Broadband Walks the Last Mile
If you want fast access from home, your only hopes are cable-modem and DSL services. Or are they?
Some happy day the fiber-optic pipelines that circle your metropolis will branch all the way into your home. Until then, most of us seeking broadband connections will depend on the slower wires already found at home: copper phone wire carrying digital subscriber line (DSL) links or coaxial television cable for cable-modem services.
But these twin pillars of “last-mile” broadband are being joined by wireless options, including two-way satellite services and cellular-like fixed wireless technologies. In the coming years we’ll also see digital TV datacasting, wireless optical networks, and maybe even dirigibles spreading digital manna down.
By year-end, there will be 10 million cable modem subscribers worldwide versus 11.5 million DSL subscribers, according to Cahners In-Stat. While that’s about double the number from the year before, it’s only a fraction of the 400 million-plus Internet users worldwide. By 2005, the study predicts, only half of all U.S. Internet subscribers will enjoy broadband connections.
So why the delay?
For cable modem and DSL installations, it’s the battle in the streets: roads need to be dug up, permits pulled and off-duty police hired. Do-it-yourself modem installation kits are streamlining the slow pace of hooking up new users, but technicians still need to be dispatched to activate connections outside the house, and providers must still invest millions in technical support. Wireless alternatives avoid the cost of digging up streets but require technicians to mount and carefully orient dish antennas.
There’s one bright spot in this struggle: it brings fiber-optic lines deeper into the neighborhoods. As a rule of thumb, the closer a home is to the fiber node where optical signals are converted to electrical, and the more fiber nodes that are deployed to serve each area, the higher the bandwidth you enjoy. As a result of this steady expansion of fiber, the 256-kilobit-per-second to one-megabit-per-second connections typical of today’s consumer broadband should range from one to three megabits per second over the latter half of the decade. That’s enough to permit applications such as video conferencing and video on demand, which perform poorly over current broadband networks.
What’s Fast Enough?
Last-mile performance already outpaces the speed of an individual connection over the Internet at large. A typical broadband modem runs at about 600 kilobits per second, but that’s the speed with which it connects to the service provider, not a typical site on the Internet. No matter how fast your modem, a variety of bottlenecks limits Internet access speed to an average of about 300 to 500 kilobits per second.
That average should rise over the coming years, but due to soaring demand, it won’t rise as quickly as the increase in last-mile performance. So you’ll probably see only incremental speed improvements over the next few years. Moving up from 56-kilobit-per-second dialup connections to 500 kilobits per second is far more noticeable than upgrading from 500 kilobits per second to one megabit per second. As broadband providers focus on signing up new subscribers, they’re not very interested in pushing your bandwidth higher.
It All Depends on Your Connections
Increasingly, the quality of a broadband service provider’s connection to the Internet is becoming as important as the speed of the broadband modem. Many broadband providers tap content distribution networks to avoid key Internet bottlenecks, grabbing media straight from content providers. Going one step further, some broadband providers store streaming media on local servers, thus making it available to you, the customer, at tiptop speed.
If the difference between local- and long-distance access continues to widen, broadband users may well spend more and more time sampling the higher-quality, but much more limited, content offered locally by the provider rather than suffer the lower speeds of the open Internet. The prospect of last-mile “super broadband” services that combine the visual quality of television with the interactivity of the Web is attractive to broadband providers, big media companies, advertisers and many consumers. Others see these “walled gardens” as a threat to open competition and diversity (see “Web Behind Walls”).
Decades from now we’ll look back at today’s so-called “broadband” services and wonder how we could have tolerated such primitive experiences. In the meantime, here’s what we can expect from cable, digital subscriber line, satellites and fixed-wireless and from further-out alternatives such as flying platforms.
Cable Modems: Setting Speed Limits
You could get much faster connections, if the cable guys cared.
Thanks to their high-capacity coaxial cabling, cable modem services offer a greater potential for speed than digital subscriber line (DSL). But in the real world, performance is only slightly faster than DSL.
