Wilamowski B.M., Irwin J.D. The Industrial Electronics Handbook. Second Edition: Industrial Communication Systems

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27-8 Industrial Communication Systems

27.3 Industrial Multimedia applications

27.3.1 Monitoring applications

Monitoring.applications.are.very.well.known.in.industrial.areas,.although.mainly.at.the.LAN.and.WAN.

leve

.Typi

cally,

.in.all.kind

.of.indu

stries

.mach

ines

.are.quit

.larg

.and.beca

use

.of.this.die

rent

.came

ras

tran

smit

.the.info

rmation

.to.the.cont

rol

.poin

.to.ensu

.the.corr

ect

.mana

gement

.of.the.mach

ine

.by.the.

work

er.

.Anot

her

.appl

ication

.is.that.the.imag

.are.requ

ired

.from.anot

her

.poin

.of.the.facto

.for.work.

supe

rvision

.from.glob

.cont

rol

.cent

ers.

. ese.syst

ems

.are.oen.used.in.area

.that.pres

ent

.a.cert

ain

dang

.for.the.work

er.

.Fina

lly,

.glob

.cont

rol

.cent

ers

.need.to.moni

tor

.the.remo

.inst

allations’

.stat

in.orde

.to.cont

rol

.thei

.perf

ormance

.(esp

ecially

.to.cont

rol

.netw

ork

.util

ities

.[SAS

06][SSA07]).

.In.all.of.

thes

.situa

tions,

.mult

imedia

.info

rmation

.is.tran

smitted

.thro

ugh

.netw

orks

.for.a.bett

.use.of.mach

ines

and.equ

ipments

.due.to.the.ric

.con

text

.inf

ormation

.tha

.mul

timedia

.has.for.the.wor

kers.

.requ

irements

.of.this.type.of.appl

ication

.are.not.typi

cally

.too.dema

nding,

.but.they.are.conn

ected

to.the.nal.use.of.the.imag

.in.the.appl

ication

.and.the.netw

orks

.avai

lable,

.since.it.can.invo

lve

.stro

limi

tations.

. e.imag

.reso

lutions

.are.usua

lly

.betw

een

.CIF.and.4CIF.or.VGA.since.thes

.reso

lutions

.are.

more.than.adeq

uate

.to.gath

.the.info

rmation

.of.inte

rest

.and.do.not.over

load

.the.huma

.capa

city

.for.

proc

essing

.this.type.of.info

rmation.

.Grea

ter

.reso

lutions

.can.be.used.if.the.imag

es,

.in.addi

tion

.to.live.

huma

.supe

rvision,

.are.store

.for.a.late

.use.(e.g

.tech

nical

.repo

rts

.in.the.cont

rol

.of.util

ities

.netw

orks,

comp

laints

.in.surv

eillance

.appl

ications).

. e.qual

ity

.of.the.imag

.is.anot

her

.impo

rtant

.para

meter,

.and.

for.moni

toring

.appl

ications,

.it.is.consi

dered

.appr

opriate

.to.have.at.leas

.30.dB..Conc

erning

.tran

smission

time

.we.can.consi

der

.here.two.grou

ps.

.In.the.appl

ications

.wher

.only.live.moni

toring

.is.perf

ormed

(wit

hout

.stora

ge)

.and.the.info

rmation

.is.used.by.the.work

.who.is.oper

ating

.the.mach

ine,

.this.late

ncy

has.to.be.lower.than.1000.ms,.since.the.machinery.has.to.be.managed.with.real-time.information..In.

the.seco

.grou

.we.can.consi

der

.the.appl

ications

.wher

.a.huma

.oper

ator

.rece

ives

.and.proc

esses

.the.

info

rmation,

.usua

lly

.from.seve

ral

.sour

ces,

.and.in.whic

.ther

.is.no.stora

ge.

.In.this.case

.the.late

ncy

.is.

conn

ected

.wit

.the.hum

.cap

acity

.for.pro

cessing

.thi

.typ

.of.inf

ormation.

27.3.2 Computer Vision applications

 ese.types.of.applications.are.characterized.by.the.use.of.image.processing.techniques.for.industrial.

autom

ation.

. ere.are.basic

ally

.thre

.appl

ication

.type

.oine.insp

ection

.appl

ications,

.onli

.insp

ec-

tion

.appl

ications,

.and.guid

ance

.appl

ications

.(suc

.as.robo

ts).

