<..Can you elaborate on why you think ADSL will not be reliable?..>
From a LOT of reading and lengthy talks and emails with many industry insiders over the years, my opinion is that though it will clearly have some success in stretching out the life of the aging copper plant, ADSL will be a telco Vietnam, far worse than ISDN was.
First, rough estimates are that 40% of the existing copper plant won't support any form of ADSL. The "bitch" is that the telcos don't know WHICH 40% will NOT support it. They can't even regional this. It might work OK for me, but it may not work for either of my next door neighbors. The distance issue is just one of the barriers.
xDSL killing load coils (placed to make the phone lines "cleaner" by "removing" copper's high frequency carrying capacity) have been installed across the country. And records have rarely been kept documenting which lines have load coils, and WHERE they are (often buried). Use of TDRs can help identify their location, but this is costly, and still requires a significant amount of time (read $$$) for removal. And if removed, the high frequency "hum" is back on the voice line.
Bridge taps are also very common, and while not necessarily xDSL "killers", they DO decrement the copper's carrying capacity - in other words, RADSL will rate adapt down - perhaps significantly effecting bit rates.
In addition, xDSL will NOT work in any bundle that carries HDSL (currently a very common T1 solution), nor in any bundle which terminates in the million plus current DLCs (digital loop carriers).
And then there is the issue of the degrading copper plant, the exact condition of which is uncertain. Even loop qualifications aren't necessarily predictive, as high freq signals have a way of infiltrating and being infiltrated (crosstalk) by RF and themselves.
So even IF an enterprise gets xDSL, it may not work consistently, not work to spec (at the bit rate contracted for), and is NOT something that most telco field technicians can in ANY way easily trouble shoot.
In addition, training telco CO technicians to handle the new and challenging problems associated with maintaining racks of high power and expensive (by telco standards) modems in the tight, already warm CO space will be formidable, with the customer the underwriter of costly learning curves.
Further, business applications like voice muxing and two way video are not possible with ADSL. Plus even the asymetrical bit rates are largely insufficient for the anticipated future application demands.
As the obvious attractive alternative, the buildout of broadband digital backbones underscores the need for fast, reliable and inexpensive digital broadband local loop solutions. Broadband fixed wireless such as Winstar, provides fiber quality BER, OC3 bit rates (155Mbps, using P-MP technology) to enterprise customers. |
