Building a Wireless Network for an Apartment Complex?

itwerx asks: "I've been asked to design a wireless infrastructure for an apartment complex. Tenants will pay an 'access deposit' and a monthly surcharge to get a PCMCIA/PCI/USB network card along with free installation and, of course, wireless Internet access. The buildings are arranged such that 2 WAP's per building should cover all the tenants (one WAP per side, far enough away to get line-of-sight through the windows). I do have a few concerns, however. All help is appreciated and when we're done we'll put up a HOWTO!"

"My concerns are the following:

• Interference between WAP's (there's several buildings) - there are enough channels if we go 802.11a but cost is a concern.
• Management of 'hitchhikers' - we're planning on manual assignment via DHCP/MAC address for tenants with others having all their HTTP requests get directed to an info page. Anybody done something different?
• Interference from WAP's and other devices that may be owned by tenants! Should we just avoid the default channel and hope for the best?!?

What other things might I need to worry about?"

Comments

interference..

[molo]

Interference between the two WAPs is not really what you have to worry about. Put them on different channels on opposite ends of the chunk of 802.11b spectrum and its done.

The real issue is interference from other devices. I hope no one has a 2.4GHz phone.. or a microwave.. or X11.. or one of the other dozens of devices on the (unregulated) 2.4GHz band. It can knock your 11Mbit down to 1.

Berkeley wireless LAN

[minesweeper]

U.C. Berkeley has been working on implementing a wireless network around campus. You can read up on the project here. It mentions some of the technical issues they face like 2.4GHz cordless phones and even interference from old microwave ovens.

Hitchhikers

[brunes69]

If you are worried about data sniffing, IPSec / WEP is your answer. If however, as I assume, you are worried about "free rides" on your bandwidth, I'd suggest PPPoE. That way no one gets on the network unless they have an account. Seeing how it is a relatively small number pf tenants I assume (less than 500 or so) it should be simple to keep a list of names / logins so as to provide a tenant with two logins should he get a second PC. This method saves you the hassle of managing a bunch of fixed IPs and MAC addresses with everyone on the network.

Security matters.

[dfeldman]

I have just one word of advise here: don't do it.

Back at my alma mater, one of the students (who thought he was clever) founded an ISP that provided 802.11b wireless access to apartments on campus. Inevitably, the WEP key he used was compromised, and student account passwords were sniffed and abused. Now, common sense would dictate that he shouldn't be responsible for what a criminal does with his network; but common sense does not reign supreme in the ivory tower of academia. What happened next was shocking: the student was disciplined, expelled, and sued for damages by the state college. Although he certainly could have won his case in front of a jury, he settled because he could not afford $15k to hire a good trial lawyer. Right now he has no degree, can't get into a good school, and is pumping gas for a living.

So, if you are considering rolling out a notoriously insecure network architecture (such as 802.11[ab]), consider the fact that you may be personally liable for anything bad that a crook does with your network. Be afraid.

df

Re:Don't bother with WiFi...

[WolfWithoutAClause]

You also need to remember that the 11MB/s provided by WiFi is shared between all users. If you have 50 "dwelling units" and two WiFi access points, you'll be offering a service with less maximum bandwidth than bottom-of-the-range xDSL...

Wrong.

Ever heard of contention ratio? Contention ratio is the ration between the actual bandwidth and the bandwidth available to each user. In this case you are providing 11 Mb/s of backbone for 50 users. Assuming a contention ratio of 50:1, which is fairly normal entry level ADSL, this wireless system can provide for ~3-11 Mb/s each for about 50 users. Or ~1-3 Mb/s per user at a contention ratio of 20:1.

and you'll be charging for $100 WiFi NICs instead of $10 PCI ethernet NICs (which many PCs now have as standard anyway)... and for a service subject to atmospheric outages (ever use a WiFi network during a thunderstorm)

Plenty of people have used it over multi-km distances with no problem.