Transmission Media Sharing • When can you share? • High Medium capacity • Why share ? • Less transmission costs • More cost-effective transmissions • How would you share? • Multiplexing
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
Inverse Multiplexing • Takes data stream from one high speed line & breaks it into portions that can be sent over multiple lower speed lines simultaneously.
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
Digital Service • Less sensitive to interference • 3 Types Digital Service • Switched/56 Service • DDS - Digital Data Service • DS Digital Signal Service
DS • T Lines are Digital Lines for Digital Transmission to deliver DS Service. • T1 = DS-1 = 1.544Mbps • T2 = DS-2 = 6.312Mbps • T3 = DS-3 = 44.736Mbps • T4 = DS-4 = 274.176Mbps