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From: "David S. Isenberg" <>


              SMART Letter #28- October 8, 1999
             Copyright 1999 by David S. Isenberg -- "making problems for 'solutions providers'" -- -- 1-888-isen-com


> A User-Owned, Self-Organizing Network
> Why Carriers Want the Network to Know Content Type
> Conferences on my Calendar, Copyright Notice, Administrivia

ROOFER MADNESS: Rooftop's wireless technology bypasses local telcos, and creates a user-owned, self-organizing, service-providerless network. By David Isenberg

Nokia's early September move to acquire Rooftop Communications may prove brilliant - if Nokia can manage radically disruptive technology. Regardless, Rooftop has convincingly demonstrated that the role of communications service provider is waning, and that self-configuring, self-service networks are close at hand.

Rooftop has produced a spread-spectrum radio plus packet router cleverly described by its trademark, "Unplug and Play." This device gives Internet service providers (ISPs) a link to customers that is not mediated by any infrastructure provider. In principle, the DSL-speed network formed by multiple devices could even run without an ISP, or with multiple ISPs - indeed, multiple ISPs would make such a network more robust.

Network architecture emerges as a multihop, multipoint network. Lauren Hipp, Rooftop's EVP of marketing, calls it a "peer-to-peer distributed networking scheme, a routed mesh." Each device is both a customer's access device and a network infrastructure node. Adjacent customers (up to a couple of miles apart) form a skein that is a natural extension of the Internet.

In theory, customers will be able to buy a device, take it home, plug it in, and log onto the Internet. In practice, today's installation issues include geography, roof rights, and how good a customer is with ladder, drill and screwdriver.

Each customer node needs a line of sight to at least one other node, and preferably to more than one. Unlike LMDS, a line of sight directly to a point of presence is not necessary - this is a benefit of multihop architecture. Even so, there are antenna placement issues; in the best case, the antenna can be placed in a window from which it can 'see' another node - but, more typically, rooftop is the name of the game. For longer distance hops, a directional antenna can be used.

While suburbs with one-story houses and many tall trees might never support a Rooftop network, Phoenix and Los Angeles are ideal environments. The San Francisco Bay Area already supports several beta nets. The world's developing nations often provide ideal environments - there are pilot networks in Morocco and Guinea. "It is critical technology where there is no existing infrastructure," Hipp says.

Adding customers improves throughput and robustness; a dense net has many alternate routes from a customer's premises to the ISP's 'airhead.' But slow acceptance is a palpable risk.

"The technology is promising, and looks scalable," says Bob Lucky, vice president of applied research at Telcordia. "But it could never get started because you need customers to create the mesh. I'd be afraid that one day the critical person between me and my ISP would say, 'Sorry, I just got DSL, so I'm going off the air.'"

Hipp rebuts this thinking. "We have a lot of demand," she says, "and a jump-start promotion for interested ISPs. We're aggressive about reaching the consumer marketplace. We have two priorities: cost and performance."

Today, Rooftop has two devices priced for small business: a $2,000 unit and a more sophisticated and powerful $5,000 device. Both, says Hipp, are on steep cost-reduction trajectories. They're being redesigned for better integration. Increasing volume will help, and components are getting cheaper. "Radio technology is jumping onto the digital price curve," she says.

There's room for improved performance, too. Each hop adds some 50 ms of latency. This limits the practical number of hops to three and it severely limits the quality of Internet telephony. But, Hipp says, "In the future, we think we can support telephony-quality voice. We haven't tuned IROS [Rooftop's proprietary Internet Radio Operating System] to optimize latency yet."

John Giannandrea of, a Silicon Valley ISP, is an early adapter of and testbed for Rooftop technology. He says that it gives new meaning to community networking. "The network grows organically," he says. "The ISP can get out of the business of planning network expansion."'s wireless customers include a gourmet restaurant, Global Village Cafe, whose owner (a former techie) wanted little to do with the incumbent telco. Other customers find a Rooftop installation easier than obtaining DSL - and DSL is more readily available in California than anywhere. Another factor is that Rooftop input/output is inherently symmetrical.

Will Rooftop pose an "Innovator's Dilemma" for Nokia? The "wireless DSL" aspect may be a bit disruptive. But the radical disruption will come as it fulfills its potential to make local telcos obsolete. Will Nokia be able to capitalize on this, or will it "make sense" for it to limit or kill the product because it threatens its current customers, the world's telcos?

The article above appeared in the October 1, 1999 issue of America's Network. Copyright 1999 Advanstar Communications.


Nicholas Negroponte, head of MIT's famed Media Lab, in a recent contribution to the discussion board, wrote that data networks "have no way of knowing which bits are voice and which are something else." Yet Negroponte once wrote (Wired 6.06, June 1998) about how some bits (e.g., your pacemaker reading when you are having a heart attack) are infinitely more valuable than other bits (e.g., the twinkly background of a banner ad).

Will telcos charge according to the cost of sending bits or by the value of those bits to the customers who send and recieve them? In other words, will the market be supply driven or demand driven? The telecom revolution is being fought over this very question.

Certainly the telcos WANT the network to know so they can charge according to what people value. The rub is that the costs of delivering bits are plummeting.

Let me put it another way. TV over Internet is around, say, 6 Mbits. Or about 1000 times voice. If the network doesn't know the difference, then the two extreme pricing scenarios are (a) to charge as if everything is voice, about $5.00 a minute for TV, and (b) to charge as if everything is video, which would make voice free by any current video pricing model. Of course there are other pricing models, but these define two important corners of the content-agnostic network.

AT&T is touting "facilities based competition." In other words, it wants to control the network from the core to the set top box. One of the main reasons for this is so it can know the content type at its origin -- if it comes from the video hole, you can charge differently than if it comes from the telephone hole. And you can charge a third price if it comes from the text-terminal hole.

Furthermore, one reason why so-called QoS, quality of service, is such a critical telco issue is because most QoS schemes require some knowledge of content so the network can treat e.g., voice different than e.g., data. Once you do that, the "network knows" and the telephone company charges differently for different content types.

Negroponte is correct that the current Internet can't tell voice from email, but there is no reason to assume that it will always be that way. There are some powerful forces working to turn the situation around. I hope that the content-agnostic network triumphs -- it is one of the characteristics that have made the Internet such a great success so far.


October 10-17, 1999, Geneva, Switzerland. TELECOM99, the every-four-year ITU extravaganza that always seems to surprise AT&T's leaders. I will be there 10/9 through 10/13 posing as a wild-mannered columnist for America's Network.

October 27-29, 1999, New York City. The New Economy Conference, with John Browning and Spencer Reiss. Plus an array of people who believe that knowledge is wealth, that bigger ain't necessarily better, and that there are more opportunities and fewer guarantees at the edge. I don't know what I'll be doing there yet, but I suspect I'll be there. Watch for the emergent agenda.

November 4, 1999, New York City. "TechBrains Seminar" with Merrill Lynch Technology Advisory Board members. Featuring Phil Neches (founder of database machine company Teradata), Don Norman (who wrote "Turn Signals are the Facial Expressions of Automobiles," and other worthwhile reads), open source spokesman Eric Raymond (who wrote the must-read essay, "The Cathedral and the Bazaar"), and several others, no less distinguished, whose work I don't know as well. I'll participate too. Email me if you are seriously interested in attending.

COPYRIGHT NOTICE: Redistribution of this document, or any part of it, is permitted for non-commercial purposes, provided that the two lines below are reproduced with it: Copyright 1999 by David S. Isenberg -- -- 1-888-isen-com

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