Voice Networks Research Articles

Forward link performance analysis of the CDMA2000* 3G1X data system

Performance analysis of data networks based on the code division multiple access (CDMA) air interface including the CDMA2000∗ 3G1X and the Universal Mobile Telecommunications System (UMTS) requires development of new methodologies distinct from those used to analyze voice networks. In this paper, we present a set of analytical and simulation techniques of different complexity that are used to investigate different aspects of data system performance on the forward link. We demonstrate how the static-snapshot simulation model is used to obtain statistically significant system-level results valid for multi-cell wide area network deployment. These simulations are complemented by the dynamic model, which takes into account details of data traffic arrival and resource management algorithms on the air interface. It also provides insight into each individual user's experience under different network loads when running different data applications over the CDMA2000 air interface. Key results of simulation models are verified via theoretical analysis techniques that demonstrate the consistency of the results obtained via different methods.

Six priorities that make a great strategic decision

Spotlights Iridium, the satellite phone system vision company, and how it stole a jump on its competitors when it started in 1998, with global communication networks for international voice, data, and fax communication – but filing for bankruptcy a year later. Declares that Iridium did not foresee some of the problems, because of lacking in deep thinking of the potential areas of difficulties. Contends that getting it right is not easy, but becomes so when a systematic examination precedes the strategic decision.

A Multiservice Voice, Data, and Video Network Enabled by Optical Ethernet

With data now approaching 60% of all aggregate traffic and expected to grow to 90% of all traffic by 2004, networks designed around all-packet architectures are being envisioned. Within this timeframe, a network vision is to deliver voice, video, and data services over a single packet-oriented network. Some entrepreneurial network providers are pursuing this vision in an even earlier timeframe.This article introduces a multiservices voice, data, and multicast video network over an Optical Ethernet architecture for residents of multidwelling units (MDU). This article reviews the network architecture for delivering these services over Optical Ethernet and addresses the challenges of handling service types with different bandwidths and latencies over a common packet-oriented infrastructure. As an example, it addresses the challenge of managing latency-intolerant traffic such as voice over IP over a common architecture as Internet data. Furthermore, it discusses the challenges of delivering over 100 channels of broadcast video as well as video on demand over the same infrastructure.

A Multiservice Voice, Data, and Video Network Enabled by Optical Ethernet

A Multiservice Voice, Data, and Video Network Enabled by Optical Ethernet

Data Networks are Lightly Utilized, and will Stay that Way

The popular press often extolls packet networks as much more efficient than switched voice networks in utilizing transmission lines. This impression is reinforced by the delays experienced on the Internet and the famous graphs for traffic patterns through the major exchange points on the Internet, which suggest that networks are running at full capacity. This paper shows the popular impression is incorrect; data networks are very lightly utilized compared to the telephone network. Even the backbones of the Internet are run at lower fractions (10% to 15%) of their capacity than the switched voice network (which operates at over 30% of capacity on average). Private line networks are utilized far less intensively (at 3% to 5%). Further, this situation is likely to persist. The low utilization of data networks compared to voice phone networks is not a symptom of waste. It comes from different patterns of use, lumpy capacity of transmission facilities, and the high growth rate of the industry.

Basestation collaboration in Bluetooth voice networks

In the near future Bluetooth may be embedded into many different types of mobile and portable devices [IEEE Personal Commun. 7 (1) (2000)]. This connectivity will enable a variety of future picocellular services such as real-time voice and data [Specification of the Bluetooth System 1.0b., Bluetooth Special Interest Group, 1999]. In this paper, we consider several Bluetooth-based telephony access point designs. Since the number of SCO links per Bluetooth node is very limited, the designs consider the use of multiple overlapping Bluetooth basestations or module coverage areas. The first scheme is a direct implementation of the telephony profile where the Bluetooth basestations/modules operate independently, without any coordination. The paper proposes several schemes which use a variety of techniques for reducing the call blocking rate using real-time communication between the basestations or Bluetooth modules. It is shown that significant improvements in blocking performance are possible using this approach. A constraint on the design of high-capacity voice access points is the potential packet loss experienced by overlapping SCO transmissions. The paper includes a worse-case characterization and discussion of Bluetooth’s shortcomings in this regard.