.In.the.rst.case

.they.are.appl

ications

.of.

qual

ity

.cont

rol.

. eir.objec

tive

.is.to.know.the.prod

uct’s

.stat

.in.orde

.to.dete

rmine

.what.furt

her

.pro-

essing

.is.nece

ssary,

.or.in.the.case.of.nis

hed

.prod

ucts,

.its.deli

very

.to.the.custo

mer.

.A.very.high.work

ing

.spee

.may.be.requ

ired

.even.thou

.ther

.are.no.hard.real

-time

.requ

irements.

.For.exam

ple,

.qual

ity

insp

ection

.of.20–8

.m/mi

.of.fabr

ic,

.but.in.whic

.the.faul

.are.store

.for.repo

.purp

oses,

.or,.in.case

wher

.it.is.nece

ssary

.to.stop.the.mach

ine,

.ther

.is.some.toler

ance

.in.the.orde

.dela

.In.the.seco

.case

the.visio

.syst

.insp

ects

.the.prod

uct

.or.the.proc

ess

.in.orde

.to.dete

rmine

.what.acti

.is.nece

ssary.

.In.

othe

.word

.the.imag

.proc

essing

.resu

.will.have.cons

equences

.on.the.prod

uction

.proc

ess

.(e.g

.regu

la-

tion

.on.the.widt

.of.rubb

.band

.[SS0

7]),

.and.ther

efore,

.ther

.are.some.temp

oral

.rest

rictions

.that.must.

be.adhe

red

.to.in.the.tran

smission

.and.proc

essing

.of.imag

es.

.In.the.thir

.appl

ication

.type

.the.info

rma-

tion

.extr

acted

.from.the.imag

.is.used.to.guid

.the.mana

gement

.of.cutt

ing

.stan

ds,

.robo

ts,

.etc.,.and.in.

whic

.cas

.adh

erence

.to.tem

poral

.req

uirements

.is.eve

.mor

.imp

ortant.

.comm

.requ

irement

.of.the.thre

.type

.of.comp

uter

.visi

.appli

cation

.is.the.nece

ssity

.of.high

quality

.imag

es.

. ere.has.been.some.work.carr

ied

.out.to.anal

yze

.the.limi

.of.imag

.degr

adation,

.but.

this.has.been.main

.for.spec

ic

.medi

cal

.appli

cations,

.and.ther

.have.been.no.stud

ies

.on.indu

strial

envi

ronments

.or.into.a.gene

ral

.theo

.to.gain.prio

.know

ledge

.of.this

. e.targ

.of.the.comp

uter

visi

.appli

cation

.dete

rmines

.the.imag

.reso

lution

.and.the.tran

smission

.time

.Typi

cal

.appli

cations

use.4CIF.reso

lution

.with.tran

smission

.betw

een

.1.and.60.fram

es/s.

.In.some.case

.more.than.one.came

Industrial Multimedia 27-9

is.necessary,.or.even.in.wide.network.inspection,.the.use.of.lineal.cameras.(lineal.cameras.are.devices.

with.a.sens

.of.only.one.line.of.pixe

.form

ing

.the.imag

.with.the.conc

atenation

.of.cons

ecutive

.line

s).

27.4 Image transmission

Since.processing.of.image/video.data.typically.does.not.take.place.in.the.camera.that.captures.the.data,.

the.data.has.to.be.tran

smitted

.over.some.kind.of.data.netw

ork.

. ere.are.tran

sport

.proto

cols

.that.den

how.mult

imedia

.data.has.to.be.put.into.data.pack

ets

.that.are.sent.on.the.netw

ork

.[W06

. is.typi

cally

also.invo

lves

.some.time

stamps

.that.are.used.for.sync

hronization

.purp

oses.

. ere.are.also.proto

cols

nece

ssary

.to.set.up.and.star

.stre

aming

.of.the.data.over.the.netw

ork.

. ese.proto

cols

.are.usua

lly

.tigh

tly

coup

led

.with.the.tran

sport

.proto

cols.

.Each.kind.of.netw

ork

.has.die

rent

.kind

.of.data.form

ats

.that.are.

tran

sported

.by.the.tran

sport

.proto

col.

. is.depe

nds

.on.the.spec

ial

.feat

ures

.(lik

.avai

lable

.band

width)

of.the.netw

ork.

