Perry,
Re: ADSL and xDSL, some clarifications are required here.
Educator,
That was an interesting find, but unless New Zealand plays
by a different set of rules, and they have their own lexicon on
the topic (which they don't), then the article you cited was more
fiction than substance. The "x" in xDSL connotes a broad
range of Digital Subscriber Line (DSL) family members, and
it is used as an expedient to cover the entire group, not as a
discrete technology. ADSL is a member of this family. As is
HDSL, VDSL, SDSL, etc.
From the ADSL home page at: adsl.com ,
What is xDSL?
XDSL is the name which as been coined for the
family of digital subscriber line technologies ranging
from HDSL through to VDSL (see accompanying Glossary)
with ADSL firmly in the middle of the speed/capacity
band.
It may be useful to bookmark this site.
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Greg,
>There are so many variants of DSL that I use xDSL.<
Congrats. You were more correct in the use of the 'x'
signifier than you realized.
Regarding your other observations,
>>Distance limitation are real and will not be solved, unless
they move to a distributive like network, where CO like
functions are moved closer the users. I have yet to hear
anything like what I just described above being discussed by
the REBOCS, or, for that matter anyone else.<<
As an FYI, such architectures actually do exist. Although
they are not being deployed at this time with any regularity.
Certainly not on a par with HFC or even regular CO-based
xDSL.
Provisions exist in the Bellcore GR-303 [which outlines the
~ Next Generation Digital Loop Standards] list of specs for
digital subscriber services, whereby concentrators are
located deep into the field in pedestals and other field
enclosures (when normal DSL distance limits are exceeded)
to support a wide range of subscriber services, including
DSLs.
One variant of this is the switched digital video (SDV)
platform which employs VDSL at 52 Mbps to the residence
to support 6.3 Mbps MPEG video and very fast Internet
access, along with POTS voice and ISDN services. ALA,
GIC/Next Level, and others have such platforms for sale,
with several of them already deployed.
The end game for this model is to deliver what its architects
consider a full service area network, or FSAN. FSAN uses
a variety of DSLs and passive optical network (PON) techniques
to deliver all of the above. For more reading on FSAN, visit
Telephony Magazine's article on this subject at:
internettelephony.com
Do a search at that site for FSAN.
Frank_C.
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