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First Look at New Long-Range Wi-Fi Technology

First Look at New Long-Range Wi-Fi Technology

My first encounter with a microcomputer was thrilling. I didn't know about "disruptive technology" yet (it was 1979), but it certainly changed my life. I dreamed of carrying a computer around with me all the time. The same thing happened the first time I saw a Web browser. More recently, the day I finally got a Wi-Fi connection to work, I wandered around yelling, "Look at this!"

Then I wandered too far and the Internet stopped. "Aw, look at that!" I cried. But I am now dreaming the dream. You know the one. High-speed Internet, all the time. But there are big-time challenges locating a hotspot, and finding the signal inside that hotspot.

I've always thought there was something just a little wrong with the plan to bring Wi-Fi to the world though, and it's all about the size of the wireless network. The 300-foot range is just too small. When I hear 802.11 fans talk about how the hotspot size is "perfect for networking" I remember being told that 64K of memory and 5MB hard drives were "perfect" for computers. I didn't buy it then. I don't buy it now.

I'm okay with the Personal Area Network (PAN) of Bluetooth (about 10 feet). I'm even okay with the 300-foot range of a wireless LAN for a house or small office. It's when people talk about stacking hotspots together to "cover an area" that my hand goes down.

I'm going to throw a little math around. Let's say we'd like to provide Wi-Fi access to Golden Gate Park in San Francisco, which covers one thousand acres (four square kilometers). Using the generous 300-foot range (92 meters, or an area of .025 square kilometers) of Wi-Fi and my handy calculator (see box, entitled, "The Ron Dennis Handy Wi-Fi Transmitter Calculator"), we'd need to install about 160 transmitters for wireless coverage! (See Figure 1.)

I don't know how large the San Francisco International Airport terminal buildings are, but I'm guessing they would be a comparable coverage challenge. Somehow, we are supposed to believe that installing and maintaining 160 transmitters is "perfect." Maybe for someone else, but I'd rather use fewer transmitters for coverage and a few more for backup. And, I don't want to just crank up the power (which is illegal anyway) or use a different standard. A dream you say?

Well it was a dream until I sat down with my new best friends at a new company, Vivato, and got a first-look briefing about their new Wi-Fi technology that has a range of 7 kilometers. This raises the Wi-Fi range from 300 feet to nearly 23,000 feet (or 4.3 miles)! Using my calculator, we would need only one of these new transmitters to "Wi-Fi the park."

In practice, according to Ken Biba, Vivato's CEO, we'd need a few more than one. "We'd need two or three," he said.

I can almost hear you asking: "Ron, that's outdoor range, what about indoors?" Well, that's what I asked Biba and Vivato's vice president of marketing, Phil Belanger, when we sat down for dinner. Indoors the effective range can go way down, sometimes to only 50 feet or so, and the 802.11 data rates drop off with distance, barriers (like walls), and interference (from things like microwave ovens).

"Our range does go down too," said Belanger. "It goes down to 2 kilometers with no data-rate drop off."

I muttered a favorite expletive quietly to myself and spoke up again. "Let's take a four-story office building, 20,000 square feet per floor, let's say four or five transmitters per floor for coverage, or about 20 transmitters, right?

"We could do it with one Wi-Fi switch," said Belanger quietly. "Out in the parking lot on a pole pointed back at the building."

A 'New Wi-Fi Physics'
Now you're thinking we were on drugs. I admit there was wine at the dinner, but this is the real deal. In the past two years Vivato has raised $20 million and used it to build a "new Wi-Fi physics," according to Biba, incorporating what they call "PacketSteering," a patent-pending technology that integrates Wi-Fi, Ethernet-style packet switching, and an innovative antenna scheme that extends the range of 802.11 from meters to kilometers. There is no change to the standard, the power levels, or the Wi-Fi cards in your laptop.

Vivato's Wi-Fi switching makes all the difference. In a normal 802.11 network you are immersed in a cloud of radiated signals ­ from the base station, and from all your mates who are also in the network. Everyone transmits in all directions ­ up to 300 feet (or less), and if you are free of interference or barriers, you can carry on a two-way data stream with the base station. Vivato uses a special, very sensitive antenna (and electronics) to send narrow (9 degrees wide) packet beams to you, and other beams to your mates. The antenna "finds you" by receiving transmissions from your conventional Wi-Fi client, and sends the information in your direction on a tight beam. The narrow beams can travel farther (thus the 2­7 kilometer range) with fewer interference problems.

The diagrams in Figure 2 show various deployment possibilities. With PacketSteering, wide area "hot zones" can join hotspots in the grassroots wireless revolution. Send a beam across the street to another building, and it's networked! From a user standpoint, it's all transparent. I went to sleep after dinner and dreamed of an unwired planet where I roamed free and untethered.

The next morning I wondered exactly what was in that wine, so I arranged to meet Kin Seto, Vivato's director of marketing, at a downtown hotel for a demonstration. San Francisco lay at my feet, 39 stories below. Seto brought binoculars so I could see the Vivato antenna a mile away on the company headquarters' rooftop. It looked like a tiny square of silver. According to Seto, this was the demo setup Vivato used to convince the FCC that their technology was within the power limits set for 802.11 and would not pose interference problems.