Trunking of TDM and narrowband services over IP Networks

AbstractThe recent interest in IP as the vehicle for transporting TDM and narrowband services stems from the possibility of using a common transport network for voice, video, and data, and the flexibility with which new services can be introduced. A key step in the evolution of networks towards a ‘broadband’ IP‐based environment is the ‘graceful’ interworking of the IP networks with the existing networks and services, particularly with the circuit switched telephone network. A ‘graceful’ interworking approach is one whose complexity is minimal and preserves the user's perceived quality of service (QoS). To interwork with a circuit switched network whose services are pre‐dominantly time‐sensitive, the IP network must essentially behave as a transparent ‘link’ in the end‐to‐end connection. This paper presents an overview of the main technical problems to be addressed when trunking TDM and narrowband services over IP networks. Copyright © 2002 John Wiley & Sons, Ltd.

VoP (voice over packet)

Organizations around the world want to reduce rising communications costs. The consolidation of separate voice and data networks offers an opportunity for significant savings. Accordingly, the challenge of integrating voice and data networks is becoming a rising priority for many network managers. Organizations are pursuing solutions that utilize excess capacity on broadband networks for voice and data transmission, as well as utilize the Internet and company Intranets as alternatives to costlier mediums. A Voice over Packet (VoP) application meets these challenges by allowing both voice and signaling information to be transported over the packet network.

Resource management with hoses: point-to-cloud services for virtual private networks

As IP technologies providing both tremendous capacity and the ability to establish dynamic security associations between endpoints emerge, virtual private networks (VPNs) are going through dramatic growth. The number of endpoints per VPN is growing and the communication pattern between endpoints is becoming increasingly hard to predict. Consequently, users are demanding dependable, dynamic connectivity between endpoints, with the network expected to accommodate any traffic matrix, as long as the traffic to the endpoints does not overwhelm the capacity of the respective ingress and egress links. We propose a new service interface, termed a hose, to provide the appropriate performance abstraction. A hose is characterized by the aggregate traffic to and from one endpoint in the VPN to a set of other endpoints in the VPN, and by an associated performance guarantee. Hoses provide important advantages to a VPN customer: (1) flexibility to send traffic to a set of endpoints without having to specify the detailed traffic matrix, and (2) reduction in the size of access links through multiplexing gains obtained from the natural aggregation of the flows between endpoints. As compared with the conventional point-to-point (or customer pipe) model for managing quality of service (QoS), hoses provide reduction in the state information a customer must maintain. On the other hand, hoses would appear to increase the complexity of the already difficult problem of resource management to support QoS. To manage network resources in the face of this increased uncertainty, we consider both conventional statistical multiplexing techniques, and a new resizing technique based on online measurements. To study these performance issues, we run trace-driven simulations, using traffic derived from AT&T's voice network and from a large corporate data network. From the customer's perspective, we find that aggregation of traffic at the hose level provides significant multiplexing gains. From the provider's perspective, we find that the statistical multiplexing and resizing techniques deal effectively with uncertainties about the traffic, providing significant gains over the conventional alternative of a mesh of statically sized customer pipes between endpoints.

The Circuit-Switched Network Design and Analysis Model: A Chronology of Its Development and Use

The Defense Information System Agency (DISA) has managerial and engineering responsibility for a circuit-switched network currently known as the Defense Information System Network—Voice. This network was originally implemented in the 1960s and was known as the Automatic Voice Network. Throughout this time, DISA has used a network design and analysis model to reconfigure the network. This model was developed in the early 1970s, has been continually enhanced, and is used on a weekly basis to engineer and manage the network. Since 1975, it has been used to save the United States (U.S.) government approximately $1,400,000,000.00. In this paper, we present a chronology of its development, enhancement, and use.

