分组语音通信技术

介绍并比较了分组语音通信中所采用的几种语音压缩编码标准,讨论了三种最主要的分组语音传输方案：ＶｏＡＴＭ、ＶｏＦＲ和ＶｏＩＰ。     

IP电话的关键技术

描述了IP电话的基本原理和几个关键技术，包括语音编码、压缩、打包、分组交换，以及为保证话音质量而采取的回声抵消等技术。     

用AAL5实现基于ATM的分组语音通信

本分析了现有应用于ATM分组语音通信的AAL1、AAL2适配方案优缺点后，提出了用AAL5实现基于ATM的分组语音通信，并就语音编码方式和时延这两个关键问题进行了探讨。     

Internet语音实时传输

随着通信技术的迅速发展,语音业务在Internet上传输变得可行。从8年前世界上第一个计算机到计算机的IP电话软件VocalTec出现至今,IP电话的概念逐渐被业界接受,语音业务在Internet上传输已基本上变为共识。     

因特网上的分组语音业务

论述了在国特网上引入语音业务的可能性、相应的技术要求和业务结构模型，并分析了国特同语音业务存在的问题。     

因特网上的话音业务及其关键技术

因特网上的话音业务（又称分组电话）是一项非常有前途的通信业务，它在将来有可能取代基于电路交换的电话业务。文章分析了分组电话中存在的关键问题，并对解决方案提出了一些建议。     

IP电话的语音压缩技术

本首先介绍了语音编码技术中对语音质量的评价方法，然后对几种典型的IP电话语音压缩技术标准进行了阐述，最后，对三种常用的IP电话语音压缩技术参数进行了比较。     

基于IP的语音／传真关键技术

本文描述了当今网络世界正在积极探索实验的基于ＩＰ的语音／传真实现垢关键技术。主要包括ＶｏＩＰ呼叫实例、ＶｏＩＰ语音质量控制方法、ＶｏＩＰ在ＷＡＮ上的带宽消耗等内容。概要地介绍了ＶｏＩＰ技术及语音质量控制的发展现状和完善手段。     

因特网中分组语音传输的丢包恢复技术浅述

在基于IP网络下进行语音通信的过程中，不可避免地会遇到数据包丢失现象，极大地影响了传输服务的质量。对此问题展开讨论，讲述了丢包的原因，对当前普遍采用的几种丢包恢复技术进行了介绍，通过比较提出了自己的观点。     

Key technologies for IMT-advanced mobile communication systems

WINNER is an ambitious research project aiming at identification, development, and assessment of key technologies for IMTAdvanced mobile communication systems. WINNER has devised an OFDMA-based system concept with excellent system-level performance for flexible deployments in a wide variety of operating conditions. The WINNER system provides a significant step forward from current 3G systems. Key innovations integrated into the system concept include flexible spectrum usage and relaying, adaptive advanced antenna schemes and pilot design, close to optimal link adaptation, hierarchical control signaling, and a highly flexible multiple access scheme. The end-to-end performance assessment results demonstrate that the WINNER concept meets the IMTAdvanced requirements.     

5G移动网络绿色通信的相关关键技术

5G移动网络绿色通信技术相对于4G技术来说,在网络速度、网络延时和网络容量上进行了不断的提升。随着我国智能化的设备不断发展,5G移动网络绿色通信技术所面向了全社会的网络。由此可以预见,在未来人们的数据传输将变得更加高速率和高性能。本文在研究的过程中,主要结合第5代移动通信系统的具体建设和关键技术,分析当前我国第5代移动通信系统能耗问题,同时对于5G绿色通信技术的关键问题进行必要的分析。     

Review of speech technologies for telecommunications

Speech is the easiest and most expressive means that people have for communicating with each other. This paper reviews the key speech technologies and discusses the associated telecommunications applications and technical challenges. It concludes with some personal predictions about future trends and opportunities in this important, exciting and far-reaching field     

白光LED室内可见光通信的关键技术

可见光通信是一项新兴基于白光LED的无线光通信技术,具有发射功率高、不占用无线电频谱、无电磁干扰、无电磁辐射和节约能源等优点,能够同时实现照明和通信的双重功能.阐述了可见光通信技术的发展动态,介绍基于白光LED的室内可见光通信系统,并对提高系统整体性能的若干关键技术进行了研究讨论,为白光LED室内可见光通信系统进一步研究提供依据.     

数据中心光通信技术

由于互联网业务的快速发展,数据中心的流量已经占据全球通信网络流量绝大部分。作为高速信息传输的主要载体,如今光通信技术已经在数据中心中得到了广泛应用,从距离几米服务器间的光互连到连接世界各地数据中心的光网络。概要介绍了数据中心的光通信技术,包括数据中心之间互连的广域网、城域网技术和数据中心内部服务器及交换机之间光互连技术,并对各个领域内一些不同的技术方案做了简要的讨论和比较。     

Visual communication technologies for computer graphics

Methods of displaying computer-generated graphic images are examined. Several alternative technologies are evaluated. Principles of operation are given for each of these advanced technologies. These color display technologies include screen cameras, film recorders, LCD projection devices, and RGB projectors. A brief survey of commercially available devices is presented     

Display technologies for portable communication devices

Telecommunications networks are rapidly advancing toward adequate capacity to support multimedia content transmission between mobile terminals. This development opens opportunities for terminal manufacturers to realize functions on the devices that previously have been considered impractical. It is necessary for the terminals, however to exploit advances in new display technologies, such as reflective-color liquid-crystal displays, bistable displays, organic emissive displays, and microdisplays, to make use of the new functionality. The state of the art of mobile phone and personal digital assistant displays as well as some of the emerging technologies are reviewed based on their applicability in new uses in mobile terminals     

Developing technologies for personal communication networks

The author reviews the technologies needed to meet the demands of the personal communication network (PCN) service, and gives the reasons why the three successful PCN applicants stated their preference for Groupe Speciale Mobile, (GSM) as the basis for PCN. Then the author discusses how, based on GSM, the DCS1800 standard (digital communication system at 1800 MHz) was elaborated by ETSI to meet PCN requirements     

Low bit-rate speech coders for multimedia communication

The International Telecommunications Union (ITU) has standardized three speech coders which are applicable to low-bit-rate multimedia communications. ITU Rec. G.729 8 kb/s CS-ACELP has a 15 ms algorithmic codec delay and provides network-quality speech. It was originally designed for wireless applications, but is applicable to multimedia communications as well. Annex A of Rec. G.729 is a reduced-complexity version of the CS-ACELP coder. It was designed explicitly for simultaneous voice and data applications that are prevalent in low-bit-rate multimedia communications. These two coders use the same bitstream format and can interoperate. The ITU Rec. G.723.1 6.3 and 5.3 kb/s speech coder for multimedia communications was designed originally for low-bit-rate videophones. Its frame size of 30 ms and one-way algorithmic codec delay of 37.5 ms allow for a further reduction in bit rate compared to the G.729 coder. In applications where low delay is important, the delay of G.723.1 may be too large. However, if the delay is acceptable, G.723.1 provides a lower-complexity alternative to G.729 at the expense of a slight degradation in quality. This article describes the attributes of speech coders such as bit rate, complexity, delay, and quality. Then it discusses the basic concepts of the three new ITU coders by comparing their specific attributes. The second part of this article describes the standardization process for each of these coders