Cable needs to increase bandwidth per subscriber in order to thrive.

Bandwidth remains one of a broadband operator’s most valued assets. As the industry evolves and advanced services flourish, it has quickly become the commodity on which revenue-generating service opportunities are dependent. However, the increased dependency on bandwidth capacity has greatly strained this commodity. More and more cable operators are finding that the legacy amount of spectrum provided to subscribers is simply not enough.

This, in turn, has created a number of challenges that operators must face in their quest to find the ultimate bandwidth-optimizing pathway. The vendor community, eager to capitalize on this need, has flooded the market with a multitude of bandwidth-supporting equipment, leaving operators with the daunting task of weed-whacking their way to find the best solution.

The advent of new and advanced services has also created a challenge for operators on how to navigate through the wealth of data that comes with new services such as 3-D, VOD, HD-quality content and over-the-top (OTT) video.

In addition, the global evolution toward greater interconnectivity has societal ramifications, spurring the creation of policies and an increasing number of regulations on the usage and delivery of bandwidth. Issues such as capping, net neutrality and quality assurance fees have all received heavy pushback from customers, leaving many operators puzzled over how to optimize their networks within political restrictions.

Today’s transport architectures require different QAM channels for the various types of narrowcast services. Advanced services such as VOD, DOCSIS data and switched digital video (SDV) are aggregated at the headend and transported onto wavelengths dedicated to specific nodes for delivery to the distribution hub.

Having the right tools in place enables cable operators to address these bandwidth constraints, which is crucial to support a sustainable, future-proof business. Advances in full-spectrum, multi-wavelength technology have paved the way for operators to mine more from their existing fiber plant without the need for expensive (and time-consuming) construction.

First introduced to the industry in 2006, full-spectrum, multi-wavelength Oband systems enable operators to multiply (up to eight times) the narrowcast capacity of their 1310 nm plant. Further development resulted in the introduction of similar technology for the C-band window.

Total Cost Per Mile

Now – with up to 40 wavelengths and both directly modulated and externally modulated full-spectrum, multi-wavelength solutions commercially available – operators have the option to select exactly what makes best sense for their network. And, of course, with a broadcast/narrowcast overlay architecture, operators have the ultimate in flexibility: up to 40 narrowcast wavelengths available over extended distances.

The upstream continues to be a larger challenge for operators. Inherently, the return path is limited, yet with DOCSIS 3.0 services, cable operators need to make ever greater use of the upstream.

No longer is it just about capacity: It’s also important to have high performance. More and more operators are deploying digital return as their gold standard. They have seen that this is the only technology that provides both the performance and the future flexibility that is required in networks. No one wants to deploy a solution today that will need to be “ripped and replaced” when DOCSIS 3.0 upstream speeds need to be increased, or when whatever other new service may be demanded.

And the latest digital return platforms are truly future-proof, with simple upgrades to support 5 to 85 MHz (and even higher), support for 1024-QAM, and achieving throughput up to 700 Mbps. Digital return provides operators with the upstream flexibility and scalability that is required today. It is a robust, thermally stable solution that supports fullload DOCSIS 3.0 channel bonding, and it exhibits the highest levels of performance over extended distances (~200 km).

With up to 80 return segments supported on a single fiber, it’s also a very fiber-efficient solution. With a significantly higher dynamic range than analog systems, the plant has greater immunity to performance degradation. As operators deploy more advanced services and subscribers become more demanding and more reliant upon their cable services, it is important to minimize subscriber service interruptions.

Aurora's Node QAMThe perception has sometimes been that digital return is more expensive than analog. This is not true. Recent generations of digital return have driven the cost of the units down. With a single return digital link now on par with an analog link, and a dual return (for a segmented node) much cheaper than analog, digital return is now a very cost-effective solution. It’s a “set it and forget it” platform, resulting in low, ongoing operating costs. With no-cost, built-in monitoring and management and the use of SFPs in all units to minimize spares costs, choosing digital return is an even easier decision.

Segmenting (or node splitting) can only take a network so far. Experience has shown that Fiber Deep and RFoG are both architectures of choice for operators that need to make that next step. As shown in Figure 1, Fiber Deep is the more cost-effective solution to deploy in urban and suburban areas, whereas RFoG is optimized for rural settings.

Not only does Fiber Deep meet the increasing need for more bandwidth, but as fiber is pushed deeper into a network and the number of actives and power supplies supporting that infrastructure are eliminated or reduced, Fiber Deep enables cable operators to achieve cost savings and reduce energy consumption significantly. In fact, a Fiber Deep architecture may reduce annual energy costs by up to 75 percent, enabling a cable network to achieve “green” results.

Leveraging some of the newer technologies that help optimize the network is another way to confront this bandwidth challenge. One such technology is distributed edge QAM technology or node QAM. The node QAM can deliver up to 158 channels of QAM-RF modulation in the node. Operators have the option of generating a full gigahertz of QAM-RF output in the node or combining node-generated channels with legacy headend-generated channels carried to the node via traditional HFC/Fiber Deep transport.

This technology supports the goals of the Converged Cable Access Platform (CCAP) initiative underway at CableLabs. The solution can deliver any mix of services – broadcast, narrowcast, cable IPTV and DOCSIS, all in the same QAM channel. This versatility enables operators to tailor service migration and growth to local needs and specifications. Moreover, as existing edge QAMs reach capacity, cable operators will no longer need to deploy bulky, power-hungry headend gear to accommodate growth. Using node QAM modules, QAMs can be allocated and configured on a node-by-node basis as service needs arise and shift. Operators have the flexibility to react to growth, regardless of whether it is IPTV, data, high-definition content or on-demand video.

The cable industry has invested wisely in its networks, always looking for ways to evolve and migrate whatever is deployed. With competition continuing to heat up from telcos, satellite and OTT service providers, cable operators need to deliver, and increase, bandwidth per subscriber in order to thrive. With their installed optical node platforms, cable operators have a silver bullet that will continue to evolve, providing scalability and flexibility, and ultimately lowering overhead costs. The competitive climate of the cable industry is dependent on its ability to deal with the bandwidth challenge in a way that best supports both the reality of the business and the future of the industry’s innovation – and, ultimately, its ability to avoid taking a “node to nowhere.”