统一消息业务在IP电话系统中的实现

文章分析了将UM业务融入IP电话系统中实现的优越性 ,确定了通过IP电话系统网守实现对UM服务器的管理机制 ,研究了该UM服务器的主要技术、系统结构、媒体信息的收发方式和安全策略等关键问题 ,完成了基于IP电话系统的UM业务的实现方案并成功开发了这一方案的UM原型系统。     

VoIP技术与趋势

VoIP一般称作为IP电话．广义上是指在数据网络上承载数据、语音、传真和视频、图像等多媒体业务，而在狭义上讲则是承载语音业务。目前VoIP系统一般由IP电话终端、网关（Gateway）、网守（Gatekeeper）三部分组成。     

呼叫转移在IP电话中的实现

介绍了IP电话网守的概念，功能和呼叫信令的两种方式，讨论了呼叫转移在IP电话中的一种实现方法，在局域网、单网守的条件下得到了实现。     

电话中话音服务质量的研究

简化的IP电话网结构如下图．图中IWF(Interworking Function)是指网关和网守等；SCN是指电路交换网(Switched Circuit Network)；IP Network是指Internet Protocol Network。     

一种H.323通信穿越对称NAT的方法

本文提出了一种对称NAT的穿透方法,可以在不改变现有NAT设备软件及其配置的前提下,解决两个私有网络IP电话终端通信问题.该方法借助于代理网守中继两个话机之间的信令和媒体流,通过对H.323协议的适当扩展完成代理网守与终端话机通信信道的建立.实践表明,该方法能够达到预期目标.     

一种支持IP电话增值业务提供的分布业务体系结构

作为一种在PSTN中得到成功应用的技术,IN将在IP电话增值业务提供中具有重要的地位。但是当前的研究侧重于通过网关实现IN与Internet的互通,这种方案的不足之处在于沿袭了传统IN集中控制的缺点。该文的重要贡献在于重新定义了IN的概念模型,提出了一种适应于IP电话环境的分布IN体系结构,探讨了将网守扩展为SSP技术途径,并通过具体被叫付费业务的实现证明了该方案的可行性。研究表明,这种基于代理的业务结构能有效地克服了原有IN结构的缺陷,在分布控制、灵活性、客户化等方面有很大的优越性。此外,我们的方案还能与已有系统综合,具有良好的演进性。     

IP电话中话音服务质量的研究

一、影响IP电话话音质量的因素简化的IP电话网结构如下图,图中IWFInterworking Function是指网关和网守等；SCN是指电路交换网Switched Circuit Network；IP Network是指Internet Protocol NIP电话的过程从时间上分主要有呼叫建立过程和通话过程,呼叫建立过程是指IP电话整个呼叫建立过程,如呼叫建立中的用户认证、信令转换等；通话过程指呼叫建立后主、被叫的通话过程.从空间上分主要有交换电话网的接入,网关的处理和因特网的传输.交换电话网的接入是指通话终端到IWF之间,包括话音数据的采样、量化和PCM编码,PSTN的交…     

一种新型智能IP电话系统设计与实现

针对现有IP电话的弱点和存在问题 ,提出一种适用于这些应用需求的新型智能IP电话系统。介绍这种IP电话具有组呼叫、广播呼叫、多级优先、热线呼叫 ,加密通话 ,遥毙 ,个性化提示信息等特色。还对该智能IP电话系统有关实现问题进行了讨论。     

一种新型智能IP电话系统设计与实现

针对现有IP电话的弱点和存在问题,提出一种适用于这些应用需求的新型智能IP电话系统。介绍这种IP电话具有组呼叫、广播呼叫、多级优先、热线呼叫、加密通话、遥毙,个性化提示信息等特点。还对该智能IP电话系统有关实现问题进行了讨论。     

基于H．323标准的IP电话附加业务

随着IP电话的快速发展,用户对基于IP电话的新业务的需求也日益增长,传统电话业务正在被移植到IP多媒体电话系统中,由于IP电话系统在信令结构方面与传统电话系统的集中模型有着本质的区别,因此基于IP电话系统的附加业务开发和控制协议的特点具有不同的特点,本文描述了基于H.323标准的附加业务的信令结构和业务设计,并与传统电话交换业务模型加以比较。     

