Broadband Data Services Research Articles

RF microelectronics for W-CDMA mobile communication systems

Third generation (3G) mobile communication systems are now just starting to be introduced. With a maximum data rate of 2 Mbit/s they will make wireless access to broadband data services like the Internet or video applications feasible. Most of the different physical layer technologies summarised under the acronym 3G are based on wideband-CDMA (W-CDMA), in contrast to existing second generation systems, which mostly use TDMA and FDMA. This has severe consequences for the design of the transceiver front-ends. During standardisation these were assumed to have an adequate RF performance yet they still present a performance bottleneck for the system. Starting with a short introduction to UMTS (Universal Mobile Telecommunications System)-the 3G standard to be deployed in Europe and already operating in Japan-this paper describes by way of example some of the test cases specified for UMTS and their impact on the analogue front-end. It is shown that accurate simulation of all the analogue and digital signal processing is necessary in order to predict the RF performance needed of today's commercial RFICs. The paper then presents and reviews some actual design examples. Finally, possible technologies and techniques for application in future mobile terminals are discussed.

UK Core Transmission Network for the New Millennium

The capacity of the BT/UK core transport network is being increased by more than 100% per year to support the growing demands from IP/ATM broadband data services and the traditional private services platform. At the same time, unit costs are reducing significantly by the introduction of new SDH/WDM technology within both long-haul and city networks. These changes are described, together with the associated developments in network management, which will enable fast bandwidth provisioning and improved network resilience.

(FTTH) system providing broad-band data over cable modems along with analog and digital video

We demonstrate that by applying cable modem technology in a 1550-nm EDFA-based fiber-to-the-home (FTTH) system we can deliver broad-band data services along with analog and digital broadcast video. The data system shares 30-Mb/s downstream and 2.56-Mb/s upstream over 64 living units, while the broadcast video system provides 77 analog channels and /spl sim/1 Gb/s of digital video.

TCP for high performance in hybrid fiber coaxial broad-band access networks

Motivated by the phenomenal growth of the Internet in recent years, a number of cable operators are in the process of upgrading their cable networks to offer data services to residential subscribers, providing them direct access to a variety of community content as well as to the Internet. Using cable modems that implement sophisticated modulation-demodulation circuitry, these services promise to offer a several hundredfold increase in access speeds to the home compared to conventional telephone modems. Initial experiences indicate that cable networks are susceptible to a variety of radio-frequency (RF) impairments that can result in significant packet loss during data communication. In the face of such losses, the transmission control protocol (TCP) that is predominantly used by data applications degrades dramatically in performance. Consequently, subscribers of broad-band data services may not perceive the projected hundredfold increase in performance. We analyze the performance of TCP under different network conditions using simulations and propose simple modifications that can offer up to threefold increase in performance in access networks that are prone to losses. These modifications require only minor changes to TCP implementations at the local network servers alone (and not at subscribers' PCs).

Advanced Wireless Access System

The key words for the future telecommunications are personalization, multi-media services and high accessibility to the network. These trends naturally lead to radio media application to access links. In this sense, this paper proposes an advanced wireless access system with a capacity supporting broadband video and data services. Concept of the system can be defined as a new radiocommunication category with advantages of both fixed and mobile systems. The system is designed to transport ATM-based signals using SHF (or EHF) bands to wireless terminals, interconnected with optical fibers at the network side. The basic system configuration is presented as well as examples of system parameters. For radio aspects the maximum service coverages of the radio base stations are calculated based on availability consideration. Preferred frequency bands for actual operation are also discussed.

Architectures for broadband residential IP services over CATV networks

The current state of the art in digital broadband access technologies to support emerging telecommunications services makes imminent the introduction of interactive broadband services-including data, video and the Internet-into the residential market. Over the last few years, much attention has been paid to the development of media access control protocols for cable TV networks that will allow the immediate support of broadband data services as the first step toward enhanced communications services for residential users. We review some of the architectural options that must be carefully considered in order to deliver Internet protocol (IP) services to such users in an efficient yet flexible manner. Future residential cable data services are expected to deliver Internet access, work-at-home applications, small business access, local area network LAN-LAN interconnect, and LAN emulation services over cable (CATV) networks.

