Physical connectivity is the foundation for telecommunications networks. Imagine that the United States had never deployed copper wires and coaxial cable to connect its homes and businesses and now wanted to design the best possible telecommunications infrastructure. There is little doubt about the best design choice—optical fiber for high bandwidth complemented by wireless for mobility and flexibility. Optical communications would give everyone the greatest possible amount of bandwidth, would be useful for essentially all applications that have been imagined, and would be future proof—it is known how to continually get more
and more bandwidth out of each fiber. The cost of installing the fiber would be no greater than the cost of a new installation of any other medium.
Today U.S. telecommunications infrastructure has little fiber to the premises, although fiber makes up most long-haul and metropolitan area networks. Realizing the goal of fiber everywhere involves a number of problems requiring research. For example, while the cost of optical components is not a significant problem in core networks because the cost is spread across many users, the components represent a nontrivial expense for local access networks, which serve only one user or a handful of users. How can the cost of optical components be reduced sufficiently to make fiber to the home affordable? What architectural approaches offer the best mix of affordability, performance, and evolvability? What are the future applications that will drive the need for increasing bandwidth
Metropolitan area networks are currently receiving much commercial attention. With today’s abundance of fiber in the core, and with access networks creating larger demands, an important focus of research is to develop architectures that effectively handle ever-greater volumes of optical transmission in metropolitan areas. Core networks themselves will require advances, and as more capability is introduced into the access networks, the need will grow to continue to improve the bandwidth-times-distance product, as will demands to increase the performance of national networks.
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