.Two.kind

.of.netw

ork

.will.be.desc

ribed

.more.in.deta

.here

.IEEE.1394.and.IP-ba

sed

netw

orks

.(ty

pically

.bas

.on.Ethe

rnet)

.[W0

5].

27.4.1 IEEE 1394

IEEE.1394.[IEEE1394],.also.known.as.FireWire.or.i.Link,.is.a.serial.bus.designed.to.connect.up.to.

63.devi

ces

.(lik

.camc

orders,

.CD.play

ers,

.sate

llite

.tune

rs,

.but.also.pers

onal

.comp

uters

.and.peri

pherals

like.hard.disk

.scann

ers,

.etc.

. e.orig

inal

.vers

ion

.of.this.bus.supp

orts

.up.to.400.Mbps

.has.an.auto

matic

con

guration

.mecha

nism

.allo

wing

.hot.plug

ging

.of.devi

ces,

.and.is.very.well.suit

.for.stre

aming

.of.mult

media

.cont

ent

.[A99

.It.supp

orts

.4.5.m.link

.and.up.to.16.hops.betw

een

.two.devi

ces

.lead

ing

.to.a.maxi

mum

dist

ance

.of.72.m.betw

een

.two.node

. is.clea

rly

.show

.that.it.is.suit

.for.smal

.area.envi

ronments

.like.

home

.or.auto

mobiles,

.but.it.is.used.in.indu

strial

.envi

ronments

.as.well

.IEEE.1394

.[IEE

E1394a]

.intr

duced

.some.new.feat

ures,

.main

.to.incr

ease

.the.bus.eci

ency

.(redu

ction

.of.idle.time

s),

.but.the.main.

char

acteristics

.were.prese

rved.

. e.newe

.vers

ion

.IEEE.1394

.supp

orts

.up.to.1600.Mbps.and.has.arch

itec-

tural

.supp

ort

.for.3200.Mbps.[IEE

E1394b].

.It.intr

oduced

.some.new.phys

ical

.media.in.addi

tion

.to.shie

lded

twis

ted

.pair.(STP

)

.copp

.cabl

.and.also.incr

eased

.the.maxi

mum

.dist

ance

.betw

een

.devi

ces

.(up.to.100.m.

usin

.opti

cal

.ber

.or.CAT-

.UTP)

. e.tran

smission

.mode

.and.codi

.of.data.is.comp

letely

.die

rent

.to.

IEEE.1394

.howe

ver,

.comp

atibility

.is.main

tained

.by.intr

oduction

.of.bili

ngual

.node

.the.physi

cal

.laye

.a.Fire

Wire

.bus.is.a.tree.consi

sting

.of.poin

t-to-point

.conn

ections

.betw

een

.the.

devi

ces.

.Howe

ver,

.the.physi

cal

.laye

.tran

sforms

.this.tree.into.a.logi

cal

.bus,.wher

.each.node.(exc

ept

.the.

node.that.is.curr

ently

.tran

smitting

.a.pack

et)

.acts.as.repe

ater.

. e.high

.laye

.(lin

.laye

.and.tran

sac-

tion

.laye

.of.the.thre

e-layer

.desig

.used.in.IEEE.1394

)

.have.a.view.as.a.bus,.wher

.all.pack

ets

.are.rece

ived

by.eve

.nod

.pro

vided

.the.use

.spe

.is.sup

ported

.on.all.lin

.in.bet

ween.

Two

.dieren

.data.tran

sfer

.mode

.are.supp

orted:

.asyn

chronous

.and.isoc

hronous

.data.tran

sfer.

. e.

isochronous.mode.has.been.designed.to.meet.the.requirements.of.multimedia.streaming..There.

are.64.isoc

hronous

.chan

nels.

.Such.chan

nel

.can.be.rega

rded

.as.a.mult

icast

.grou

.In.fact

.the.pack

ets

.are.

tran

smitted

.to.each.node.on.the.netw

ork,

.but.the.hard

ware

.insi

.the.node.usua

lly

.lter

.and.disc

ards

pack

ets

.of.isoc

hronous

.chan

nels

.that.are.not.of.inter

est.

. ere.is.a.reso

urce

.mana

gement

.mech

anism:

band

width

.and.chan

nel

.can.be.reser

ved

.at.the.isoc

hronous

.reso

urce

.mana

ger

.(a.func

tionality

.prov

ided

by.one.of.the.node

.in.the.netw

ork)

.and.are.then.guar

anteed.

