Open Systems Interconnection reference model. It describes seven layers: (1) physical layer, (2) data link layer, (3) network layer, (4) transport layer, (5) session layer, (6) presentation layer, and (7) application layer.
Published in Chapter:
Development of a University Networking Project
Almudena Moreno Mínguez (Universidad de Valladolid, Spain) and Enrique Crespo Ballesteros (Universidad de Valladolid, Spain)
Copyright: © 2008
|Pages: 14
DOI: 10.4018/978-1-59904-885-7.ch055
Abstract
A communications channel has an important dependence for the channel capacity (C, in bps) to channel bandwidth (W, in Hz) ratio; this is capacity per unit bandwidth on signal to noise ratio (S/N, power of the signal over power of noise). Shannon’s formula gives an upper limit for this dependence (Shannon & Weaver, 1949), C/W=log2 (1+S/N), which represents channel efficiency. Phase lock loops for waves and data symbols in the presence of noise have been given (Reis, Rocha, Gameira, & Carvalho, 2005).