when last we saw our hero (Saturday, Aug 03, 2002), Bryan Halvorson was madly tapping out: > steve ulrich wrote: > > > > > > handwaving about FSO and other technologies aside, putting APs on > > buildings downtown is fraught with some different challenges, i.e. - > > you'd have to be on top of the tallest buildings within the downtown > > area with fairly high gain antennas to compensate for the LOS issues. > > > > putting antennas on the plymouth building (visi location) is of > > dubious value given the relatively modest height of the facility and > > the surrounding buildings. getting on other buildings with decent > > connectivity might be better but i surmise that this would be priced > > a bit rich for our tastes. > > The tallest buildings aren't always the best for applications like this. > In a base to mobile/portable situation where you have fairly low gain > antennas, typically 8 db on the base and 5 db on the mobile, the normal > usable range for 802.11b without amplifiers on each end is only around > a half a mile. To cover much of downtown is going to take alot more than > one site. i definitely agree with you here. it would seem that creating "cell" zones with the appropriate coverage would be the way to go down here. but i surmise that the hotspot approach for downtown would be preferrable, given the large number of networks i've encountered downtown with my laptop. > The plymouth building has quite a few taller buildings around it but > I believe that it's fairly open to the north so it could be used as > a hub for point-to-point links in that direction that will get us > closer to the areas that we want to cover. I believe that there's > also a path down hennepin ave which could get us to the Walker Art > Center. The Walker isn't real high but it is much more out in the > open and I think that we could talk them into letting us put > something on the roof fairly easily. They'd love the idea of having > network access in the sculpture gardens. i've been reviewing some maps of downtown as of late and i think that the best route from the plymouth building would be north (directly up hennepin ave.). there's not much in the way of large buildings in that direction. to the south there's a fair amount construction taking place with the new developments on block 'e' and to reach the walker would likely require multiple hops. the notion of putting access on the walker is quite intriguing. coverage of the loring park would likely be handy especially for monday nights in the summer while i can't see what's going on with the movie in the park, i could pull out my laptop and be productive. > From the Walker we can branch off with more point-to-point links to > other places of interest. iirc - kent is a couple blocks away from the walker on the south side up the hill. i don't know what his visibility is to the walker but that might be an option for hopping down towards uptown. > > > If anyone is planning on doing this, are you looking at 802.11b, > > > a, or that motorola canopy stuff? 802.11b is 1/5 the speed of > > > 802.11a, and 802.11a isn't too much more expensive. Wouldn't it > > > make sense to use a faster technology? > > > > > > .11a seems to offer the greatest amount of b/w for the buck but my > > only hangup with it is the modest distance that it can support. > > this may not be as big an issue with the appropriate antenna h/w. > > perhaps the RF wonks amongst us can comment on this ... > > Well, we're going to need point-to-point links to get between the > different areas we want to cover. The links can be whatever we need > them to be to get the job done. I think we'll always want to have > 802.11b at the user access points. If we start maxing it out we can > add an 802.11a card there. If we start out using the cheaper > equipment we can always move things around later as our needs > change. > -- steve ulrich sulrich at botwerks.org PGP: 8D0B 0EE9 E700 A6CF ABA7 AE5F 4FD4 07C9 133B FAFC