Designing a Municipal Wireless Service?

EvilTwinSkippy asks: "I am on a team generating a proposal for the Wireless Philadelphia Initiative. In short I have to figure out how to cover 135 square miles of city with Wifi. I'm reading through the requirements. (Not linking to them, no fair slashdotting the customer, or my employer.) I have already figured out that supporting Wireless B and G simultaneously has to go. As does supporting cars traveling at 60mph. And getting 1MB sustained across the network is a pipedream. In the end, I'm looking down the barrel of designing a network this is projected to have 160,000 users in 5 years, over at least 3000 nodes. I know that Rooftop mesh networks are going to be a large part of the design, as will Linux boxes acting as routers and access points. What massive network issues has 4 years of electrical engineering, and 10 years of hacking routers and servers not prepared me for?"

I've done this before.

[Naikrovek]

Not for a city the size of Philly but for cities of 200k people.

Find the highest point in a particular region of town, and get the rights to put a weatherproof box and an antenna up on a tower near there. (cell phone companies are very good at finding the best points to place a tower or antenna. you should follow their lead.) in the weatherproof box put a soekris board running linux and two wireless cards and antennas on them. One card will be a backbone 802.11g link with a directional, high gain antenna, the other a customer link with a 802.11b omni antenna.

do that for every region that needs coverage.

Find points where multiple region APs can see, and do the same as above, but get a horizontally polarized omnidirectional antenna. they're expensive, but worth it. Connect all the regional APs to this. Run a T1 into whatever computer controls this antenna.

do that for every group of regions.

viola! citywide wirless. a true star topology.

there are some details i'm leaving out, but this should give you a good idea.

run zebra on the linux APs to handle routing.
use backbone redundancy where possible, the APs will fail occaisionally.

Re:Answer: Impossible

[ebrandsberg]

Now put this in context of deplying a city-wide network. See the problem? As wifi, would it classified as amateur radio or as a part 15 basis? If part 15 (as the sticker on my USB wifi adapter says), that means that if this city-wide network messed with Amateur radio services, then the city's network would have to shut down, correct? Doesn't sound safe to invest time and money into by me.