[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]
Re: [PLUG] Wireless network - Swarthmore
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