On-demand real-time video delivery

The digital content market is growing rapidly. Market research reports indicate digital video content is expected to grow to $130 billion worldwide by 2011. This includes on-demand digital video streaming, television services such as Video on Demand (VoD), Subscription Video on Demand (SVoD) and Pay-Per-View (PPV). Also included in this market is on-line video advertising, Internet Protocol Television (IPTV) and mobile TV.

Growing demand for media-rich, just-in-time content and an expanding universe of mobile devices capable of real-time viewing are placing great demands on networks. The inexorable network migration from a centralized, core-based architecture that assumes low-capability access devices, to an edge-based, distributed network architecture that is accessed by intelligent devices is also changing the underlying networking paradigm. Also, shifting is the manner in which content is delivered and consumed. Traditionally, broadcasters determined unilaterally which content they would distribute and when. And while there remains demand for this distribution modality, it is rapidly falling out of favor in large swaths of the viewing population because of growing demand for on-demand, just-in-time delivery.

However, the challenge of delivering the right content in front of the right person at precisely the right time, using whatever device and access modality the customer wants to use to view the desired content is placing unprecedented challenges on the network delivery infrastructure. In other words, real-time, unicast content needs to be delivered on-demand to any of the three screens, be it a TV, a PC or a Mobile appliance as the customer desires at the highest Quality of Experience. The content could range from short clips and TV episodes to full movies and can be professional grade, conversational or user generated content popularized by the growth of social networking. The content has a popularity quotient attached to it, and has spatial and temporal distribution in its request. The challenge that network designers face is how to build a highly scalable, efficient and robust real-time content distribution network.

The forces shaping the on demand video and real-time media delivery market are as varied as the players in the market. The market comprises traditional telco operators, cable providers, wireless players, ISPs, satellite companies, and content delivery networks (CDNs) to name a few. To one degree or another they are all affected by the evolution that is underway today. Telco's are marshalling their resources to offer fiber-deep networks capable of delivering all forms of content with equal quality to all subscribers across a single converged optical infrastructure. Verizon FiOS and AT&T U-Verse are prime examples of this evolution. They recognize that customers want access to content and their response is to ensure that the network they operate in the near-term and beyond will be up to the task. In the cable side of the industry, Data Over Cable Service Interface (DOCSIS) 3.0 is the most visible, high impact force at work.

As part of the move from analog to digital, cable channels are shifted, freeing up channels that can then be bonded to provide faster Internet access -- currently as much as 100 Mbps, soon to be 160 Mbps and beyond. The move also allows cable operators to provide IPTV over DOCSIS-based networks, thus accelerating the move to IP across the board. For bandwidth efficiency, DOCSIS 3.0 allows operators to isolate and dedicate a downstream video feed to any and all users who want to watch it at the same time, simulating the way linear TV works and making the network significantly more efficient. ISPs benefit from this transition as well.

Equally important is the continued use of switched digital video (SDV) as a delivery option. SDV has the ability to free up as many as 50% of the available bandwidth by sending only the channels that are actually being watched at that point in time, thus supporting a "content-on-demand" model.

On the wireless side, the evolution to both mobile IP and broadband are beginning to create excitement. Fourth-generation wireless (4G) is, by definition, IP-based, bringing the advantages of IP all the way out to the mobile device -- its ultimate destination. And the move from Code Division Multiple Access (CDMA) and Global System for Mobile communications (GSM) as perceived end state technologies toward the real end states Universal Mobile Telecommunications System (UMTS), High-Speed Packet Access (HSPA), Long term evolution (LTE) will deliver on the promise of these emerging technologies. HSPA offers the equivalent of DSL, with 3 Mbps of downstream bandwidth and half that upstream, while LTE promises much more -- 300 Mbps of download speed, enough to deliver any service available today to a mobile user, including content-on-demand, high-def video, and other media-rich, bandwidth-intensive services.

The satellite companies have not been sitting idly by, either. Today they offer far and away the largest number of high-definition television channels, and will continue to for some time to come. The satellite companies are facing the challenges of distance and technology demonstrated by the distance-related delay inherent in satellite propagation, which means that interactive services will always suffer from latency. By entering into terrestrial content hosting agreements with Content Delivery Networks (CDN), this issue is somewhat circumvented, however, challenges remain nonetheless.

CDNs are a collection of networked servers that use the Internet as their transport backbone and co-operate to deliver hosted content to subscribers from whatever source makes the most sense for each download transaction. The advantages that CDNs offer to the customer are improvements in performance, scalability, and cost efficiency. Figure 1 shows a unified view of a video distribution network.

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Figure 1: Unified View of Video Distribution Network

There are a number of commercially viable CDNs in the market today including Akamai, Limelight, CDNetworks and Level3. Their existence -- and success -- are directly related to the two factors discussed earlier: First, growing demand for media-rich content delivered to mobile devices. Second, the migration of networks from centralized to edge-based and peer-to-peer (P2P). Supported by the success of such early entrants as BitTorrent, LimeWire, Napster and KaZaA (which ultimately morphed into the highly successful Skype VoIP service), peer-to-peer went from the shadowy side of legitimacy to full-blown success, culminating in contracts between P2P providers (BitTorrent) and major Hollywood movie providers (Warner Brothers) for the legal distribution of content across their networks.

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