WIFI-Municipal

If you run or work for a government entity, start reading here:

Otherwise, what you're really doing is starting a WISP (wireless internet service provider).

Good luck.

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BTW - most have failed - since as a community effort, they were usually FREE, and built to fund themselves with ads - but most never workout - and get closed down -

- Boston - Naperville, IL, Aurora, IL -

Yes, but they keep coming. Insanity is doing the same thing over and over, but expecting different results. Ever notice that municipal network proposals usually appear just before an election?

By coincidence, I gave a talk on why mesh networking sucks to a small group yesterday at the local Linux users meeting. Actually, it's a dry run for a larger talk that I might be giving in the future. Much of the talk was on municipal wireless mess starting with Metricom. The live demo of how a store and forward repeater slows thing down didn't quite work because I screwed up and didn't bring a laptop with a gigabit port.

Here are the files and the outline from the talk: There are a few mistakes and it is lacking in detail. I plan to expand it over the next few weeks into a web page that's more readable.

Quiz: What's wrong with this picture of a wireless mesh network?

While doing the usual frantic last minute research on the topic, I noticed that the premier municipal wireless site only had one entry under "mesh" in 2013, one in 2011, and a huge number between 2004 and

2010, when mesh was the hot ticket: The site has some date indexing problems, but it seems that mesh wireless is not very popular these days.

Actually, there are many successful wireless mesh networks. However, they don't carry consumer internet traffic. They carry IoT data, such as PG&E's 900 MHz smartmeter mesh.

Quiz: What's wrong with this picture of a wireless mesh network?

not sure... wouldn't the mesh have sub-nets, each with their own GW ?

here's a couple of our local attempts -

Nope. It's a bit tricky. You really have to experience a badly designed urban municipal wi-fi network in order to answer the question. There were 4 people in the audience that had prior WISP experience. All got it right immediately. Most of the others didn't know anything about RF and I had to explain (in detail). Spoiler hint: It's about RF.

Oh, photo credit is from the

ebook, chapter 8. The free ebook is well worth reading, or at least skimming.

Ugh. That's ugly. Far more politics than technology involved. That's the real weak link in municipal wi-fi. Even if the system gets built, funded, and actually works, administration and maintenance are heavily politicized and usually under funded. You have my sympathy.

MetroFi brings back fond nightmares: I wasn't impressed with their system design and installations. For example, the Santa Clara Metrofi system spent about 80% of its air time spewing ARP requests and broadcasts, leaving very little for actual useful traffic. Under MetroFi, that was never fixed.

Unfortunately, such system tend to raise from the dead like zombies, usually just before elections. Santa Clara is no exception: The concept is unique. If anyone complains about getting exposed to harmful wi-fi radiation and turning their brain to mush, Santa Clara simply threatens to pull the plug on the free wi-fi, which people find very convenient. Without the utility part, they also threaten to raise taxes to buy a proper smartmeter system. I'm not sure if the threats work, but I like the idea.

I lack experience in this sort of network, but AP physics tells me that when you have multiple waveforms broadcast on the same frequency you get interference patterns.

Also, are some nodes repeating for others? That will bog things down, won't it?

Elijah

------ plus it tracks your movement through area in the network, right?

True, but that doesn't apply to wi-fi. In a rooftop situation like that in the picture, every rooftop can supposedly see every other rooftop. In order for everyone to hear everyone else, everyone has to be on the same RF channel (or frequency). With a simplex CSMA/CA (carrier sense, multiple access, collision avoidance) scheme used in wi-fi, you can only have one transmitter on the air at a time. Therefore, no interference. One only transmits when the channel is clear.

Reality is of course not so neat. There are radios that can't hear or see each other. This is known as the "hidden transmitter" problem. If two transmitters do come on at the same time, and the collision is detected, the transmitters intentionally jam each other out to prevent the collided signals from being received as garbage. The two transmitters than invoke a backoff algorithm, where each tries again, but at different time delays.

However, that's not what's wrong with the picture. I'll drag this out for another day or two and then explain what's wrong.

Yes, store and forward does slow things down. Again, only one transmitter in the "air space" can transmit at a time, including nodes that repeat the data. If the data needs to go through a 2nd node, the maximum throughput is cut in half. If it goes through a 3rd node, the throughput is 1/3. And so on. Using full duplex repeaters and backhauls largely solve that problem, but there's no evidence of that in the drawing.

Yep, but only with the resolution equal to the coverage area of one node. That can be a fairly large radius if on a rooftop. You might get lucky and be located to within a city block, but not more accurately.

Ok. Time's up (because I'm going to playing dish installer during the next few daze and am going to be busy).

The problem with the picture is that all the communications is happening on the rooftops and very little where the users are located. Most of the users are near the ground, where the RF from the rooftops never reaches. Many are inside the buildings, where there might be a cable running from the rooftop mesh node to their home/office router. More likely, they're just another wireless node on the mesh, which might be able to see another rooftop node, but only if it's on a nearby rooftop. They're unlikely to hear the node on their own rooftop because of all the bulding material the signal needs to pass through and the not so trival detail that the antenna pattern is optimized for talking to other rooftop nodes, not users in the buildings. Otherwise, it's a nice looking drawing of a rooftop mesh network that mostly talks to itself.

Hello Jeff, I have seen and started to revisit wifi business, since there are now models to share revenue directly with location owners, based on businesses advertising onto portal.

You can checkout

Let me know, if this is something you would like to partner in Santa Cruz area or nearby.

Regards, Kenneth Fax Skype: kenfax Linkedin.com/in/KennethFax