Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
xdsl and ireland ?
-
15-11-2000 5:11amJust thought you might like to take bets on which 1 we will get here in ireland ?hehehe[3.2]What are the various types of xDSL?
There are several forms of xDSL, each designed around specific goals and
needs of the marketplace. Some forms of xDSL are proprietary, some are
simply theoretical models and some are widely used standards. They may
best be categorized within the modulation methods used to encode data.
Below is a brief summary of some of the known types of xDSL technologies.
ADSL
Asymmetric Digital Subscriber Line (ADSL) is the most popular form of
xDSL technology. The key to ADSL is that the upstream and downstream
bandwidth is asymmetric, or uneven. In practice, the bandwidth from
the provider to the user (downstream) will be the higher speed path.
This is in part due to the limitation of the telephone cabling system
and the desire to accommodate the typical Internet usage pattern where
the majority of data is being sent to the user (programs, graphics,
sounds and video) with minimal upload capacity required (keystrokes and
mouse clicks). Downstream speeds typically range from 1.5Mbps to 9Mbps.
Upstream speeds typically range from 64Kbps to 1.5Mbps.
ADSL Lite
A lower data rate version of Asymmetric Digital Subscriber Line (ADSL)
has also been proposed as an extension to ANSI standard T1.413 by the
UAWG (Universal ADSL Working Group) led by Microsoft, Intel, and Compaq.
This is known as G.lite in the ITU standards committee. It uses the
same modulation scheme as ADSL (DMT), but eliminates the POTS splitter
at the customer premises. As a result, the ADSL signal is carried over
all of the house wiring which results in lower available bandwidth due
to greater noise impairments.
CDSL
Consumer Digital Subscriber Line (CDSL) is a proprietary technology
trademarked by Rockwell International.
EtherLoop
EtherLoop is currently a proprietary technology from Nortel, short for
Ethernet Local Loop. EtherLoop uses the advanced signal modulation
techniques of DSL and combines them with the half-duplex "burst" packet
nature of Ethernet. EtherLoop modems will only generate hi-frequency
signals when there is something to send. The rest of the time, they will
use only a low-frequency (ISDN-speed) management signal. EtherLoop can
measure the ambient noise between packets. This will allow the ability
to avoid interference on a packet-by-packet basis by shifting frequencies
as necessary. Since EtherLoop will be half-duplex, it is capable of
generating the same bandwidth rate in either the upstream or downstream
direction, but not simultaneously. Nortel is initially planning for
speeds ranging between 1.5Mbps and 10Mbps depending on line quality and
distance limitations.
G.Lite (see ADSL Lite)
HDSL
High Bit-rate Digital Subscriber Line (HDSL) is generally used as a
substitute for T1/E1. HDSL is becoming popular as a way to provide
full-duplex symmetric data communication at rates up to 1.544 Mbps
(2.048 Mbps in Europe) over moderate distances via conventional telephone
twisted-pair wires. Traditional T1 (E1 in Europe) requires repeaters
every 6000 ft. to boost the signal strength. HDSL has a longer range
than T1/E1 without the use of repeaters to allow transmission over
distances up to 12,000 feet. It uses pulse amplitude modulation (PAM)
on a 4-wire loop.
IDSL
ISDN based DSL developed originally by Ascend Communications. IDSL
uses 2B1Q line coding and typically supports data transfer rates of 128
Kbps.
RADSL
Rate Adaptive Digital Subscriber Line (RADSL) is any rate adaptive xDSL
modem, but may specifically refer to a proprietary modulation standard
designed by Globespan Semiconductor. It uses carrierless amplitude and
phase modulation (CAP). T1.413 standard DMT modems are also technically
RADSL, but generally not referred to as such. The uplink rate depends
on the downlink rate, which is a function of line conditions and signal
to noise ratio (SNR).
SDSL
Symmetric Digital Subscriber Line (SDSL) is a 2-wire implementation of
HDSL. Supports T1/E1 on a single pair to a distance of 11,000 ft. The
name has become more generic over time to refer to symmetric service at
a variety of rates over a single loop.
VDSL
Very High Bit-rate Digital Subscriber Line (VDSL) is proposed for
shorter local loops, perhaps up to 3000 ft. Data rates exceed 10 Mbps.
If the rumor is true that genesis is going to use vdsl then us country bumpkins are going to be shagged grrr
[HIV]Stonemason
0
Advertisement