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?"

3000 unattended servers?

[kansei]

Sounds like overkill - too expensive and too frail.

Consider using dumb access points with battery backup, the kind that can be replaced easily and without much configuration. Centralize your authentication mechanism on the back end.

Re:Don't lead the pack

[lanswitch]

Not so funny, but (hopefully) informative: check out www.wirelessleiden.nl/english . They already have an extensive wireless network, and are willing to help others wiht advice and such. See website for more.

Re:3000 unattended servers?

[Anonymous Coward]

I'm not a networking guru(esp. not wireless), but if you use repeaters(those little devices that DLink/Netgear sell) and throw those all over the city, jack them into a switch with a single DHCP server and a single router .. Couldn't you escape the problem of a handoff requiring you to get a new IP?

And in the meantime .. The submitter should probably check 802.11n specs. I realize it isn't done yet, but if you're going to wait five years, please don't start off with(what will be then) seven year old technology. And he may be able to cover more area with less devices, reducing cost, maintenance, headache(yes .. each device would cost more).

Why not B and G? and speed

[RomulusNR]

Correct me if I'm wrong, but I thought G appliances were backwards compatible with B appliances.

Seems G would be the way to go. Higher cost, but better longevity and compatibility and potential bandwidth.

As for concerns about speed: Here's the thing that gets me about WiFi speed potential (or Ethernet for that matter) when it comes to an open network: What difference does the speed of the line to the node make as long as it's at least as fast as the pipe you'll be using on the back to connect out to the world? Sure, this will matter to the municipal government, who presumably will have lots of internal point-to-point traffic, but not the public, who just want to surf the net.

Here's another question: Are municipal governments still subject to regulations on output, or being governmental, can they crank up the wattage? One wonders if metropolitan WiFi would benefit from greater output allowances. You'd need less APs, etc; instead of trying to put a city-owned piece of hardware on every downtown building, you could increase their range and put them further apart.

Re:Answer: Impossible

[MaggieL]

2.4 GHz isn't "unregulated".

The primary allocation is to amateur radio; other users are there on a Part 15 basis, which explains your experience with your neighbor's phone. You're required to accept any interference from other devices on the band. Since I hold a licence for that band, I'm a primary user, and if interfered with by a Part 15 device can require that they fix the problem or shut down.

If I can find them.

There are commercial solutions

[bradleymon]

There are solutions from commercial providers for reliable metro-scale Wi-Fi mesh networks. These are installed in Philadelphia (pilot) now, New Orleans, Los Angeles, Oklahoma City, Corpus Christi, and Chaska, MN, to name just a few. Check out muniwireless.com for info about how communities around the world are doing this.