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Introduction of Data Communications

Data Communications

ComponentsMessage, Sender, Receiver, Medium, Protocol

Data Representation

Text, ASCII, Unicode, ISO, Numbers, Images, Audio, VideoDirection of Flow

Simplex, Half-Duplex, Full-Duplex

NetworksDistributed Processing

Network CriteriaPerformance, Reliability, Security

Physical StructuresType of connection, Point-to-point, Multipoint, Topology, Mesh, Star, Bus,

Ring

Categories of Networks

LAN, MAN, WANThe Internet

HistoryInternet Today

ISP, NSP, regional ISP, Local ISP

Protocols and Standards

ProtocolsSyntax, Semantics, Timing

StandardsDe facto, De jure

Standards organization

ISO, ITU-T, ANSI, IEEE, EIAInternet StandardsRFC

Network Models

Layered TasksSender, Receiver and Carrier

Hierarchy

Services

Internet Model TCP/IP protocol suite

Peer-to-Peer Processes

Interfaces between layers, Organization of Layers

Functions of LayersPhysical Layer, Data Link Layers, Network Layers, Transport Layers,

Application Layers

Summary of LayersOSI Model

Signals

Analog and Digital

Analog and Digital Data and Signals

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Periodic and Aperiodic Signals

Analog Signals

Sine WavePeak amplitude, Period and Frequency, Two extremes

Phase

Time and Frequency DomainsComposite Signals

Bandwidth

Digital SignalsBit Interval and Bit Rate

Digital Signal as a Composite Analog Signal

Digital Signal Through a Wide-Bandwidth Medium

Digital Signal Through a Band-Limited mediumDigital versus Analog Bandwidth

Higher Bit Rate

Analog versus Digital

Low-pass versus Band-passDigital Transmission

Analog TransmissionData Rate Limits

Noiseless Channel: Nyquist Bit Rate

Noisy Channel: Shannon Capacity

Using Both LimitsTransmission Impairment

AttenuationDecibel

DistortionNoise

More about signals

ThroughputPropagation Speed

Propagation Time

WavelengthDigital Transmission

Line Coding

Some CharacteristicsSignal Level vs Data Level, Pulse Rate vs Bit Rate, DC components, Self-

Synchronization,

Line Coding SchemesUnipolar, Polar, Nonreturn to zero(NRZ-I, NRZ-L), RZ, Manchester,

Differential Manchester, Bipolar

Other Schemes2B1Q, MLT-3

Block Coding

Steps in TransformationDivision, Substitution, Line Coding,

Some common Block Codes

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4B/5B, 8B/10B, 8B/6T

Sampling

PAMPCM

Sampling Rate: Nyquist Theorem

How many bits per Sample?Bit Rate

Transmission Mode

Parallel TransmissionSerial Transmission

Asynchronous Transmission, Synchronous Transmission

Analog Transmission

Modulation of Digital DataDigital to Analog Conversion

Bit Rate, Baud Rate, Carrier Signal

ASK

FSKPSK

QAMBit/Baud Comparison

Telephone Modems

Modems StandardsV.32, V.32bis, V.34bis, V.90, Traditional Modems, 56K Modems, V.92

Modulation of Analog Signals

AM

FMPM

Multiplexing

FDMMultiplexing process

Demultiplexing process

The Analog HierarchyOther applications of FDM

ImplementationRadio, Television broadcasting, cellular telephone system

WDMTDM

Time Slots and Frames

InterleavingSynchronization

Bit Padding

Digital Signal (DS) ServicesT Lines

Inverse TDM

More TDM applications

Transmission Media

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Guided Media

Twisted Pair Cable

Coaxial CableFiber-Optic Cable

Unguided Media:Wireless

Radio WavesMicrowaves

Infrared

Connecting LANSConnecting Devices

Repeaters

Hubs

BridgesFiltering, Transparent Bridge, Forward, Learning, Loop Problem, Spanning

Tree, Dynamic Algorithm, Source Routing Bridges, Bridges ConnectingDifferent LANs

Two-Layer SwitchRouter and Three-Layer Switches

Adv Dip

Circuit Switching and Telephone Network

Circuit-SwitchingSpace-Division Switch

Time-Division Switch

TDM BusSpace- and Time- Division Switch Combinations

Telephone Network

Major ComponentsLATAs

Making a Connection

Analog ServicesDigital Services

A Brief History