Wi-Fi puts windblown California islands on the Web

A point-to-point link gives the wildlife-filled Farallones more bandwidth than many homes have

The hardy team of biologists stationed on the Farallon Islands, a minuscule set of outcroppings in the Pacific just west of San Francisco, suffers a lot of inconveniences.

After all, they're living on islands made up mostly of rocks, drinking filtered rainwater and using solar power that wanes during the short days of winter. Just to get out to the island and back, they rely on a band of private boat skippers who are willing to sail the 47-kilometer (28-mile) stretch of ocean between the city and the islands and then have their boats lifted to shore on a crane. The Farallones have no dock, because none would survive the wind and rough seas, according to Russ Bradley, who works on the islands for about 18 weeks of the year as Farallones program manager for the Point Reyes Bird Observatory.

In some ways, the Farallones feel more than 28 miles away from civilization, according to Bradley. "Just the transportation and the logistics of working and living out here is a whole challenge in itself," he said.

But for the past year or so, the inhabitants of the two small, restored 1870s homes that make up the human settlement on the islands have enjoyed faster Internet access than many residents of highly wired San Francisco, which they can see on a clear day. The island's denizens usually get between 6M bps (bits per second) and 12M bps, which is on the high end for a typical cable modem connection. They even have fiber straight to their homes, a luxury many U.S. residents are still anxiously waiting for.

The difference is that the fiber on the Farallones ends at the top of Lighthouse Hill -- actually a steep, rocky peak nearly 370 feet high -- where it's plugged into a dedicated, 50km point-to-point Wi-Fi network.

Using off-the-shelf access points, a special antenna, computer modeling, and some trial and error, two local Internet veterans have brought broadband to a place where seals outnumber humans. Fittingly, they did it mostly for the sake of the seals, and for the other marine mammals and birds that inhabit the Farallones, a tightly protected wildlife preserve that is home to the largest seabird colony in the continental U.S.

The Farallones network came about after the U.S. Fish and Wildlife Service, the California Academy of Sciences in San Francisco, and the nonprofit Point Reyes Bird Observatory in nearby Marin County all decided around the same time that the islands needed a better digital lifeline. Internet pioneers Tim Pozar and Matt Peterson teamed up to design and build the system, which went live in April 2009. There are people on the islands year-round, but never more than eight at a time, between staff biologists and interns. In addition to keeping them in touch with the world during stints of six weeks or more on the islands, the network carries critical data about the state of local wildlife and supports a full-time webcam for research and educating the public.

The previous methods of communication on the Farallones couldn't have supported all that, at least not reliably, according to Bradley, who has been working stints on the islands since 1998. At that time, the only voice line out was a two-way VHF marine radio. It could reach conventional phones on the mainland, but the conversations were awkward, he said.

"You had to depress this button while you were talking, and then release it and have a two-second delay before the other person could talk," Bradley said. This usually required a hurried explanation of the system to the person on the other end of the line. Even worse, using the radio meant hiking up to the lighthouse, where it was set up with a direct line of sight to a fire station on the mainland.

About four years ago, seismologists from UC Berkeley upgraded the Farallones' Internet access so they could track the movements of the San Andreas Fault by comparing GPS (Global Positioning System) data. The islands sit on the opposite side of the fault from San Francisco.

The seismologists set up consumer Wi-Fi routers on the lighthouse and on a building on the seaward side of San Francisco. That system is still in place but has never been very fast or reliable, according to Bradley. It also tended to crash -- literally -- because the antenna mounting couldn't stand up to the weather.

Pozar and Peterson approached the challenge methodically, but even they had to swap out their first set of radios. The current system, in use since November, is the best yet, according to Bradley.

The heart of the network is the long Wi-Fi link between the base of the Farallones lighthouse and a tower at one of the highest points in San Francisco, on Twin Peaks. The link has two IEEE 802.11n radios on each end, one of which works in the 5.8GHz frequency range and the other in the 2.4GHz band. The radios, from Ubiquiti, each run on Power over Ethernet and consume 8 watts or less of electricity, lower than typical enterprise access points. The 5.8GHz radio uses 2x2 MIMO (multiple in, multiple out) technology for increased throughput. The 2.4GHz radio has a single antenna connector.

