Re: [EFM] EFM Requirements
Thank you, Sherman,
so we come to 9.5Mb/s for a "regular" customer possible downgrades in the
bit rate for out-ranging ones. However, this number you got putting two video
channels which are in principal asymmetric. Here I come to a requirement:
Downstream = 9.5 Mb/s
Upstream = 1.5 Mb/s + 1.5 Mb/s = 3 Mb/s (I added another 1.5 Mb/s for
better data interactive services).
Looks close to the original VDSL requirement 22/3 Mb/s!
Am I interpreting you right?
Vladimir.
Sherman Ackley wrote:
> Before you can determine a minimum bit rate, the application needs to be
> determined. Today, the high bit rate services are connections to web
> hosting sites, corporate LANs and for video delivery to consumers.
>
> For the business customer, they only have a choice of a T1/E1 private over a
> SHDSL connection. What would be ideal is if the bandwidth could operate
> like an ethernet LAN in that it could go 1 Mbps outbound while going 5 Mbps
> inbound and the next instant go 4 Mbps outbound and 2 mbps inbound.
>
> For the consumer, most carriers are looking at being able to provide
> integrated broadband services which would include VoIP, two MPEG-2 @4 Mbps
> each and internet access at about 1 Mbps. When you add 2 each @4 Mbps + 1
> Mbps + 500 Kbps you get about 9.5 Mbps. It would be nice to be able to do
> this for the Copper serving area out of the CO or DLC serving area. That is
> about 12,000 ft.
>
> The system should be symmetrical in terms of the maximum bit rate. It does
> not mean that it should be two way simultaneous at the same bit rate. For
> example, a T1 provides 1.536 Mbps simultaneously in both directions for a
> total 3.072 Mbps. In the case of ethernet, the 10 Mbps can be used
> alternatively in either direction or dynamically allocable as needed between
> the two directions. ADSL has a fixed 6:1 traffic ratio. That is, if the
> outbound is 6 Mbps, the inbound is 1 Mbps for a total of 7 Mbps. If you
> need 2 Mbps for inbound, you are out of luck.
>
> I have not personally installed an FS-VDSL service at a home so that I am
> not fully aware of the complexities.
>
> -----Original Message-----
> From: Vladimir Oksman [mailto:oksman@broadcom.com]
> Sent: Wednesday, August 15, 2001 4:15 PM
> To: Sherman Ackley
> Cc: 'Stds-802-3-Efm (E-mail)'
> Subject: Re: [EFM] EFM Requirements
>
> Sherman,
>
> I have a sympathy to this list of 5 - seems as a strong step forward.
> Some
> small questions.
> 1. You say: "Reach is more important that bit rate". What is the minimum bit
> rate you keep in mind?
>
> 2. You say: "data rate needs to be dynamically allocable between downstream
> and
> upstream flows". Does it mean that system actually is not required to be
> symmetric (or "about symmetric")?
>
> 3. From some discussions in FS-VDSL I got an impression that VDSL will
> require
> some installation at the NID (because people still don't believe that it
> could
> run over the home wiring) including connection to the CPE gateway. Does it
> sound
> acceptable?
>
> Thankfully,
>
> Vladimir.
>
> Sherman Ackley wrote:
>
> > It is great to get more practical field experience and information to help
> > in defining the requirements for the EFM working group.
> >
> > Seems we are arriving at a consensus that some things that are important
> > requirements. These include:
> > 1. Reach is mort important than raw bit rate.
> > 2. Self install by an untrained consumer is a must.
> > 3. The home network hides behind a gateway/firewall of some kind for
> > security resons.
> > 4. There are at least 5 home networking technologies. These are 10-baseT
> on
> > new dedicated CAT5 data wiring, HomePNA on the existing phone line, 802.11
> > wireless and HomePlug over the power line, and I almost forgot HomeRF
> > (excuse me for saying it to an 802 group)
> > 5. You cannot predict what consumers will use it for, therefore the data
> > rate needs to be dynamically allocable between downstream and upstream
> > flows.
> >
> > When multiple services ride over the same physical media, it is desireable
> > that they not interfere with each other.
> >
> > One of the best frequency coordination jobs was done by the video
> industry.
> > It is possible to place Cable Modem, off air TV, CATV and DBS on the same
> > coax without interference. Today, the same is true with analog voice,
> ADSL
> > and HomePNA. It is not true with VDSL.
> >
> > Since you install DOCSIS modems, did you notice that you can put the modem
> > on any video outlet and it works. You can also move it to another room
> and
> > it will work.
> >
> > It would be interesting to find out what percent of ADSL installations use
> > splitters versus filters. Does any one have any statistics on this?
> >
> > -----Original Message-----
> > From: Fletcher E Kittredge [mailto:fkittred@gwi.net]
> > Sent: Wednesday, August 15, 2001 12:23 PM
> > To: Sherman Ackley
> > Cc: Stds-802-3-Efm (E-mail)
> > Subject: Re: [EFM] EFM Requirements
> >
> > On Mon, 13 Aug 2001 11:31:06 -0400 Sherman Ackley wrote:
> > > 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.
> >
> > Sherman;
> >
> > I'm in the rural Northern New England market. We have a fair
> > number of rural phone companies up here; they serve about 18% of the
> > market.
> >
> > I don't understand the "essential" statement above. Does this
> > mean that if EFM doesn't work with HomePNA, EFM is worthless or is
> > there some other definition of "essential". Where the 75% figure
> > comes from?
> >
> > It sounds like you have a good, detailed understanding of how
> > the customer will use this protocol. My experience has been that it
> > is difficult to predict in less than the most general terms how
> > a protocol will be used. Two illustrations which are vivid to me are
> > ATM, which was to replace the Internet protocols, and DSL, which was
> > to allow video on demand over phone lines.
> >
> > > Finally, feedback on these ideas from other service providers and
> vendors
> > is
> > > invited.
> >
> > I think your emphasis on the importance of reach is spot on and I
> > could not agree more. I think the analysis of how the service will be
> > used should not be used to make decisions. It is impossible to know.
> >
> > regards,
> > fletcher