We fired up a laptop and a PDA, both equipped with off-the-shelf Wi-Fi cards, and were immediately connected at high speed to the Internet. We watched movies and talked about the technology.

"Can I move around up here and still get a signal?" I asked.

"Of course. The beam is nine degrees wide, so there's plenty of room. Also, there are several radios in our system," said Seto. "One of them is dedicated as a scanner, looking for signals from users. Once a user is found, another radio sends a beam out and lights the user up. That switch covers a 90-degree range, so you can be here, then move across town, and get a connection as easily as we just did. Also, the same scanning technology can be used to find the rouge wireless networks that are potential security leaks in a company."

John Richey, Vivato's technical marketing manager, joined us for lunch. We talked about my Golden Gate Park example and they both agreed that three transmitters would do the job. "It would be great to do something like that to get the word out," said Richey. He told me about a project he did years ago, an attempt to Wi-Fi a small town with hundreds of transmitters ­ a major headache that would be much less complicated with this technology.

Vivato is working on a whole different scale for Wi-Fi, and now I had seen it in action. I wanted another point of confirmation, so I swapped e-mail with Geoff Baehr, general partner, U.S. Venture Partners (USVP), who led Vivato's $20 million funding round last year.

Why Vivato?
I asked him why Vivato? "We knew Ken Biba due to his previous work with USVP, Xircom, and Agilis," said Baehr. "Good ideas don't hang around long, so we jumped on the opportunity. We decided to invest using the usual criteria: market, team, technology, finance."

Baehr is right on about the team. The core team members of Vivato are veterans of Xircom, AirTouch/Vodafone, Hewlett Packard, Agilent, Texas Instruments, Intel, Aironet, and Alcatel. Their collective experience (integrating the disciplines of local area networks, high-performance packet switching, wireless wide area network deployment, and RF and antenna design as well as IC design) is built into Vivato's PacketSteering technology.

Baehr's due diligence for USVP included conversations with professors at MIT, Stanford, UCSD, and "mainly, loads of customers who validated the pressing pain. We sure think that Ken and crew have the generic aspirin."

He's right. I hadn't looked at it that way, but if we did have the challenge of covering Golden Gate Park with Wi-Fi, we would have headaches for sure. Vivato is more than a pain reliever though. It's providing gasoline for the Wi-Fi fire. You can visit Vivato at Products are expected in the first quarter of 2003.

Extending the Range of Wi-Fi
Radio waves are similar to sound waves. To extend the range of sound waves, such as voice sounds, you can increase the power of the waves (speak louder), increase the focus (use a megaphone or the old string and cans), or decrease the throughput speed (speak slower). The same is true for Wi-Fi range. The FCC restricts 802.11 power ­ we can't increase it. We don't want to decrease the throughput speed. The only option left is to focus the waves. There are many stories, all true, about extending the range of 802.11 to several miles using directional antennas (or even the legendary potato chip can).

Focusing the waves works fine for fixed sites, like beaming a signal across a street, as long as you don't move anything at either end. The magic of the Vivato switch system is its ability to direct multiple focused beams simultaneously, in different directions. The Wi-Fi "coverage" is actually tight beams following users as they move around so there is no lost connection.

Handy Wi-Fi Transmitter Calculator
The Ron Dennis Handy Wi-Fi Transmitter Calculator (to be used only for comparisons, not for real-life installations):
T = A/R where:
T = number of transmitters you'll need
A = area to be covered
R = Wi-Fi range area
(3.1416 times the Wi-Fi range squared)

More Stories By Ron Dennis

Ron Dennis, Wi-Fi editor of Wireless Business & Technology, is a technology pioneer and a Palm fanatic. He's now reporting for WBT from the islands of Hawaii. He cofounded Livemind, Inc., led the third-party developers group at AOL, and created AOL's Web Hosting Service and Software Greenhouse. He has also guided several Internet startups.

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Most Recent Comments
Chaur-Fong Chen 01/15/03 10:28:00 PM EST

My question is simple: Is this technology uni-directional? How can I send data from my PDA to another device 4.3 miles away? I am assuming my PDA is equipped with the regular 802.11b card.

anonymous 01/10/03 07:19:00 AM EST

The FCC restriction is a total power emitted constraint... so when you focus what you are putting out, it goes farther.

Ron Dennis 11/22/02 12:11:00 PM EST

I couldn't agree more Craig. According to their Web site, there is no increase in gain, and no problems with the FCC. To quote Vivato:

Question: How do Vivato Wi-Fi switches create the increased Wi-Fi range? With high power radios?

Answer: No. The radios transmit at the same power levels as conventional Wi-Fi products. The increased range comes from antenna gain.

Craig Cohen 11/22/02 11:45:00 AM EST

I have been over these calculations before and when you increase the gain, you inherently increase the dBM's. To focus this much power will surpass the FCC regulations. If they have found away around this, I would be very happy to deploy this product immmediately.