Re: [PLUG] Wireless network - Swarthmore

[Chris "Magnus" Hedemark <chrish@trilug.org>]

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On Wednesday, June 11, 2003, at 01:06 AM, Stratos Parisiou wrote:

> If you are using plain vanilla GPS without the DGPS (Differential GPS) 
> to
> check for your altitude, you may be off by up to 200 feet for the 
> altitude.
> I would recommend some other for of testing the altitude, preferably an
> altimeter (make sure it's calibrated within the hour or so).

The GPS in question is a Garmin eTrex Summit.  It has an altimeter 
built in.  The altimeter is configured to self-calibrate automatically.

> I have access to a building in Ridley Park Borough and also locations 
> in
> Upper Darby.
> 	From Ridley Park, I cannot see (line of sight) the Philly buildings.
> 	From Upper Darby, I can see most of the Philly buildings.
>
> Does anyone have an estimated cost of each complete "cell"?

The back haul repeaters will cost more than the smaller 
omnidirectional-only nodes.  Each back haul connection requires its own 
antenna and wireless card.  You will have trouble putting more than two 
wireless cards on a system board.  As mentioned in a previous post, I'm 
working on something now to get costs way down to where the access 
point itself is a smaller cost compared to the antenna attached to it.

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?

The bright side to this may end up being 802.16, which should have 
better range and allow for a one-to-many relationship between a single 
Philadelphia node and many suburban nodes.  802.16 is not out there 
yet.  However, towns like Swarthmore have enough of an interest in 
something like this that they would be likely to set up their own local 
mesh for town-level connectivity and worry about the back haul link 
later, if they didn't want to eat the cost of both ends of that link.
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