That’s because while cable networks are theoretically capable of between 10 and 27 megabits per second, cable operators usually apply limits of between one and two megabits per second per user. And because bandwidth is shared, most users rarely achieve those limits. The more neighbors who log on, the lower the speed.
“The average cable modem speed is between 500 and 750 kilobits per second,” says Mike Paxton, an analyst at Cahners In-Stat. Late at night, says Paxton, you often get up to one-megabit-per-second performance, but during peak hours, the speed often drops between 200 and 300 kilobits per second.
To improve performance, cable operators are extending fiber-optic networks deeper into neighborhoods and creating more fiber nodes (the junction boxes that convert the higher-capacity fiber-optic signals to electrical signals running over coaxial cable). By reducing the number of houses being served by each node, bandwidth increases.
In addition, cable operators can open up more bandwidth by reducing the number of TV channels running over the same networkalthough it’s rarely economically feasible to do so.
In fact, given the general lack of competition they face, cable providers are not terribly motivated to improve your experience. But they are busy adapting their networks and modems for telephony, a capability already offered by most DSL providers. Modems adhering to version 1.1 of the Data Over Cable Service Interface Specifications cable modem standard will arrive later this year, making it easier for cable providers to deliver voice service over the same lines used for TV and Internet access.
DSL: The Bandwidth Plays On
As phone companies reach out to touch more broadband customers, they will slowly boost bandwidth.
Running over the same copper wires as telephone services, digital subscriber line (DSL) is inherently a slower technology than cable. Yet it holds some tricks up its sleeves.
While cable modems operate much like PC adapter cards hooked up to a local area network, DSL modems are more like dial-up modems. They’re based on a fixed connection to a similar modem at a phone company central office, so your bandwidth shouldn’t change even when your entire neighborhood decides to watch the Academy Awards online. (One caveat: certain providers do “oversubscribe” their networks, so that a central office’s connections to the Internet get overloaded, thus reducing bandwidth for all.)
Although typical DSL lines deliver about 500 kilobit-per-second service, speeds will climb. Cahners In-Stat analyst Ernie Bergstrom says that most new consumer DSL lines deliver about 784 kilobits per second downstream and 384 kilobits per second upstream. Over the next few years, “they’ll try and drive that up to one megabit per second with better multiplexing equipment,” says Bergstrom, referring to the core technology that sits between DSL and fiber-optic lines at the central office.
These cautious speed improvements won’t require either additional fiber deployments or new customer equipment. In fact, existing DSL modems can handle between 1.5 to 7 megabits per second. Almost no one gets that kind of speed today, basically because of DSL’s distance limitations and because phone companies are too busy signing up new customers to worry about offering premium services.
Boosting It Back Up
Phone companies sell DSL service to consumers in an “asymmetric” ADSL format in which downstream bandwidth is much higher than upstream, similar to cable.
With symmetric DSL, the upstream and downstream bandwidths are balanced, making it useful for applications such as videoconferencing or Web hosting, both of which require large upstream capacities.
Most of the money made in the DSL market comes from selling symmetric DSL services to small businesses, because $300 a month seems like a bargain to a business that’s been shelling out $1,000 a month for conventional T1 1.5-megabit-per-second service.
On newer cable networks there’s nothing stopping providers from delivering similar symmetric services, but older networks require costly upgrades to increase the “back channel” for uploads.
While the cable companies dominate the affluent suburbs, inherent distance limitations in DSL technology have largely restricted service to more urban residential areas. Beyond 12,000 feet from the closest central office, customers are generally limited to 256-kilobit-per-second service, and few providers serve customers beyond 15,000 feet. New line-extension equipment has been developed that can extend DSL’s reach to between 18,000 and 24,000 feet. It will take years to extend these networks, however, and, unlike cable, DSL will continue to trade off bandwidth for distance.
“DSL was a little slow in getting started because of the distance problems,” says Bergstrom, “but [providers] are feverishly out there trying to extend their services.”
