Pressure from telcos pushing fibre further out into the network has led cable operators to deploy DOCSIS 3.0 technology. For now, that equates to higher headline broadband speeds, but what are the opportunities for delivering IP video over DOCSIS? Graham Pomphrey reports.

Headline broadband speeds continue to rise across Europe as telcos have turned to fibre to boost their offerings and cable operators begin to roll out services based on DOCSIS 3.0. For the latter, despite a slower start than some may have anticipated, 100Mbps services have launched in various markets, most recently with Germany’s Kabel Deutschland (KDG) and Telenet in Belgium. While it may take some time for DOCSIS 3.0-based broadband to become a mass market offering (for various reasons, including the cost of network upgrades and the cost of replacing existing in-home equipment), operators are already considering using the technology to deliver video services into and around the home.

“We’re confident that ultimately we’ll end up in an all-IP world and all cable operators will end up as IPTV operators, but that’s some way off,” says Paul Stallard, head of system management, solution area TV, Ericsson. “High-speed data services are currently carrying a lot of over-the-top video from the likes of YouTube and iPlayer but to turn that into a managed IPTV solution that’s comparable to the one they supply today over the standard cable path is still some way off. The cost of DOCSIS 3.0 is still a barrier, as are the legacy boxes that operators have.”

For now, while commercial strategies for DOCSIS 3.0 vary by operator, simply being able to market super-fast broadband continues to be the main reason for operators to deploy the technology, especially as telcos will struggle to compete with speeds of 50-100Mbps.

“Deploying DOCSIS 3.0 can be a proactive or a pre-emptive move,” says Pascal Portelli, vice-president gateways and connected devices, Technicolor (formerly Thomson). In the Netherlands, for instance, telco KPN began offering high-speed services before the country’s leading MSOs UPC and Ziggo launched DOCSIS 3.0-based services. UK operator Virgin Media, meanwhile, started offering high-speed services before incumbent telco BT launched FTTH.

Business models for DOCSIS 3.0 also vary. “Typically, cable operators will charge more for DOCSIS 3.0 services, while some will use it as a way of attracting new customers,” says Portelli. Virgin Media’s high speed broadband service is helping the operator boost subscriber numbers and ARPU – it says that over 40% of customers that are signing up for its top-speed product (50Mbps) are new customers to its broadband service. The service costs £38 (?44). Telenet’s new 100Mbps offering will cost ?99 per month, while KDG will charge EUR49.90.

Video over DOCSIS

While DOCSIS 3.0 is enabling cable operators to forge ahead of their rivals in the race to market high headline download speeds, what role will it play in delivering video, and why are operators considering this approach? For a start, moving much of the video content to the IP network would free up spectrum on multicast networks, improving bandwidth. It would also enable operators to launch the kind of interactive services that can be offered by IPTV operators, such as new on-demand services, the ability to connect to websites and less restrictive advertising models. It would also make it easier to deliver content around the home via low-cost set-tops to additional TVs, PCs, mobile phones and other CE devices.

The types of video service operators may deliver over IP will vary, as Gil Katz, who heads up cable solutions marketing at Harmonic, explains: “There are many different flavours of video over IP, including simple over-the-top services, which the operators don’t have much control of. Then you can look at video over IP within the home. There are discussions about using gateway devices that will deliver IP within a home network. Operators might also deliver IP video all the way from the headend – a true IPTV service.” He says that hybrid operators that already have HFC and DSL networks are looking for a single platform for CPEs, while other operators are looking at IPTV to resolve networking issues. “Old, badly maintained home RF networks can affect the cable operator’s entire network. Moving to IP with a single RF device in the home back to the network means they can eliminate a lot of the noise that back from the home and degrades the quality of the network. Some operators will turn to IP sooner rather than later,” says Katz.

However, the transition to delivering IP video services is likely to take time as operators will want to get the most out of their current HFC networks. Operators will likely use IP initially to deliver VOD before using it to deliver all linear channels as well, according to Mike Gannon, EMEA manager, technical pre-sales, Motorola Home and & Networks division. “As the TV world migrates towards on-demand viewing, we’ll see a migration of how that content is delivered to the home. Broadcast will be around for a considerable time – the equipment to deliver it is well known, economical and cost effective.” The challenge for the industry, he says, is to migrate customers to the next generation of service delivery “responsibly and economically” with appropriate management systems.

The speed at which this happens will come down to individual business cases, says Stallard: “There’s an investment involved in moving to IP video delivery and currently we see it as being too high to make a full IPTV solution viable for cable operators. With the current investment that operators have made in MPEG-2 and MPEG-4 set-tops they need to get the most from that investment. The stepping-stone is to allow multi-screen activity within and around the home but to do it effectively using different delivery paths. Customers don’t care whether TV comes over cable or IP as long as they get a good service and operators can continue to innovate.”

