Cable modem/CMTS

Moto Wields Upstream CMTS Blade

Cable MSOs aren't expected to tap into the upstream channel bonding capabilities of Docsis 3.0 until sometime next year, but that isn't stopping some of the sector's top suppliers from preparing for that day.

Among that group, Motorola Inc. (NYSE: MOT) is already setting its sights on a new cable modem termination system (CMTS) module dedicated entirely to the upstream, Cable Digital News has learned.

The RX32, as it's being called, is awaiting some finalized chips but is slated for a formal introduction in early 2009, according to Kevin Keefe, VP of marketing for Motorola's Access Networks Solutions division. While a standard card for Motorola's flagship CMTS, the BSR 64000, supports two downstreams and eight upstreams, the RX32 module will provide 32 dedicated upstreams.

Motorola expects to show off a reference model of the RX32 at two upcoming industry tradeshows: The Cable Show (May 18-20 in New Orleans) and the Society of Cable Telecommunications Engineers (SCTE) ' Cable-Tec Expo (June 24-27 in Philadelphia).

The kind of work Motorola is pursuing on the upstream is already well underway on the downstream side of the Docsis house. In fact, the three major CMTS suppliers -- Cisco Systems Inc. (Nasdaq: CSCO), Arris Group Inc. (Nasdaq: ARRS), and Motorola -- have already developed or have started to develop ultra-dense downstream CMTS modules. In addition to giving operators the ability to bulk up their downstream capacity, the cards should also drive down costs on a per-port basis considerably. (See CMTS Downstream Prices Plummet.)

That trend also reflects the fact that most initial Docsis 3.0-based "Wideband" deployments are focusing on downstream channel bonding. (See Comcast Enters the Wideband Era and Videotron Hits the Gas .)

Moreover, most operators are expected to employ an "integrated" CMTS architecture (and denser downstream modules) to support early Docsis 3.0 rollouts. Eventually, some MSOs will migrate to a modular CMTS architecture that allows the individual scaling of upstream and downstream capacity and the sharing of QAM resources. Under the modular approach, the CMTS "core" chassis would provide the upstream capacity, with edge QAMs supporting all the downstream.

In Motorola's case, expectations that MSOs will start with the integrated approach has resulted in the TX32, a card for the BSR 64000 CMTS that supports 32 downstreams. The TX32 has entered some "live plant testing" with MSO customers and should head into full production this quarter, Keefe says.

The "T" in the TX32 module stands for "transmit"; the "R" in the RX32 is for "receive."

While Motorola is creating an upstream-only card for integrated CMTS architectures, some vendors doubt such a product will be necessary for some time -- or at least aren't ready to announce any upstream-only CMTS modules.

Arris is working on module that packs in 16 downstreams but believes that its existing CMTS card configuration will give its MSO customers enough upstream capacity for the foreseeable future.

Arris's game plan, according to chief strategy officer Tom Cloonan, is to reuse its CMTS cards for Docsis 3.0 upstream processing in tandem with some new software. Today, those cards already support 12 upstreams and two downstreams.

"We have boards today that can be turned into 3.0 upstream processing boards," Cloonan says, noting that one C4 CMTS chassis houses 21 card slots. "From a density point of view… that's going to last for a while."

— Jeff Baumgartner, Site Editor, Cable Digital News

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