VoIP技术--语音和数据的集成

介绍了VoIP(Voice over IP)的基本组成构件即网关(Gateway)、网守(Gatekeeper)的概念和用途。讲述了语音在IP网上传输的基本原理，语音和数据、数据和IP包之间的转换和传送过程。在H．323协议栈的基础上详细讲述了H．248，H．225，H．245等通信协议和语音编码G．729，G．23l，G．7ll等协议。最后对VoIP的语音服务质量作了较为详细的阐述。     

H.323: the multimedia communications standard for local areanetworks

This article provides an overview of ITU-T Recommendation H.323, “Visual telephone systems and equipment for local area networks which provide a non-guaranteed quality of service.” This recommendation applies to multimedia communications over packet-switched networks, such as Ethernet, which run TCP/IP, IXP/SPX, or other related protocols. In addition to the multimedia terminal, other H.323 components are defined which provide for conference admissions (gatekeeper), multipoint communications (multipoint controller, multipoint processor), and interoperability (gateway) with terminals on other types of networks. H.323 has application to a variety of network media, including local area networks, enterprise networks, metropolitan area networks, wide area networks, dial-up line connections to LANs, and the Internet. This provides the capability to have global multimedia communications from the desktop using existing network infrastructures     

基于H.323网守的呼叫中心模型设计

通过对当前呼叫中心模型和Ｈ．３２３网络及其网守的分析,提出了一种新的基于Ｈ?３２３网守的呼叫中心模型。     

A multilayered mobility management scheme for auto-configured wireless IP networks

The convergence of wireless and IP has led to the need for IP to handle mobility. The Mobile IP protocol was developed to facilitate IP mobility. However, it has a number of shortcomings for dynamically auto-configured networks. Mobility protocols like Mobile IP with Location Registers (MIP-LR) and Session Initiation Protocol (SIP) have been developed to address some of its shortcomings. Micromobility protocols like Cellular IP have been developed to address other shortcomings of Mobile IP. We present a new integrated mobility management scheme that advantageously combines the strengths of SIP and MIP-LR with the benefits of a micromobility management protocol similar to Cellular IP. A prototype implementation of our scheme is explained, and lessons learned in the prototyping process are presented.     

TCP/IP协议的ASIC设计与实现

文章介绍了一种TCP/IP协议族传输、处理TCP数据和IP数据报过程的ASIC设计-TCP/IP协议处理器的硬件实现。简单介绍了TCP/IP协议，着重介绍了TCP/IP协议处理器系统结构以及各模块设计。硬件实现的TCP/IP协议处理器提高了IP数据报的处理速度，更重要的是，将Internet网络数据传输从传统的依赖电子计算机系统的模式中解放出来，实现了脱离计算机系统环境建立Internet网络连接。     

Combinatorial Mobile IP: A New Efficient Mobility Management Using Minimized Paging and Local Registration in Mobile IP Environments

Combinatorial Mobile IP, a new mobility management scheme for Mobile IP, is proposed and analyzed. We present how to adopt mobility management schemes on cellular networks and adapt them in Mobile IP without disrupting the nature of the Internet. We apply widely used mobility management schemes such as hierarchical architecture and paging in cellular networks to Mobile IP. We restrict paging to the area that has to be paged using local registrations. In this way, we show that the total signaling costs of Combinatorial Mobile IP are reduced compared to other micro-mobility protocols such as Mobile IP Regional Registration and P-MIP. Random walk on a connected graph is used to analyze the performance of Combinatorial Mobile IP.     

IP核评测流程的研究

对于系统芯片设计，IP的质量是至关重要的。要对口进行质量评估，首先要有一套相应的评测标准、评估方法学和评测流程。因此提出了一种基于第三方评测机构的IP核评测流程．从口核工业界标准，口核静态性能方面研究了口性能测试技术、相关算法和工具。     

Opening up the black box

Since semiconductor intellectual property (IP) first emerged on the integrated circuit (IC) design scene over a decade ago, it has offered the promise of shaving months off of development time while allowing for the inclusion of many more functions in a design. At the heart of the problem is the need by IP providers to protect their development investment. Few IC designers can afford to pay the often high price for access to IP source code, so IP suppliers provide significantly less costly 'black box', or encrypted, versions for use with specific design tools. The problem with this is not only that the IP vendor is saddled with the cumbersome task of maintaining multiple IP core versions for various tool sets, but, more importantly, that it is an incomplete solution. To address the need for a means to protect IP from piracy while making it easier for the IF supplier to deploy and the IC designer to use, Synplicity has developed and introduced an open IP encryption/decryption methodology. It takes advantage of features in the most recent release of Verilog and commonly used encryption mechanisms in a new usage model that could become an industry standard