However, as the cost of updating networks and deploying new CPE devices comes down, there will be a point where the benefit of the IPTV solution – in terms of serving multiple devices, having a simplified infrastructure, and also enabling services within the home – makes that investment feasible, says Stallard. “We have a connected home group that builds a set of solutions based around sharing content around the home and beyond the home network,” he says. “These kinds of services will be very important for operators to increase revenues and once they are in the IP world they can offer more of those services. It would take a brave person to predict exactly when this happens. There are some operators still looking to do their first digital upgrade, in which case it’s a much more interesting proposition to go from analogue to IP.” Other operators that cannot afford to completely overhaul their video offering overnight will probably use DOCSIS 3.0 technology to deliver IPTV services to the secondary screens within the home – like the PC – but continue to use DVB-C for the main TV set, using legacy set-tops. Another option is to continue delivering DVB-based broadcast video to existing subscribers and deploy IP video over DOCSIS to some new customers. “The traditional cable infrastructure does what it’s is supposed to do so operators can’t afford to throw it away over night. It’s a case of deploying IP-based video in some places for new customers whilst keeping the legacy infrastructure in place for some time,” says Thomson’s Portelli.

Changing from DVB-C to IP delivery is not a decision cable operators will take lightly. Having already invested heavily in network upgrades and the rollout of MPEG set-top boxes, they will need to turn their attention to the access technologies associated with DOCSIS 3.0, and there are various options available to them from the headend to the transport network and into the home.

Technology choices

Networks that have been upgraded to DOCSIS 3.0 are now in a position to deliver high quality video, according to Charles Cheevers, chief technology officer at Arris. “A 50Mbps service is good enough for any level of HD video and operators are experimenting with IP over standard DOCSIS 3.0 CMTS and EMTAs – it all works but not to scale,” he says. “Operators need spectrum to be able to provide these services. They’re not going to completely replace their MPEG video tier with an IP tier – they’ll have to offer the same services in parallel and that uses up more spectrum.”

The high cost of delivering video through the CMTS, which lies at the heart of the DOCSIS network will be a big issue for cable operators. Various technologies exist to try and reduce the cost to cable operators of delivering IP video. Modular CMTS, or MCMTS, is a standard developed in parallel with DOCSIS 3.0. “You can have a universal edgeQAM which can act as the downstream to DOCSIS but can also act as the QAM for your broadcast and VOD services as well,” says Stallard. “You have one edge device that you can deploy from day one and use for all your various service. As part of the migration you can move more bandwidth from your traditional cable infrastructure to your DOCSIS bandwidth.”

Arris’s Cheevers agrees that from a technology perspective, MCMTS is a good idea because it enables MPEG video and DOCSIS to be delivered via the same physical hardware. However, he says, problems may well persist in terms of managing the system efficiently: “CMTS is managed and maintained in a single box versus MCMTS where you need three solutions. The problem we see from the management side is that if you have a problem you have to look at three different boxes. You also have the problem that most operators at the moment aren’t unified in terms of video and data management – they have two separate organisations for doing broadband over DOCSIS and video over MPEG.”

Cable operators are also showing an interest in using MCMTS solutions for CMTS-bypass, which delivers IP-based video but bypasses the CMTS. Harmonic believes that delivering IP video through the edgeQAMs using MCMTS is a better alternative to delivering it through the core CMTS. “The idea is that the cable modem will be able to receive data though the CMTS and video through an edgeQAM that can do DOCSIS encapsulation. The cable modem speaks a DOCSIS protocol language back to the headend, explains Katz.” 

Consumer equipment

The equipment used in the network to support DOCSIS 3.0 has been available for some time, with many operators (an estimated 70% of operators globally, according to Cheevers) already deploying CMTS devices. That alone does not mean that operators can offer DOCSIS 3.0 services – the biggest stumbling block is the lack of CPE devices capable of receiving such services. “Almost ubiquitously, operators started to put CMTS capacity into the network through 2009 in order to sell 3.0 services and offer higher subscription packages,” says Cheevers. “The CPEs have been slower to roll out. There are still a dominant number of CPE devices being shipped for DOCSIS 2.0.”

Operators moving towards IP video will inevitably work with a hybrid broadcast/IP network for a certain period of time, which means home gateways are looking more likely than ever to feature in future CPE deployments. “We are seeing a lot of interest for gateways with a lot of connectivity – typically four Ethernet ports, WiFi and in some cases with voice integration. It makes sense for operators to go beyond standard gateways – it’s not a cliché, operators really do want to own the home,” says Thomson’s Portelli.

