Transcript ICSA 341/733 Data Communication & Networking

Transmission Media Sharing
• When can you share?
– High Medium capacity
• Why share ?
– Less transmission costs
– More cost-effective transmissions
• How would you share?
– Multiplexing
Multiplexing vs. No Multiplexing
Multiplexer
Types of Multiplexing
• Frequency Division Multiplexing (FDM)
• Wave Division Multiplexing (WDM)
• Time Division Multiplexing (TDM)
– Synchronous
– Asynchronous (Statistical TDM)
Frequency Division Multiplexing
• Analog signaling & transmission.
• Total bandwidth = sum of input bandwidths
+ guard bands.
• Modulates signals to different frequency
• Uses
– Radio broadcasting and television
FDM - Multiplexer
FDM - Demultiplexer
TDM - Synchronous
TDM - Asynchronous
Inverse Multiplexing
• Takes data stream from one high speed line
& breaks it into portions that can be sent
over multiple lower speed lines
simultaneously.
Multiplexing and Inverse
Multiplexing
Analog Services
• Analog switched
– Dial- up, voice networks
– PSTN – Public Switched Telephone Network
• Analog Leased
– Conditioned Lines
Multiplexing Efficiency
• Multiplex signals from lower bandwidth
into high bandwidth lines
• Many analog lines into fewer bigger
channels
• FDM used
• Hierarchical structure
Analog Hierarchy
Digital Service
• Less sensitive to interference
• 3 Types Digital Service
– Switched/56 Service
– DDS - Digital Data Service
– DS Digital Signal Service
DS Hierarchy
DS
• T Lines are Digital Lines for Digital
Transmission to deliver DS Service.
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T1 = DS-1 = 1.544Mbps
T2 = DS-2 = 6.312Mbps
T3 = DS-3 = 44.736Mbps
T4 = DS-4 = 274.176Mbps