Experts suggest that there are two or three ways to increase capacity and flexibility that don't involve prohibitively expensive rebuilds. The focus today is on bandwidth reclamation and switched digital video (SDV) -- with an advanced form of bandwidth stacking offering an interesting option.
Bandwidth reclamation should, perhaps, be called bandwidth reassignment. In this scenario, analog signals in a given channel range are replaced with their digital equivalents. Bringing digital signals to homes requires that low cost digital terminal adapters (DTAs) be provided to older -- generally second and third -- TV sets that lack digital tuners.
This approach is being taken by 40,000-subscriber Antietam Cable in Maryland, which currently is at 750 MHz. President Brian Lynch said that the goal is to free up 40 to 45 6-MHz QAM channels. This, he said, would enable the system to move from 56 to 75 or 80 HD channels and open capacity for commercial services.
"We worked through the numbers of going deep to fiber and moving to 1 Gig capacity," Lynch said. "We talked about switched digital video. A few operators are doing this as a first course. We looked at this and don't get ROI. There also is a baked-in higher operating cost."
Antietam is using headend and premises gear from Evolution Digital. Evolution President Brent Smith said the avoidance of rebuilds is a sign of the times. In the past, operators approaching banks or the public markets for upgrade funding would be able to point out that they dominated their markets.
This no longer is true. "Now they've got significant amounts of competition from satellite, telcos and ultimately OTT," Smith said. "When you look at economics for cable operators to go from 750 MHz to 1 GHz or some other high bandwidth level, they have to figure ROI on much a smaller penetration of homes passed. Now there are smaller actual numbers of customers, and the math doesn't work. ROI and payback are much further out."
Bandwidth reclamation for MDUs, hospitality suites and other bulk accounts is accomplished either on a set-by-set basis or through the type of chip that BroadLogic OEMs to vendors who integrate it into on-premises equipment that does the transfer for the entire building, said BroadLogic Vice President of Marketing Rich Peske.
Switched Digital Video
A second major option is transmission of programming only to the devices that ask for it. Proponents of SDV say it is far cheaper and results in significantly more capacity delivered to subscribers. "Ninety-nine out of 100 choose the SDV route vs. the DTA route," said Joseph Nucara, the CEO of SDV vendor Adara Technologies. "Even for a small operator, the difference is between millions in capex and tens of thousands in incremental operating costs vs. a tenth or twentieth in a hosted SDV offering."
Bandwidth reclamation and SDV vendors are going after the same pool of potential customers. SDV relies on an uninterrupted two-way connection between the subscriber gear and the headend. Any problems in the plant or the box, critics of this approach say, results in a disappointed subscriber and, often, a truck roll.
Nucara concedes that SDV isn’t viable in a one-way system, but points out that most operators now offer high speed data, which means that their network is bidirectional. He points out that bandwidth reclamation projects must deal with problems arising from old in-home wiring that impact the less forgiving digital signals that are substituted for analog.
Another criticism of SDV that its effectiveness shrinks as the popularity of the programming for which it is being used grows. Nucara responded that SDV’s value is elminating the need to broadcast all channels to all homes. Therefore, avoiding the delivery of a popular channel to a home is as valuable as eliminating delivery of an unpopular channel. In both cases, the operator reduces delivery by one stream.
A slightly different approach is being taken by InnoTrans Communications. The company is using dense wavelength division multiplexing (DWDM) between the hub and the node to increase the number of channels that can be delivered by a factor of eight, said CEO Mani Ramachandran. DWDM and its cousin, wavelength division multiplexing (WDM), focus on reducing the spacing between paths in a laser transmission. This increase in data carrying capacity translates into more channels and lets operators eliminate nodes or reduce their size.
Cable operators always will strive for more bandwidth. What is different today is that the effort is occurring against a landscape of the transition to IP networking. This, combined with the expected evolution in networking techniques and technologies and the economic challenges of a full rebuild, is opening the gates to creative solutions.
The bottom line is that the drive to bring more services to subscribers is happening on a broader playing field. "Most operators want to have bandwidth for IP services, from data to multiscreen distribution around the home," said Gary Schultz, the principal analyst for Multimedia Research Group, a consultancy. "High definition will continue to be a driver, but the overall driver for this is the eventual migration to IP."
Carl Weinschenk is Senior Editor for Broadband Technology Report. Contact him at firstname.lastname@example.org.