do we need wireless networks

7/29/2019 Do We Need Wireless Networks

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wireless needs (work)Do we need wireless? Wireless needs a lot of work! ;)

...Wireless networks:why, when & where of WLANs

Marco Zennaro, [email protected]& Carlo Fonda, [email protected]

RadioCommunications Unitof the ICTP-ARPL

Trieste, Italy

Workshop on Wireless Technologiesfor South Asian Countries

I2IT Pune, India

October 10 - 21, 2005
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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Disclaimer

This is not a(serious) lecture!

Its just anintroduction to afew arguments for

the lab activities.And it gives brieftentative answersto basic questions...


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Agenda

first, the big question(s)then, lets define the battlefield( in our lab, what does wireless mean? )

finally, we will look at the schedulein the meantime, we will discuss afew questions about WLANs

during this hour, we will also try to indentify acommon background: skills and knowledgeabout wireless, open source, networking, etc...


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Wireless questions

The Big Questionfixed or mobile

technology: various issues


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The Big Question


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to wire or not to wire?

any difference betweenwires and wireless?

...youre saying we needto go wireless, but...

why? when?

how can we decide?


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why? when?

how can we decide?


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Poll: You & Wireless

You are interested in wireless computernetworking:

A) for teaching/academic purposes

B) for a practical implementation

C) neither of themD) both of them


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why? when?

how can we decide?


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Wired vs Wireless

Local Area Networking


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Distance and Line-of-sight

The cost of a wirelessnetwork increaseswith the distance (andwith the bandwidth),the relation is usuallynon-linear.

A wireless network

connects one or morelocations that you canvisibly see.


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Co-location and interferences

Co-location of morenetworks usually affectsthe performances.

Spectrum management(frequencies and usagecoordination) is required

at both local andinternational level (ITU).

Interferences may occurfrom other e.m. sources.


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Radiopropagation and environment

Performances of wirelessnetworks may be affectedby the properties of theatmosphere (troposphere,

ionosphere), of the terrain,of surrounding structures.

Worst case scenarios (i.e.bad weather days) mustbe considered.

Wireless network designrequires both technical

and scientific knowledge.


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Fast deployment and re-location

Wireless networks canbe deployed in a veryshort time, i.e. for:

disaster recovery networks

rapid changes ofcommunication needs

Wireless equipmentcan be recycled andre-located in a shorttime, upon the need,saving time and

previous investments.

M bili


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MobilityWireless networks can

connect mobile users.The fixed networkinfrastructure is today:

what telephony has been for the past 50years,

a primary communication service;what a good library structure has been forthe past 500 years,

a primary knowledge source;what an efficient road system has been forthe past 5000 years,

a primary escape way frominsulation:

Mobility is the nextstep forward! (Now to

5 years? Or ... ???)

fi d bil ?


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... fixed or mobile ?

Mobile Wireless Access:

mobile phones (ETACS, GSM...)mobile data (1G, 2G, 3G, 4G...)

Fixed Wireless Access:

last mile problem / long links

leapfrog poor or expensivetelecom infrastructures

difficult environment

fi d bil ?


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... fixed or mobile ?

Mobile Wireless Access:

mobile phones (ETACS, GSM...)mobile data (1G, 2G, 3G, 4G...)

Fixed Wireless Access:

last mile problem / long links

leapfrog poor or expensivetelecom infrastructures

difficult environment


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Poll: Fixed or Mobile

You are interested in:

A) mobile wireless (voice/data)B) fixed wireless (access to Internet)

C) neither of themD) both of them

fi d bil ?


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33

0

200

400

600

800

1000

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

YEAR

USER

S(Millions)

Mobile Telephone Subscribers Internet Users

Source: ITU World Telecommunication Indicators Database.

fixed or mobile ?

In this lab, now, we will practice withtechnologies for fixed wireless access:

its cheap

PnP easy

PTT-free

In future: ?


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Wireless technology


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fixed wireless technologies

38

WWAN


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fixed wireless technologies

38

WWAN


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Quiz: WiFi & WiMAX

Is it true that...

A) WiMAX reaches a greater distance

compared to WiFi? (Yes/No/Maybe)

B) They both use the same modulationbut different power limits? (Y/N/M)

C) WiFi is an insecure technology? (Y/N/M)

D) Im not sure about the differences.

WLAN & WMAN


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wireless networks were designed(in 90es) for the LAN (indoor)market, but in developingcountries WLANS are muchmore useful outdoor, as MANs(or even WANs), for distancesup to 10 Km (or 50 Km, or ...)

WLANs & WMANs

f i l


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cost of wireless

the enormous success of thistechnology has led to a dramaticprice reduction for the radiodevices:

>1000 US$ in 1992


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speed of wireless

the available data transfer rate

on the same radio channel(bandwidth of 20 MHz) hasincreased from 1 Mbps to 54

Mbps (even more Mbps for some non-standard implementations)

i l t d d


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wireless standards

wireless networking has grownincredibly fast thanks to a wide

adoption of common standards:

802.11, 802.11a/b/g protocols

WiFi certification

brand/model intercompatibility

i l LAN


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wireless LANs

indoor/outdoor networkdistribution among many clients

typical distance: 10 - 100 m

Point-to-MultiPoint structure:

master station (access point, AP)

client station (PCI card, PC card,

USB device, wireless bridge)

i l MAN

6"%#)#''71&&8


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wireless MANs

used by ISPs (Point-to-MultiPoint)

typical distances: 1-5 Km

a large number of clients

coexistence problems (max. 3

non-overlapping channels)

line-of-sight, security issues,

remote management

!"#$%&'#(&)" *+

,-.$# /000

1#-2)3

04"5#

i l MAN


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wireless MANs

community/institution/company:

Point-to-Multipoint (mesh?)

