Cable Modems (fwd)

[David Lesher <wb8foz@nrk.com>]

  {fwd}
  From: Lars Poulsen <lars@silcom.com>
  
  This is an attempt to start a fresh discussion about cable modem technology.
  I am submitting this both to the TELECOM DIGEST (telecom@massis.lcs.mit.edu)  
  and COM-PRIV@lists.psi.com, as well as to a couple of people I have discussed
  related issues with in the past.
  
  Many of us believe that the best bet to give the local telephone companies 
  competition is the CATV operators. When it looked like such a competitive  
  battle was coming up, the "Baby Bells" (the local telephone companies in the 
  USA) started buying into cable TV companies in the UK (United Kingdom of  
  England, Scotland Wales and Northern Ireland) in order to understand the game 
  from the other side. They seemed to be quite successful.
  
  Now, in the US, we are seeing the telephone companies pushing to be alllowed to  
  become ISPs (Internet Service Providers) through unregulated subsidiaries.
  And the Cable companies are trying to start pilot projects with Internet  
  access.
  
  I asked an Australian, who said OPTUS (the "dominant" telco in Australia, which
  is also the "dominant" CATV operator) is rolling out cable modems for INternet  
  access:
  
  > >Which system have they settled on in your part of the world ?
  > >What is the upstream bitrate ?
  
  >** from John Wiltshire <jw@qits.net.au> 08/27/96  4:24pm +1000
  > Check out www.optus.net.  They have most of the information I
  > am using there.
  
  That turned out to be a singularly uninformative piece of propaganda. Here are  
  some quotes:
  "It isn't here yet - but it is coming."
  "Cable modems tend to be implemented using one of the following technologies".
  
  The company I work for has decided that it is strategically important for us to  
  build a cable modem. We are hiring staff to work on it. But after we have  
  started to talk to cable system operators and cable equipment builders (hybrid
  fiber-to-coax gateways) I have concluded the following about cable modems:
  
  1. There are a few technically successful demonstrations. Some of these are
     quite successful, running a virtual ethernet over two separate cable 
     channels (one out, one upstream).
  2. The ones that are technically impressive (as described above) tend to use
     ether-to-coax boxes that cost USD 3000-USD 5000 apiece. Service at this 
     price is not commercially viable.
  3. Systems that have achieved significantly useful uplink bandwidth, have
     generally had to rebuild much of the low-level infrastructure to make it 
     work. It would have been cheaper to run a new pair of telephone wires to 
     the homes. (But then the telephone company would be more likely to win the
     game than the cable company. In OZ, they are the same, in the US, the game 
     is perceived to be a horserace between the telco and the cable company.)
  4. When the cable companies in the UK (which were owned by the US local 
     telephone companies) rolled out telephone service to compete with British 
     Telecom (in what was seen a a preview of the coming US battle between the 
     telcos and the cablecos) they actually ran a telephone pair to each 
     household. They designed a TV coax cable with a telephone pair attached 
     on the outside, and this was used in all new TV cable installation. Thus, 
     they had the telephone pair pre-positioned when they rolled out telephone 
     service. It is obvious, that the apparent success of this "telephone service 
     by cable companies" demonstration does not demonstrate anything of relevance 
     to the US market.
  5. There are about 15 incompatible modulation schemes, most of which can 
     provide 10-30 Mbps "downstream", but most of which provide only a shared
     upstream capacity of around 2Mbps. Some systems derive NO upstream bandwidth 
     from the cable, but use a telephone call (V.34) for the upstream path.
  
  Clearly, there is a significant mismatch between the hype and the reality.
  
  In such an environment, it is generally useful to have a discussion to check  
  the facts. Gentle readers, have are been misled, or are the facts really that  
  different from the hype and the market expectations ?
  
  
  
  / Lars Poulsen - lars@silcom.com - http://www.silcom.com/~lars/ 
  
  
  
  
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