While no one has the proverbial crystal ball, a few things are becoming clear. First, consumers want their TV content on a variety of different devices. Second, with the popularity of apps stores, it’s only a matter of time before cable will have to allow outside applications on its networks.
The use of OpenCable—tru2way—technology certainly is one viable way to deliver apps to the TV set. But as far as delivering video to multiple screens and leveraging the widest range of development and interactivity, an Internet protocol (IP)-based approach has strong advantages.
For cable operators, with their established video delivery technology in place and working just fine, the idea of switching to IP video delivery can cause the mind to swim. The confusion starts with the very definition of IP video delivery. Is it IPTV?
Surprisingly, the definition of IPTV isn’t entirely clear. It seems that, at least anecdotally, IPTV is associated both with telcos, such as Verizon, that are not transporting video in IP format from end-to-end, and with those such as AT&T, that are using IP all the way to an IP set-top box in a subscriber’s home.
But what about cable? Is a cable headend that uses IP for video delivery providing IPTV?
“A cable IP video headend is more than that,” said Gerhard Franz, president of Blankom USA. A cable headend traditionally uses RF modulated channels of a fixed bandwidth to deliver video. Although most large systems are already delivering IP-based video to the edge of the network, at that point edge quadrature amplitude modulation (QAM) modulators associated with the cable modem termination system (CMTS) use MPEG to transport the video over the last mile to a cable set-top, Franz explained.
“The IP network effectively ends at the edge QAM (modulator),” said John Horrobin, manager, cable product marketing at Cisco.
So a cable headend delivering IP video is a hybrid IPTV provider, using both IP and MPEG for transport.
Although the CMTS was originally added to the HFC network to provide data, it has been co-opted for voice and video delivery as well. Running IP video through the CMTS frees up bandwidth on the 6 MHz channels that are used for linear video, said Franz.
Video going through the CMTS is actually MPEG video encapsulated in IP and treated like data. And channel bonding as specified in DOCSIS 3.0 can increase throughput even more.
On a Multichannel News webinar in May, Louis Williamson, senior engineering fellow, Time Warner Cable, said that there are “two ways we deliver our services: over an MPEG-2 network for video and DOCSIS network for high-speed data and voice.” But the urge to converge is strong.
“There’s this growing desire to get down to one network,” he continued. “I think we all believe the future is going to be IP over the DOCSIS network. People want to move to DOCSIS through CMTS.”
But there’s an ongoing debate about the use of the CMTS.
Some vendors, Harmonic and BigBand Networks being the most vocal, assert the CMTS should be left for data and voice, while IP video should bypass the CMTS. These vendors offer products to deliver IP video to stand-alone edge QAM modulators.
Operators at the Multichannel webinar were lukewarm, however, about the CMTS bypass idea.
“Bypass technology has its attractiveness in the near term,” said Doug Ike, VP, advanced video and applications engineering, Charter Communications. “It’s a technology that’s trying to adapt to traditional technology that we have today—basically MPEG-2 encapsulated in IP, but really isn’t using IP protocol like the Internet—such as HTTP. (Bypass) seems to be a near-term solution, but in the long term, does it get us to more of a converged environment?”
Williamson said, “(Bypass) just feels like another network to me right now.”
Despite the desire to avoid stopgap measures and build the best network for the future, cable has a history of cobbling old and new technologies together, usually motivated by economics.
Proponents of bypass point out that stand-alone edge QAM modulators are substantially cheaper than downstream CMTS ports.
“The appeal from a cost standpoint is (bypass) lets us do an evolution and not so much a rip and replace,” said Jay Rolls, SVP, technology architecture, Cox Communications.
While big cable operators grapple with CMTS vs. bypass, not to mention legacy MPEG set-tops vs. enhanced DOCSIS cable modems, small cable operators and telcos just entering the video arena may have the advantage when it comes to IP video delivery.
SureWest Communications, an operator in Sacramento, CA, and Kansas City, KS, with about 100,000 total subscribers, has purchased the assets of overbuilders and has had to deal with legacy telco plant (comprising fiber as well as some copper), in addition to legacy HFC plant.
SureWest decided to leave the Kansas City HFC plant as a traditional RF plant, but upgrade the telco plant in Sacramento to all fiber delivering IPTV, said Bill DeMuth, CTO of SureWest.
“Sacramento is fiber to the home, IP-based all the way through,” DeMuth said. “At the home, we put IP-based set-top boxes, which are dramatically lower (cost) than traditional RF set-tops.”
For systems like Sacramento that have only recently begun offering video, IPTV is a forward-looking choice.
“When you talk about tier 2s and 3s, some are greenfields; some analog service providers don’t even have a digital platform yet,” said Gil Katz, senior director of cable solutions, Harmonic. “They know they need to move to digital to survive in this competitive environment.”
For systems just getting into video, it makes sense to go all-digital, to deploy IP-based set-tops and then deliver IPTV. “IP gives a beautiful platform for interactive and for new applications,” said Katz.
But for traditional cable systems already in place, it’s more complicated. At SureWest’s system in Kansas City, the company is looking at its options.
“Long term, I would imagine we would move to some hybrid form of IP,” said DeMuth. “We’re going to have to figure out how do we transition those set-top boxes. At this point, I don’t have all the answers as what would be the best way to migrate.”
But at least smaller operators don’t have such a massive installed based of legacy set-tops to worry about. And they don’t necessarily have to worry about CMTS bypass, either, said Blankom’s Franz. “For a smaller operator who is not yet limited (running out of bandwidth), this CMTS bypass is not an issue; he simply does not need it,” said Franz.
On the other hand, some smaller operators and service providers are facing constraints. CMTS-bypass proponent GoBackTV is one vendor aiming a cable IPTV package (edge QAM modulators, resource manager and custom CMTS) at this market.
IP video via Internet modem
As if things weren’t complex enough for large and small operators alike, there’s over-the-top (OTT) video to factor into the equation.
“Cable can evolve its pipe to do IPTV, and then the question becomes, ‘Why do they even need to do IPTV over cable?’” said Marc Tayer, SVP of business development, Imagine Communications, which offers bandwidth-efficiency technology for personalized TV. “They (cable operators) already have a very efficient, cost-effective method of delivering secure TV to millions of subscribers.”
Now, with DOCSIS 3.0 channel bonding, cable can also deliver video via IP through the cable modem, said Tayer. Anybody with a high-speed Internet connection can now watch an increasing amount of video that flows over the cable plant via the Internet pipes.
“A typical state-of-the-art service provider will have up to 500 signals total in a managed network,” said Tayer. “The open Internet is unlimited—millions of pieces of content instead of hundreds. It’s a whole new paradigm for service providers to give access to content anytime, anywhere. The best way to scale up to millions of streams is really through IP.”
But the challenge will be delivering the OTT video at the same high quality subscribers are accustomed to with the TV set.
“We can’t ignore the growth of video on the big Internet too,” said TWC’s Williamson. “I want to design a network that handles not only what I do with broadcast, multicast video, but I have to be able to support that growth in the over-the-top video, too.”
For now, two separate networks handle those tasks. If Williamson’s design goals, however, align with the desire to “get down to one network” that he noted earlier, then convergence—that long-standing buzzword—could actually be inching closer to reality.
Linda Hardesty is the associate editor of Communications Technology. Reach her at firstname.lastname@example.org.