Speech and Video Telephony Quality Characterization and Prediction of Live Contemporary Mobile Communication Networks

Quality of Service (QoS) characterization and prediction is of utmost importance in contemporary operating cellular communications networks. Measurements data of speech and video telephony have been collected using modern experimental equipment. More specifically, key performance indicators of radio, speech and video quality are evoked. The objective of our study is to critically investigate the performance of speech and video telephony at live cellular networks correlating significant QoS parameters from radio and the service side. Simple non-linear regression models are also proposed for speech and video quality prediction. Finally, the paper represents the splendid positive influences of the continuous performance evaluation for the optimization of the mobile networks. There are also briefly given guidelines for mobile networks benchmarking.     

Voice and Internet Multimedia in UMTS Networks

Voice telephony is the predominant service on today's cellular mobile networks, in terms of number of customers, revenues and network usage. However, it is difficult to predict how long this will be the case given the rising demand for new Internet multimedia services. It is therefore essential that 3rd generation (3G) mobile networks support a voice telephony service, but also that these networks are also capable of providing Internet multimedia services using the same technology.This paper provides an overview of how voice telephony is provided in the initial phase of the universal mobile telecommunications system (UMTS). It then describes how this is expected to evolve in later phases — so that voice telephony becomes one of a large number of multimedia services provided from a common Internet protocol-based mobile network.     

UK cellular radio developments

The spectacular development of cellular technology in the UK is briefly reviewed and some of the less obvious developments required to cope with market demand and a multiswitch network are described. These have resulted in the UK having two of the largest mobile networks in the world today, using some advanced techniques which will be applied more universally in the pan-European digital cellular system planned to open in 1991     

Future trends in digital telecommunication transmission networks

New technology is needed by digital transmission networks for the increased bandwidth, performance and reliability requirements of existing and future telecommunication services, such as broadband ISDN. Increased flexibility, automation and control are also major issues being addressed. The combination of these factors has led to the development of synchronous digital hierarchy (SDH) networks to replace existing asynchronous networks during the 1990s. These issues are reviewed and further developments to bandwidth-transparent optical networks indicated for the twenty-first century     

You'll never talk alone [cellular radio networks]

The transition in the 1990s from analogue to digital technology in cellular radio networks marked a turning point in mobile telephony, heralding a future of ubiquitous, low-cost, personal communications. The global growth of personal communications has continued at an incredibly rapid pace. The commercial pressures in today's markets are such that the development of future standards and systems are driven not simply by technology, but by commercial opportunity and market pull. In this respect personal communications has gone up a gear since the development of the early GSM digital cellular standards. The opportunities to apply PCS technology into adjacent markets and applications are huge, with new products and services limited only by imagination     

Telecommunications

The author discusses advances and changes in: Internet; multichannel optical fibre networks using erbium-doped fibre amplifiers and wavelength division multiplexing; HDTV; digital radio; satellites for mobile voice telephony; the auction of wireless telephony licences; and unlicensed personal communication systems     

Interoperable wireless data

Data services offered over cellular networks are described. The limitations of data transmission over analog cellular networks and the main challenges to be met in defining a standard for effective data transmission over digital cellular channels, devoting particular attention to North American developments, are discussed. Some of the technical characteristics of the analog and time-division multiaccess (TDMA) digital cellular systems in North America are compared, including interfaces, internetworking functions, home and visitor location registers, layering of protocols, initiation of data service, and timing and synchronization     

Regulatory challenges for the transition of public telephony to the Internet

Fixed and mobile telephony with other telecommunication services are moving to a fundamentally different infrastructure as the transition proceeds from the public telephone network to the Internet. There are many opportunities to make significant progress on major developments such as separation of operator independent functions, modular design, and the integration of other desirable features of sustainable Internet solutions. This progress also means that the impacts of some shortcomings of currently competitive telephony services will decline??another benefit of the transition. However, because telephony services are essentially being ??emulated?? over the Internet infrastructure, other aspects of these services will be changed in ways that could affect the public good. In particular, trust-related issues such as authentication and validation, along with their business implications, present significant challenges. This paper explores these issues, including the opportunity that industry and the regulators now have to address them, and suggests approaches to sustainable solutions that can benefit all the stakeholders in this transition.     