Reducing complexity for converged voice/data networks and services architecture

The telecommunications industry today is facing an increasing degree of complexity due to the proliferation of available technologies and separate implementations of voice and data networks and services. Recent trends in the industry toward a convergence of telephony/computer technologies, networks, and services create an opportunity for reducing complexity in the converged voice/data network. The converged telecommunications network will be packet based, providing integrated voice/data/video services with third-party programmability to any subscriber, anywhere, over any access media. This paper describes an architectural approach to meet these challenges. A set of guiding principles is formulated and used for developing the converged network and service architectures. These principles, which provide an overall framework for partitioning network and service functions into components, are illustrated using the planned 7R/E™ Packet Solutions system and service architectures to build component-based converged voice and data services with interfaces to operations, administration, maintenance, and provisioning (OAM&P) frameworks for industry-grade reliability, availability, and security.

A network management system solution for diverse and converged voice and data networks

The rapid evolution of the telecommunications industry has resulted in the convergence of voice and data transport over a myriad of diverse architectures and technological domains. To overcome the problems that inevitably accompany such a heterogeneous environment, Lucent Technologies is developing a phased inter-domain network management solution. The new system architecture will enable service providers to integrate the diverse technologies of multiple vendors, rendering transparent any differences among the heterogeneous network equipment. This paper presents an overview of the proposed Inter-Domain Management System architecture being developed by Lucent's Communications Software Group.

Voice and multiservice network design over ATM and IP networks

Asynchronous transfer mode (ATM) and Internet protocol (IP)-based networks have enabled the introduction of a multitude of computing and communications applications and revolutionized the data services market. Rapid acceptance of Internet applications by users has demonstrated the potential for explosive service growth in data networking. However, voice services still generate most of the revenues for telecommunications service providers. The next challenge for these providers and their vendors, therefore, is to incorporate an integrated network that will implement the traffic characteristics and demands associated with the different service types to provide cost-effective and efficient voice and data services. We analyzed such multiservice network architectures and designed backbone wide area networks (WANs) based on ATM and Internet protocols to handle the varying demands of both voice-only and multiservice traffic. This paper describes our design methodology, our network architecture considerations, and our results obtained from several specific network studies that drive equipment and facility capacity requirements.

Digital loop carrier solutions for voice and data networks

Lucent Technologies' SLC®-2000 digital loop carrier (DLC) system has traditionally been used to provide telephony services ranging from “plain old telephone service” (POTS) to digital data systems (DDS) to integrated services digital network (ISDN) over T1 and SONET digital facilities. This paper describes how the SLC-2000 Access System has been evolved recently to support clear channels for lines that traditionally use bit robbing to carry in-band signaling information. This enhancement restores modem performance that has degraded due to robbed bit signaling (RBS) and provides subscribers with improved data services. The paper also discusses enhancements to the SLC-2000 system to provide subscriber access not only to the circuit-switched telephony network but also to the packet-switched data networks for integrated voice and data services.

Using data on digital cellular and PCS voice networks

Many new digital cellular and personal communications services (PCS) networks that provide both voice and data communication capabilities are being installed in the United States and around the world. Current cellular and PCS handsets primarily target voice telephony, but the next generation will also support data services. In this paper we review the current offerings in wireless handsets that support both voice and data services and also present our design for a next-generation wireless handset. We discuss the tradeoffs in selecting an operating system and input device, and in designing a user interface. The physical design of our user interface and the wired network infrastructure support applications such as telephone directory, electronic mail, and Web browsing. The result is a small, user-friendly handset featuring handwriting recognition, foldable video graphics adapter (VGA)-sized liquid crystal display (LCD) screens, and the Inferno™ operating system.

