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San Francisco's Got Free Wi-Fi
Carpoolio writes "If you're living in San Francisco, chances are you can connect, for free, to the BARWN -- the Bay Area Research Wireless Network. BARWN broadcasts an 802.11 signal from the top of a big hill near San Francisco, and anyone with a clear sight line to the signal can connect. Another set of wireless nodes are being placed around town by SFLan, making Wi-Fi available to tens of thousands of people."
Free as in WIFI?
Wow, that must be some magic access point. Mine can only handle about 30 people before it's saturated. How did they overcome that limitation of 802.11b?
According to the article, The hill has a few directional antennas that provide access to 30 or so stationary access points scattered around the area. I assume those access points also have directional antennas pointing back. This would seem to indicate that in order to get online, you have to be near one of the access points, not simply in view of the hill.
Can anyone tell me the likelihood of tracking down a spammer at a laptop in a city the size of San Francisco?
I ran a benchmark on my quantum computer, now I can't find it anywhere!
It'll be nice when things like this become ubiquitous and someone starts manufacturing WiFi "cell" phones that use Vonnage or some such thing.
It's been my experience that iChat has near cell sound quality, so having a small hardware iChat (or whatever you use) client with 802.11b access would be pretty sweet.
Just blanket the city with this and we're set.
It will be brought to it's knees from the sheer mass of freeloading P2P traffic, not to mention all the worms looking for fresh hosts to infect.
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
Look, no one should complain about a "free" connection, but I'm curious to know how fast the typical user's connection really is. After all, the access point has to be connected to a terrestrial data line, which has limited bandwidth. Of course, the more people find out about this, the slower it gets for everybody, right? Does anyone know if those who provide "free" wireless access have an upgrade plan to handle the additional traffic?
Most folks think spam when it comes to large wireless networks. I'm thinking P2P -- it'll be a bit tougher to trace shared music across a public wireless network than it would be on someone's home DSL connection.
Of course this could also be a haven for computers that don't have the latest patches, have print/file sharing enabled, and don't have personal firewalls activated. For those who want to run in this, be careful.
The thing about free wireless (that I love) is that it keeps the Ashcroft-types up at night worrying about anonymous "terrorist" freespeech, and it gives the telco-types and the WISP-wannabes the middleman middle finger.
Community owned and operated, adhoc wireless mesh networking will be the future of free ubiquitous access despite some peoples early attempts to coopt it. It's similar to how FedEx thought they could own the Fax business in the 80s. Can't blame 'em for trying I guess.
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Power to the Peaceful
from the top of a big hill near San Francisco, and anyone with a clear sight line to the signal can connect. Another set of wireless nodes are being placed around town by SFLan, making Wi-Fi available to tens of thousands of people
In other news, the CDC and the Cancer Research Institute have sent observers in the city of San Francisco. When asked about their presence, CDC operatives declared they were here to monitor the results of an undisclosed "full-scale experiment".
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
This is paid for by tax dollars
Actually, it's paid for by the Bay Area Wireless Users Group
That doesn't make it free, it means you already pay for it with the taxes you already pay.
Also, it's not clear if they meant free as in beer, or free as in freedom. If they allow anyone to go online without registering or anything, then it's both!
It would seem that if you have a clear line of sight to multiple APs, then you could combine them and have more bandwidth than a single AP-channel connection would provide.
This is called "concurrent multiple association" or simple multiple assocation / AP hopping, and it's something i've been working on off and on for a little while. I talk about it in a bit more detail on the Janus Wireless pages, but I have yet to get anything stable ready for prime time use.
The current problem with multiple association is that you need a very low latency interface to the network radio's at a packet injection / monitor mode level.
I've been able to get this to work in a very crude and inefficient manner with cisco/prism cards used for monitor mode recv of packets, and prism2 based cards for packet injection to implement the multiple association and data packet injection.
There is some hope that the newer cards, specifically the atheros 802.11a/g cards with a reversed binary HAL driver could provide the requisite low level functions to do this efficiently.
But then you are faced with another problem: aggregating the UDP datagrams from multiple sources into a single address space similiar to the way mobile-IP has a dedicated "public" host which acts as your intermediary as your IP changes without breaking existing TCP connections.
I've played with this a bit as well on a dedicated host that has a few IP's, and it works like a NAT that collates UDP datagrams from a wide variety of sources and converts them into the desired TCP/UDP/etc communication from that public endpoint.
In short: for multiple association you need a number of new driver and radio interfaces for:
1) very low latency packet injection and monitor style recv.
2) specialized mobile-IP like drivers on the client that present a virtual interface (ethX) to then host while using injected datagrams over the various multiply-associated wifi links for transport.
3) a dedicated public host with an IP it can allocate to you that accepts all of these incoming UDP packets from various source addresses (all the AP's you are using) and combines them into standard IP traffic from that public IP (ala mobile-IP as well).
None of this is extremely difficult (with the newer cards) but it is a lot of code, and a lot of work, and requires some dedicated host resources.
Now, for the cool part. When you do have all of these pieces in place, it allows you to:
- Simply add cards to your system for more bandwidth. The multiple association throughput is limited only by the number of AP's you can talk to, and the number of cards you have to monitor and inject packets with. It scales nicely barring interference problems.
- Maintain extremely high throughput as you move anywhere within range to open AP's! You could aggregate the upload capacity of 30 AP's to get a 10Mbps link to the net and maintain this constant fat uplink as you drive around the city.
- Enjoy extremely reliable / robust communications. Since you are no longer dependant on a single AP, you dont have to worry about connection dropping, clients messing with your signal, etc. Your aggregate connection is spread over a number of AP's which means problems with individual AP's make only a very small impact on overall connectivity.
This is really the way things are headed, and its only a matter of time before they become useable and widespread.
There are tons of free hotspots in the New York City metro area as well.
I am one of the people building SFLAN. Our map is a little outdated (and the San Bruno Mountain node is in the wrong spot). SFLAN and BAWRN have some 30 nodes in as many locations in San Francisco and a few outliers in surrounding counties. If you are in San Francisco and want to try it out, Cole Street is well covered. The SSIDs are sflanNN or BARWN-xxxxx; DHCP, no WEP.
The nodes are owned and paid for by individuals, many of whom are members of the Bay Area Wireless User Group. The Internet bandwidth for SFLAN is sponsored by the Internet Archive. If you live in SF and want to buy a node to connect your house and your neighbors, contact us.
We like to keep these networks as free (as in speech and beer) as possible. And it's working out so far. I hear Tim Pozar's neighbors keep him happy with occasional pies...
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