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Introduction

As the popularity of the Internet grows, more businesses and telecommuters are looking to Internet service providers (ISPs) for increased bandwidth at less expensive rates. Businesses are increasing their use of the Internet for all types of communications, from e-mail and file transfers to Web service and electronic commerce. Yet these applications are hampered by access technologies.

For the past several years, ISDN technology has delivered a partial solution to the Internet access problem. ISDN circuits link businesses, branch offices, home offices, and telecommuters to the Internet over a 64 or 128 Kbps line. However, ISDN service is difficult to set up and still not widely available. And given the bandwidth-hungry nature of multimedia and the World Wide Web (WWW), ISDN cannot deliver acceptable performance.

Fortunately, high-bit-rate digital subscriber line (HDSL) technology offers an attractive alternative. HDSL equipment sends data digitally over ordinary phone lines at speeds many times faster than ISDN or voice-band modems. Its robust transmission scheme enables data to be sent over a single twisted-pair copper wire at speeds up to 768 Kbps in both directions. With a throughput rate six times higher than that of ISDN, this mature, stable technology is ideal for high-bandwidth applications.

Using HDSL, ISPs can offer their existing and prospective customers fast and economical Internet access that meets the needs of bandwidth-intensive applications. This helps ISPs to differentiate themselves from other providers, including the giant Inter-Exchange Carriers (IXCs) and Local Exchange Carriers (LECs). And most significantly, ISPs can deliver this higher-speed access at a cost equivalent to ISDN.

High-speed Internet Access Fuels HDSL Demand

According to International Data Corporation, the number of people using the Internet is expected to quintuple in just five years, from approximately 40 million in 1995 to nearly 200 million by the year 1999. The number of WWW users is expected to increase by 15 times during the same period. (Source: PC World, October 1996.)

Telephone companies and other service providers around the world will spend nearly $5.3 billion in 1998 to install new Internet equipment designed to handle burgeoning Internet use by businesses, according to Infonetics Research, a San Jose, Calif.-based research firm. (See figure below. Source: CommunicationsWeek, October 28, 1996.)

Given the unprecedented boom in Internet use and frustrations with slow access in the local loop, high-speed remote access to the Internet is one of the most promising applications for HDSL. Though larger companies use T1 or T3 lines to connect to Internet Service Providers (ISPs) or directly to the Internet backbone, branch office connections and remote users typically use voice-band or ISDN modems to gain access over the public switched telephone network.

Remote users thus are dismayed to notice a discouraging difference when logging onto corporate networks or the Internet from home versus the office. File transfers and graphics-rich Web searches are slowed to a crawl. Today's fastest analog modems can transmit data at speeds of only 56.6 kbps, far below the throughput rates taken for granted at the corporate office. Even bonded 128 kbps ISDN is not up to the demands of applications such as real-time multimedia and videoconferencing. (At 128 kbps, ISDN provides barely one percent of Ethernet’s 10 Mbps rate.)

On the other hand, HDSL devices can connect remote users to the Internet at speeds up to 768 kbps. HDSL connections bring real-time motion to video, clarity to audio, and quickness to large file transfers. And because HDSL creates a permanent connection, it enables ISPs to offer value-added, continuous customized services like stock quotes, newscasts, software revisions, and weather reports.

Data Privacy Ensured

Data privacy is another key advantage HDSL. Because HDSL transmissions use existing phone lines, there is a unique, point-to-point connection between each user and the network. As a result, one user cannot see another user’s data, either accidentally or intentionally. This secure dedicated line also ensures that the quality of service for HDSL-based access networks is constant for each user and will not degrade based on the number of active users or the amount of traffic on the access network.

Low Financial Investment

HDSL modems are attractively priced when compared to other DSL solutions. HDSL is far less complex, more integrated, and less power-hungry than other DSL technologies. Said Kieran Taylor, a broadband consultant for TeleChoice, "In its current incarnation, HDSL is much less expensive than ADSL, and it holds tremendous promise to fulfill high-bandwidth demand for the near term." He expects HDSL to dominate the market through 1999.

Summary

Regardless of which business applications HDSL is used for, network managers and subscribers alike will appreciate the reassurance of using a reliable telephone network that has been in continuous use for more than 70 years. Telephony providers have an existing, comprehensive infrastructure to address customer support, billing, and installation.

ADC Telecommunications Solutions

ADC Telecommunications' multi-phased DSL/ATM initiative supports end-to-end equipment solutions for high-capacity business networks—from the central office to the subscriber premises.

The Cellworx^™ product family addresses HDSL/ATM Internet access for both the business subscriber and the service provider. Products include the SAT-300^™ HDSL Access Router, the RAC Remote Access Concentrator, and the AAC-3^™ Multi-service Access Concentrator.

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