While retaining the emphasis on point-to-point digital communications of the previous edition, this revision adds a basic presentation of data and circuit-switched (telephone) networks. The material uses local area networks (LANs) as the key example. The material is first presented in a qualitative fashion, with examples drawn from real networks and systems, to spur the reader's interest and show its relevance. A quantitative analysis then follows, in this case using queueing theory. Also included in the book is a discussion of modern lightwave (fiber optic) transmission systems. This section begins with a discussion of the DS3 (45 Mbits/s) transmission format, continues with a discussion of SONET, the new optical transmission format hierarchy, and is then followed by quantitative sections deriving performance limits for various types of coherent optical communication. The book also features material on convolutional coding, including a performance evaluation of Viterbi decoders, with an application example drawn from a recent space mission; trellis coding, Minimum Shift Keying (MSK); and QAM techniques applied to digital radio.