RE: [EFM] EFM Requirements
Dear Ramu,
The only way to calculate what can be carried over a copper pair is with capacity calculations. These take in to account the mutual affects between pairs and the limitation on the transmitted power density. A additional method is to look at the rates provided by existing systems that are standardized for the public network. These systems (SHDSL, ADSL, VDSL) provide an aggregate rate (up and down) that is indicative of what can be acheived at the different ranges.
The public network standard bodies have performed calculations for 1/2 a mile during the VDSL standardization. These calculations assumed 20 additional systems in the binder, a limit of -60 dBm/Hz on the PSD and of course, legacy systems in the cable plant. At 1/2 a mile, with AWG26 cables and all 20 systems providing service, a system can provide a symmetric rate of about 13-15 Mbps.
For 12 Kfeet, I suggest you look at ISDN, ADSL and SHDSL for a feeling of what you will get. From a capacity calculation point of view, with a PSD level of -40 dBm/Hz, you can provide less than 1Mbps in either direction.
The FSAN, a group of operators, has a capacity calculation tool on their website. This tool is open for anyone to calculate what can be provided over the public copper plant. It provides realistic values and is an independant tool. It is at: http://www.fsanet.net/index.html
Best regards,
Steven
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-----Original Message-----
From: ramu [mailto:ramu_raskan@xxxxxxxxxxxxx]
Sent: Monday, August 20, 2001 12:21 AM
To: stds-802-3-efm@ieee.org
Subject: Re: [EFM] EFM Requirements
Rich, you may not be _advocating_ new copper drops (hopefully no one is!), but the scenario you describe would require it. The vast majority of in-place copper simply does not drop into the scenario you describe.
But, for the sake of argument, let's say new copper was laid so that everyone was within a half mile. What kind of sustained, symmetric bandwidth are you suggesting you can provide at 1/2 mile distances over 26AWG pairs, and what happens if this ever needs to be increased? Anyone else who has a copper solution that would like to answer is welcome to also. For comparison purposes, what sustained, symmetric bandwidth you could provide at 12,000 feet would be useful to hear also, since 12000 feet seems to be a number that is of interest to many here. Please provide any other assumptions made to arrive at the bandwidth numbers. Patrick Stanley from Elastic, can you provide you numbers for this scenario please?
Thank You.
--
On Sun, 19 Aug 2001 12:59:38
Rich Taborek wrote:
>
>Ramu,
>
>It seems we have a major misunderstanding. I'm not advocating any new
>copper drops. I believe that Vladimir's note, which I responded to, was
>not advocating new copper drops for the first/last 0.5 mile as well.
>This is what Vladimir referred to as the "copper tail". The copper tail
>connects to the residence/business on one end and fiber on the other.
>
>The ONLY issue my response addressed was whether the fiber architecture
>0.5 miles away from the residence/business was PtP or PON. It is at the
>copper/fiber juncture that E/O conversion is obviously required. I
>further assume that the bandwidth requirements at this 0.5 mile central
>point are such that high bandwidth technologies such as 1000BASE-X or
>even 10GBASE-X make more sense than PON.
>
>I do like the idea of FTTH, but I'm being practical and noting that if
>the fiber gets to 0.5 miles of the home that high enough bandwidths can
>be achieved.
>
>By "more scalable" I mean that a PtP fiber architecture is more scalable
>than PON. I note that one can deploy existing cost effective technology
>such as PtP 1000BASE-X and achieve 1 Gbps throughput. I expect that the
>relative cost of achieving the same throughput with PON would run two
>orders or magnitude or so more.
>
>I hope this helps.
>
>Best Regards,
>Rich
>
>--
>ramu wrote:
>>
>> Rich, not sure I understand the logic behind some of your points, but the simple answer appears to be that it requires new trenching for the new copper drops, which will never fly. If I misunderstand, please elaborate.
>>
>> I don't quite get you conclusion: 'since E/O is required, 1KBaseX is significantly more cost effective, scalable, and simpler than PON.'
>>
>> If E/O is required in the field it can't be PON. Whether it is significantly more cost effective cannot be judged without detailed designs of each. Whether it is more scalable I guess depends on your definition. Simpler is hard to imagine, but again may depend on definition. If you could elaborate your view I would be interested.
>>
>> Since you are suggesting an active architecture with new electronics in the field, I for one would welcome a discussion of such a network architecture that had fiber for the last thousand feet. No one has addressed that at all to my recollection. None of the architectues is perfect in all respects so an all-fiber active architecture undoubtedly has some advantages.
>>
>> ==================================================================
>> Vladimir,
>>
>> It would seem that the most cost effective approach for a 10 mile EFM
>> solution would be to use standard point-to-point 1000BASE-X or 10GBASE-X
>> for the first 9.5 miles and then a 0.5 mile copper tail for the
>> first/last half mile. Since E/O conversion is required at the 9.5 mile
>> mark, standard 1000BASE-X or 10GBASE-X technology would be significantly
>> more cost effective, scalable and simpler that PON at that point. I
>> expect that there will be switching equipment located at the upstream
>> (10 miles away) side, negating any benefit of a PON split at that point.
>>
>> Please tell me what's wrong with this picture?
>>
>> P.S. I understand that this does not address the rural market portrayed
>> by Frank Miller in this thread, but neither does PON.
>>
>> --
>>
>> Best Regards,
>> Rich
>
>---------------------------------------------------------
>Richard Taborek Sr. Intel Corporation
>XAUI Sherpa Intel Communications Group
>3101 Jay Street, Suite 110 Optical Products Group
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