4003-420-01/4005-740-01 Data Communications and Networks I Module 2. Data Transmission -- Lecture Notes Prof. Alan Kaminsky -- Fall Quarter 2012 Rochester Institute of Technology -- Department of Computer Science Key Organizing Principle For This Course What do I need to know about topic X to write network applications? What issues related to topic X affect network application design? Transmission Media Physical characteristics Bandwidth -- Hz, KHz, MHz, GHz Length (distance) -- m, km Effect of physical characteristics on data communication Bit rate -- bps, Kbps, Mbps, Gbps Latency -- sec, msec, μsec, nsec Types of transmission media -- bandwidth? distance? where used? Copper wires Glass fibers Radio Satellites Geosynchronous satellites LEO satellites LEO satellite arrays Microwave Infrared Laser (free space) Satellite related links NASA Orbital Debris Program Office: http://orbitaldebris.jsc.nasa.gov/ Iridium Satellite LLC: http://www.iridium.com/ Real time satellite tracking: http://www.n2yo.com/ Digital Communication Digital signals Bit encoding Bit transmission Bit rate Bit interval Relation between bandwidth and bit rate Nyquist's Theorem: C = 2 B log2 K Shannon's Theorem: C = B log2 (1 + S/N) Calculating the time to send a group of bits Single hop Multiple hops Including latency and transmission time Physical Layer Issues Affecting Network Application Design Transmission media issues Bit rate issues Latency issues Data Communications and Networks I • 4003-420-01/4005-740-01 • Fall Quarter 2012 Course Page Alan Kaminsky • Department of Computer Science • Rochester Institute of Technology • 4486 + 2220 = 6706 Home Page Copyright © 2009 Alan Kaminsky. All rights reserved. Last updated 10-Sep-2009. Please send comments to ark­@­cs.rit.edu.