Wireless Community Summit Tackles Digital Divide

jens writes "More than 150 participants (including Matt Westervelt, Seattle Wireless) from 30 countries will discuss on how to overcome the digital divide building wireless community networks. The freifunk.net summer convention 2004 takes place from 3rd to 10th September in Djursland, Denmark. The convention's location is well chosen -- DjurslandS.net (in Danish) itself is probably the most ambitious wireless community network of the world. About 200 volunteers installed more than 100 masts on the remote area's 32 000 sq mi. Using the wireless standards 802.11a/b/g about 1'500 households enjoy a symmetric 1-2 MBit internet connection via WI-FI (the WI-FI network has 8 direct uplinks to the danish backbone and several DSL fallbacks). The wireless4development track organized by wire.less.dk will show other projects how to follow the DjurslandS.net example. The convention starts off with a 3 day program including VoIP, development for the meshcube and antenna building and finishes off with a 5 day hands-on workshop."

Comments

Switch Theory

[Anonymous Coward]

Anyone know enough about Cellular Switching theory and wants to start an open architecture for switches using 802.11?

One day the 2.4ghz spectrum is going to be saturated that the technology used in TDMA (time division) and CMDA (code division) will be used to separate the communication. Switching technology is actually quite simple (once theory is applied to practice) and 802.11 equipment could be used to hop frequency just like cellular does. Now if you can get some inspiring engineer to handle pass-off of equipment then you have yourself an open architecture to replace Cellular with VOIP wireless.

Re:Switch Theory

[rokzy]

The new Motorola CN620 automagically switches to WiFi in hotspots.

Re:Switch Theory

[TommydCat]

TMI filters on!

For CDMA at least, I doubt many AP owners will want to purchase a stratum-3 clock source or better to keep the strict timing requirements, let alone tackle the technical aspects.

Most CDMA cell systems use [C]BSCs ([centralized] base site controllers) that derive timing from the MSC (mobile switching center) which in turn keep the BTSs (cell sites) in sync using timing derived from the DS1s that connect the two. The sites themselves need to know the precise GPS coordinates (a couple hundred feet off can really affect the timing in this system). The BTSs (cell sites) use a "PN offset", basically a time slot, for each sector (cell sites usually have 1-3 or 6 sides that act independantly) to keep from colliding on the same channel. RF Engineers wake up screaming in the night because a little overlap of two sectors in the system that overlap time slots will clobber usability. At 1.9GHz, weather plays a significant role (water reflects like a mirror, leaves eat up the RF which someplaces disappear in the fall), ensuring the need that the system has to be tuned constantly.

The cell phones listen to the "sync channel", then sync to and descrypt the "long code" to catch up and keep in sync with the system.

Summarizing this rather sloppy overview of CDMA, such an AP network would require 1) precise timing 2) precise coordinates (to keep BTSs/sites from colliding on same channel), 3) a strict sector/site management plan, and 4) active management of coverage. Note that this precludes anything like WDS - each point needs a backhaul or you could potentially bring the available bandwidth down by 2^(number of sectors adjacent to repeater).

Needless to say, I think the average layman is out of his league trying to link up a homebrew network in his neighborhood using CDMA.

TDMA could work with sloppy timing, but isn't that basically what 802.11b/g is now?

Pringles - Available in Denmark?

[justanyone]

Are Pringles even available in Demmark?

On that note, it seems like the antenna would not be the most expensive thing to buy as an extra, being usually aluminum in a nice shape. So, do people have links to cheap antenna sales locations and/or directions for build-your-own?

On a personal level, I'd be okay with running a CAN (community area network - is this the right terminology) if I could make sure I interoperate well and share bandwidth across 2 or 3 (or more) uplinks (comcast or DSL included). But, I don't know if this is possible, illegal, immoral, mischievieous, evil, okay, cool, encouraged, verboten, slimey, offbeat, and/or reprehensible in anyone's eyes but my own.

Any ideas? Links?