“Part of the rationale [for using home gateways] is the ability to manage a hybrid network, but also people are starting to expect a home network offering,” he says. “They expect high quality WiFi to be part of the offering, which goes hand in hand with DOCSIS 3.0. It is the way to go for bandwidth-intensive applications, such as YouTube and so on, but it also makes sense for IP video delivery.” However, he says, the volumes of deployed DOCSIS 2.0 devices will continue to be significantly higher than DOCSIS 3.0 devices for the rest of the year, with DOCSIS 3.0 gateways only deployed where significant numbers of customers are willing to pay more for services, or where competition is acute. “DOCSIS 3.0 is backwards compatible with 2.0 devices so there will be a coexistence of both technologies on the same network for a long time. But in Europe, home gateways will be key.”

Arris’s Cheevers agrees. The company recently acquired set-top vendor Digeo and intends to use the business to develop home gateways. “Next year will be the sweet spot for cable gateways,” he says. “A gateway with multiple tuners can be configured to suck in MPEG video off the network, which it then encapsulates into IP that can be sent around a home network. They can interact with IP set-tops, which are much cheaper, as well as numerous other end devices.”

Motorola’s Gannon agrees that the DOCSIS-enabled home gateway will become the choice of operators however they choose to deliver content to the home, although he adds that the form the devices take remains to be seen. “Will it be a separate box that sits under the stairs, or a DOCSIS 3.0 set-top residing under the TV? Operators are looking at the best ways of delivering both existing services and new services at a responsible pace and the fact is that set-top boxes will have a place in the home for some time to come,” says Gannon.

Extra services

The ability to offer new value-ad services to TV subscribers lies at the heart of delivering video services over IP. Being able to do so relatively quickly and easily will be important and the gateway is likely to play a central role. Eran Rom, CEO of NDS-owned gateway middleware company Jungo explains: “Everybody is trying to find the most compelling and justifiable application that they can monetise – but no one knows what the killer application will be. They need to be able to introduce services cost effectively and quickly.” The company has developed software packages that enable cable operators to develop service applications in an open platform. “This is something we developed for scenarios where the gateway, being in the centre of the residential home network, can be used to help launch additional services. It is the last mile that the MSO still controls. They own the equipment so they can access it, control it and introduce services,” he says. For the time being, he adds, the gateway will be used to convert the QAM-delivered broadcast stream to IP within the home, but that ultimately, when operators go to an all-IP network (which he says will take many years) the boxes will become pure transport devices. “If you have QAM-to-IP requirements, the hardware is much more expensive; it requires tuners and the software has to handle it. Most will eventually upgrade their back-end systems to full IP and then there will be no need to translate to IP within the home and the gateway will be part of transport mechanism. It will be much easier.”

Cable operators face difficult business decisions about how best to migrate to IP-delivered video. Whatever technology choices they make, they will be acutely aware that viewers aren’t impressed with the delivery mechanism as long as they have access to the content and quality services they want and that at least match those offered by alternative providers.

Sidebar: Fibre opportunities for cable operators

DOCSIS 3.0 is seen by some as a staging post on the way to network convergence between cable and telcos as all network providers push fibre closer to the edge. Cable operators are no doubt asking themselves how well placed existing HFC networks are to compete in the future with fibre upgrades by telcos.

In the majority of cases, HFC can match and surpass DSL broadband speeds through upgrades to DOCSIS 3.0 equipment. However, there are certain circumstances where rolling out FTTH makes sense for cable operators. “As we move into HDTV and even 3DTV, we’ll need more bandwidth for those services. That’s driving the downstream requirements; the need for speed in data services will also drive upstream requirements on the network,” says John Dahlquist, vice-president of marketing for Aurora Networks, a company that specialises in fibre-deep technology. “Fibre deep is about using the fibre that’s already in place and where it had one wavelength on it previously, it can be extended up to 40 wavelengths. Only when you get into the neighbourhood do you push fibre that little bit deeper, which minimises costs,” he explains. “It’s a gradual evolution of your cable plant which means you’re not ripping it out and starting from scratch. We’ll see the death of the amplifier, which ends up being a real bottleneck. It will be replaced by a smaller node that means you don’t need all the coax in between.” 

Another technology available to cable operators is radio-frequency-over-glass (RFoG), a technique that transmits conventional DOCSIS traffic over fibre. The cost of the technology could prove prohibitive, however, and is likely to be limited to greenfield sites such as new housing developments (where cable operators want to compete with telcos delivering FTTH) and areas that are sparsely populated.

“The idea behind RFoG is to enable cable operators to seamlessly transition from their traditional cable system to FTTH but still use the same back office, business structure and hardware they’re used to installing and maintaining,” says Dahlquist. “However, while its certainly a compelling technology, it seems to only be cost effective in a rural or lower density neighbourhood, which can be adversely affected by the signal losses associated with coax.”