Hi Mike, you think *you're* confused? I think the company (Advent) may be confused:
Some places they say they're a modem, others they say they just require a standard NIC at the sub. When we talked about them a while back I felt sure they needed a modem...but there are now some conflicting references (see below):
/*----modem references----*/
from a whitepaper on the company website:
The Ultraband technology consists of an
Ultraband Modem Termination System
residing at the cable head-end and an Ultraband
Subscriber Modem (USM) that resides at the
subscriber premises.
and from various articles on their website:
But where telephone subscribers have a physical pair of wires dedicated solely to their connections, Advent's cable modem subscribers would have a "virtual" wire. The company is using technology that can split a single cable wire into different channels
Advent's equipment "is a very dense rack of modems to do dedicated channel allocation and modulation to deliver an Ethernet signal across to each user," Fruhling said.
/*---NIC references---*/
...but from other articles on the company website:
The technology necessary to use Advent's system, a network interface card, costs about $30 and is already installed in many computers.
and
UltraBand is a broadband high-speed data delivery mechanism with bandwidth to spare but does not use cable modems
and
"You're taking digital media to the home, converting it to analog, putting it into that cable modem and then converting it to digital to go to the computer. Why not just put a NIC card in the computer and go all the way?, Johnson said."
---------------------
So which is it?
They also claim their system coexists on the coax with analog and digital TV channels and DOCSIS cable modems (so it has to be modulated up, to an unused portion of the spectrum--in the upper region since that's the only part unassigned. Baseband is already occupied, and that's where generic ethernet would sit ).
So the NIC comment above must just mean the output of their modem connects to the PC via ethernet (has to be 100Mb ethernet to support their claimed 40 Mbps (which implies 256QAM operation over a 6MHz channel, and that's no given to always work)). My conclusion: it is a modem. A proprietary modem--requiring a 100Mb ethernet card in addition. Exactly what MSO's want to get away from and why they devoted so much effort to DORKSIS. Slim to no chance it can be very cheap since no manufacturing scale, and a company that may or may not be around in 2 years.
And from various other articles on their website there are claims of node sizes of 50, 100, and 150 (hey its a network...it has to be shared at some point as you move back). In one reference they are using 180MHz of upper spectrum (which gives them thirty 6-MHz channels to work with) 40Mb of data per 6MHz channel, to (choose one: 50,100,150) users per node. I don't know what they are doing for upstream. There is never any mention of that--but they have to put it somewhere in that upper spectrum they are allowed to use.
They make claims of streaming DVD video and HDTV, but 40 Mbps muxed to 100 users...they better hope no more than a few users on a node try to do that simultaneously. Now if each individual user gets sole use of a 6MHz channel (and this is implied in one of the articles, but contradicted in another) they'd be OK (as long as no more than 30 wanted this simultaneously); I just don't see how the MSO's would go for that though. [putting my MSO hat on:] 1 user per 6 MHz channel when they could be selling that same channel to a couple hundred via DOCSIS, granted at reduced data rates?
Maybe more specifics will be released in the future...I kinda doubt it though. |
