The Evolution of Communication Systems

This chapter discusses the evolution of communication systems. It provides an overview of the quality-of-service (QoS) definitions and the evolution toward converged, IP-based next-generation networks. Both the underlying transmission infrastructure and the overlaid transport networks are discussed. The telecom and the data networking industries have changed over time, particularly with the convergence of user requirements and expectations. The need for real-time media formats such as audio, video, and gaming has certainly increased the bandwidth requirements. Real-time audio- and videoconferencing over data networks have created a need for the same real-time QoS guarantees that the telecom industry has enjoyed since the inception of digital telephony. Protocol frameworks such as asynchronous transfer mode, or ATM, started the concept of QoS in response to networks converging to carry data with varying requirements. ATM can provide QoS guarantees on bandwidth and delay for the transfer of real-time and nonreal-time data. A starting point for the definition of QoS comes from the Internet Engineering Task Force. The goal of a QoS framework is to ensure that data are transferred in a deterministic manner that at least meets the performance requirements of each service being delivered.