Time Warner Cable Is Switching Up


Time Warner Cable says it plans to roll out switched broadcast video technology in several markets this year, and eyes a potential 2006 national rollout that would allow it to reclaim up to half of its digital channel capacity between hub locations and consumer homes using switched technology.

The MSO believes it could place half its digital channel lineup — plus video-on-demand streams — on switched broadcast video (SBV), saving gobs of bandwidth to expand its video-on-demand, HDTV programming and other new services.

At the same time, the MSO is committed to rolling out digital simulcast to half its digital-subscriber base this year.

By definition, digital simulcast increases the amount of spectrum Time Warner Cable needs to set aside for video, but switched broadcast video allows it to reclaim all of that bandwidth, and more, for future applications.


“What we need to do is move to switching technology, and get a lot more efficiency out of existing bandwidth,” said Time Warner cable senior vice president of strategy and development Kevin Leddy.

Like other operators, Time Warner Cable has deployed Gigabit Ethernet transport from the headend to its hub locations, providing plenty of capacity for thousands of channels. The traditional bottleneck is between the hubs, where the quadrature amplitude modulation (QAM) units sit, and the home.

Time Warner Cable is looking to set aside 16 QAMs, or about 160 “channels,” for switched broadcast video at those hub locations.

The MSO would install video switches in those hubs, which typically pass 20,000 homes. About 1,000 switches would cover the entire cable footprint.

Time Warner Cable also would split service groups from today’s 2,000 homes passed to about 500 homes. A typical node of 500 homes passed would encompass 150 digital subscribers.

Based on viewing habits gleaned from Austin, Texas, and Honolulu, Time Warner believes that any batch of 150 digital customers chooses from a maximum of just 20 unique channels at any given time. Thus, the company would dedicate two QAMs (20 channels) for switched-broadcast video in each service group.

“This is about creating a sustainable digital network,” Leddy said.

“The history of cable has been chapter after chapter of system upgrades,” said Leddy, who’s been researching switched-broadcast video for years. “That’s not the right approach anymore.

“We ought to get to a model where we can offer any new channel or service that requires bandwidth within the 750 MHz [systems] that we’ve built across the country. We need to get to a switched environment.”

Time Warner Cable tested switched broadcast video using a BigBand Networks Inc. switch in Austin. It also tallied viewership numbers from Austin and the Oceanic Cable system in Honolulu.

“Lightly viewed” content — that is, programming viewed for less than 20% of the day — could be housed in 16 QAMs, the company determined. That would include 160 “channels” of linear content, HDTV and VOD.

“You put the channels that are not viewed too much onto a switch and take them off the dedicated linear broadcast capacity,” Leddy said.

“The efficiency is about 65%,” Leddy continued. “Using switching, we can get 2.6 networks into the space occupied by one today.”


The newly opened bandwidth could be used for an expansion of VOD and HD, or for the launch of any new linear network.

“The biggest bandwidth hog is HD,” Leddy said. Time Warner Cable carries about 15 HD networks per system, he estimated. “We could carry as many as 50 HD networks once we have switched-broadcast video. Most of those networks would be on the switch.”

He added: “16 QAMs also would support a lot more VOD. SVOD is very popular. The numbers are growing rapidly there. We’re also seeing lot of growth with music and news on demand.”

VOD might eventually require six to seven QAMs, Leddy said, which would be opened up with switched broadcast video.

New linear networks could be launched as long as they were carried on the switched broadcast video side, he said.

Switched broadcast video costs pale in comparison to an upgrade to 870-MHz systems.

“We always need more capacity in this industry,” Leddy said. “The cost to go to 870 is roughly $1 billion. The cost of switching is a fraction of that. It makes a lot of economic sense to grow bandwidth this way and it is not nearly as disruptive to the customer base.

“For bandwidth calculations to work, you need to have relatively few customers sharing those 16 QAMs,” Leddy added. “You need to get service groups pretty small,” he said, reducing today’s nodes of 2,000 homes passed to 500 homes, which translates to 150 digital customers.

“The switch can handle huge numbers of customers,” Leddy said. “But the service group needs to be small so we get to 150 subs sharing a couple of QAMs.

“If a service group doubles and we have 300 subscribers sharing only two QAMs, the odds might be lot better they would be watching more than 20 services,” he said.

And if more than 20 different channels were requested at one time, the result would be a busy signal — something Time Warner doesn’t want to face.


SBV will follow on the heels of Time Warner Cable’s digital-simulcast rollout. The company plans to have half its digital subscribers seeing all-digital pictures by year’s end.

“It gets us the benefits of better picture quality, enhanced-TV applications and, if we can get a full simulcast, we can take the analog component out of the set-top boxes,” Leddy said.

The MSO hasn’t made final decisions on where encoding — national, regional or local — will take place, Leddy said.

“We’re still looking at all the options,” he said. “There is the complexity of ad insertion. Are you better off doing local encoding and local ad insertion or national/regional encoding and local ad insertion?”

One option is to use Time Warner Cable’s regional ring architecture, and do the encoding at the MSO’s seven regional data centers. That would allow the cable company to buy more expensive, but higher quality, 16 to 1 encoders for some networks.

“You can’t afford to buy those for every cluster, but you can afford to buy them for regions,” Leddy said.