Broadband to the home (BTTH): architectures, access methods, and the appetite for it

The demand for high-volume data transfer to the home for interactive multipurpose residential multimedia applications (such as tele-education, interactive on-demand entertainment, home shopping, browsing the World Wide Web to retrieve up-to-date information) and telecollaboration, including telecommuting to work, are continuously increasing. Technological advances and the 1996 Telecommunications (Deregulation) Act allow both telephone and television service providers to compete in each other's territory for providing broadband services to the home (BTTH). BTTH refers to broadband data services which may or may not use a high bandwidth link. It essentially gives the end user an impression or feeling that megabit-rate data transmission is occurring to/from the terminal, so the benefits of broadband services are enjoyed at the most convenient time within the comforts of home. It can be achieved for example, by using twisted pair copper wire telephone line using various types of digital subscriber line (xDSL) modems installed at both ends of the line. Issues and challenges of BTTH are discussed, in addition to describing future position(s) of the traditional service providers.

Economics of residential broadband access network technologies and strategies

This article presents a techno-economic assessment of the evolution of the access network segment toward broadband data service delivery, including in-depth sensitivity analysis of key issues faced by the infrastructure providers. The line costs and payback periods of different access network technologies for infrastructure broadband upgrades are examined, subject to variation in parameters like the existing infrastructure, the broadband take rate, civil work costs, revenues, and rollout year. The work should enable establishment of guidelines for broadband infrastructure upgrade strategies.

Cable access beyond the hype: on residential broadband data services over HFC networks

Current efforts in digital data transmission over hybrid fiber coaxial (HFC) networks will provide an efficient data transport mechanism for the "last mile" to residential users and will enable a very large number of services to the home. Provision of these services requires a complete end-to-end network architecture that provides an efficient connection between the server and the end user. Thus, it is necessary for the currently isolated HFC islands to gradually evolve into an efficient, highly connected, high-speed network. In this article, the authors review HFC networks and establish that they provide a more attractive and promising solution than the alternatives for "last mile" connectivity to the home, such as telephone connections. A list of broadband services are listed that are enabled by the high-speed data capabilities of HFC networks, and the necessary end-to-end infrastructure to support these applications is described, as well as possible evolution and migration paths for developing these end-to-end network architectures.

Forecasting broadband demand between geographic areas

The authors employ a two-step solution: first, produce an aggregate forecast for each data service for each geographical area; then, these aggregate forecasts are broken down into forecasts of demand for broadband data services within and between the geographical areas.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Data communication in ATM networks

An increasing number of customers require LAN access with high bandwidth and low delay over long distances. To satisfy these needs, several high-speed network techniques have been developed. Asynchronous transfer mode (ATM) is superior compared to other networking technologies, as it offers high bandwidth and is scalable in the sense that the bandwidth capacity of an ATM system is not fundamentally limited to the technology itself. Initial ATM installations will operate as subnetworks of existing networks and MAC layer protocols. One of the main challenges in ATM is the transparent support of existing connectionless LAN services. Several activities have been launched within international standard bodies and forums to specify ways of providing data communication services over ATM. Most notable examples are Switched Multimegabit Data Service (SMDS) and the similar Connectionless Broadband Data Service (CBDS) supported mostly by public network service providers. But also other approaches such as IP over ATM, and LAN emulation that show more adherence to the existing local and campus area networking paradigms. The article presents the requirements and architecture of the LAN emulation service. It describes the alternative methods for carrying IP packets over ATM, a public broadband service architecture and CBDS. The traffic management aspects of the data communication services are also discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Frame relay: a solution for high bandwidth networking

Before public broadband data services based on the Asynchronous Transfer Mode become available, the frame relay network is expected to be introduced in private/public networks. This tutorial first describes the technology and future importance of frame relay networks in providing high speed data services. Then it reviews the general frame relay protocol structures. The paper also emphasizes the two important aspects of frame relay: congestion management and interoperability.

Broadband applications and services of public switched networks

The results of work done at AT&T Bell Lab. on broadband data and video applications that may be used over a public switched network like that of a telephone company are summarized. Data and video applications and network services associated with these applications are discussed. While data applications are initially seen as being provided to business, video applications are expected to be aimed at residential users. These applications are presented in separate sections. The author describes example applications for broadband data services that could be offered to business within the next five years, namely: distributed computing; data distribution; electronic mail; and data retrieval. The following video applications are also described: video telephony; video teleconferencing; two-way enhanced video services; one way video/image distribution; video/image database retrieval; and video electronic mail.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>