Data and Computer
Communications
Multiplexing
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Multiplexing-Data Communication and Computer Networks-Lecture Slides, Slides of Data Communication Systems and Computer Networks
These are a set of Lecture Slides on the subject of Data Communication and Computer Networks at Univeristy of Delhi by Dr. Sonam Zinta. It includes: Multiplexing, Frequency, Division, Synchronous, Time, Statistical, Voiceband, Carrier, Systems
Typology: Slides
2011/2012
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Data and Computer
Communications
Multiplexing
Multiplexing
multiple links on 1 physical line
common on long-haul, high capacity, links
have FDM, TDM, STDM alternatives
Multiplexing
Frequency Division Multiplexing
Synchronous Time Division Multiplexing
Statistical Time Division Multiplexing
Frequency Division
Multiplexing
FDM Voiceband Example
Transmitted TV Signal
Wavelength Division
Multiplexing
FDM with multiple beams of light at different freq
carried over optical fiber links
commercial systems with 160 channels of 10 Gbps lab demo of 256 channels 39.8 Gbps
architecture similar to other FDM systems
multiplexer consolidates laser sources (1550nm) for transmission over single fiber Optical amplifiers amplify all wavelengths Demux separates channels at the destination
also have Dense Wavelength Division Multiplexing (DWDM)
Wavelength Division
Multiplexing
Synchronous Time Division
Multiplexing
TDM
System
Overview
Data Link Control on TDM
Framing
no flag or SYNC chars bracketing TDM frames
must still provide synchronizing mechanism
between src and dest clocks
added digit framing
one control bit added to each TDM frame identifiable bit pattern used on control channel eg. alternating 01010101…unlikely on a data channel compare incoming bit patterns on each channel with known sync pattern
TDM Example
Digital Carrier Systems
long-distance links use an TDM hierarchy
AT&T (USA) and ITU-T (International) variants
US system based on DS-1 format
can carry mixed voice and data signals
24 channels used for total data rate 1.544Mbps
each voice channel contains one word of digitized data (PCM, 8000 samples per sec)
same format for 56kbps digital data
can interleave DS-1 channels for higher rates
DS-2 is four DS-1 at 6.312Mbps