Voice Networks Research Articles

Future photonic transport networks based on WDM technologies

It is expected that the explosion in Internet traffic implies a paradigm shift from a voice network to a data-centric network. The first and most important requirement of future transport networks is the large bandwidth transport capability which enables the paradigm shift. In addition, requirements for new service attributes are becoming more tangible. Furthermore, high reliability will be indispensable because the multimedia network will be the basis for the information society. To develop the robust and efficient networks that satisfy the requirements above, new network architectures and technologies should be developed. Photonic networks employing dense WDM technologies appear to be the solution. In this article, first the basic concept of the future photonic network is depicted. Next, the capability of large-capacity fiber transmission is shown. The critical degradation factor of fiber nonlinearity is analyzed, and the effectiveness of distributed amplification is quantitatively demonstrated. Furthermore, advances in fiber amplifiers which greatly widen the usable fiber window are shown. Other key technologies such as absolute frequency referencing and multiple channel frequency management techniques are also discussed.

Performance evaluation of packet data services over cellular voice networks

In this paper we develop a Markov chain modeling framework for throughput/delay analysis of data services over cellular voice networks, using the dynamic channel stealing method. Effective approximation techniques are also proposed and verified for simplification of modeling analysis. Our study identifies the average voice call holding time as the dominant factor to affect data delay performance. Especially in heavy load conditions, namely when the number of free voice channels becomes momentarily less, the data users will experience large network access delay in the range of several minutes or longer on average. The study also reveals that the data delay performance deteriorates as the number of voice channels increases at a fixed voice call blocking probability, due to increased voice trunking efficiency. We also examine the data performance improvement by using the priority data access scheme and speech silence detection technique.

Nigerian Universities Network Πgateway to the world

The Nigerian University System (NUS) comprises forty-two institutions in more than twenty-four states and the Federal capital territory. The Nigerian Universities Network (NUNet), aims to create a linked environment at the national level for access to and distribution of information required by each university through campus-wide voice and data communications networks. The NUNet project will be implemented in phases, for completion in 1999. Other computerized network projects in Nigeria include the Academic Computer Network, the Regional Informatics Network for Africa and the Cooperative Network for Researchers in Agriculture, Health and Education. More investment by the private sector is needed to get the local Internet explosion off the ground and launch Nigeria fully into the Information Age.

The work of the encyclopedia in the age of electronic reproduction

The public Internet is currently far smaller, in both capacity and traffic, than the switched voice network. The private line networks are considerably larger in aggregate capacity than the Internet. They are about as large as the voice network in the U.S., but carry less traffic. On the other hand, the growth rate of traffic on the public Internet, while lower than is often cited, is still about 100% per year, much higher than for traffic on other networks. Hence, if present growth trends continue, data traffic in the U.S. will overtake voice traffic around the year 2002 and will be dominated by the Internet.

Voice over PacketStar gateway solution for service provider networks

The global communications industry is undergoing fundamental transformations on multiple fronts led by technology and regulatory forces. The growing demand for telecommunication services on a worldwide basis is fueling an expansion of the industry in this last decade of the 20th century. International standards have played a key role in the expansion by ensuring interoperability and economies of scale. Growth in data traffic has caused most of the expansion, necessitating a convergence of voice and data networks to improve the use of infrastructure, minimizing investment and operations costs. Furthermore, today's multiple network solutions, such as virtual private networks (VPNs), leased line networks, and the public switched telephone network (PSTN) can be consolidated through Internet protocol (IP) and asynchronous transfer mode (ATM) technologies, resulting in additional operational savings. Finally, such enhanced services as universal mailboxes, voice/video conferences, and broadcasts are now feasible through integrated access and multiservice access devices.

The Internet and other Networks: Utilization Rates and their Implications

Costs of communications networks are determined by the maximal capacities of those networks. On the other hand, the traffic those networks carry depends on how heavily those networks are used. Hence utilization rates and utilization patterns determine the costs of providing services, and therefore are crucial in understanding the economics of communications networks.A comparison of utilization rates and costs of various networks helps disprove many popular myths about the Internet. Although packet networks are often extolled for the efficiency of their transport, it often costs more to send data over internal corporate networks than using modems on the switched voice network. Packet networks are growing explosively not because they utilize underlying transport capacity more efficiently, but because they provide much greater flexibility in offering new services.Study of utilization patterns shows there are large opportunities for increasing the efficiency of data transport and making the Internet less expensive and more useful. On the other hand, many popular techniques, such as some Quality of Service measures and ATM, are likely to be of limited usefulness.