. is.mean

.that.qual

ity

.of.servi

.is.pro-

ided.

. e.requ

irement

.for.the.guar

antee

.of.isoc

hronous

.band

width

.is.that.all.node

.have.to.obey.the.

rule

.of.IEEE.1394.and.reser

.band

width

.and.chan

nel

.befo

.they.are.used

.Sinc

.this.is.not.enfor

ced

by.hard

ware

.or.sow

are,

.node

.viol

ating

.thes

.rule

.can.comp

romise

.QoS.. e.sour

.can.send.one.

isoc

hronous

.pack

.every.125.μs.(lea

ding

.to.8000.isoc

hronous

.cycl

es/s).

. e.allo

wed

.size.of.the.pack

corr

esponds

.to.the.reser

ved

.band

width.

.In.case.of.error

.no.retr

ansmission

.occu

rs,

.so.timi

.is.guar

an-

teed,

.but.not.deli

very.

.On.the.other.side

.the.asyn

chronous

.tran

sfer

.mode.is.used.for.deli

very

.of.vari

able-

length

.pack

ets

.to.expl

icitly

.addr

essed

.node

. ere.is.an.ackn

owledgment

.and.a.retr

.proc

edure

.in.case.

of.error

. eref

ore,

.the.deli

very

.of.inte

ger

.data.can.be.guar

anteed,

.but.timi

.is.not.guar

anteed.

27-10 Industrial Communication Systems

In.the.area.of.streaming.multimedia.data,.asynchronous.transactions.are.not.used.for.the.transfer.

of.mul

timedia,

.but.the

.are.use

.for.con

trol

.pur

poses.

.IEC.618

83-1

.use

.asy

nchronous

.tra

nsactions

.for.

set

.and.tea

rdown

.of.iso

chronous

.con

nections,

.whi

.als

.inc

ludes

.the.iso

chronous

.res

ource

.man

age-

ment

.[IE

C61883-1].

.Hig

her

.lev

.con

trol

.pro

tocols

.lik

.AV/

.are.bas

.on.IEC.618

83-1

.and.use.asy

nchro-

nous

.tra

nsactions

.to.com

municate.

.Rea

l-time

.tra

nsmission

.of.aud

.and.vid

.dat

.is.wel

l-standardized

by.the.ser

ies

.of.IEC

61883.

.IEC.618

83-1

.de

nes

.gen

eral

.thi

ngs

.lik

.a.com

mon

.for

mat

.for.iso

chronous

pac

kets

.as.wel

.as.mec

hanisms

.for.est

ablishing

.and.bre

aking

.iso

chronous

.con

nections

.[IE

C61883-1].

 is.al

.in

cludes

.ti

mestamps,

.wh

ich

.ar

.us

.fo

.sy

nchronization

.[W

Z03].

Transmission

.of.dat

.in.the.dig

ital

.vid

.(DV

)

.for

mat

.[IE

C61834-2]

.(ty

pically

.use

.on.han

dheld

dig

ital

.vid

.cam

eras)

.is.spe

cied

.in.IEC.618

83-2

.[IE

C61883-2].

.An.adv

antage

.of.thi

.for

mat

.is.the.

hig

.qua

lity

.and.a.low.com

plexity

.of.enc

oding

.and.dec

oding

.bec

ause

.it.doe

.not.use.the.sop

histicated

int

erframe

.com

pression

.tec

hniques

.kno

.fro

.MPE

G-2.

.On.the.oth

.han

.it.imp

oses

.rat

her

.hig

ban

dwidth

.req

uirements

.(ab

out

.25.Mbp

.for.an.SD.for

mat

.DV.vid

.str

eam,

.toge

ther

.wit

.aud

.and.

oth

.in

formation

.it.yi

elds

.ab

out

.29.Mbp

s).

For

.tra

nsmission

.of.aud

.dat

.IEC.618

83-6

.is.use

.[IE

C61883-6].

