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Cranking Up Cable Uploads

The neglected upstream side of cable's two-way broadband street is now getting some love.

With the initial launch of DOCSIS 3.0, the industry has focused on super-charging downstream speeds of broadband services. Comcast, for example, offers top download speeds of 50 Megabits per second, but upload speeds max out at 10 Mbps.

Now, cable-technology vendors are working to power up the upstream.

Arris, at The Cable Show '09 this month, was showing its C4 cable-modem termination system delivering four upstream channels bonded together, to deliver a sustained throughput of between 100 and 106 Mbps.

Over the next five years, “we're going to be challenged mostly by having to provide a lot of bandwidth, and the upstream in particular is an area we need to focus on,” Arris chief strategy officer Tom Cloonan said on a panel during the Society of Cable & Telecommunications Engineers' Conference on Emerging Technologies, held at the show.

For its part, Motorola is developing a high-density module for its BSR 64000 integrated cable modem termination system that would provide 48 ports of upstream capacity — dramatically increasing the upload speeds possible through DOCSIS 3.0 technology.

Motorola's currently shipping TX32 downstream module supports 32 QAM channels in a single slot in the CMTS, to deliver DOCSIS 3.0 channel-bonded services of up to 200 Mbps downstream. The RX48 module, targeted to be available by mid-2010, would provide 48 upstream ports per chassis slot.

“We're going to have the card and the technology when the market's ready for it,” said Floyd Wagoner, director of global marketing and communications for Motorola's Access Networks Business.

DOCSIS 3.0 vendors are using synchronous code-division multiple access (S-CDMA) technology to reduce noise in the spectrum below 20 MHz for upstream channels.

“If the battle on upstream is 'I need more,' it's important to clean up the spectrum so you can reach below 20 MHz,” Wagoner said. “It's a more thoughtful approach than just throwing hardware at it.”

Meanwhile, the team behind now-defunct spectrum-expansion company Vyyo is getting ready to relaunch with a new name — Javelin Innovations — and a strategy to deliver MSOs an additional 500 MHz of upstream capacity.

While Vyyo was pitching a system that would expand a cable plant's capacity to 3 GHz, Javelin is specifically targeting upstream bandwidth, CEO Wayne Davis said.

In addition, the new company plans to license the technology to other tap and amplifier vendors, which would integrate it into their own products, rather than sell products directly to MSOs as Vyyo was attempting to do.

According to Davis, the company's new approach won't require any changes on the customer-premises side and only simple upgrades to taps. But the Javelin approach will preserve the upstream 5 MHz to 42 MHz frequency range, by “stacking” multiple legs of the upstream spectrum in space above 1 GHz.

“This will be the biggest innovation in the HFC space in decades,” Davis said in an interview. “Node splits will be a thing of the past.”

Node splits are used to increase bandwidth to a service area, by reducing the number of homes per fiber-optic cable.

Javelin is based in Atlanta with offices in Englewood, Colo. Vyyo hired Davis, a former chief technology officer for Charter Communications, as CEO in March 2007.

Last October, Vyyo was taken private by an investment consortium led by the company's former chairman and CEO, Davidi Gilo, in a deal worth $45 million. Goldman Sachs is also an investor in Javelin.