modem technology are unable to provide large quantities of high-quality video-on-demand. And distributing content within the home in a useful way—i.e., at least as well as do today’s conventional consumer electronics (television, radio, and stereo systems)—remains a significant “systems integration” problem involving broadband hardware and software, inhome networking, and consumer appliance design.

There are, nonetheless, a number of places with experience in new broadband applications. The limited pool of users with broadband at home today, together with a larger set of users who access the Internet at high speeds in the workplace or through the networks of academic institutions, provides some indication of the sorts of applications that could emerge on a mass-market basis. Experimentation in industry and academic laboratories provides another source of indications of potential applications. These early adopters and their applications may not generalize completely, and not all of these services will necessarily succeed from a business standpoint, but they do illustrate how people respond to the availability of broadband and integrate it into their activities at large. This chapter explores the characteristics of a variety of present and future applications and examines some of their technical and related socioeconomic features.

CLASSES OF BROADBAND APPLICATIONS

Key technical characteristics—the bandwidth (upstream and downstream), latency, jitter, addressability, and “on-ness” (always-on), as defined in Chapter 2—distinguish several currently deployed or potential classes of applications. This section outlines the overall characteristics of each class and provides one or more specific examples of applications within each class. Notwithstanding their seeming variety, possible applications by and large depend on a few core, or primitive, signal or traffic types and connection characteristics, such as always-on. These core traffic types are characterized by their basic data rates, by whether they rely on file download or streaming (which in turn may have particular latency and jitter requirements), and the like. Performance and quality trade-offs reflect the interaction between the broadband link and other capabilities such as coding and compression and local storage.

Although there is no rigorous taxonomy of broadband applications, it is useful to draw associations between key characteristics of broadband and major application classes. For example, video-on-demand and other media streaming applications rely on the availability of downstream bandwidth, while information appliances require always-on service even though the bandwidth requirements may be low (see Table 3.1). Also of interest are “composite” applications that rely on a set of capabilities. For



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