Seemless WiFi w/Repeaters or Bridges?

eduncan911 · #1 (**permalink**) 08-06-2006, 06:22 PM

Hello all. I've done a bit of searching, and this thread seems to be the closes to what I am looking for.

http://www.wirelessforums.org/wirele...atch-4822.html

I've been trying to plan this for a few months, and the HOA is finally in a position to have me move forward with this.

I live in a building I need to make WiFi - to save us all money on Internet. It's five stories tall, but each story is ~15' with extremely thick 3' of concret for each floor. Each floor has about... 20,000 rectangler sq ft. The walls are waffer thin single sheet drywall with metal 2x4s (argh!).

I figure about 3 devices per floor.

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Now the complications/exceptions to the normal "run a AP to each floor" methods and such are:

Seemless Walking from floor to floor to rooftop pool
I can only run a single CAT5 to each floor
Low budget (we're all paying for it out of our HOA dues)
Low Latency is a must (1/2 of us are online gamers)
Very low maintenance/fix if something were to fail (i.e., just reconfig a Repeater and put it back).

The first in that list is something that I've struggled to do in other wifi networks in the past.

Seemless wifi (can I coin that phrase?

) is what I describe as showing only one Wireless Network on the SSID list. Connecting to that SSID, and able to walk loft to loft, from the basement to rooftop - all without having to connect to a different network. This also gives the ease of having just one encryption key (that will change periodically).

I know that repeaters should be the answer here on different channels, but reading up on half-duplex versions (which seem to be the only ones I can find) may not be the best solution. Also, I'm looking at about 15 to 17 devices total.

Are there enough channels for that? I don't think there is.

I'm a bit fustrated in planning this. I know an Access Point would be required per floor, and the connect two repeaters to that AP. But, that would give me 5 different SSIDs.

Can I convert Linksys WRT54Gs to a Repeater? I've flashed my WRT54G with the DD-WRT firmware and LOVE IT! I was wondering - I can get these in almost surplus now. I've done the WiFi bridging (as testing) and that's not exactly what I am looking for as the WiFi was only used to bridge the two LAN segments. Cool, but I can run a CAT5 to each floor. So not needed here.

I guess I'd have to give up on having a common SSID across all floors. The current thinking is just an AP per floor, with soemthing like "1ST FLOOR", "2nd FLOOR", etc as the SSIDs. And a repeater at each end of the hallway.

I read where these half-duplex repeaters are about 4mb/s. Is that per client that connects? Or is that for the entire device?

I.e. everyone would have to share that 4mb/s if connected to that repeater/channel?

Are there such devices that I can just connect to a LAN that would cut down on the performance issues if the repeaters? Maybe a LAN-to-WiFi repeater if it exists?

Yeah, I've been thinking about this for a while... Oh, and I am open to any other suggestions/configurations - even if totally different hardware setup/cat-5 runs. I'd appreciate any feedback (details).

NZLamb · #2 (**permalink**) 08-07-2006, 06:01 AM

Sounds like quite a project!

Due to the network layout using repeaters, etc you might need to compromise and expect a little lag.

Repeaters also mean you get half of the total network speed, so use 802.11g (54Mbps) for best results. Remember that with one AP per floor, everyone on that floor shares a single 54Mbps connection, so with a large number of users don't expect blazing performance for doing heavy file transfers. Repeaters will slice into this even harder as the data needs to be resent for each client on a repeater.

If you are using WRT54Gs (good choice BTW!) and can only get one cable between floors, why not run cables accross each floor and hook up three units as cabled APs using the built-in switch? The same switch could also daisy-chain each floor and then you have used all four ports for a good use.

That way the load gets spread much better and you could use the 1,6,11 channel rule on each floor (SSID can still be the same though) to minimise interference. It also means if you lose a single AP there is less risk of it dropping all the clients on one floor.

Roaming seems to depend greatly on clients as well as access points. The Intel wireless cards used in Centrino notebooks seem to do it very well (and allow the roaming behaviour to be configured) while some generic chipsets really struggle.

With such a big project you are going to have to experiment to see what works best. I certainly think you are heading on the right track though!

eduncan911 · #3 (**permalink**) 08-07-2006, 02:06 PM

Thanks man.

About the multiple APs per floor, I've thought about that. But wouldn't that give me 3 SSIDs, per floor? I'm just trying to think what murder that would look like when browsing SSIDs to connect to.

Right now, if I open my laptop and turn on SSID and browse for wireless networks, I count 21 networks in the list... Only 4 I know of in the building.

We live in a busy neighborhood, so that's why I was hoping on keeping the list of SSIDs down.

Unless I am missing something? Wait a second here. You said the "1,6,11 channel rule". What rule is that?

Wait another second.

I think I see what you mean. Setup three APs, with the same SSID (per floor), but on three different channels. Ah hah! Then the user's computer will "flip" from one channel to another in search for a better connection.

That's a great idea (if I am right)!

Oh man... I think you just helped me complete the final piece of the design.

Thanks!

EDIT: Heh, I just read where you said "1,6,11 channel rule on each floor (SSID can still be the same though)". Doh! So I can do the same SSID, per floor. Nice.

eduncan911 · #4 (**permalink**) 08-07-2006, 07:56 PM

Attached is a diagram of what I've come up with now, with 3 APs per floor (and another single AP for the rooftop pool/lounge). I'll daisy chain them (not pictured) since the building is over 100' tall, and running CAT5e to 100' isn't the best for throughput.

The large blank area is for the Telco I plan on pitching to everyone. Replace everyone's analog line/phone service with two T1s (48 units in the building).

Haven't started cost estimate, but when I get rid of the crummy cable service and 14 analog BUSINESS lines we have coming into the building right now - I just may have enough in the budget for a fract T3/OC3.

Edit: Argh. Forum settings won't let me attach a 50 KB file (fyi, I work for CommunityServer). See link below.

(click for full image)

NZLamb · #5 (**permalink**) 08-08-2006, 04:55 AM

Exactly what I had in mind, in fact I was close to drawing something very similar to post earlier (go Visio!!)

Just to clarify earlier, the 1, 6, 11 channel rule basically means each AP should use one of those channels each to reduce overlap as this is a common problem with 2.4GHz 802.11 networks. Though I think you seem to have that sussed out anyway.

eduncan911 · #6 (**permalink**) 08-08-2006, 05:30 AM

Yeah . Sometimes it's just easier to draw it up to visualize it.

And I'm sure people here would love to see the "words" drawn out.

When I complete it, I'll post another. Maybe you can throw it up on the website as an example or something.