[EFM] Re: [EFM-Copper] [Fwd: Existing Loop Lengths]
It looks like the Splitterless DSL paper refers to 0.5mm wires (are popular in
Europe). By this paper 12kft loops cover about 70% of US subscribers, seems
close to Telecordia report.
Vladimir.
"Stanley, Patrick" wrote:
> Troy,
>
> While the data you attached is a marketing document, the U.S. distribution
> curve appears to align well with the Telcordia loop survey (reference
> below).
>
> Furthermore, during our reach debate at the LA meeting, I incorrectly quoted
> Telcordia's loop length/coverage statistics. I stated that 12kft reach
> covers 85% of the loops in North America. Upon further review, I noted that
> the Telcordia Loop survey (which can be viewed at
> http://www.ieee802.org/3/efm/public/may01/stanley_1_0501.pdf ,slide 6) is
> normalized to 26AWG wire. Therefore, a reach of 12kft of 24AWG wire
> (approximately 9kft of 26AWG wire), would only cover about 70% of the
> market.
>
> This survey only shows working length, which does not include bridged tap
> lengths. Because 78% of loops contain bridged taps, and 70% of bridged taps
> are <1000ft in length, which impact xDSL performance, a given performance on
> 12kft of 24AWG, without bridged taps, will actually cover a much smaller
> portion of the market.
>
> Comparing echo cancelled ADSL performance on 8kft of 26AWG wire, to
> performance on CSA Loop #1, which contains 7.7kft of 26AWG wire, and a 600ft
> bridged tap, you see the downstream bandwidth drop from 8.6Mbps (with 10
> self Disturbers) to 1.6Mbps (with 10 self disturbers). To get the same level
> of performance, with no bridged taps, the loop length would have to be
> extended to 14kft of 26AWG wire. Thus, for a given rate, the reach with a
> bridged tap is only 60% of the reach without one, for this case. If this
> same ratio held, then achieving 9kft (26AWG) reach w/o bridged taps could
> give 5.5kft reach with, which would only cover about 45% of the market.
>
> Thus, to reliably reach real-world working lengths of 12kft of 24AWG wire,
> one would have to design for a reach of 20kft, 24AWG, without bridged taps.
>
> Regards,
> Patrick
>
> -----Original Message-----
> From: Troy Manary [mailto:troy@xxxxxxxxxxx]
> Sent: Thursday, October 25, 2001 2:30 PM
> To: Copper
> Subject: [EFM-Copper] [Fwd: Existing Loop Lengths]
>
> I posted this to P2P but it is probably as useful, if not more so, to
> copper heads too.