Overview of wireless personal communications

This article presents an overview of the current state of wireless communications, including relevant ongoing activities in technology development, standards, and spectrum allocation. The authors discuss cellular radio, cordless telephony, and wireless data systems. Ongoing and planned future developments are summarized. The presentation is oriented toward broad coverage rather than technical depth. However, brief discussions of the air interfaces for existing digital cellular and digital cordless systems are provided, because the air interface bears heavily on system capacity and the environments in which the system can be used, as well as on the cost and complexity of the equipment     

Modems for emerging digital cellular-mobile radio system

Digital modem techniques for emerging digital cellular telecommunications-mobile radio system applications are described and analyzed. In particular, theoretical performance, experimental results, principles of operation. and various architectures of π/4-QPSK (π/4-shifted coherent or differential QPSK) modems for second-generation US digital cellular radio system applications are presented. The spectral/power efficiency and performance of the π/4-QPSK modems (emerging American and Japanese digital cellular standards) are studied and briefly compared to GMSK (Gaussian minimum-shift keying) modems (proposed for European DECT and GSM cellular standards). Improved filtering strategies and digital pilot-aided (digital channel sounding) techniques are also considered for π/4-QPSK and other digital modems. More spectrally efficient modem trends for future cellular mobile (land mobile) and satellite communication system applications are also highlighted     

The Short Message Service: Standards,infrastructure and innovation

The Short Message Service (SMS) is a teleservice developed by the Global System for Mobile Communication in the mid-1980s for second-generation mobile networks. SMS is made up of standards, protocols and infrastructure that make text messaging the most popular data service on mobile networks. The teleservice has been used in all subsequent generations of mobile telephony. This article discusses the development of the SMS teleservice standards (GSM 03.40), how it has influenced mobile telephony infrastructure, and how it remains a lasting communication innovation today. It historicizes text messaging standards and their technical realization by describing the network architecture and elements required for SMS transmission. This article illustrates how SMS standards and infrastructure represent a significant innovation to mobile telephony in the late twentieth century.     

Handoff with DSP Support: Enabling Seamless Voice Communications across Heterogeneous Telephony Systems on Dual-Mode Mobile Devices

In this paper we investigate the problem of voice communications across heterogeneous telephony systems on dual-mode (WiFi and GSM) mobile devices. Since GSM is a circuit-switched telephony system, existing solutions that are based on packet-switched network protocols cannot be used. We show in this paper that an enabling technology for seamless voice communications across circuit-switched and packet-switched telephony systems is the support of digital signal processing (DSP) techniques during handoffs. To substantiate our argument, we start with a framework based on the Session Initiation Protocol (SIP) for vertical handoffs on dual-mode mobile devices. We then identify the key obstacle in achieving seamless handoffs across circuit-switched and packet-switched systems, and explain why DSP support is necessary in this context. We propose a solution that incorporates time alignment and time scaling algorithms during handoffs for supporting seamless voice communications across heterogeneous telephony systems. We conduct testbed experiments using a GSM-WiFi dual-mode notebook and evaluate the quality of speech when the call is migrated from WiFi to GSM networks. Evaluation results show that such a cross-disciplinary solution involving signal processing and networking can effectively support seamless voice communications across heterogeneous telephony systems.     

全面解析数字电视

普通公众距离数字电视越来越近,无需电视,掌上电视、手机、笔记本电脑都将成为数字电视的收视终端,同时自主研发、自主制造的数字电视芯片日趋成熟,这些进展都预示着数字电视的“大时代”与百姓生活近在咫尺。数字电视对普通百姓而言,不仅能传输更好的画面,更大的优势在于“广覆盖”和“移动性”。模拟电视因为技术所限,凭借电视塔的信号很难覆盖广大农村,而在乡村建有线网成本太高,同时模拟电视也无法“边走边看”。而这些弊病正是数字电视的长处,特别是“国标”相对欧美标准的优势。     

The ideal communications service [PCN]

The development of personal communications network (PCN) technology in the United Kingdom is reviewed. It is argued that the perceived benefits of PCN, smaller handsets, improved communication quality, and increased capacity of the PCN technology, as compared with the competing cellular networks, are expected to give the personal communications concept mass-market appeal. Future technological developments for PCNs and issues concerning PCN development, including competition, pricing strategy and penetration, market confusion, and technological limitations, are discussed     