.It.is.use

.by.con

sumer

.ele

ctronic

aud

. equ

ipment

. lik

. CD. pla

yers,

. amp

liers,

. spe

aker

. sys

tems,

. etc

. Usu

ally,

. aud

. is. dis

tributed

. as.

unc

ompressed

.aud

.sam

ples

.at.44,

100

.or.48,

000

.Hz.sam

ple

.rat

.but.oth

.dat

.for

mats

.are.sup

ported

.as.

wel

.But.aud

.dis

tribution

.is.de

nitely

.mor

.of.int

erest

.in.hom

.env

ironments

.tha

.in.ind

ustrial

.one

Transmission

.of.MPE

G-2

.tra

nsport

.str

eams

.[MP

G2]

.ove

.IEE

.139

.is.spe

cied

.in.IEC.618

83-4

[IEC61883-4].. is.allows.the.distribution.of.digital.television.over.IEEE.1394,.since.both.DVB.and.

ATS

.use.MPE

G-2

.tra

nsport

.str

eams.

.MPE

G-2

.pro

vides

.a.goo

.tra

de-o

.bet

ween

.qua

lity

.and.uti

lized

ban

dwidth.

.A.ty

pical

.PA

.TV.pr

ogram

.re

quires

.ab

out

.6.Mbp

.add

ition

.to.the.two.pos

sibilities

.bas

.on.IEC.618

.men

tioned

.abo

.to.tra

nsmit

.vid

.in.DV.

or.MPE

G-2

.dat

.for

mat,

.the

.is.ano

ther

.pro

tocol

.tha

.is.pri

marily

.tar

geting

.ind

ustrial

.env

ironments

(al

beit

.the

.are. som

. Web. cam

eras

.usin

.thi

.pro

tocol

.as.wel

l):

. the.Ins

trumentation

.&. Ind

ustrial

Dig

ital

.Cam

era

.(II

DC)

.pro

tocol

.[II

DC1394].

. is.is.a.ver

.simp

.pro

tocol

.(no

.bas

.on.IEC.618

83)

tha

.tra

nsmits

.unc

ompressed

.dig

ital

.vid

.ove

.iso

chronous

.Fir

eWire

.cha

nnels.

. er

efore,

.it.req

uires

sign

icantly

.mo

.ba

ndwidth,

.bu

.do

.no

.re

quire

.en

coding

.an

.de

coding.

27.4.2 IP-Based Networks

IP,.the.Internet.protocol,.is.a.very.widely.used.network.protocol.. e.main.reason.is.that.it.can.be.used.on.

top.of.alm

ost

.eve

.low

.laye

.net

working

.sys

tem

.(Et

hernet,

.tok

.rin

.IEE

.139

.etc

.[AS

T03].

. es

net

works

.wer

.not.des

igned

.for.the.pur

pose

.of.mul

timedia

.tra

nsmission

.and

.the

refore,

.hav

.som

.wea

nesses

.wit

.reg

ard

.to.rea

l-time

.dat

.tra

nsmission.

.QoS.is.ver

.lim

ited.

. er

.are.mec

hanisms

.for.QoS.

in.IP.net

works,

.but.the

.pro

vide

.onl

.so.gua

rantees.

. e.res

ource

.res

ervation

.pro

tocol

.(RS

VP)

.is.the.

sta

ndard

.pro

tocol

.to.res

erve

.res

ources

.in.IP.net

works

.[WZ0

1].

.In.fact

.RSV

.is.onl

.a.sig

naling

.pro

tocol

for.res

ource

.res

ervation

.req

uests

.and.doe

.not.by.its

elf

.res

erve

.res

ources.

.IP.net

works

.onl

.oe

.bes

.eo

ser

vices,

.and.the

refore,

.QoS.is.usu

ally

.onl

.ach

ieved

.by.ove

rsizing

.the.net

work

.and.pro

viding

.muc

.mor

per

formance

.tha

.nee

ded

.in.ave

rage

.to.ensu

.goo

.per

formance

.eve

.in.wors

t-case

.sce

narios.

Besides

.the.so-

called

.int

egrated

.ser

vices

.app

roach

.wit

.per

-stream

.res

ervations,

.the

.is.als

.the.dif

ferentiated

.ser

vices

.app

roach,

.whi

.doe

.not.pro

vide

.per

-stream

.res

ervations,

.but.has.adv

antages

.in.

sca

lability

.[WZ

01].

.Bel

.IP,.on.the.Ethe

rnet

.lay

er,

.IEE

.802

.1p

.als

.pro

vides

.som

.kin

.of.QoS.mec

ha-

nism.