Point-to-Point (larger distance,less coexistence problems)

line-of-sight, security issues

radiolink planning

and design

!"#$% &'#(&)" *+

!"#%&'()( *+,-.

/%

01*2%!345$6 %*

7*"!8

/%

/%/%

6%*$9:;-?'@

/!,+'-.,

7"9$6;A'B8

!"#/;


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P2MP MANs

Point-to-MultipointStar topology, one AP, many stations

Omnidirectional antenna for APDirective antennas for stations

APSTA

STASTA

P2MP MAN ( )


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P2MP MANs (cont.)

coexistence problem:APs use omni antennas, so they mayinterfere with other APs or stations

different channels can be used, but only3 channels are non-overlapping

coordination is required among APs

P2MP MAN ( t )


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P2MP MANs (cont.)

Mesh topologymany nodes

complextopology

dynamicwork inprogress!

P2P MAN (WAN )


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P2P MANs (WANs)

wireless long distance links (


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Power Budget

!"#$% "&$% '()*+,-$

!" !#

$% &%

'" '#

(#))*+,-.)*/011

2"

2#

345

65

L t li k ?


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Low-cost links?It is possible to build inexpensivelongdistance radiolinks, withold PCs, Linux OS, offtheshelfWiFi devices (sold for indoor),homemade antennas:

200-500 US$ per links (less?)

skills are required, but you canfind plenty of information and

tutorials, just surfing the WWW

B i t ?


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Buying antennas?

B i t ?


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Buying antennas?

A t ki


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Antenna making


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Meaning of wireless

L t i !


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Lets summarize!

fixed wireless (WiFi)unexpensive solution (WiFi)

(not WiMAX, for now)standard, off-the-shelf (WiFi)

indoor for outdoor (mod WiFi)P-t-P , P-t-MP, long links, mesh

DIY (antennas, APs)


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Schedule for Workshop on Wireless Technologies for South Asian Countries (October 10 21,2005):Venue: Wireless Laboratory, International Institute of Information Technology, Pune-411057, India

D AY D ATE/Day

Session I9.30 AM 10.30 AM

Tea/Coffee10.30 AM 11.00 AM

Session II11.00 AM 12.00

noon

Session III12.00 noon - 1

PM

Lunch1 PM 2

PM

Session III2 PM 3 PM (ForOct 10, 2.00 PM

3.30 PM)

Tea/Coffee3.00 PM

3.30 PM (ForOct 10, 3.30PM 4.00

PM)

Session IV3.30 PM 5.30 PM

(For Oct 10, 4.00 PM 5.30 PM)

1 Oct.10Mon

Registration and Administrative Matters(I2IT) Inauguration of the

Workshop

Review of WirelessCommunications

(RajeshS)

2 Oct.11Tues

Antenna and Radio WavePropagation

(CarloF)

MobileCommunications

(RavindraJ)

Internetworking

and RoutingTechnologies(BharatC)

Internetworking and

RoutingTechnologies

(BharatC)

Networking Laboratory(AjithK, VinayakP and

RAs)

3 Oct.12Wed

Dessera a Indian Festival Holiday (Visit to Panchgani and Mahabaleshwar)

4Oct.13Thus

Linux(TomasK/MarcoZ)

Linux Lab (TomasK,AmitH, AjithK,

RAs)

Linux Lab(TomasK, AmitH,

AjithK, RAs)

GSM/GPRSTechnologies(VinayakP)

Basic Antennas Lab/dBMaths.

(MarcoZ, RAs)

5 O ct .1 4 F riWi-Fi Technologies

(TomasK)

Wi-Fi HardwareReview

(TomasK)

Wi-Fi Lab(TomasK, CarloF,

MarcoZ,VinayakP, Ras)


MarcoZ, VinayakP,Ras)


MarcoZ, VinayakP, Ras)

6Oct.15

SatVisit to Giant Meter wave Radio Telescope (GMRT), Narayangaon

7Oct.16

SunOpen

Co-sponsored by:

Pune Subsection

International Institute of Information Technology, Hinjawadi, Pune 411057, India (www.isquareit.ac.in)

Laboratory schedule

OpenSo rce & Lin


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why is it important for wireless?

network device (router, gw,...)software AP, firmware upgrade

wireless troubleshooting toolsbandwidth optimization

OpenSource & Linux

OpenSo rce & Lin


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why is it important for wireless?

network device (router, gw,...)software AP, firmware upgrade

wireless troubleshooting toolsbandwidth optimization

OpenSource & Linux


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Poll: You & Linux

You know:

A) how to install and setup a Linux PCB) how to manage text files in Linux

C) what Linux is, but not how to use it

D) I dont know anything about Linux

Networking


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Networking

TCP/IP

routing

advanced networking

(optimization, etc...)

Networking


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Networking

TCP/IP

routing

advanced networking

(optimization, etc...)


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Poll: Networking

You know:

A) well enough about the 7 OSI layersB) how to split a network in subnets

C) how to configure TCP/IP on your PC

D) not very much about networking

WiFi networks


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WiFi networks

AP configuration

architectures of WLANsfirmware upgrade

power budgetlong distance link

Antenna DIY


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Antenna DIY

different antennas

measurements on antennas

using a Spectrum Analyzer

making of two antennas

Antenna DIY


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Antenna DIY

different antennas

measurements on antennas

using a Spectrum Analyzer

making of two antennas


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Quiz: Antennas

True or false:

A) an antenna can be good fortransmitting and bad for receiving

B) a parabolic grid receive only halfsignal compared with a parabolic dish

C) TV antennas can be used for WiFi

D) antennas are mysterious things


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Thank you

for your attention!

Any question?

do we need wireless networks

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