September 16, 2008

DOCSIS 3.0 Silicon and Beyond

By Jonathan Tombes

Texas Instruments is at IBC in Amsterdam this week showing off a Swiss-Army knife style, DOCSIS 3.0 cable modem chipset.

The latest in TI's Puma 5 family of DOCSIS 3.0 products, the TNETC4840 increases the number of downstream channels available for bonding by four, making it capable of powering an 8x4 (eight downstream, four upstream) cable modem or video gateway.

The minimum configuration of bondable channels required by DOCSIS 3.0 specs is 4x4. The addition of this "quad QAM" demodulator positions TI's cable modem technology beyond the DOCSIS 3.0 4x4 "sweet spot" of a minimum, aggregate bonded-channel downstream throughput of 160 Mbps suited to the near-term data and EMTA (telephony) markets.

The 8x4 configuration potentially doubles that downstream speed to 320 Mbps, placing a DOCSIS-based data product closer to the throughputs available on Verizon FiOS (see DOCSIS vs. FiOS comparisons here), enabling it to act as the foundation for what TI calls a "transport gateway."

"This has been part of the strategy from the beginning," said Peter Percosan, executive director of broadband strategy for TI's Digital Connected Home business.

Percosan underscored the TNETC4840's baked-in capacity to bend to circumstances. "The real science is creating this analog front end," he said. "That is what allows you to interface with multiple tuners."

Possible configurations range from a single wideband and four narrowband tuners to eight narrowband tuners. "At that point, you have full-spectrum flexibility," he said.

Moving beyond the standard 64 MHz - or, in TI's implementation, 100 MHz - of "catcher bandwidth" available for bonding to the entire spectrum, is could transform devices powered by this chipset platform into digital gateways.

 "When you start mixing and matching legacy video and IP video and UP unicast ... that's when you really need the flexibility of full-spectrum tuning capability."

Microtune provides TI with its tuning technology.

Full spectrum gateways are still a few years away from consumers. So far, Percosan is looking at large deployments of existing Puma 5 solutions taking place internationally, primarily in Japan and Europe. He said the United States and Canada were the sites for pilot markets.

- Jonathan Tombes

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