.But.thi

.is.ver

.wea

.It.jus

.all

ows

.de

ning

.pri

orities

.of.ind

ividual

.Ethe

rnet

.pac

kets.

.It.doe

.not.

res

erve

.res

ources

.and.doe

.not.pro

vide

.any.gua

rantees.

.One.pro

blem

.of.IP.net

works

.is.tha

.tra

nsmis-

sion

.of.aud

.and.vid

.is.not.ver

.wel

l-standardized.

. er

.is.a.wid

.var

iety

.of.dat

.and.tra

nsmission

for

mats,

.op

.an

.pr

oprietary

.on

es,

.wh

ich

.ar

.no

.co

mpatible

.wi

.ea

.ot

her.

.IP-

based

.net

works,

.man

.di

erent

.pro

tocols

.are.com

monly

.used.for.rea

l-time

.tra

nsmission

.of.mul

timedia.

. e.mos

.pri

mitive

.one.is.HTT

.the.hyp

ertext

.tra

nsfer

.pro

tocol.

. er

.are.imp

lementations

.tha

use.HTT

.to.str

eam

.rea

l-time

.aud

.dat

.But.bes

ides

.some.adva

ntages

.(it.is.ver

.sim

ple

.and.wor

.wel

Industrial Multimedia 27-11

with.proxies.and.rewalls),.it.also.has.many.disadvantages..It.does.not.support.multicast,.only.unicast..

 ere

fore,

.if.more.than.one.node.is.list

ening

.to.the.stre

am,

.sever

.conn

ections

.have.to.be.esta

blished

.that.

use.the.corr

esponding

.mult

iple

.of.the.neces

sary

.band

width.

.Furt

hermore,

.HTTP.is.based.on.TCP,.whic

is.a.reli

able

.prot

ocol,

.that.is,.it.does.perf

orm

.retr

ansmission

.of.pack

ets

.that.were.not.tran

smitted

.corr

ectly.

 is.is.comp

letely

.inad

equate

.for.real

-time

.tran

smission

.becau

.the.retr

ansmitted

.data.will.oen.be.late.

and,.ther

efore,

.usele

ss.

.In.fact

.the.use.of.HTTP.is.just.an.exte

nsion

.of.prog

ressive

.down

load

.(the.prese

nta-

tion

.of.a.mult

imedia

.le.star

.whil

.down

loading),

.but.it.was.neve

.desi

gned

.for.real.stre

aming.

.much.more.suit

able

.prot

ocol

.for.tran

smission

.of.mult

imedia

.data.is.real

-time

.tran

sport

.prot

ocol

(RTP

)

.as.prop

osed

.in.RFC1

889,

.whic

.is.usua

lly

.based.on.UDP.and.in.prin

ciple

.supp

orts

.mult

icast

.as.well.

as.unic

ast.

.It.also.incl

udes

.time

stamps,

.whic

.are.used.for.sync

hronization

.purp

oses;

.but.it.has.to.deal.

with.the.fact.that.in.IP.netw

orks

.ther

.is.no.glob

.time.base.that.is.sync

hronized

.auto

matically.

.Real

-time

stre

aming

.prot

ocol

.(RTS

.can.be.used.for.setti

.up.the.tran

smission.

. ere.are.also.prop

rietary

.prot

cols

.like.Micr

oso

.media.serve

.(MMS

)

.or.Real.deli

very

.tran

sport

.(RDT

)

.and.othe

rs.

. ey.have.simi

lar

feat

ures

.and.are.used.by.the.tool

.of.the.corr

esponding

.comp

anies

.(Mic

roso,

.Real

Networks,

.etc.

Many

.die

rent

.(ope

.and.prop

rietary)

.form

ats

.for.audi

.and.vide

.exis

.and.can.be.tran

smitted

.in.an.

RTP.stre

.[W05

.Conce

rning

.audi

.the.most.impo

rtant

.open.form

ats

.are.unco

mpressed

.audi

.with.16,.

20,.or.24.bit.reso

lution

.and.MPEG.comp

ressed

.audi

.stre

ams.

.For.vide

.RFC2

250

.spec

ies

.how.to.tran

smit

MPEG.vide

.elem

entary

.stre

ams.

