DATA COMMUNICATION Lecture-32
Recap of Lecture 31 The Telephone System Analog Services Digital Services T-Lines
Overview of Lecture 32 T-Lines in Analog Transmission Fractional T-Lines E-Lines Fiber To The Curb (FTTC) Error Detection and Correction
T Lines for Analog Transmission Using PCM and TDM, T lines can be used for analog transmission
T Lines for Analog Transmission
T1 Frame
Fractional T Lines Allows several subscribers to share one line by multiplexing their transmissions Their transmissions are interleaved through a device called a DSU/CSU (digital service unit/channel service unit)
Fractional T Lines
E Lines Europeans use a version of T lines called E lines Line Rate(Mbps) Voice channels ------------------------------------------------ E-1 2.048 30 E-2 8.448 120 E-3 34.368 480 E-4 139.264 1920
Digital Signal Service
Fiber to the Curb (FTTC) Devised by telephone and cable TV companies to employ optical fiber while keeping the expense down From a central office to the curb: optical fiber From curb to the subscriber premise: twisted-pair or coaxial cable
FTTC in the Telephone Network Twisted-pair is multiplexed in the junction boxes Optical signals are multiplexed using WDM
FTTC in the Telephone Network
FTTC in the Cable TV Network Coaxial cables are multiplexed in the junction box Optical signals are multiplexed using WDM
FTTC in the Cable TV Network
Types of Errors An electromagnetic signal is subject to interference from heat, magnetism, and other forms of electricity Single-bit error: 0 1 or 1 0 Burst error: Multiple bits are changed
Types of Errors
Summary T-Lines in Analog Transmission Fractional T-Lines E-Lines Fiber To The Curb (FTTC) Error Detection and Correction
Suggested Reading Section 8.5, 8.7, 9.1, “Data Communications and Networking” 2nd Edition by Behrouz A. Forouzan