A Window on Westmount Ville Marie

Gerry:
My gut feeling is that fiber is better, but that is because I live in a relatively sophisticated urban/semi urban environment. The rational or non-gut reasons for choosing fiber over satelite would be:

1. A satelite is a very large expensive single point of failure. The loss of the Galaxy IV satelite last week and the subsequent chaos in hospitals which rely on pagers routed through this satelite is ample proof that even though satelites are 99.999.... etc% reliable, the .0000001 % failure of some satelite may make the supposed Y2K problem look like a tea-party. In order to remove the single pointedness one must have backup(s) at a few mega-bucks per unit.
2. The latentcy of geo-stationary satelites can be a problem. If one is only watching a video feed of a sports event, then a second or two delay in seeing the stanley cup winning goal is irelevant. On the other hand anyone who has had a phone converation which is routed over satelite, say to the Philipines can vouch for the "user unfriendliness" of such a link.

   Any one in centralized computing services knows that response times of a second or two are the threshold of human tolerance. Above that and you are in trouble. Below that and your everybodies friend.

3. In order to have bi-directionality in satelite systems you must have access to an up-link (another expensive single point of failure to which one would probably be connected by fiber anyway). The receiving dishes are cheap because they are small because the satelites transmit in the multigigaherz range. This means lots of wavelengths can be gathered up in a pizza dish hence lots of gain for a very weak signal. I suspect to reverse the flow of data reverses the economics,if it is done out individual households not to mention the problem of identifying who it is on earth that is sending.
4. Fiber already has seen wide spread deployment for GENERIC high speed bidirectional digital communication. I suspect that any modern commucation technology could and actually is moving to run over it (and be happy except maybe for bandwith considerations but we know the rate of improvement of bandwith). Satelite on the other hand relies on future systems such as hundreds of low-orbit satelites (which may have to fall out of orbit now and again in order to be close enough to earth) to deliver what fibre is already delivering.
5. In summary perhaps we should look at the characteristics of the modern GENERAL PURPOSE communications systems that we are building before committing to one type of plumbing or another.

   They are bidirectional,high-speed (second or subsecond response time), SWITCHED (or routed) NETWORKS. It is perhaps worthy of note that one of the most successfull of networks is the neural network of the human brain. It also performs sophisticated functions, reconfigures itself in response to major failures (strokes, small projectiles etc..).

   The "plumbing" best suited to build this sort of system and which is being used daily is fibre. This does not preclude the use of satelites but only in cases where it is not practical to use fibre.

   The first CMSA/CD network was built by the University of Hawaii (ALOHA Net) and was satelite- based because it was networking computers on the various islands. The protocols and messaging scheme were later popularized by Xerox under the name Ethernet ( presumably because it used the ether as a transmission medium) Needless to say, were ethernet to have been constrained to run over satelite we would live in a far different world today.

   Michael
   

   ---

   
   

   The Gazette for

   
   
   
   
   Search The World for
   of The Web Usenet FTP Newswires and then The Web Usenet FTP Newswires STOP
   Wait a max. of Ten Twenty Thirty Forty Fifty Sixty Seconds