Transporting voice traffic over packet networks

POTS networks are being rapidly superceded by newer, packet-based ones, which allows a greater facility for voice traffic. This article explores the practical issues involved in deploying voice networks over ATM, frame relay and IP. © 1998 by John Wiley & Sons, Ltd.

Bandwidth assignment paradigms for broadband integrated voice/data networks

Broadband Integrated Services Digital Networks (BISDNS)/Asynchronous Transfer Mode (ATM) are expected to support diverse applications demanding different bandwidth and Quality of Services (QoSs). Particularly for integrated voice and data networks, voice traffic results in call losses and data traffic suffers from longer delays should networks have insufficient bandwidth. The main goal of the paper is to analytically determine optimal bandwidth allocated to voice and data by means of a queueing model with heterogeneous arrivals and multiple designated channels. The accuracy of analytical results is confirmed by simulation results. On the basis of the analysis, the paper proposes a bandwidth assignment paradigm for the assignment of network bandwidth to voice and data in an effort to guarantee minimal data delay and voice call blocking probability. The run time complexity of the bandwidth assignment computation and paradigm construction is shown to be polynomial bounded. Consequently, the resulting bandwidth assignment assures QoSs in terms of data delay and voice call blocking probability under various network loads.

Parallel simulations of wireless networks with TED

We describe the TeD /C++ implementation of WiPPET , a parallel simulation testbed for mobile wireless networks. In this article we emphasize the techniques for modeling of radio propagation (long- and short-scale fading and interference) and protocols for integrated radio resource management in mobile wireless voice networks. The testbed includes the standards-based AMPS, NA-TDMA and GSM protocols, and several research-oriented protocol families.

Successful ATM Network Implementations

ATM promises increased functionality and performance for users and decreased costs for corporate voice and data networks. the tips provided here focus on the vendor selection and installation processes, which are critical to the successful design and implementation of an ATM network.

Real-time voice over packet-switched networks

We discuss the architecture and technical viability of transporting real-time voice over packet-switched networks such as the Internet. The value of integrating voice and data networks onto a common platform is well known. The telephony industry has proposed the ATM standard as a means of upgrading the Internet to provide both real-time and data services. In contrast, voice services may be added to traditional IP networks that were originally designed for data transmission alone. We consider the feasibility and expected quality of service of audio applications over IP networks such as the Internet. In particular, we examine possible architectures for voice over IP and discuss measured Internet delay and loss characteristics.

Broadband virtual private network signalling

In the corporate voice networks, the virtual private network (VPN) configuration is particularly useful where a shared network infrastructure can be more cost effective and flexible than dedicated leased lines. Current standards for VPN use the international narrowband private signalling system QSIG. Private network signalling standards for broadband networks are also developing rapidly and one can expect that the new emerging signalling systems such as ECMA's BQSIG and ATM Forum's PNNI will play a leading role in the broadband VPN in the future.

Managing IP services over a PACS Packet Network

We have developed a system and network architecture to provide IP services in the Personal Access Communications System (PACS). IP datagrams are delivered to PACS users through the PACS packet-mode data service, achieving more efficient usage of wireless resources and supporting multimedia applications such as MBone audio and video. The architecture presented in this article augments the PACS voice network with IP routers and backbone links, called the PACS Packet Network (PPN), and is connected to the global Internet via gateways. Compared to the cellular digital packet data (CDPD) network, which employs its own network-layer mobility protocol and thus supports roaming within the CDPD network only, we have incorporated Mobile IP into the PACS handoff mechanism to further achieve global IP mobility. We have also developed native PACS multicast and a group management scheme to efficiently handle dynamic IP multicast and MBone connectivity. These features seamlessly integrate PACS into the global Internet and provide standard-conforming IP services with global mobility.

Voice and Telephony Over ATM for Multimedia Network using Shared VCI Cell

This paper presents new multimedia Asynchronous Transfer Mode (ATM) networks which are capable of transmitting voice data efficiently and serving smooth evolution from the existing narrowband voice networks. Fully ATMized networks are characterized by having both rerouting function and switching function. The rerouting nodes multiplex plural calls going through the same route into one ATM cell, namely shared virtual channel identifier (VCI) cell. The shared VCI cell includes fellow cells which contain call data and its VCI. The rerouting node is integrated into a single chip by using CMOS technology. The multimedia ATM networks can be readily implemented by attaching the rerouting nodes to the standard ATM switches.

