In favor of an enhanced network interface for multimedia services

The future will see networks that are increasingly heterogeneous in transport media (such as wireless, public telephone network, Internet, and broadband ATM), terminals (from desktop supercomputers to personal digital assistants with limited wireless bandwidth), applications, and network services (including continuous-media (CM) datatypes in addition to data). Aside from seamlessly supporting this heterogeneity, goals for a well-thought-out network architecture should include high traffic capacity (especially on wireless links, for example through joint source/channel coding), high subjective quality (including low delay), privacy by end-to-end encryption, and enhanced connectivity (including multicast and mobility). Past attempts at defining an internetworking protocol suite for CM services have concentrated on resource reservation for delay guarantees. This paper summarizes a number of other issues relating to CM services, with particular emphasis on wireless access links, pointing out that the highest subjective quality and traffic capacity cannot be obtained by simply adding wireless access to existing broadband networks and compression standards. The simplistic approach of transcoding (conversion from one compression standard to another) has a number of undesirable characteristics, among them a network infrastructure relatively closed to change and inconsistent with privacy. We describe a framework based on decomposing CM (video, audio, graphics, animation) into substreams at the network interface (as proposed in standards like IPv6 and ST-II in the Internet), as well as at internetworking interfaces, and propose other characteristics of this interface. We point to new opportunities tailored to CM services, like annihilation of stale information and progressive delivery services.