Bandwidth: How Much Is Enough, and Where Will It Come From?

The questions have been around the cable industry since the first coax was spooled between two amplifiers to improve TV reception: Is there enough bandwidth, and how can that bandwidth be best used to serve a variety of purposes? The questions are being revived today. No one is screeching that the sky is falling, but cable must face a bandwidth-crunching future where there are more problems than just how to add the 18th version of the Discovery Channel. Of the three, the most threatening-must-carry legislation-is the least likely to happen. It’s also the one that would create the most immediate and impactful turmoil. Government threat "If the government were to require that, we would accelerate efforts to move to all-digital to try to recover the analog spectrum," says a senior industry technologist speaking on background. "The problem there is you have to make a big investment in set-top boxes to make those (existing analog TV) sets work." Still, the source says, the government doesn’t usually interfere this deeply in the industry’s workings, "and when they do, it’s always a mistake. For the government to mandate we do fiber or something like that would be very bad for us." Must-carry opens a nightmare scenario that would stretch, and probably snap, cable’s 15+ years-old hybrid fiber/coax (HFC) network structure. Anything short of that draconian measure, though, could be handled by the network’s built-in flexibility. That does not mean, though, that cable can sit back and enjoy the benefits of the networks without doing some work to make them more efficient or to squeeze out every ounce of available bandwidth because the cable TV model, and what it means for the network, is changing. "We need to do something," says David Large, an industry consultant who has been sounding alarms about cable’s potential bandwidth dilemma at various trade gatherings. Large argues that cable’s networks were designed to handle linear, predictable schedules of broadcast program content. Symmetrical services such as on-demand are making that model obsolete by consuming chunks of downstream and, importantly, upstream bandwidth. Since cable was built on the model of broadcast video, there’s very little upstream available to handle increased demands, and there is a crisis in waiting. "We clearly have to do something about the upstream very soon," Large says. No reason to panic There’s no reason to panic, says Chris Bowick, Cox Communications’ CTO, who pointed to a number of ways that cable can better manage the bandwidth it has to meet future demands. "One tool that we have is switched digital broadcast or switched digital video," said Bowick. Cox trialed switched video in Tyler, Texas, and "the technology looks pretty promising for the future." Time Warner Cable, too, is following the switched trail and "will begin rolling out switched digital in a couple markets this year," a corporate spokesman said. "Switched digital will save us bandwidth to continue expanding our VOD (video on demand) and HDTV programming, as well as other new services." Another way to squeeze more bandwidth from what’s already there is to reduce the size of nodes where the "last-mile" shared network can become congested. Nodes were designed to be split when traffic got heavy; so when they need to be chopped smaller, it’s "a good problem to have," Bowick says. Most U.S. MSOs also are following their Canadian brethren down the digital simulcast path, transmitting an all-digital lineup to subscribers with digital set-tops while maintaining an analog stream for (analog) TV sets and nonpremium subscribers. The goal is eventually to move everything over to digital and reclaim analog bandwidth. "That will work as the digital boxes get cheaper," says the senior industry executive. Managing bandwidth that’s there Cable can manage the bandwidth that’s already in place. Vyyo’s Xtend Networks subsidiary and Narad Networks are both pitching technology they say will let operators squeeze more out of existing bandwidth without touching-or, in some cases only lightly touching-the HFC infrastructure. Cox uses Xtend to pick bandwidth off the residential network and move it into a space above the 860 MHz spectrum up to the 3 GHz level. That new stream of bandwidth can then feed targeted business customers with high-speed data without running fiber to the premises because it is, for all intents and purposes, virgin bandwidth residing in existing coax. "The capability inside that piece of coax is tremendous," says Bill Keating, Xtend’s CEO. "The existing plant, the existing coax, the existing HFC network, with small additions of Xtend’s technology, can dramatically advance the bandwidth that’s lying there waiting." Xtend then lets cable operators target customers or groups of customers with high-bandwidth offerings. While starting primarily as a way to feed commercial users off the residential network-and this is the way Cox is doing it-it can also be used for bandwidth-hungry residential services such as multiple channels of HDTV running alongside super high-speed data. Disrupting the network Xtend, though, requires a network disruption to put in the equipment, says a senior industry technologist, and that can be a problem when cable networks are increasingly running voice services that must be online all the time. "It’s a great technology to greatly increase your capacity, but you have to take the system out of service to cut these amps in," the industry source says. "That’s an engineering challenge for them, but they’re liable to come up with an answer." It’s not a serious