RE: [EFM] EFM Requirements
The inputs you are providing are very interesting and important since the rural area is not easily covered, even with today's xDSL technologies. I know that in Europe and in the Far-East (APAC and Japan) the loop lengths are much shorter and I wonder what percentage of North America is located in the type of environment that you described.
As an active participant in the ETSI and ITU standardization groups, the discussion and targets you have raised bring back memories from a couple years ago. The target of VDSL standardization was maximum reach but as technical evaluations began, reality sank in. Capacity calculations based on Shanon's limit created a clear trade-off between distance and rate. The trade-off curve is "simply" achieved by using Shanon's limit while taking in to account several other limits. A new public system can not interfere with existing systems, it can not exceed certain transmission levels (emission reasons) and it must cope with similar systems that are providing service at the same time (self FEXT in other words). All of this forced service providers like yourself to make a choice: What service will be provided at what range. Of course a mix of services is possible but even these must be compatible with each other.
If maximum reach is the only parameter, one can easily predict the available service based on ADSL/SHDSL rates. From your inputs, and the inputs of others, video service is a must with a bit rate in the range of 10-20Mbps. I assume it is because people will pay for video while fast Internet is not billable. Of course, if the service is video then the bit rate must be guaranteed and not best effort as in flat rate Internet access. Bit rates of 20Mbps are "limited" to about 4500 ft. That is the result of many technical discussions between vendors and operators as yourself (and many capacity calculations as well).
In all the deliberations of what the EFM should achieve, I think that we should keep in mind that there is a trade-off curve and it is not enough to specify the required range or rate. We should try to specify points on the curve that are within the limits defined by Shanon's capacity theorem. The achievable rates vs. ranges of all the xDSL technologies provide us with reference points on that curve. If our target is to provide high quality service and bandwidth of 10-20 Mbps, we will have to limit ourselves to achievable ranges which can be guaranteed to all users.
A final remark. Perhaps not all applications will be able to use the results of the EFM. This is another trade-off we can consider. Not every environment can use 10/100BaseT and some result to 802.11 for a solution. Once again it is bandwidth for range and flexibility.
6 Hagavish St.
Poleg Industrial Park
Email: steven.haas@xxxxxxxxxxxx <mailto:steven.haas@xxxxxxxxxxxx>
Tel: +972-9-8924186 (direct)
Tel: +972-9-8924100 (switchboard)
From: Sherman Ackley [mailto:SAckley@xxxxxxxx]
Sent: Tuesday, August 14, 2001 5:58 PM
Subject: RE: [EFM] EFM Requirements
I guess I did not fully express my hopes for the EFM workgroup.
First, I would like to appologize for my error in converting kf to km. The
distances that I was trying to convey was 10 Mbps at 12kf (3.6 km) and the
higher rate out to 5 kf (1.5 km).
Today, the deployment of DSL using ATM based technology is expensive,
difficult to administer and cannot meet the future needs of consumers due to
the fixed outbound to inbound ratio. My hope is that the EFM working group
will develop the standards for the second generation of DSL that is better,
faster and cheaper than ADSL or VDSL and can move traffic equally well in
both directions (like Ethernet).
Reach is more important than raw bit rate. And, the standard should allow
for rate adaption to the cable environment. Avoidance of a splitter is
important to succeed in the marketplace. Today, in the USA, over 90% of DSL
deployments are splitterless because the service providers found they could
not succeed if they were forced to dispatch an installer to install a
splitter on the side of the house.
The service should operate on a point to point basis with the modem in the
house/business. There, the user will install a firewall to separate their
home network from the Internet access service. The consumer can be expected
to move the modem from room to room and they will expect it to work from any
jack. They do not understand being restricted to just one jack. What this
means is that the Internet access service and the home networking must be
divided by spectrum on the same cable pair. This should be possible through
the use of intelligent filters such as those used today to separate voice
The consumer electronics industry has hundreds of products on the market
based on the clear demarkation between access and local networks. This
demark has become so basic that Microsoft is including the firewall and home
networking in the Windows XP Operating System.
First applications of EFM have been driven by service providers finding an
application for a technology with limited capabilities. When the (bit
rate)X(reach) product is increased, the applications will change rapidly.
If you are looking at the Telcordia loop surveys (I was part of the team
that collected the 1983 data), that should be an excellent guideline to
determine what percent of subscribers can be served without expensive and
time consuming fiber over build construction.
From: Christophe.DEL-TOSO@xxxxxx [mailto:Christophe.DEL-TOSO@xxxxxx]
Sent: Tuesday, August 14, 2001 9:28 AM
To: Sherman Ackley
Subject: Re: [EFM] EFM Requirements
Dear Sherman, first of all thank you for your inputs on the possible
requirements for EFMC.
Actually, I have two concerns.
The first one concerns your penetration scenario. I thought that EFMC
was targeted primarily (but not exclusively) for MDU/MTU market which
de facto means EFMC systems will be deployed in urban areas with a lot
of home/office buildings, high density of population and relatively
short ditances from distribution points to end customers (some surveys
said in between 500 to 2000 feet in most of big cities worldwide).
