A key hurdle to widespread gigabit-speed Internet is the high cost of getting fiber optic lines over the last mile — from the fiber backbone in nearby streets to each house.
But increasingly, cellular operators, broadband providers including Google Fiber and several start-ups are exploring a new, less expensive way to bridge the last mile gap: wireless technology.
Google Fiber — which named San Diego as a potential city for building an ultra-fast fiber optic Internet network — said last month that it would pause future fiber optic rollouts in San Diego and seven other potential Google Fiber cities while it explored new approaches.
Among those is wireless, including high frequency airwaves, which can deliver gigabit data rates over short, line of sight distances but also tend to bounce erratically off obstacles and degrade in rain or fog.
"Millimeter wave is one of several different technologies [Google Fiber] is looking at, but it does seem to have the most promise," said Karl Bode of broadband watchdog DSL Reports.
"There are line-of-sight issues here, and weather can impact signal," Bode said. "As such, you need transmitters relatively close to the home, meaning you still have some notable deployment costs. Still, that's cheaper than digging up streets, which is why Google is interested."
Don't expect Google Fiber to incorporate wireless into fiber networks anytime soon. There are still many questions about how viable wireless can be, and what licenses would be required from federal regulators in various airwave bands.
But recent improvements in antenna technology and beam-forming techniques to more precisely steer these high frequency airwaves are fueling optimism about their ability to span the last mile. Certain high frequency airwaves have been earmarked to become part of the spectrum dedicated for upcoming gigabit class 5G cellular networks.
Last week, Verizon Communications Chief Executive Lowell McAdam spoke at the Intel Capital Global Summit in San Diego about the bandwidth capabilities of millimeter wave 5G technology, calling it "wireless fiber," said Murthy Renduchintala, president of Intel's mobile and Internet of things group.
"He's basically saying if I can get high-speed wireless fiber to the house, it would make deployments much more rapid and much more economically viable," Renduchintala said.
Verizon built its Fios fiber optic TV and Internet network in nine states but stopped expanding into new markets in 2010, in part because of high installation costs.
In October, San Diego's Qualcomm said it would deliver the first 5G mobile modem chip, called the Snapdragon X50, next year for testing. It expects to reach top-end download speeds of 5 gigabits per second when shows up in commercial devices in 2018.
Qualcomm is targeting the X50 for mobile handsets. But analysts think that "fixed wireless" markets — such as boxes that link the fiber optic backbone in the street to individual homes — also are potential uses of this technology.
With five gigabits of bandwidth, users could download an entire digital movie in less than a minute.
Skyriver, a San Diego start-up, recently completed field trials for millimeter wave point-to-multipoint technology to fuel gigabit broadband. The company said it has been acquiring spectrum rights in millimeter wave bands in several markets.
For Google, affordable bandwidth is the key to its Web businesses such as Google search and YouTube. In 2012, it got into the Internet service provider business with Google Fiber. Today, 12 cities nationwide either have Google Fiber up and running or are in development.
Google has worked with these cities to install fiber on existing power poles, among other things, to keep costs down. The company's entrance into the high speed Internet business has spurred cable and telecom competitors to ramp their fiber optic rollouts — though most have limited expansion to new housing developments.
Google has been talking with eight additional cities — Los Angeles, San Diego, San Jose, Portland, Phoenix, Chicago, Jacksonville and Tampa — as the next potential markets for Google Fiber expansion.
Last month, it put those plans on hold, raising concern that it had lost its enthusiasm for Google Fiber.
In its third quarter earnings conference call, Ruth Porat, chief financial officer of Google parent company Alphabet, said the firm will continue to be an Internet service provider in the 12 cities where fiber is deployed or in the development pipeline.
Last year, Google purchased San Francisco-based Webpass, which uses point-to-point microwave to deliver high speed Internet to urban apartment buildings, condo complexes and businesses in San Diego and five other cities.
The company is licensed in the 70/80 gigahertz spectrum bands, according to a Google spokesperson. It installs large antennas on top of buildings to deliver point-to-point Internet. Its then distributes bandwidth to each apartment or office.
"In San Diego, Google Fiber and Webpass will work together to extend and accelerate deployments via point-to-point wireless," a Google spokesperson said in an email. "In addition as we've said, we're actively expanding our road map to include innovative technologies like fixed wireless that expand access to more people, faster."
A key question is how far can a high bandwidth wireless signal travel to connect the fiber node to homes? Some companies have claimed the signals can travel a bit over a mile (about two kilometers) in tests. But industry analysts think it's unlikely to be that far in actual deployments.
"I don't think there will be any trouble going a couple hundred meters, but I think a lot of engineers are trying to figure this out," said Christopher Taylor, director of radio frequency/wireless components at industry research firm Strategy Analytics.
Freeman writes for the San Diego Union-Tribune.