Help from a Steady Fiber Diet
Within five years, Bergstrom says, DSL providers will accelerate their projects to extend fiber deeper into neighborhoods and closer to homes. As a result, bandwidth will start to rise into the multiple megabits per second.
Eventually, DSL providers will offer so-called Very High-Speed DSL (VDSL) to customers within a few thousand feet of a central office. Requiring new customer equipment, VDSL is capable of speeds between 3 and 20 megabits per second, enough bandwidth for video-on-demand services. Qwest is experimenting with VDSL in the Phoenix area, but such networks won’t be widely available for another decade. By then, cable modem networks should be running at similar speeds.
Satellites Finally Go Both Ways
Vendors now can dish out broadband without any need for dialup.
If you are beyond the reach of wired broadband providers, look to the sky. Satellites are hereas long as you have a clear southern exposure.
Until recently, satellite services were limited to Hughes’s DirecPC, an expensive, one-way service that required a separate land-based Internet account for the return channel.
Last fall, however, a partnership between Gilat Satellite Networks, EchoStar Communications and Microsoft introduced a two-way service called StarBand that sells for around $70 a month. StarBand’s service offers up to 500 kilobit-per-second downloads and 150 kilobit-per-second uploads.
Earlier this year, Hughes introduced a two-way version of DirecPC that offers up to 256 kilobit-per-second uploads along with the standard 400 kilobit-per-second download package. Hughes’s partnersincluding DirecTV, EarthLink and Pegasus Communicationslaunched the service at similar price points this year.
These early satellite services transmit over the same low-frequency (11.7 to 12.7 gigahertz) Ku-band transmissions used by satellite TV, and after some minor modifications can use the same dish. They can’t quite compete with landline broadband in either speed or cost.
What’s more, due to the over-35,000-kilometer hops between the home, the satellite and the land-based satellite facilities, satellite services suffer from high latencythe time lag between initiating an Internet request and receiving a response. Usually, the half-second delay is hardly noticeable, but it’s all too obvious with real-time applications such as multiplayer games and video conferencing.
In a few years, a new generation of satellites using the higher-frequency (18 to 31 gigahertz) Ka-band will reach the skies, promising performance between 512 kilobits per second and three megabits per second. (As with cable, satellite performance degrades depending on the number of users in a given service area, making actual rates difficult to estimate.)
Several companies, including Hughes and Alcatel’s SkyBridge subsidiary, plan to introduce Ka-band Internet services. At first, most of these services will target businesses, but a few will also offer services to consumers. Some services, such as SkyBridge, use a string of Low-Earth-Orbit satellites flying at only about 1,500 kilometers above the surface, thus improving bandwidth and reducing latency.
Due to the high costs and risks of launching and maintaining satellites, most analysts expect them to play a fairly limited role in the U.S., primarily serving rural customers. However, the technology may well lead the market in developing nations that lack landline networks.
Fixed Wireless Fills Gaps
Businesses forgotten by cable and DSL can select from a growing menu of alternatives.
Like satellite access, fixed wireless service will fill the gaps left by cable-modem and DSL coverage in the inner city, smaller communities and isolated suburbs. Encompassing a variety of cellular, radio and microwave technologies, fixed wireless requires a dish antenna on the roof, much like a satellite dish.
Many smaller providers offer fixed wireless service, but the major players in the consumer area are long-distance carriers such as WorldCom and Sprint. Similar to cellular technology, these fixed wireless services deliver much higher bandwidth than mobile broadband services because the system does not have to track down a moving target and because the receiver is more powerful than a cell phone’s.
Launched last November in Memphis, WorldCom plans to expand its service in 30 markets nationwide by the end of 2001. Its initial focus will be on small businesses and apartment complexes. A similar service from Sprint is now available in over a dozen U.S. cities.
Most fixed wireless services range from 384 kilobits per second to 1.5 megabits per second, with a 32- to 56-kilometer range from each base station. For all but the slowest and lowest frequencies, line-of-site orientation is required, and performance is lowered by excessive foliage, sometimes requiring ungainly roof platforms to reach above the leaves.