.If.audi

.and.vide

.are.to.be.tran

smitted

.in.one.stre

am,

.MPEG-

.tran

sport

stre

ams

.can.be.used

.but.the.conc

ept

.of.RTP.is.to.tran

sport

.each.medi

.in.a.sepa

rate

.stre

.rath

.than.usin

multiplexes..Digital.video.in.the.DV.format.of.IEC.61834.[IEC61834-2].can.be.transported.in.RTP.according.

to.RFC3

189

.[IEC

61883-2].

.Howe

ver,

.it.shou

.be.ment

ioned

.that.this.is.a.form

.comm

only

.used.on.IEEE.

1394.[IEC

61883-2]

.but.not.on.IP.netw

orks.

.Impo

rtant

.prop

rietary

.form

ats

.are.Real

Audio

.and.Real

Video.

IPv6,

.the.succ

essor

.of.IP.versi

.4,.has.some.adva

ntages

.conc

erning

.mult

imedia

.stre

aming.

.Mult

icast

has.been.inte

grated

.into.IPv6

.so.ever

.comp

liant

.impl

ementation

.supp

orts

.mult

icast.

. ere.are.feat

ures

(esp

ecially

.the.ow.labe

.shou

.be.ment

ioned)

.that.make.the.prov

ision

.of.QoS.for.stre

ams

.easi

er.

 e.func

tionality

.of.Inte

rnet

.Grou

.Mana

gement

.Proto

col

.(IGM

.is.inte

grated

.into.ICMP

.(Int

ernet

cont

rol

.mess

age

.proto

col).

. e.“mul

ticast

.list

ener

.disc

overy”

.(MLD

)

.used.for.the.signa

ling

.betw

een

rout

ers

.and.hos

.is.a.sub

protocol

.of.ICM

Pv6.

27.5 Conclusions

Multimedia.has.a.wide.range.of.applications.in.the.industrial.area.. ese.applications.also.have.a.wide.range.

of.requ

irements,

.like.reso

lution,

.fram

.rate

.imag

.qual

ity,

.late

ncy,

.etc..Indu

strial

.comm

unications

.netw

orks

prov

ide

.the.nece

ssary

.infra

structure

.for.many.appl

ications.

.In.this.chap

ter,

.indu

strial

.mult

imedia

.appl

ica-

tions

.and.thei

.part

icular

.requ

irements

.are.disc

ussed.

.Compr

ession

.tech

nology,

.which.is.need

.in.many.

appl

ications

.due.to.band

width

.or.stor

age

.limit

ations,

.is.brie

y

.revi

ewed.

.Fina

lly,

.two.die

rent

.exam

ples

.of.

netw

ork

.and.the.asso

ciate

.prot

ocols

.for.tran

smission

.of.mult

imedia

.data.are.pres

ented.

acknowledgment

 is.work.was.partially.supported.by.de.MCYT.of.Spain.under.the.project.TSI2007-66637-C02-02.

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28-1

28.1 Introduction

 e.use.of.wireless.communications.in.industrial.environments.poses.a.dierent.set.of.challenges.than.

depl

oyment

.in.home.and.ente

rprise

.envi

ronments.

.Sign

icant

.amou

nts

.of.elec

trical

.nois

.such.as.vari

able

.freq

uency

.driv

es,

.comp

eting

.radi

.syst

ems,

.rada

.and.micr

owave

.sour

ces,

.and.weld

ers

.are.pro-

uced

.in.ind

ustrial

.env

ironments.

.Sig

nal

.att

enuation

.and.re

ects

.are.alw

ays

.pre

sent

.[1]

.plac

ement

.of.wire

less

.acce

.poin

.(APs

.or.radi

.node

.and.adju

stment

.of.tran

smitter

.powe

to.matc

.rece

iver

.sensi

tivities

.is.more.cruc

ial

.in.indu

strial

.sett

ings

.wher

.the.reli

ability

.of.the.over

all

syst

.can.aec

.plan

.safe

.and.secu

rity

.as.well.as.oper

ational

.cost

.Data.late

ncy,

.the.time.dela

.expe

rienced

.when.data.is.sent.from.one.poin

.to.anot

her,

.as.well.as.possi

ble

.data.corr

uption

.can.aec

.syst

perf

ormance.

Security

. is. a. sign

icant

. obst

acle

. to. wide

. deplo

yment

. of. wire

less

. tech

nology

. in. ente

rprise

. and.

indu

strial

.envi

ronments.