A brief history of mobile communication in Europe

Since the introduction of mobile telephony in the early 1950s in Europe, US and Japan the demand for this service exploded. It seems that the latent demand for mobile telecommunication services for decade’s continued to be very strong. After the introduction of cellular technology the capacity of the services became able to meet the massive demand. Next and future generations of mobile telecommunication technologies bring increased transmission speed and more versatile services. This forces network operators to organise multi sourced information flows supplied by service providers to increase the network effect of the system instead of providing the network infrastructure and leave the content to the users as in pure voice telephony. The drivers and inhibitors behind the emergence and recent developments of mobile telecommunications systems in Europe, are highlighted in this paper. Liberalisation of the telecom markets in Europe drove new entrants to the market and curbed excessive pricing. However, in recent years the lack of challenging service is the main cause for the wavering development of newer generations of mobile telecommunication services.     

Implementation of PCNs using DCS 1800

The digital cellular system (1800 MHz) (DCS 1800), a standard for personal communication networks (PCNs) that has been developed by the European Telecommunications Standards Institution (ETSI), is discussed. The GSM 900-MHz cellular standard, from which DCS 1800 is derived, is reviewed. GSM/DCS 1800 network interfaces and signaling, implementation of PCNs using DCS 1800, PCN cellular design, PCN transmission networks, and the services and functionality of DCS 1800 are described     

Communications [technology analysis and forecast]

Several spectacular changes in the communications scene over the past few years will have a still stronger impact in 1997. Most obviously, the World Wide Web has been expanding. Showing a nice mixture of optimism and concern, the telecommunications establishment is mulling how best to exploit the Web commercially while deploying such packet-switched networks as the integrated services digital network (ISDN) and such subscriber access technologies as asymmetric digital subscriber line (ADSL) to keep the telecom infrastructure from being overwhelmed. Amid the competitive pressures generated by deregulation, telecom companies have more incentive than ever to squeeze as much performance as possible out of their existing infrastructure. Hence the attraction of local-access technologies like ADSL for boosting the capacity of installed copper subscriber loops, and long-haul technologies like wavelength division multiplexing (WDM) for boosting the capacity of installed optical fiber. Wireless local-area networks (LANs) are benefiting from spread-spectrum technology, just as cellular telephony is. Also planned is provision of satellite-based, global mobile voice and datacom services to pocketsized, hand-held devices     

Cell phones answer Internet's call

Cellular service providers, handset manufacturers, and system integrators are captivated by the promise of the wireless Internet using third generation cellular telephony. The leading contender to be the global standard for third-generation cellular telephony is the Universal Mobile Telecommunication System (UMTS). This is a wideband CDMA system designed to be smoothly backward-compatible with GSM, and also the leading member of the IMT-2000 family of third-generation systems sponsored by the International Telecommunication Union (ITU). The developments of this technology and its impact on the telecommunications industry worldwide are discussed     

Mobility support for IP-Based networks

IP-based wireless networks will become the core of next-generation mobile networks. Mobility support plays an important role in all IP-based wireless networks for providing multimedia applications. In this article we address various major issues in mobility support for IP-based networks. Existing technology, including Mobile IP, Mobile IPv6, and other related techniques, are discussed. The issues of mobility support for wireless LANs, wireless WANs, 2-3G cellular networks, and next-generation heterogeneous mobile networks are also addressed in this article.     

Wi-Fi hotspot networks sprout like mushrooms

What began as a plaything among technology buffs in the United States has quietly evolved into the fastest-growing wireless data application in the world. All over, networks based on the IEEE's 802.11b wireless local-area networking standard, known also by the commercial trademark Wi-Fi, have been springing up-and not only in businesses and other self-contained organizations but in public places like waiting rooms and coffee shops as well. Now, increasingly, service companies are stringing these "hotspot" networks together to create what could soon be the world's largest wireless data network. It is in Europe, however, where the creation of transregional Wi-Fi networks may be taking off the fastest and where opportunities and challenges are coming into sharpest relief. IEEE 802.11b has prompted some serious concern about its potential impact on third-generation mobile technologies. The Europeans have championed 3G cellular telephony in global standards organizations, as a successor to its hugely successful Global System for Mobile Communications (GSM).