Bowick: 750 MHz Enough If Bandwidth Used Wisely

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As cable operators continue to put the finishing touches on upgrades to boost bandwidth and open the door for new services such as video on demand, they also are taking an intimate look at several technology tools and techniques designed to better utilize spectrum and bandwidth. That could remove the need for costly upgrades in the foreseeable future.

One person who is actively pondering these tools and their potential is Cox Communications Inc. vice president of engineering and chief technology officer Chris Bowick. Today, Cox has completed more than 80 percent of its plant rebuilds and upgrades.

Methods being considered or currently used to better employ the bandwidth available include grooming the digital spectrum, reclaiming analog spectrum and shifting to standards-based systems for high-speed data services.

"I continue to believe that 750 [MHz] is enough if we use it wisely," Bowick said.

"Our primary focus so far has been to not waste digital spectrum as much as the industry has in the recent past."

For example, some MSOs tap "digital grooming" technology to manipulate multiplexed digital programming, allowing them to groom out signals that aren't provided to customers, and groom in others that are. Terayon Communication Systems Inc.'s CherryPicker, which it absorbed via the acquisition of Imedia Corp., is one example of the equipment available for the task.

"In some instances, we'll take a feed directly off the satellite and fill up an entire 6 MHz chunk of spectrum with digital programming, not all of which we would necessarily offer to our customers. In essence, we're wasting some bandwidth in that channel," Bowick explained.

That's one of several concepts and tools Bowick and his team are exploring.

Another bandwidth-efficiency concept revolves around a shift to 256 QAM (quadrature-amplitude modulation) from 64 QAM in the digital downstream, which likely will grow in importance when VOD truly reaches a critical mass of cable subscribers.

Bowick estimated that a cable network's efficiency would improve by 40 percent with 256 QAM employed. It's all in the math: 64 QAM handles 27 megabits per second for a 6 MHz channel, while 256 QAM boosts that figure to about 38.9 Mbps.

"We haven't pursued that with the intent in mind of just gaining back some spectrum," Bowick said. "We just haven't had the need to do that yet. It's just a tool in our arsenal today."

Reclaiming analog spectrum is another bandwidth-saver, a point both Bowick and AT&T Broadband executive vice president of broadband services and chief technology officer Greg Braden discussed during last month's Cable-Tec Expo in Orlando, Fla.

"We're duplicating some analog programming up in the digital tier. Obviously, we could begin to reclaim that bandwidth fairly easily," Bowick said.

Before that can happen, digital take rates among cable subscribers must continue to rise to new heights. At some point, it will make sense to migrate the least-penetrated analog pay services up to the digital tier, he added.

The continued migration of high-speed services from proprietary to Data Over Cable Service Interface Specification (DOCSIS)-based systems also will aid operators in utilizing their bandwidth more efficiently. That's because DOCSIS networks occasionally are introduced in areas that originally housed proprietary gear for cable-modem services long before DOCSIS gear made it through Cable Television Laboratories Inc.'s battery of tests. That means some DOCSIS networks essentially ride shotgun with proprietary systems in some markets today.

"All of our current systems that deploy proprietary also deploy DOCSIS, though our primary purchase today is on the DOCSIS side," Bowick said. "That's not wasted bandwidth, but we could gain some efficiency by migrating to DOCSIS over time. You don't want to strand capital, so you'll only do that when you absolutely need the bandwidth."

When that happens, a cable operator would basically recapture an entire channel to be tapped for other services or applications.

Bowick readily admits that each of these concepts, technologically, is easy to accomplish. Though, how they fit into the marketing side of the cable equation brings to light a spate of other issues. For example, the idea of moving typical analog programming to the digital side has the potential to meet some programmer resistance.

Cox vice president of video product management Lynne Elander agreed that such a move requires some very careful planning between the MSO and its programmers and video customers.

"Having a nice, robust [analog] product is important and continues to be an advantage over DBS," she said. "On the other hand, you want to give customers the best experience they can have with their product. Having ESPN and MTV in digital is a pretty compelling product, so it's a tough trade-off."

She said Cox and programmers have yet to hold any particular conversations pertaining to a move from analog to digital. However, "programmers are living this every day, and they know what the challenges are," Elander said. "There's not a crystal clear answer. It's a process, and it will continue to evolve."

At the same time, the challenges involved in digital-to-analog conversions go beyond technology, hence more reasons for engineers and marketing practitioners to be on the same page.

"This is not an engineering problem, and it won't be an engineering solution," Elander said. "Just because you can do something with a technology, doesn't always mean that you should do something with that technology."

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