Your figures (i.e., 100 households reached in a perimeter of 3 km)
seem to be far more pessimistic.
I think that to help in defining what could be the optimal reach and
bit-rates for EFMC, it would be interesting to first identify the key
market segments: i.e., MxU, FTTB + EFMC, others and then to collect
some recent figures on the percentage of people reached (penetration)
in the case of these different deployement scenarios with figures on
the current situation and on the forecast.
Some old statistics for US only (from two surveys by Telcordia
technologies : 1983 and 1990 ) were presented at the EFMC meeting in
May 2001. I think this could be a good starting point and we should
maybe try to update these figures and extend the survey to other
countries in the world.
I think that having the support and the help from telcos, regulatory
bodies, independant auditors would facilitate the work.
Having a clear picture on the type of deployment scenarios and on the
targeted applications could be of great help to define requirements
for EFMC (e.g. in terms of reach, bit-rates, network topology).
My second concerns is about HPNA. I don't understand clearly the
coexistence issue with HPNA.
For me, there are two possible scenarios
1- the EFMC system is placed at the entry point of the household like
a gateway (in that case it is connected to local server or the central
distribution point outside). Then, inside the house, data distribution
is ensured by HPNA. In that case, one just have to implement a simple
passive filter at the EFMC gateway to isolate the Home network from
I would even say that it shall be mandatory to do so otherwise
your HPNA could be uncontrolable and disturb a lot the outside world
which will never be tolerated neither by telcos nor by service
For information at the Geneva ITU meeting in February, Telecom Italia
raised this problem of HPNA isolation.
2- Your home/office network is a LAN or a point-to-multipoint EFMC
(i.e. a set of EFMC-PHYs connected together) .
In that case, there is no need for in-house/in-building distribution
through HPNA and so pb of coexistence with HPNA is avoided.
Many thx in advance for your feedbacks.
Very best regards
Christophe Del-Toso, STMicroelectronics
______________________________ Reply Separator
Subject: [EFM] EFM Requirements
Author: SAckley (SAckley@xxxxxxxx) at internet
Date: 8/13/01 5:31 PM
Service Provider Requirements for Ethernet in the First (two) Mile(s):
Sherman L. Ackley, CTO
The National Rural Telecommunications Cooperative provides services to over
350 member independent telephone companies who serve over 6 million access
lines. Ethernet in the first mile is the most promising technology for the
delivery of integrated voice, video and data services in the suburban and
rural areas served by our Members. As the Chief Technology Officer for
NRTC, I would like to submit some practical requirements as seen by the
service providers most likely to implement this technology in the USA. The
intent of this contribution is to help the study group prepare the
requirements document based on actual needs.
The user locations will be 90 percent residential and 10 percent business.
Of those businesses, 90 percent will have 10 or fewer PCs.
The system must work over standard high capacitance telephone outside plant
cable. Binder group integrity is not assured. The technology should not
force removal of bridge taps and end sections. It needs to operate without
degradation at binder group fills over 70%.
System reach is the most important aspect of the design. Ethernet in the
first mile must operate over the longest reach possible. The number of
households and small businesses served by a node is proportional to the
square of the reach. For example, a reach of 3 km can serve about 100
single-family homes per node. Doubling the reach to 6 km increases the homes
served per node to 400. And with a 12 km reach, 1600 homes per node can be
served. This assumes 100 percent subscribe. At 25 percent subscription,
short reach technology gets down to some dismal financial outlooks in terms
of cost per revenue producing subscriber as well forcing the construction of
too many street corner server nodes.
Coexistence with HomePNA on the same cable pair is essential. This feature
will be necessary in over 75% of households served with Integrated Broadband
services. For example, a data stream of 10 Mbps will support two MPEG-2
high-resolution standard TV signals. The DSL will carry this to the primary
service set-top box/home gateway that can be located anywhere in the house.
The Gateway device will terminate the video and data for use at the primary
TV, it will then forward the second video and data over the same cable pair
to other set-top boxes and PCs within the house using HomePNA.
Peer-to Peer (or server to server) communications requires that the service
be adaptable so that full rate is available upstream or downstream as
required by the user generated traffic. For example, it is now possible to
record MPEG-1 video on a camcorder and e-mail it over the Internet.
Unfortunately, sending the e-mail over a conventional fixed data rate
ADSL/VDSL system takes forever for the 20 Mbps file.
There is little demand for sending three simultaneous MPEG-2 video streams
to the home. This is based on the analysis of over 20 million DBS and
digital cable subscribers. In fact, two streams are required in only 30
percent of households. It is far more economical to install a second
Ethernet Subscriber Loop (ESL) for the one in 100 who want three HDTV videos
than to burden all with the high costs required to support a higher bit rate
short reach technology such as VDSL.
In conclusion, long reach is of paramount importance. For delivery of two
Standard TV signals, 10 Mbps at 12 km is required. For one HDTV plus one
Standard TV, 20 Mbps at 12 km is desired. Also, the selected technology
should allow data to flow in either direction at the full data rate.
Finally, the technology should be spectrally compatible with HomePNA without
requiring the use of a splitter at the residence.
Finally, feedback on these ideas from other service providers and vendors is