Transcript DSL Technology

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Digital Subscriber Line (DSL) is a technology
that provides digital data transmission over the
existing wires of local telephone network.
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DSL (Eng. Digital Subscriber Loop) - a digital
subscriber loop, the family of broadband
access to the Internet technology
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DSL service is delivered simultaneously with
regular telephone on the same telephone line.
This is possible because DSL uses a higher
frequency.
It assumes that digital data does not require changing
into analog form and back to digital form.
Digital data is transmitted directly to the computer, as
is, exploiting the maximum bandwidth and the wide
range of unused frequencies available in the existing
copper wire of telephone networks for high-speed
broadband communication.
Moreover, the signal can also be separated, if one
chooses, so that some of the bandwidth is used to
transmit an analog signal for simultaneously using the
telephone line for voice.
Over the Wire: You are connected
to another ADSL modem which also
has a POTS splitter, which separates
voice calls from data.
Telephone Calls: Voice calls are
routed to the phone company's public
switched telephone network (PSTN)
and proceed on their way as usual.
Internet Requests: DSL Access
Multiplexer links many ADSL lines to a
single high-speed asynchronous transfer
mode (ATM) line, which in turn connects
to the Internet.
Back at You: The requested data is
retrieved from the Internet and routed
back to you.
DSL is actually not a
physical line, but a
modem pair. One DSL
modem is located at the
customer premises
(Customer Premise
Equipment or CPE) and
another DSL Access
Multiplexer (DSLAM) is at
the Central Office (CO).
These two modems create a Digital Subscriber Line or
DSL. DSL modems transmit data at the rate of up to
160 Kbps over copper lines, up to 18000 feet.
DSL Modem or DSL Transceiver, as it is also referred to
as, is connected to the customer’s computer via USB
or a 10-Base T connection.
DSLAM at the Central Office or the Access Provider is
the one that actually makes the DSL happen . It
accepts connections from various customers and
aggregates them into a single high capacity
connection to the Internet. In addition, the DSLAM also
does IP routing and Dynamic IP address assignment.
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ADSL(Asymmetric Digital Subscriber Line)
Most home and small business users typically use ADSL.
The transfer of data from the internet to PC is much faster
than the transfer from PC to internet.
Downstream speeds for ADSL range from 1.59 Mbps, while
upstream speeds are up to 1.5 Mbps, for a distance of
18,000 feet from the service providers premises.
SDSL(Symmetric Digital Subscriber Line )
Does not allows to use the phone at the same time. But
internet speed of sending and receiving data is same.
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HDSL(High bit/data rate Digital Subscriber Line)
HDSL was the first DSL technology that used a
higher frequency spectrum of copper,
twisted pair cables.
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ISDN DSL(Integrated Service Digital Network)
Symmetric data rates of up to 144 kbps using
existing phone lines.
Capable of using the same modem or
terminal adaptor used for ISDN and is always
available.
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RADSL(Rate Adaptive Digital Subscriber Line)
RADSL it is automatically adapts the speed
depending on the quality of the signal. Modern ADSL
technologies are usually RADSL technologies.
The Adaptive version of the asymmetrical access,
called RADSL (Rate Adaptive DSL), allows for
automatic adjustment of co-operating modems to
the capacity available in the transmission route at
the given moment. It is the most effective form of
transmission via existing information channels with
dynamically changing capacity, even during usage
of a given telecommunication service.
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VDSL(Very high-bit-rate Digital Subscriber Line)
VDSL technology can be recognized as
development of ADSL standard and, at the
same time, compatible with services based on
SDH or ATM technologies.
It Provides high speed internet connection but
works only over a short distance.
VDSL permits transmission in both asymmetrical
and symmetrical mode, guaranteeing
throughput up to 56 Mbit/s in the asymmetrical
mode and 26 Mbit/s in each direction in the
symmetrical mode.
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DSL service is always ON and we can still use
the phone for voice calls.
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Broadband speed is much faster than dial up
service.
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Fixed monthly billing, regardless of time usage.
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Digital data is directly transmitted to computer
as digital data which uses much wider
bandwidth for transmitting
DSL has one significant downside:
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As you move away from the central
office , the connection becomes slower.
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This results is distortion of signal.
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It is highly likely that xDSL will become
widely adopted particularly among
high-speed Internet "power users" as
well business requiring fast access to
various networks, provided naturally
that the prices come down.
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xDSL technology offers a viable interim
solution to the bandwidth problem
while fiber optic cables are being
installed.