A Climate That’s On Their Wavelength

Publish date:
Updated on

For cable engineers, the name of the game is squeezing more out of the bandwidth they have in their current-day systems.

Irrespective of which service executives talk to Wall Street about — whether it’s video-on-demand, HDTV or home networking — the cable industry is also proclaiming that the days of multibillion-dollar upgrades are over.

Those capital expense cutbacks — or the end of the spending bubble, one might say — have hit many vendors hard.

But some companies are thriving, especially such transport-business players as BigBand Networks Inc., Internet Photonics Inc. and Harmonic Inc. Cable’s push to add additional VOD storage and streams, or its plans to bolster HDTV services, dovetail with the business plans of those companies.


“The VOD trends have been about scaling the library of content and having the network to provide the capacity,” said Internet Photonics vice president of marketing Gary Southwell. “It’s making sure operators have enough bandwidth scaling.”

“Two years ago, a few Gigabits was all I needed,” he said. Now 10-Gb wavelengths are common, and Internet Photonics has introduced a 40-Gb product.

Internet Photonics provides Gigabit Ethernet technology to fill the VOD and HDTV transport needs of six of the top 10 MSOs.

That was enough to draw the attention of Ciena Corp., which entered an agreement to buy Internet Photonics last month.

“There is a massive migration to multiservice transport,” as MSOs look to add more VOD content, sign up more on-demand homes and swell the ranks of HDTV subscribers and channels, Southwell said. “They want to make sure they have headroom” as usage expands.

On Friday nights, some VOD nodes are already reaching the 25% usage mark, operators have reported.

That can cause overloads or denial-of-service messages.

“Operators are concerned about that,” Southwell said.

Factor in new services — such as HDTV in VOD, in which a movie can consume five times as much bandwidth as a standard-definition film — and “that has a huge potential impact of bandwidth,” Southwell said.

At the same time, operators are pushing HD VOD because it’s a feature direct-broadcast satellite providers cannot replicate.


Cablevision Systems Corp. has already launched an HDTV on-demand service, and other MSOs “are moving forward quickly” in its footsteps, said Southwell.

But high-def VOD requires an upgrade to add optical modules, and perhaps even additional Gigabit Ethernet blades, he said.

The transport technology is evolving to a point at which each service would have its own wavelengths.

“We’re designing to handle transport of any technology,” Southwell said. “You could have VOD on one wavelength, then have [a high-speed data] backhaul and even [voice-over-IP telephony] on a third channel. You can map those through the network.”

Ohio-based operator Buckeye Cablesystem is using the Internet Photonics 10-Gb product and separating services via wavelengths.

“You just flip the switch in the capability,” he said.

Even wireless backhaul has crept into the transport mix.

“Some cable systems have proximity to [cellular phone] towers,” Southwell said. Thus, instead of using T1 lines for backhaul feeds — and paying line charges — some cable systems are looking at the cellular option for backhauls.

Said BigBand vice president of corporate development Seth Kenvin: “2004 will be the year HD VOD will be rolled out on a broader scale.

At the major systems, people will want to offer this in 2004, and that will impact capacity requirements and stream counts. That’s probably the big new thing.”

Kenvin said “the industry is still building towards 10% initial concurrency take rate and a fair number of systems are getting close to that.” BigBand can support HD VOD with its edge quadrature amplitude modulation devices, he said.

The big impact, in terms of HD VOD, is getting more GigE QAMs into the system, he said. BigBand’s line of Broadband Media Router products also can support switched broadcast, Kenvin said. It can handle a stream count north of 10,000, he said.

Rate-shaping, which allows operators to shoehorn more channels into their GigE wavelengths for VOD and HD, is also a big issue, Kenvin said.

Kenvin said BigBand has trialed its switched broadcast technology. “Signals come in live at the headend, then gets provisioned to different nodes, like VOD,” he said, depending on what customers want to watch.

The trial consisted of switching 160 channels into eight QAMs, instead of the normal 16, said BigBand product marketing manager Mike Bauer. That allowed the MSO to get a 50% gain in bandwidth.

“That will prove to be very feasible,” he said. “You can add more channels without increasing the number of channels.”

IP transport is also getting lots of attention these days, as MSO start to shift VOD content around metro rings using Internet protocol.

“We’re supporting video-over-IP for metro networking purposes,” Bauer said. “We’ve equipped edge devices with high jitter tolerance. That’s designed to remove very high jitter.

“GigE was not built for video,” he added. “It was built for data. Digital video is very precise on how much time you have with the stream. At the edge, we can look at a series of content and re-time the packets.” MSOs also are talking about sharing bandwidth across services in the same QAM, Bauer said, avoiding the separate silos for VOD, standard broadcast and HD VOD. “That’s been a very strong requirement and also what we’ve been promoting for awhile.”

Harmonic also sees the continued evolution of GigE transport to carry all manner of traffic, and the evolution of VOD where QAM modulation is moving out to the edge.

“GigE is the most efficient in terms of dollars,” said Harmonic director of product marketing, broadband-access networks Iain Drummond.

For VOD, “the servers are centralized, but the QAM modulation has moved out to the edge. You can move content around very easily and at the edges do the modulation.”

Operators are really focused on lowering their per-stream costs.

“There is a real interest to the cost of VOD,” he said. “What is your transport cost per stream?” he said, is often the first question asked these days.


“What’s interesting is the convergence of VOD with commercial services,” as well as high-speed data and VoIP, Drummond said.

“If you have a CMTS, the content is the data. You look at the GigE pipe as a means of moving around all forms of IP content, whether that’s VOD, HD VOD, HSD or VoIP traffic.

“Some say: ‘Let’s converge all into one network.’ Some people say: ‘We’ll carry data and voice over one wavelength and carry video traffic over a separate wavelength but on the same fiber.’ ”

The latter approach might make the most sense, he said.

“The traffic is very different,” Drummond said. “You have got a huge amount of data flowing in one direction. Using a unidirectional network to carry that data and a small narrow back channel is the most effective way to transport VOD. With VoIP transport, you need a very symmetric network and high levels of resiliency.”