Theoretically, an 802.11n radio with 2x2 MIMO can deliver throughput of more than 300M bps .The fiber running down the side of Lighthouse Peak could easily handle that, though the Ethernet switch being used with the radios is limited to 100M bps.

However, two problems prevented Pozar and Peterson from setting up a broadband connection that would have made online gamers on the mainland truly jealous. One is atmospheric attenuation, in which a signal traveling from land to island can be distorted by conditions such as rain or fog. Over 50km, those conditions can weaken a signal, and fog in particular is a well-known feature of the coast off San Francisco.

A related problem, called refraction, can occur even under the best conditions. When it's warm and sunny between San Francisco and the Farallones, the seemingly clear air may be filled with evaporating ocean water that rises to a few hundred feet, then suddenly stops. When the wireless signal hits the line between moist and dry air, the barrier can act like a lens, bending the signal out of its intended path and down into the water.

Because of refraction, the rare days when the Farallones can be seen from the mainland often are the worst for communicating with the islands. The network went out during a stretch of good weather just last week, Pozar said.

Both atmospheric attenuation and refraction cause signals to fade. The engineers tackled these problems with several steps, including using powerful antennas and narrow channels. An IEEE 802.11n radio can use channels as wide as 40Mhz, but Pozar limited the channel width to 10MHz, creating a more focused signal. This sacrificed speed for distance.

"Because we're going over 50 kilometers of water, I'm being extremely conservative. So I've actually cranked this back to only around 12 megabits," Pozar said.

The radios are bolted to the base of the lighthouse and connected to a router that's built around a Soekris Engineering communications mainboard, and in turn to a Cisco Catalyst 2950 Ethernet switch. Pozar and Peterson could have set up another Wi-Fi network between the lighthouse and the biologists' homes, but they opted for fiber as a faster, more reliable solution. They lay the single-mode fiber right down the mountain alongside a powerline.

The 5.8GHz Wi-Fi access point is the primary link, the 2.4GHz Wi-Fi is the backup, and the seismologists' older wireless LAN gear is the fallback to that, Pozar said. This setup fuels nearly everything digital that happens on the Farallones, including wildlife reports, blogging, Web surfing and VoIP (voice over Internet Protocol) on the VoicePulse service. Pozar estimates uptime at more than 98 percent.

"There's never been a day when the Internet has been fully down," Bradley said.

The Academy of Sciences has also been happy with performance of its webcam, which delivers 30 frames per second of near-high-definition video using 512K bps of the Wi-Fi link. Researchers at the Academy, the Fish and Wildlife Service and the bird observatory move and zoom the camera remotely.

"People have been excited to get a glimpse of the island," said Kathi Koontz, a project manager at the Academy. "No member of the public can physically set foot on the island, so it's giving people a unique view that they haven't been able to get previously." The Academy now plans to upgrade the webcam to higher definition (consuming 1M bps) and use it in a temporary exhibit about the Farallones in its museum, Koontz said.

The whole project, funded by the Academy of Sciences, cost less than US$10,000, Pozar said. The City of San Francisco donated tower space on Twin Peaks for the mainland antennas and access to its fiber network for backhaul from there. The Internet Archive, in Berkeley, donates Internet transit for the network.

Despite all the moral and financial support, setting up and working on the network has been an especially challenging IT project, according to Pozar. During the birds' nesting season, hard hats are required for protection against divebombing, and protective clothing is needed to keep off the birds' pungent droppings, he said.

The project was also an exercise in preparation.

"I sort of liken it to the Apollo moon missions," Pozar said. "You have to have everything packed up and take everything out there that you can, and expect every sort of contingency, because there's no Radio Shack on the island."

Because of the complex logistics of getting a boat ride out to the islands and waiting for the right weather, it could take months to get back out to the Farallones if something went wrong, Pozar said. As a precaution, he set up the radios for the islands and tested them on a hill in San Francisco before hauling them out for installation.

Still, Pozar, who says he has worked as a radio broadcast engineer in the Northern California delta, set up Internet access at low-income housing projects in San Francisco and started the city's first ISP, has no regrets.

"The Farallones was just such an ultra-cool hack," Pozar said.

Copyright © 2010 IDG Communications, Inc.

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