EE 104: Introduction to Communications

Professor Andrea Goldsmith

Outline

Course Information and Policies

Communication Systems Today

Future Systems

Design Challenges

Course Information(see web or handout for more details)

Instructor: Andrea Goldsmith, Packard 371, andrea@ee, Ext: 56932, OHs: W 11am-12pm, Th 5:30-6:30.

Class Homepage: www.stanford.edu/class/ee104 TAs:

Jaron Charles, jcharles@stanford, OHs: Th 7-9pm, Email W 8:30-9:30pm

Nikola Stikov, nikola@stanford, OHs: F 11am-1pm, Email Th 6-7pm

Class mailing list: ee104-students (automatic for registered students), ee104-staff for instructor/TAs, guest list available

Discussion Section: W 6:15-7:15pm; not televised Book: An Introduction to Analog and Digital

Communications

Grading: HWs 30%, Midterm 30%, Final 40% No Lectures Jan. 15 and Feb. 24

Other lectures that week start at 12:50pm, or can schedule makeups

Class Policies Exam policy: Exams must be taken at their

scheduled times. Exceptions only in very rare circumstances. Midterm: 2/12 from 12:30-2:05 Final: 3/20 from 8:30-11:30am.

HW policy: Assigned Friday, due following Friday. Lose 25% credit

per day late. Up to 3 students can collaborate on 1 writeup. All

collaborators must work out all problems.

SITN students: HWs must be faxed or postmarked by HW deadline for

regular students. Exceptions must be cleared in advance.

Exams must be taken at same time as for regular students.

Communication Systems

Provide for electronic exchange of multimedia dataVoice, data, video, music, email, web pages, etc.

Communication Systems TodayRadio and TV broadcasting (covered later in the

course)Public Switched Telephone Network (voice,fax,modem)Cellular Phones Computer networks (LANs, WANs, and the Internet)Satellite systems (pagers, voice/data, movie

broadcasts)Bluetooth

PSTN Design

Local exchange Handles local callsRoutes long distance calls over high-speed lines

Circuit switched network tailored for voice Faxes and modems modulate data for voice

channel DSL uses advanced modulation to get 1.5 Mbps

Local SwitchingOffice (Exchange)

Local SwitchingOffice (Exchange)

Long Distance Lines(Fiber)Local Line

(Twisted Pair)

FaxModem

Cellular System Basics

Geographic region divided into cells Frequencies/timeslots/codes reused at spatially-separated locations (analog systems use FD, digital

use TD or CD) Co-channel interference between same color cells. Handoff and control coordinated through cell base stations

BASESTATION

Cell Phone Backbone Network

BSBS

MTSO PSTN MTSO

BS

San Francisco

New York

Internet

Local Area Networks (LANs)

LANs connect “local” computers Breaks data into packets Packet switching (no dedicated channels) Proprietary protocols (access,routing, etc.)

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Wireless Local Area Networks (WLANs)

WLANs connect “local” computers (100m range)

Breaks data into packets Channel access is shared (random

access) Backbone Internet provides best-

effort service

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InternetAccessPoint

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Wide Area Networks:The Internet

Many LANs and MANs bridged together

Universal protocol: TCP/IP (packet based).

Guaranteed rates or delays cannot be provided.

Hard to support user mobility. Highly scalable and flexible topology

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Bridge MANLAN

Satellite andFiber Lines

Bridge LAN

Satellite Systems

Cover very large areas Different orbit heights

Geosynchronous (GEO) versus low earth orbit (LEO)

Optimized for one-way transmissionPaging, radio and movie broadcast

Most two-way systems struggling or bankruptExpensive alternative to terrestrial systemA few ambitious systems on the horizon

Bluetooth

Cable replacement for electronic devicesCell phones, laptops, PDAs, etc.

Short range connection (10-100 m)1 data (721 Kbps) and 3 voice (56 Kbps)

channelsRudimentary networking capabilities

Future Systems

Nth Generation CellularNth Generation WLANsNth Generation InternetWireless EntertainmentSensor Networks Smart Homes/AppliancesAutomated Cars/FactoriesTelemedicine/LearningAll this and more…

Ubiquitous Communication Among People and Devices

Design Challenges Hardware Design

Precise componentsSmall, lightweight, low powerCheapHigh frequency operation

System DesignConverting and transferring informationHigh data rates Robust to noise and interferenceSupports many users

Network DesignWorldwide anywhere any-time connectivitySpeed

Main Points Communication systems send information

electronically over communication channels

Many different types of systems which convey many different types of information

Design challenges include hardware, system, and network issues

Communication systems recreate transmitted information at receiver with high fidelity

Focus of this class is design and performance of analog and digital communication systems