CE 4228DATA COMMUNICATIONS AND NETWORKINGIntroduction

Networks

Networks

Data Networks

Communications!

Communications

• Communication means conveying information• Usually categorized by the types of information

• Person-to-person• Telephone• Mobile phone• SMS• CB radio• Radio• Remote control

• Free TV• Cable TV• Newspaper• Letter• Email• WWW

Communications – Classifications

• Delivery time• Slow → non-electronic

• Newspaper, letter

• Fast → electronic• TV, telephone

• The scope of this course is limited to fast delivery time, electronic communications

Communications – Classifications

• Medium• Copper wire

• Telephone

• Waveguide or fiber optics• Cable TV

• Free space• Mobile phone

• Information type• Voice

• Mobile phone

• Video• TV

• Data• Email, WWW

Communications – Classifications

• Information flow• Simplex

• TV, SMS

• Half duplex• CB radio

• Full duplex• Telephone

• Full duplex exists only in physical system, but not in application level

• Information distribution• Unicast → one-to-one

• Telephone

• Multicast → one-to-many• Cable TV

• Broadcast → one-to-all• Free TV, radio

• Sometimes broadcast is considered as a special case of multicast

Communications – Model

Communications – Model

Communications – Model

• Source• Generate data to be transmitted• Voice, audio, video, text, digital data, etc.

• Transmitter• Convert data into transmittable signals• Can be viewed as 2 separate tasks• Input transducer

• Translate information into electric signal• Microphone, for example

• Transmitter• Modulation, filtering, encoding, transmitting, etc.

Communications – Model

• Receiver• Convert received signal into data• Can also be viewed as 2 separate tasks• Receiver

• Filtering, amplifying, demodulating, decoding, etc.

• Output transducer• Revert to the original information format• Loudspeaker, for example

• Destination• Take incoming data

Communications – Model

• Transmission system• Carry signals• Twisted pair, coax, fiber, air, etc.

• Goal is to minimize |m' − m|• In a two-way communication system, both the

transmitter and the receiver are implemented within one physical unit

Communications – Networking

• Point-to-point communication system• Link-level issues

• Signaling, bit rate, medium, connector types, filtering, amplification, equalization, synchronization, error control, flow control, etc.

• Addressing, connection establishing, switching, routing are non-issues

A B

Communications – Networking

• Deterministic link sharing

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A B

Multiplexing

Communications – Networking

• Communication network• Network issues such as addressing and routing are

essential

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3

45

6

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Networks

• Point-to-point communication usually not practical• Devices are too far apart• Large set of devices would need impractical number of

connections

• Solution is communication networks• Wide area networks• Local area networks

Networks – WAN

• Wide area networks• Large geographical area• Crossing public rights of way• Rely in part on common carrier circuits• Alternative technologies

• Circuit switching• Packet switching

Networks – WAN

• Circuit switching• Dedicated communications path established for the duration

of the conversation• Telephone networks

• Packet switching• Data sent out of sequence• Small chunks of data at a time

• Packets

• Packets passed from node to node between source and destination

• Used for terminal to computer and computer to computer communications

Networks – LAN

• Local area networks• Smaller scope

• Building or small campus

• Usually owned by same organization as attached devices

• Very high data rate

Networks – MAN

• Metropolitan area networks• Middle ground between LAN and WAN• Private or public networks• High speed• Large area

Networks – Wireless

• Wireless LAN• Wi-Fi

• Wireless WAN• Cellular systems

• Personal area networks• System interconnection• Bluetooth

Networks – Classification

Networks – Trends

• Traditional communication networks• Voice Telephone and cellular networks• Video Cable and satellite TV networks• Data Computer networks• Communication revolution

• Digital age• Driven by innovations in digital communication, signal

processing, computer, IC, optics and wireless technology

Networks – Trends

• New generation of communication networks• Voice Telephone and cellular networks• Video Cable and satellite TV networks• Data Computer networks• Use of Internet• Integrated service with differentiated QoS

CE 4228 – Outline

• Signals & bandwidth• Transmission systems

• Transmission media• Transmission signals• Multiplexing

• Data link control• LANs• WANs

• Protocol architecture• OSI• TCP/IP

CE 4228 – Prerequisites

• Signals and Systems• Frequency domain

• Communications• Modulations

CE 4228 – Requirements

• www.facebook.com/patrachart.abac• academic.eng.au.edu/~ce4222/• Download slides• “I cannot teach anybody anything, I can only make

them think.” - Socrates