[EFM] EFM Requirements
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
invited.