Next-Generation Network Architecture (NGNA)

Despite all the talk about cable convergence and service bundling over a single pipe, today multi-system operators (MSOs) still deliver these services separately, albeit over a common physical infrastructure. Building separate "silos" for video, data, and voice services has accelerated deployment for MSOs, but led to inevitable equipment, operational, bandwidth, and back-office inefficiencies. Through the Next-Generation Network Architecture (NGNA) project, top North American cable operators are exploring options to unify their Internet Protocol (IP) and MPEG video infrastructures, a move they hope will drive down equipment costs, reclaim valuable HFC spectrum, and enable high-value digital services.

The pitfalls of cable's current service and infrastructure silos are not unlike the inefficiencies experienced by incumbent telcos with their legacy circuit-switched voice networks. In a circuit-switched network, any connection, such as a telephone, fax, or dialup modem call, is allocated a fixed link for the duration of the session, whether or not any data is actually being transmitted. It is no wonder that telecom players have been moving as quickly as possible to a packet-switched architecture where data streams are carried over a common pipe, consuming bandwidth only when bits are actually transmitted. This creates bandwidth and equipment savings through the statistical multiplexing of traffic.

Similarly, in cable, today's analog and digital television signals are typically allocated fixed "broadcast circuits," where video channels each occupy dedicated QAM modulator and spectrum capacity, regardless of whether or not the content is actually viewed. Through NGNA, cable operators are exploring options to create a multimedia packet-switching architecture to maximize efficiencies in the transport of IP and MPEG traffic.

Fulfilling the NGNA vision requires a new class of Digital IP Cable Edge device that integrates the functionality of a high-density edge QAM modulator platform, Docsis cable modem termination system (CMTS), and video processing. The idea is that IP traffic (data, voice, and video) and MPEG traffic (broadcast and on-demand standard and high-definition video) flow over a common Gigabit Ethernet backbone to the cable network edge. Then, this NGNA edge platform dynamically routes the service to the appropriate customer premises device, whether it's an MPEG set-top, IP set-top, cable modem, or PacketCable E-MTA.

What kinds of services and applications may evolve through NGNA? At the top of the list is delivering niche broadcast, on-demand, and high-definition video content via IP to Docsis-enabled set-tops using bandwidth-saving codecs, not to mention interactive television applications.