Managing optical networks

The surge in demand for access technologies such as cable modems, xDSL, and wireless data suggests that information will be the most valuable commodity in this new millennium. Eventually, data will constitute 99% of the content sent over telecommunications networks. The demand for information will require carriers to apply new methods and technologies to migrate their existing voice networks to data networks. An intelligent optical core using wavelength division multiplexing (WDM) will meet a carrier's needs for scale, provisioning, and restoration and will increase overall efficiency. The overall efficiency of tomorrow's network will be a reflection of today's optical transport protocol. Currently, Lucent Technologies' WaveStar™ LambdaRouter and its optical network navigator system (ONNS) enable a distributed network-wide control plane that specifically addresses the current core network requirements for wavelength provisioning and restoration. The ONNS is based on and adopts mature Internet protocol (IP)-centric protocols, and it provides effective traffic restoration and traffic engineering capabilities in the optical network to satisfy a customer's optical layer needs. Furthermore, it is designed to facilitate control plane integration with data networks and to have the flexibility to accommodate future network-related needs as they arise. Therefore, Lucent's LambdaRouter (with its distributed control plane) is the appropriate solution for controlling optical data networks today and in the future.

DEFINITY® enterprise communications server ATM integration

The distributed switching architecture of the DEFINITY® Enterprise Communications Server (ECS) enables straightforward, cost-effective integration of both local and wide area ATM transmission and switching infrastructures. ATM integration can be provisioned in new systems and retrofitted in the substantial installed base of DEFINITY ECS systems as needed to enhance customer value. The DEFINITY ECS ATM interface is a new DEFINITY ECS platform component designed to comply with established (and emerging) standards of the ITU and the ATM Forum. Its adherence to standards allows it to interwork with a wide range of data and ATM infrastructures, and its software-based flexibility permits continuing compliance as ATM standards evolve. Integrating DEFINITY ECS and ATM enables a natural migration from today's separate data and voice networking environments to enhanced comprehensive networking environments with higher customer value. This network convergence places DEFINITY ECS customers at the leading edge of communications technology.

Simulation of the Harmful Consequences of Self-Similar Network Traffic

For a long time, the area of network traffic research has lacked adequate traffic measurements. During the past years, large amounts of network traffic measurements have become available, collected in the Web and high-speed networks. Measurements of real traffic indicate that burstiness is present on a wide range of time scales and show evidence of self-similarity and long-range dependency. Many traditional models originating in conventional voice networks either assumed that the underlying time series are short-range dependent or do not focus on the various, interrelated network components affected by bursty traffic. In order to provide explanations for empirically observed phenomena, such as burstiness in terms of physical network parameters, we need to develop models that can allow for the details of the complex architecture of today's networks and can analyze the interrelated network parameters that ultimately determine the performance and operation of a network. In the paper, we investigate the harmful consequences of burstiness on various network components using a model implemented by a discrete event simulation methodology. The methodology based on a modified version of the M/Pareto model can measure network performance parameters, such as the momentary utilization of links, response time, and the queuing performance of interconnected switches and routers along the traffic paths. Our paper intends to narrow the gap between existing, well-known theoretical results and their applicability in everyday, practical network analysis and modeling. Our methodology can help network designers and engineers, the ultimate users of traffic modeling, understand the dynamic nature of network traffic and assist them to design, monitor, and control complex, high-speed networks in everyday practice.

Transport of mobile application part signaling over internet protocol

The convergence of voice, data, and video networks is creating a new environment for telecommunications. In response to the changes, telecommunications equipment manufacturers and service providers are competing fiercely to bring an optimum solution to customers. The evolution of GSM to GPRS and to UMTS is a cellular wireless industry endeavour to meet this demand. This evolution will see the core wireless network infrastructure change from circuit-switched to packet-switched where voice and data are transported using IP as the common protocol. However, this poses a number of challenges, one of which is how to run the key mobile application part signaling protocols over IP. MAP defines the application protocols between switches and databases (e.g., MSC, VLR, SGSN, HLR) for supporting mobility management, security management, radio resource management, and mobile equipment management. UMTS supports both circuit-switched and packet-switched services.

Too Much Fiber?

Although long-distance networks have unused capacity, many analysts say that does not add up to bandwidth glut. Internet and voice network traffic is expected to double every year for the rest of the decade, and the unused capacity will allow plenty of room for networks to grow without the installation of new fiber.