Overview
In the past, video, audio, voice, and data services required at
least four separate networks. Video was distributed on coaxial lines,
audio over balanced lines, voice used copper cable pairs, and data
services required coaxial or twisted pair cables. This multiple
network environment was expensive to install and difficult to maintain.
ISDN is different. It integrates voice, video, and data over the
same network and cable plant with quality not available in previous
switched services. It offers features such as on demand networking,
automatic bandwidth availability and on the fly connectivity. These
advanced services are available, in large part, because ISDN is
digital.
The Integrated Services Digital Network (ISDN) is becoming a mainstream
telecommunications network that will serve a wide variety of users'
needs. Experts call ISDN the telecommunications network of the 21st
century, the foundation upon which to further build the information
age. With its narrowband and broadband aspects, the ISDN data highway
will evolve from today's switched telephone and dedicated leased-line
networks to become a unified global network carrying voice, data,
video, interactive pictures, and other services to homes and businesses.
Once touted as the ultimate subscriber technology, ISDN has seen
slow deployment until recently, due to lack of standardization and
high cost. Most Regional Bell Operating Companies (RBOCs) deliver
ISDN as a dial-up, metered service. This means that during business
hours users are charged for each minute the ISDN connection is operating.
ISDN has also lost appeal as analog modems have reached the 56
Kbps level. Modem suppliers now provide software that lets users
use two 56K modems as a single 112 Kbps connection, close to the
data rate available from an ISDN connection.
At the other end of the spectrum, DSL and cable modem services
are delivering bandwidths that are an order of magnitude greater
than ISDN. While ISDN will not be disappearing any time soon, all
projections indicate that growth in the ISDN market is flattening.
It is expected that ISDN will be relegated to applications where
cable modem or DSL service is not available.
Market Research
Analysts indicate there are approximately 2 million ISDN lines
deployed in the U.S., representing about 1.1% of all lines. International
Data Corporation predicts the worldwide installed base of DSL modems
from the total Internet connectivity methods to be growing from
14.9% in 2000 to 20.4% in 2002, with a worldwide installed base
growing from 14.87 million to 28.61 million units.
Xilinx Solutions
Xilinx provides significant value in an ISDN modem when used to
interface various ASSPs together, resolving differences in their
interface control signals. The in-system programming capability
of Xilinx devices enables features to be upgraded while the product
is in the field, as well as decreasing the time-to-market for the
product. The Spartan™-II FPGA or XC9500XL CPLD devices are ideal
candidates for this low-cost application.
As ISDN modems evolve into residential gateways, they will support
multiple home networking interfaces. Spartan-II FPGAs provide system
integration and interconnectivity to these interfaces, hence provide
decreased time-to-market, increased time-in-market, and the rapid
product proliferation in this market. Please view the presentation
to see how Xilinx solutions can help you build products for this
fast evolving market place.
Analog
/ Dial-up
Cable
xDSL
ISDN
Satellite
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