But WiFi has 1990s bandwidth; you’ll be frustrated trying to download your daughter’s video. WiMAX can break the bandwidth barrier, but it’s a costly, centralized technology that has to be rolled out by large institutions. Fiber is even more of a long-range investment, and requires labor-intensive installation.
The promise of Ronja is mesh technology that can deliver 10 Mbps and can be built by an amateur in his or her own home for $100 per unit. The specs are all open-source. Where costs or regulations delay the stringing of cable or fiber, this technology could quickly bring neighborhoods into the twenty-first century in terms of bandwidth and universal service. Applications such as interactive video teleconferencing and remote application access with large remote data storage become immediate possibilities.
Ronja was developed by Karel “Clock” Kulhavý with a large community of helpers. Kulhavý, an embedded software developer with a degree in computer networking, grew up in Prague but now lives in Zurich. The knowledge of electronics and mechanics he applies to Ronja work was always something of a hobby for him.
The project name officially stands for Reasonable Optical Near Joint Access, but actually came from a movie character. Although the specs were first released in 2001, a lot has been learned from real-life use since then.
The device is a long tube weighing about 15 kilograms, easily installed on a chimney, roof, or other location, and delivering 10 Mbps over line of sight with a range of 1.4 kilometers.
The technology is Free Space Optics, using spectrum in the infrared-to-red range. The last I heard, this range is totally unregulated (unless the color red is outlawed somewhere), except for limits to ensure safety on the eyes, with which Ronja is compliant. The spectrum is 480,000 GHz, compared to 2.4 GHz for WiFi 802.11b and 5.7 GHz for WiFi 802.11a. Ronja works in the rain or snow, but begins to lose high frequencies in fog, and drops connections only in dense fog.
Note the scalability of a line-of-sight transmitter. To set up a mesh, one can install multiple tubes at one site (as illustrated by these photos) while avoiding the interference that would occur with most WiFi antennae.
Kulhavý tells me he watches movies streamed over Ronja and has used it to transmit DVD-quality video through two hops without jerkiness or drop-outs.
The Ronja team currently counts 146 registered installations in at least 9 countries. The largest installation is in Prague, where the CZFree.Net community network has 29 links built with Ronja transmitters. A glance at the credits and mailing list archives reveals a passionate community of amateurs sharing insights and images concerning what parts to order and how to solder, clamp, and install Ronjas.
Low cost drives many of the design decisions. For instance, the LED is a simple automobile brake light. PCBs and LEDs for Ronja are on sale. Imagine the speed at which this could spread if a commercial enterprise mass-produced the devices!
But Ronja’s development, done in a totally open source manner and with specs licensed under the GPL, may be moving too fast for commercial manufacture at the moment. The team is hoping in the near future to extend the range to 3 km and the speed to 100 Mbps. Eventually, with a laser costing $2, they hope to reach 1 Gbps.