problem, responds Keating, who says downtime is minimal and is part of any normal cable operation. "Almost anything you do, you’re going to do during network downtime," he says. "It’s a minimal amount of downtime for all these benefits to have hundreds of channels of HD and an infinite amount of data speeds." Narad, like Xtend, uses its technology to target customers. And, like Xtend, Narad has an MSO backer-Cablevision Systems, which is using the technology for commercial customers with symmetrical speeds up to 100 Mbps. In its initial deployments, Cablevision is holding those speeds to 50 Mbps symmetrical but, if needed, will use the greater capability. And, like Xtend, it’s all working over existing coax networks. Bidirectional bandwidth evolution "There’s an evolution of our ability to offer higher speed bidirectional services, and Narad is one way of doing it," says Wilt Hildenbrand, Cablevision’s executive vice president of technology and engineering. While the majority of Cablevision’s subscribers, both commercial and residential, can be fed by existing "wholesale" DOCSIS-based technologies and their increasing speeds, "I started looking at how to send even higher speeds, non-DOCSIS structured data, to small businesses over coax," said Hildenbrand. "We were comfortable enough with Narad to move it out of the lab to what we’re going to call a limited deployment with a couple customers who have very specific needs … for high symmetrical data rates." Though the technology’s use is targeted to specific customer needs, Hildenbrand admits that he’s enamored with the technology and what it can do and finds it "intriguing that I can get to 100 Mbps symmetrical data on coax without having to rebuild, without having to extend fiber we have out there in the network, even though we can do that as well," he says. Narad, though, goes counter to an industry move to follow DOCSIS to higher speed plateaus, eventually using DOCSIS 3.0 and channel bonding to deliver unthought-of speeds over existing networks. Standardized DOCSIS technology provides a more "wholesale" approach to data delivery where everyone can get a piece of the bandwidth vs. Narad’s targeted out-of-band play. "These two coexist," insists Chuck Kaplan, Narad’s COO. "One does not displace the other. That doesn’t conflict with the need for additional spectrum for additional kinds of services, particularly telecom services, whether they’re voice or data. Commercial exacerbates the issue." Network surveillance Yet another way to increase bandwidth capability is not to increase it at all, but to manage it better. That’s the approach of service control switch vendors such as Ellacoya, P-Cube (now Cisco Systems), Sandvine and Tipping Point (now 3Com). Ellacoya’s gear, for instance, monitors DOCSIS network usage, determines who’s consuming what bandwidth-or more specifically, data capacity-and lets operators determine where the bandwidth should be targeted. It also helps cable operators deal with yet another bandwidth speed bump: peer-to-peer (P2P) users who consume more than their share of data networks with symmetrical data capacity-rich content transfers. "(Cable operators) can use the platform to enforce policies about how much traffic should be allowed. That frees up capacity that was going to peer-to-peer file sharing and allows it to be used for interactive applications," says Paul Varley, Ellacoya’s product manager. "The net result is the subscriber perceives a better experience because the interactive applications perform better; the Web pages come faster; the e-mail comes faster; IM (instant messaging) is not slow." In other words, by keeping a closer watch on what’s happening on the network, an operator can offer the perception of better speeds without doing a thing to the plant. "There’s a lot of life left in the plant," says a senior technology executive speaking on background. "I’m not worried about the ultimate capacity of the plant." What does worry this executive and others is "the way the spectrum is used." And that, perhaps more than anywhere else, is where the industry is headed, looking at such things as digital simulcast and a gradual migration of analog to digital; switched digital; higher efficiency modulations; and using specific technologies to jury-rig what’s already in place. "There is a bandwidth squeeze because of the inefficiency of the current plant," the senior exec says. It is, he says, "the same story the industry has had for a very long time. We are very effective in deploying evolutionary technology; we take what we have in the plant, and we evolve it toward a better network, and we avoid these big revolutionary steps that cost so much money." The competition, though, is taking those big revolutionary steps and spending a lot of money to one-up cable’s offerings. No matter how the story is spun, fiber-to-the-premises (FTTP) is capacity-heaven that HFC will be hard-presed to match. It’s also a strategy that’s been dismissed as too costly and too far out to be very damaging to cable in the near term. "Those guys are serious. They’re going to go off and do this, and they have plenty of money," one senior MSO tech executive says. "It would be a mistake for us to blow them off; however, we still have so many weapons we haven’t even pulled out of the quiver, and I feel much better about being able to do this." Even if they do come, it shouldn’t make a difference in how cable manages its bandwidth, says Hildenbrand. "I try not to focus on that. I focus on doing the best we can with what we’ve got," he says. Jim Barthold is a contributor to Communications Technology. Reach him at [email protected].