Documentary on Dying Philly Wi-Fi Network

said by Matt:

There isn't money in WiFi as a service right now. It simply isn't reliable enough and has capacity restraints. Perhaps when 802.11n comes out it will help a bit, but right now 802.11b/g has too many technical limitations.

I think LTE and WiMAX will make all this moot soon enough anyway.

said by knightmb:

I run a wi-fi ISP. It's reliable and has plenty of capacity. The problem is on the part of poor planning for it or using proprietary solutions/equipment that are also of poor quality.

I'm sure the other more advanced wireless solutions will certainly dominate and I look forward to them. But to say the current technology is not up to par is simply incorrect. Experience trumps logic.

said by Matt:

I have built public WiFi hotspots and engineered quite a few more. You probably offer point-to-point connectivity, rather than try to blanket an entire metro area, which is what I was referring to.

WiFi works well for Point-to-Point connectivity, but not for omnidirectional coverage.

said by knightmb:

Actually, it's a blanket omni-directional coverage. The point-to-point doesn't scale very well because of the limitation of the wi-fi itself in terms of timing and ACK distance limitation based on the speed of light (or radio waves in this case). Instead we used the wireless distribution model, but it's not the lazy wds setup because they would cause a major packet storm (or someone could do it on purpose to jam up the entire network). Everything is actually based a smart wds setup in which each part of the city has it's distance calculated between AP points. Then we factor in the speed of light through the air (since air slows down the speed of light a little) in which the timings of each AP is then synced on the processor speed of each unit and how fast it can process the packets. There is a little fudge factor in it of course as trying to calculate down to the nanometer isn't feasible. Instead, it's calculated down to the meter.

From that, each customer can use their residential equipment (built in laptop wifi or we provided adapters as well) to connect to the network.

The wi-fi equipment that comes with your laptop or PCI cards you buy for the average PC, just plain "suck" in terms of signal to noise ratio and signal gain. That's why you need equipment to make up for this limitation. Each AP isn't just a clone of another, but all dynamically adjust to what the customer is using.

Basically instead of trying to blanket everyone with some "common" setting, each AP can adjust based on the power/limitations of the client. So if customer A laptop struggles with the service because it can't handle low MS beacon settings, the AP can be adjusted to be "slower" to allow the laptop to maintain a stable signal. But customer B who has a PC and a better wireless card can handle higher rates without problems, the AP can be adjusted for them as well.

The common problem I've seen with all the public wi-fi is that of "throw more hardware at it" approach, where you get these expensive AP equipment on 50 light poles every square mile and just throw enough hardware at it and everything will work right?

We've learned from the mistakes and failures of other large wi-fi projects. One of them being the beacon internal being set to insanely high value like 250 on a city wi-fi. I've also seen massive WDS packet storms from close AP points because they weren't configured properly and got into an infinite loop bouncing the same packet around in a circle. A lot of the AP units I've seen for city wi-fi don't have AP isolation of any kind. That means I can connect to the access point and run my own subnet/IP range completely independent of the overlay network and it will repeat the packets through out the entire network.

Short of running around town with illegal jamming equipment, the wi-fi has been very rock solid. Even during some severe storms, which surprised me. We've had our share of hack attempts as well (to try and get free service), but with how we have things planned out, it isn't easy to fly under the radar without someone noticing something isn't right on the network.

This reply turned out to be a little longer than I thought, so my apologies for all the technotalk, but I'm not going to call the other companies that tried to large outdoor wi-fi losers. I don't know what conditions they were trying to work within. For all I know, the city was pushing them to do something that they knew wouldn't work but had no choice otherwise. Our advantage has been time and testing. We didn't have this project thrown at us with a deadline. We approached it and did a ton of testing before finally going public with it. That testing has saved us a ton of time because the issues we encounter in the field, we've already encountered in testing and found solutions for. One good example is bluetooth devices. Those jam the heck out of 2.4 GHz devices, but we found a solution to this that was as simple as a firmware upgrade to the AP we use. Had we mass deployed and then started to get a ton of tech support calls of non-working service; we could have been scratching our heads for months trying to figure out why some customers get perfect service and others can't get squat. The only variable being a blue-tooth mouse or phone headset for example.

said by Tzale:

Don't you operate under FCC Part 15? So I could go to Franklin, TN and operate my ham radio and knock out your WISP legally since I am a primary licensed user of the 2.4ghz band?

-Tzale

said by knightmb:

You could in theory of course, but not with a Ham license as that's out of your allowed legal range last I checked. The funny thing is, if someone did, we would have so many AP, that we could triangulate where you were jamming from and just send the FCC after you for "causing harmful interfere". Our AP are just below the legal power limit, so the only way to beat it would be to over-power the signal, but even then you have to break the spread spectrum if you are really going to "jam" everything. Either way, the law works against you both ways. It's not impossible of course, but we would know, and even have a good idea of where to find you. You would have a lot of angry residents after you too

I see it no different than Cell phone Jammers. They exist, they work, but illegal as hell here. We do have measures to protect from a basic attack just in case. That's another one of those "what if" questions we tested a while back. A simple wireless card hack can turn it into a data/garbage spewing device quite easily to test with. Though not on the power levels that one could do with stronger equipment of course. Our concern was someone with a laptop causing problems more than someone driving around in a van with some 500 watt high powered transmitter. We weren't trying to defeat the van people.