The Chips Fall for DOCSIS 3.1

Two major chipmakers -- Broadcom and STMicro -- have introduced DOCSIS 3.1 chipsets, further setting the stage for the expected rollout of the cable industry's next-gen broadband spec and gigabit speeds later this year.

Broadcom Corp. (Nasdaq: BRCM) made the bigger splash of the two at the CES show in Las Vegas earlier this week, introducing the first system-on-a-chip (SoC) for a DOCSIS 3.1 cable modem. Its new product is the BCM93390 modem reference design, a hybrid chipset that supports both the current DOCSIS 3.0 specs and the coming DOCSIS 3.1 specs so that it can be used both now and in the future.

For the benefit of the D3.1 specs, the Broadcom chipset features two OFDM (orthogonal frequency-division multiplexing) downstream channels that are both 196MHz wide and two OFDM-A upstream channels that are 96MHz wide. As a result, it can generate cable modem speeds as high as 4 Gbit/s to 5 Gbit/s in the home, according to Broadcom executives. The product also supports Integrated WiFi in a cable modem gateway, enabling wireless speeds of up to 2 Gbit/s in customer homes.

To support D3.0, the BCM93390 features support for 32 single-carrier D3 QAM downstream channels and eight single-carrier D3 QAM upstream channels. It also includes software support for Packet Cable voice and e-router applications, including the emerging RDK-B software stack for cable set-tops and broadband gateways.

Jay Kirchoff, VP of marketing for Broadcom, said the chipmaker is now sampling the BCH93390 design and expects it to go into full production in the second half of the year, which is when such leading MSOs as Comcast Corp. (Nasdaq: CMCSA, CMCSK) and Liberty Global Inc. (Nasdaq: LBTY) plan to start deploying DOCSIS 3.1 in their initial markets. He said Broadcom is also developing a similar DOCSIS 3.1 chipset for cable modem termination systems (CMTSs), a necessary element for fully rolling out the gigabit speeds that the spec enables.

"We are working on it feverishly," Kirchoff said. "Even a gig is very tough without the CMTS."

While Broadcom grabbed the CES spotlight Tuesday with its announcement, it's certainly not the only chipmaker preparing feverishly for the upcoming DOCSIS 3.1 era. For instance, STMicroelectronics NV (NYSE: STM) made its own splash at CES this week, demonstrating its new D3.1-based platform on the exhibit floor.

The STMicro demo featured data downstreaming over a single 96MHz-wide channel using OFDM with subcarrier modulated in 4096 QAM, as well as upstream data over an 80MHz channel modulated in 1024 QAM. It also featured RDK-B gateway software, like Broadcom's demo.

The moves by Broadcom and STMicro come as the cable industry continues to gear up for the mass deployment of gigabit speeds across the globe, starting as early as this summer. Unlike the industry's current flagship broadband spec, DOCSIS 3.0, which tops out at about 1 Gbit/s downstream and much lower speeds upstream, DOCSIS 3.1 is designed to enable downstream rates as high as 10 Gbit/s and upstream speeds as high as 2 Gbit/s.

For the latest on urban network innovation, visit Light Reading's dedicated Gigabit Cities content channel. And watch for forthcoming details on Light Reading's Gigabit Cities Live event, to be held in May 2015 in Atlanta.

While a few MSOs, such as Cox Communications Inc. and Suddenlink Communications , are starting to offer 1Gbit/s downstream service in select markets now using all-fiber lines, most cable providers are waiting for the rollout of DOCSIS 3.1 so they can broadly launch gigabit service over their hybrid fiber-coax (HFC) plants. But, with such major rivals as Google Fiber Inc. , AT&T Inc. (NYSE: T) and CenturyLink Inc. (NYSE: CTL) beginning to deploy gigabit service in major markets and Verizon Communications Inc. (NYSE: VZ) waiting in the wings, cable operators are increasingly anxious to get started themselves. (See Cox Goes Gaga Over Gigabit.)

"We've been contacted by all of the top five [US MSOs], as well as 80% to 90% of the top ten," Kirchoff said, noting that there's also strong interest in Europe, Asia, South America and Australia. "Cable operators see D3.1 as their primary means of competing" with the gigabit deployments of fiber-to-the-home networks, he said.

Indeed, as part of Broadcom's announcement yesterday, the world's two biggest MSOs -- Comcast and Liberty Global -- stated their general intentions to launch gigabit service to their high-speed data customers in the second half of the year. Although both MSOs stopped short of actually endorsing Broadcom's new product, they made it clear that they intend to start leveraging DOCSIS 3.1 technology as soon as possible.

"The next generation of DOCSIS technology supports the gigabit speeds our subscribers will increasingly demand over time,' said Balan Nair, executive VP and CTO of Liberty Global in a prepared statement. "DOCSIS 3.1 will enable Liberty Global to deliver an even richer experience once we begin deploying this cost-effective technology during the second half of 2015."

Tony Werner, executive VP and CTO of Comcast, seconded the notion. "DOCSIS 3.1 is a critical technology for Comcast to provide even faster, more reliable data speeds and features such as IP video to our subscribers' homes by harnessing more spectrum in the downstream," he said in his prepared testimonial. "By more effectively using the cable plant to grow our total throughput, we expect to offer our customers more than 1-gigabit speeds in their homes in 2015 and beyond."

— Alan Breznick, Cable/Video Practice Leader, Light Reading

610Alpha 1/9/2015 | 11:29:30 AM
Why not Convert HFC to All Fiber? Since most of the big cable companies operate on a HFC why don't they figure out a way to convert their HFC to an all Fiber network? 

They have fiber to the optical node already so why don't they just replace the copper from the optical node to the houses with Fiber.  Granted it would probably require a different Optical Node, maybe a new set top box, and a lot of Fiber.

My knowledge of HFC is based on the diagram here: 


I say that because I admit my knowledge of HFC is limited but I am very interested in this topic and want to understand this better.

What is the farthest distance from the Optical Node to a customer's house that DOCSIS 3.1 could guarantee Gigabit? 

I think that if the Cable companies would have solved the problem of converting their HFC to all Fiber they would have saved money in the long run instead of wasting all this time and money on DOCSIS 1.0, 1.1, 2.0, 3.0, and now 3.1.
f_goldstein 1/8/2015 | 5:59:33 PM
Sufferin' symmetry! The wider downstream capabilities of American cable networks with DOCSIS 3.1 are crippled by the narrow upstream window, 20-42 MHz.  Increasing upstream speed, which is the real limit, will require real outside plant work. Either they have to replace the low-split nodes (and any amps left in the distribution plant) with higher splits, or they have to overlay 900+ MHz upstream capacity, where plant attenuation is relatively high.  Cable boxed itself into a corner here, refusing to  install remotely-controlled dual-split nodes (it was suggested to CableLabs by consultants working on DOCSIS) when HFC was being rolled out.  So Europe will get more benefit than the US.

Higher-order QAM is also sort of farcical, given the spotty typical plant quality.  HFC was  wonderful tech and allowed the 1980s distribution plant to remain in place when they upgraded the trunking to fiber.  But that was 15+ years ago, and we're seeing proposed band-aids like this one rather than a consensus on how to upgrade the aging, deteriorating distribution plant to fiber. Of course nobody's going to spend much on (ever-costier) copper when fiber is coming, some day...
danielcawrey 1/8/2015 | 3:14:35 PM
Everything is IP In the home, everything is all about IP. This is why DOCSIS 3.1 is so important for providers like Comcast.

Now, here's hoping that they can make their interfaces much more user friendly to make cable more Netflix-like. 
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