Regarding cable vs. telephone, I don't think this is as simple as it's often made out to be. While it's true that the cable system is a shared medium up to the first headend, whereas ADSL is (ideally) isolated up to the local office, many of the security and bandwidth issues are similar.
In cable, many of the privacy issues can be resolved with cryptography, as in the virtual private network concept. It may be possible that rouge devices could be used to compromise certain types of security---e.g. destruction of a particular users data stream---however this type of interruption can also be effected in ADSL by climbing the phone pole in front of your house and inserting the proper tech. In fact, ADSL systems may be less secure for the mere fact that they are considered secure, and therefore simple precautions like authetication protocols will not be used.
Regarding bandwidth, the cable system must multiplex all the users of the common medium onto a fixed bandwidth. But, an ADSL system must also do this, it's just at the local office; that's what the DSLAM does that our company is hoping to sell. Just as the cable system can't offer a lot of bandwidth if everyone in your neighborhood is trying to download video-on-demand, in the same way it's doubtful that your local office could handle multiplexing very many megabit/sec data streams, at this date.
I do believe ADSL is better though:
1) It's simpler... since the access medium is not shared, the modem hardware is simpler, and hopefully therefore cheaper.
2) Infrastructure upgrades are simpler. To add more shared bandwidth, the phone company need only to add another fiber from the local office to wherever. In cable, the shared medium goes to the doorstep, and a lot of ditches would need to be dug to modify it. The simplest way to increase the bandwidth per user is probably to add more multiplexers downstream, i.e. decrease the number of users sharing the medium.
3) More people, especially businesses have phone access. I'm told.
4) Psychology. cable<->TV phone<->computer. cable may or may not be able to live up to the expectation of video-on-demand, but the phone system will definitely allow you to surf 20x faster. (I'm using one right now, and I feel good!)
Well, those are my unsubstantiated musings... let's hear some informed criticism!
Ken |