Review of software tools and methods used in operational support systems development

This paper provides some background to the diversity of software development environments and tools used within BT. Past and present approaches to the subject are described, along with some of the lessons learned along the way. The paper explains why BT is concerned to use modern tools to give higher productivity and describes the work going on to standardise the operational support systems infrastructure and reduce the large number and variety of tools used. The company‘s huge software portfolio, covering systems of all sizes from standard (but very large) invoicing systems to complex systems which interact in real time with the voice and data networks, means that BT has to live with a diverse set of software environments and the large variety of tools which go with them. The challenge is to control the diversity in a rapidly changing industry.

Broadbandloop: a full-service access network for residential and small business users

There is a worldwide effort to define a full-service access network. The Broadbandloop project was formed by a European consortium funded by the European Union with the objective of defining a strategy for evolution from a narrowband voice and data network to a broadband network. The project is defining a system concept based on new innovative PON technology, which enables fiber to cost effectively penetrate close to the customer, and VDSL technology for transmission over twisted copper pairs. The system concept is validated in field trials in Denmark, Portugal, and Poland. The article describes the different requirements for a full-service access network, the system concept, and technologies developed. Results from modeling of broadband traffic and the corresponding bandwidth are given. The cost effectiveness of using new optical fiber vs. reusing existing telephone copper plant has been evaluated, and results from these studies are presented.

The ATM enterprise network switch: Enabler of network transformation

A revolution is in progress that is dramatically changing the way information networks are designed. The introduction of a new form of switching, asynchronous transfer mode (ATM), in both in-building and wide area environments will revolutionize the way networks of the future operate. Network transformation is the process of evolving corporate networks towards multimedia, dynamic-bandwidth, ATM-based infrastructures. This article will discuss numerous approaches to integrating ATM switching and cell-based routing, and will introduce a new wide area product class which has evolved in the marketplace: the ATM enterprise network switch (ATM ENS), which consolidates cell-based routing, ATM switching and multimedia consolidation on a single high-performance platform. It will then discuss various approaches to consolidating voice and video traffic over an ATM ENS, with a particular focus on traffic management implications. Finally it will discuss two key transition issues in the transformation of corporate networks through the deployment of ATM ENS-based networks: support for migration from virtual private voice networks, and the need to allow connectivity to remote sites using more bandwidth-effective alternatives to ATM transmission.

Dimensioning network resources for IN services

As Intelligent Network (IN) services are deployed globally, there is a need to ensure that IN network resourees are cost-effectively dimensioned. Within the framework of a constrained optimization problem, this paper highlights and discusses the issues that must be considered in formulating the IN network dimensioning problem. The discussion will focus on those new aspects which distinguish the IN network dimensioning problem from the traditional dimensioning problem of circuit-switched telephone voice networks.

Low voltage wiring handbook: design, installation, and maintenance

Low voltage electrical systems provide power to data processing and telecommunications equipment. This is a practical guide to designing, installing and maintaining data processing and telecommunications (low voltage) wiring systems in any facility. Procedures that are affected by IEEE, NEC, ISO and vendor group standards are covered. The text also includes information on the various industry standards that have been developed over the past several years. It presents guidelines on selection criteria and cost estimating for the purposes of assuring economy of design and installation. A simple guide to the design and implementation of Integrated Voice and Data Networks is presented.

User involvement for effective customization: an empirical study on voice networks

This paper addresses the role of customer involvement in effective customization of projects, products, or services. Relationships between variables such as project effectiveness, user involvement, supplier efficacy for service to the client, and project complexity are studied. The conditions necessitating involvement are also explored. The case of voice network customization is examined. A questionnaire is designed to measure the variables of the study. Factor analysis gives two factors of project complexity: project size/cost; and user inexperience. Findings provide evidence that user involvement is positively related to network project effectiveness. Supplier efficacy for service is positively and significantly related to user involvement and project effectiveness. The implication is that suppliers with a service-orientation can motivate user involvement and achieve client satisfaction, In addition, user inexperience is positively related to user involvement showing the importance of learning as a motivator for customer participation. >