Technology from Cisco Systems and others, however, is overcoming the multi-path-interference problem caused by foliage and increasing the bandwidth possible with non-line-of-sight receivers. Cisco’s technology, called Vector Orthogonal Frequency Division Multiplexing, boosts overall bandwidth by more than 20 percent. And because antennas don’t need to be several dozen feet tall to peer over trees, it reduces installation costs while increasing customer demand.
Mobile services in Europe and Asia currently deliver limited broadband services to cell-phone users. Within a few years, faster so-called 3G services will begin to offer mobile bandwidth of up to 384 kilobits per second (see Mobile Web vs. Reality). That may not be much, but those very same 3G transmitters also can serve fixed receivers with up to 2-megabit-per-second service. If demand for mobile broadband is not as high as expected, 3G providers may switch to the fixed-access market.
On the high-end of fixed wireless services, companies such as Teligent serve up point-to-point digital microwave services at a much higher frequency range. Aimed at corporate customers, these high-end fixed wireless services offer performance between 20 and 150 megabits per second. Although pricey, limited in range and prone to weather interference, their high-bandwidth capability may give them a future role in consumer broadband service.
Airing It Out
Competing with digital microwave is free-space optics, or fiberless optical, which shoots light beams through thin air. AirFiber, Terabeam and other companies provide laser-based wireless services that can potentially offer bandwidth in the hundreds of megabits per second. (Last month Texas Instruments even unveiled an optical alternative that lets you install 100-megabit-per-second Ethernet networksrather than just point-to-point links.)
Because the laser signals can penetrate an office’s glass windows, you don’t need to plant a dish on the roof. However, there are distance limitations, and fiberless optical is particularly susceptible to weather interference, like heavy rain or snow.
Tuning in TV Data
As broadcasters get ready for digital TV, they’ll become “datacasters” as welldownloading massive mounds of info for all you Internet mouse potatoes.
By law, TV broadcasters must convert completely to digital broadcasting capability by 2006. In addition to using their new spectrum for providing high-definition TV broadcasts, many broadcasters want to tap it for broadcasting data at rates of several megabits per second.
With services such as those being developed by iBlast Networks, broadcasters would continually datacast the most popular Web pages and other downloadable content to PCs equipped with digital TV adapter cards and small indoor antennas.
Although a separate Internet access solution would be required for the upstream return path, the idea is that the datacasting service can push so much of the Web onto your PCapproximately 75 gigabytes a day in the case of iBlastthat you’ll spend more time interacting with their hard drives at instantaneous speeds than requesting information over the Internet.
Broadcasters have a lot of money to throw at this technology, and they don’t want to be left behind. iBlast completed a three-month field trial in April and hopes to introduce commercial services by year-end.
Satellite-like services without the cost of launching satelliteswhat’s not to like?
Two other broadband alternatives are truly blue-sky.
Sky Station, headed by Alexander Haig, plans to fly a fleet of 250 huge dirigibles above major cities, providing 2- to 10-megabit-per-second connections. Using the 47-gigahertz spectrum, each geostationary, solar-powered blimp is designed to hover at an altitude of 21 kilometers, providing service to over 100,000 broadband users spread over 19,000 square kilometers.
In addition to Internet access, the Sky Station platforms should be capable of providing telephony, videoconferencing and TV service. Unlike satellites, time lags should not be a problem. Sky Station, which hopes to launch its first platform in 2002, claims that latency will be less than 0.5 milliseconds compared to 250 milliseconds for typical satellite services.
The HALO Network, planned by Angel Technologies in partnership with Raytheon, is testing high-altitude planes. These piloted aircraft would circle major metro areas at the height of 52,000 to 60,000 feet, offering two-way communication at anywhere between 1 and 12.5 megabits per second.
Each service area would stretch between 50 and 75 miles in diameter. Three planes would rotate in eight-hour shifts, handing off their digital payloads (equivalent to 650,000 T1 1.5-megabit-per-second circuits) before landing to refuel.