讯原语和实现。     

面向未来移动通信终端的片上网络设计

随着通信技术和集成电路技术的飞速发展,功能越来越强的移动通信终端产品层出不穷。未来移动通信终端不仅要支持更高的数据传输速率,而且要融合更多的功能,同时还要支持多协议以实现无缝接入。这些特征要求使得未来移动通信终端片上系统需要集成更多的IP核,同时对IP核之间的通信协作效率要求更高。当前片上系统广泛使用的总线结构已经无法满足未来移动通信终端的上述要求,取而代之的将是片上网络结构。片上网络具有较好的可扩展性、灵活性、以及可重用性,并且可以在IP核数目增加时保持良好的性能。本文重点介绍了面向未来移动通信终端片上网络设计的几个关键技术,包括设计目标和约束条件、拓扑结构、布局、仿真等。根据这些关键技术,本文总结了面向未来移动通信终端的片上网络设计流程,详细阐述了各关键技术之间的相互关系,最后用一个例子来对该设计流程进行具体说明。     

Evolving public safety communication systems by integrating WLAN and TETRA networks

This article contributes to the evolution of public safety communication systems by specifying a novel solution for integrating WLAN and Terrestrial Trunked Radio (TETRA) networks. The specified solution allows TETRA terminals to interface to the TETRA Switching and Management Infrastructure (SwMI) over a broadband WLAN radio access network, instead of the conventional narrowband TETRA radio network. These terminals are fully interoperable with conventional TETRA terminals and can employ all TETRA services, including group calls, short data messaging, packet data, and so forth. In addition, however, such terminals can support a range of brand new capabilities enabled by the WLAN, such as broadband data services, true concurrent voice and data services, simultaneous reception of many group calls, reduced call setup and voice transmission delays, improved voice quality, and so forth. The specified solution is solely based on IP multicast and Voice-over-IP (VoIP) technologies and thus fits ideally to the all-IP architecture being introduced by the MESA project for the next generation of public safety and disaster relief communication systems.     

A Solution of Secure Communication in the Current and Future Mobile Network

1　Introduction　The mobile network is making people s lives more conve nient. Using mobile terminals people can talk to anyone atany time and at any places. And we want more. People willask if I can send short messages to Tom without others beingable to obtain their meanings. When I use my mobile phonetransferring my credit card, can anyone filch my credit cardpassword? Can I safely using my mobile phone to exchangestock? And so on…　Unfortunately, the answer is no nowadays. People canno…     

基于Android手机虚拟机平台虚拟管道的研究与设计

本文主要论述了Android手机虚拟机平台上双操作系统之间通过虚拟管道（Vpipe）实现通信的过程。为了满足用户对高性能移动终端的需求,本文提出了一种可靠性强、高效率的虚拟管道,实现移动终端上实现双操作系统通信功能的技术方案。该方案的难点在于NV数据的存储、管道的设计、以及采用多通道的方式,保证操作系统之间数据的正确交互。     

低轨卫星系统中的一种带优先级的信道预留策略

在卫星通信系统中,可能需要同时支持地面普通终端及一些快速移动特殊终端的通信,因此需要综合考虑不同类型终端的通信服务质量要求。该文从切换的角度考虑,针对两种不同用户终端及非均匀的业务分布,提出一种带优先级的信道预留策略。通过理论分析和仿真结果表明,该策略提高了特殊用户的切换性能,对低轨卫星通信系统的研究有一定的参考价值。     

欧洲新一代移动通信终端生态化设计及评估

绿色环保越来越多地被欧美高端客户作为移动通信终端进入其采购名录的准入要求,结合欧洲市场的需求对移动通信终端的生态化设计要求和评估方法进行了解析,最后建议我国移动通信终端厂商积极参与高端市场的绿色行业组织、尽早建立绿色产品管理体系,及时应对新兴准入要求。     

基于IMS技术的物联网网络

物联网时代,需要通过不同的接入方式接入不同网络的通信终端之间的通信互联。本文通过分析物联网中的通信业务的特点,结合IMS技术的优点,提出了一种基于IMS技术的物联网网络架构,并介绍了一种基于IMS技术的视频通信系统的应用示例。     

Multimedia services interoperability in next-generation networks for the residential environment

This article presents an open and functional architecture based on a next-generation network solution in order to seize its converged nature to guarantee interoperability among different platforms and terminals. The defined architecture is an integrated solution for end-to-end communication of various IP multimedia subsystem platforms marketed by different vendors, belonging to several operators located in different countries across Europe and supporting multiple terminals and technologies in order to experiment with a new broadband telephony service for the residential environment. This work addresses, in particular, the interoperability problems of name resolution and implementation of the Session Initiation Protocol Interface at the terminal as a key use in such a scenario. Also, several advanced services are developed and tested within the proposed architecture as a proof of concept of the IMS capability for quick service creation and deployment. The architecture proposed contributes to the reduction of obstacles and barriers among the European countries in order to adopt NGN architectures, allowing a new type of communication that is more complete and flexible.     

Scheme for Expanding the Capacity of Wireless Access Infrastructures through the Exploitation of Opportunistic Networks

The emerging wireless world should encompass the use of cost-efficient networking paradigms in order to provide extra resources to an operator??s infrastructure for the provision of services. Opportunistic networks (ONs) are a promising solution towards this direction. The proposed approach assumes that ONs are operator-governed, coordinated extensions of the infrastructure which are dynamically created, maintained and terminated, upon request. Opportunistic networking could be used for the capacity extension of wireless access in order to address opportunistically the issue of the overloading of an infrastructure element. This paper describes the problem of capacity extension in the wireless access, providing a mathematical formulation and also proposes a corresponding solution approach. Evaluation results are also presented in order to obtain some proof of concept for the proposed solution. According to the obtained results through the simulations terminals that switch from a congested BS to an ON may experience an average decrease of their consumption of around 25?%. Also, through the creation of ONs in order to redirect traffic from the congested BS to neighboring cells, a reduction of 15?C25?% in the transmission power of the congested BS is observed. Also, the quality of communication is benefited, as delay of successfully delivered messages drops approximately 15?C35?%, compared to the congested situation. Moreover, regarding energy aspects, it is presented that terminals which switch to ON need around 27?% lower transmission power to communicate with their neighboring terminals. On the other hand there is a cost to the intermediate nodes that will handle increased traffic, which is an increase of 19?% in average of their transmission power.     

GEO与LEO间激光通信轨道特性仿真

为了优化GEO与LEO间激光通信系统的性能,建立了卫星通信轨道特性仿真模型。通过对一年内卫星数据的分析可知,卫星通信终端间的多普勒频移变化范围约为5109 Hz,可以使用多普勒频移补偿方法减少GEO与LEO之间的多普勒频移影响。对于相干通信,终端必须进行频移补偿;提前量角的范围大于激光束散角,因此终端需要进行提前量补偿,激光通信系统可根据提前量角对视轴进行提前修正,以减少相对速度对激光通信的影响;太阳干扰和地球遮挡的时间较长,应该进行卫星组网以改善可通率,在通信过程中应根据通信终端时间,优化两个通信终端的工作流程;GEO和LEO终端的视轴变化情况不同,因此应该为卫星设计不同结构。