| William H. Magill on Wed, 11 Jun 2003 11:28:06 -0400 |
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On Wednesday, June 11, 2003, at 06:30 AM, Chris Magnus Hedemark wrote: There is also a hidden cost of the back haul connections; you need someone on the other end. For the really far connections, like Swarthmore to Philadelphia, both ends of the connection will have to use highly focused antennas that will end up being used exclusively for that one link on both ends. While Swarthmore may have a strong incentive to uplink to Philadelphia, does a Philadelphia node operator have a reciprocal obligation to pay for their access point? If so, the Center City host would have an unfair burden of responsibility to fund all of the demand for back haul links. And would the building management allow *that many* antennas on the premises for free? I doubt that you will get any commercial roof space for free, especially in the city. It is a well known fact that roof tops are prime real estate for Cell sites, and agents charge accordingly. And any "reasonably situated" building has been contacted many times since the cell build-out began several years ago. You allude to the back-haul problem at the central hub... each suburban site requires a dedicated hub site. So with a 2 antenna limit per AP, that means the central hub is going to need a lot of real estate for not only multiple antennas, but for multiple electronics as well. Also, long-haul directional antennas need to be substantial devices. They have to be capable of being aimed precisely and then anchored in such a way as to preclude ANY movement of the antenna. Since the slightest movement of the antenna will cause a tight-beam to shift dramatically at the receiving end over 15 miles, and a wide-beam requires much more transmitter power for the same distance. Don't forget, that the proximity of the AP to the Antenna is an important factor. Transmission losses attributable to the line from the AP to the Antenna can be just as devastating as foliage and fog. T.T.F.N. William H. Magill # Beige G3 - Rev A motherboard - 768 Meg # Flat-panel iMac (2.1) 800MHz - Super Drive - 768 Meg # PWS433a [Alpha 21164 Rev 7.2 (EV56)- 64 Meg]- Tru64 5.1a magill@mcgillsociety.org magill@acm.org magill@mac.com _________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.netisland.net/mailman/listinfo/plug-announce General Discussion -- http://lists.netisland.net/mailman/listinfo/plug
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