. e.secu

rity

.issu

.and.prot

ocols

.as.well.as.deplo

yment

.guid

elines

.are.pre-

ented

.for.wire

less

.loca

.area.netw

orks,

.pers

onal

.area.netw

orks,

.and.mesh.netw

orks

.that.may.conc

ern

indu

strial

.user

.rela

tionship

.betw

een

.vari

ous

.wire

less

.netw

orks

.in.terms.of.range.versu

.data.rate.(num

ber

.of.bits.

proc

essed

.per.unit.of.time

)

.is.show

.in.Figu

.28.1

. ose.are.wire

less

.perso

nal

.area.netw

ork

.(WPA

N),

wire

less

.metr

opolitan

.area.netw

ork

.(WMA

N),

.wire

less

.loca

.area.netw

ork

.(WLA

N),

.and.wire

less

.wide.

area.netw

ork

.(WWA

N).

.WWAN.typi

cally

.assu

.prot

ocols

.such.as.IEEE.802.

.or.wire

less

.regi

onal

.area.

netw

ork,

.whil

.WMAN.incl

ude

.IEEE.802.

20,

.or.mobi

.broa

dband

.wire

less

.acce

.(MBW

A).

. ese.wire

less

.netw

orks

.are.in.deta

.spec

ied

.by.IEEE.stan

dard

.spec

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.[2,3

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uitous

.netw

orks

belo

.to.WPAN.tech

nologies.

. ese.are.(low

est

.to.high

est

.data.rate

)

.ZigB

ee,

.Bluet

ooth,

.and.802.

15.3

(hig

.data.rate.WPAN

. is.chap

ter

.pres

ents

.netw

ork

.secu

rity

.issu

.and.solu

tions

.of.WLAN

.WPAN

and.mesh.networks,.in.the.order.which.is.representative.of.their.market.size.and.their.longevity.in.the.

mark

etplace.

Industrial Wireless

Communications

Security (IWCS)/C42

28.1. Introduction.....................................................................................28-1

28.2

. Wirel

ess

.LAN.Sec

urity...................................................................28-2

Security.Issues/Attacks.on.WiFi. •. Security.Mechanisms. •. .

Deployment.Issues

28.3. PAN.Security....................................................................................28-6

28.4

. Summ

ary...........................................................................................28-8

References.....................................................................................................28-8

Milos Manic

University of Idaho

Idah

Fal

Kurt Derr

Idaho National Laboratory

28-2 Industrial Communication Systems

28.2 Wireless LaN Security

WLAN.standards.extend.the.functionality.of.a.wired.LAN.providing.location.freedom.(cable-free.net-

working).

.WLANs.are.based.on.the.IEEE.802.11.standard.. e.most.widely.used.WLANs.are.in.the.

industrial,.scientic,.and.medical.(ISM).radio.band..Table.28.1.shows.the.802.11.Protocol.Family.. e.

IEEE.802.11n.standard.was.nalized.in.September.2009.and.published.in.October.2009..Many.“dra.

IEEE.802.11n”.products.were.available.in.the.marketplace.prior.to.the.adoption.of.this.standard.

28.2.1 Security Issues/attacks on WiFi

 e.characteristics.of.the.wireless.communications.channel.leave.WiFi.communications.open.to.attack.

(authentication,.access.control,.encryption,.jamming,.interception,.and.hijacking).[4–6].. ese.charac-

teristics

.are.discussed.further.in.this.section.

Authentication

.is.the.process.of.verifying.that.someone/something.is.authentic;.i.e.,.the.claims.they.

make.are.true..Security.protocols.are.used.to.authenticate.computers.in.possession.of.a.cryptographic.key.

and.users..Mobility.and.ease.of.connectivity.are.advantages.of.wireless.versus.wired.communications.

Access

.control.is.necessary.to.protect.against.unauthorized.use.of.wireless.communications.systems..

Several.approaches.to.controlling.access.to.a.wireless.LAN.include

. 1..Use.of.shared.keys

. 2.. Media.access.control.(MAC).address.ltering.by.a.wireless.AP

. 3..Link-layer.security.protocols

. 4.. Firewalls

. 5..Virtual.private.network.(VPN).encryption.in.order.to.provide.security

IEEE 802.22

IEEE 802.20

WiFi

IEEE 802.11

IEEE 802.15.3

IEEE 802.15.3a

IEEE 802.15.3c

WWAN

WMAN

WLAN

WPAN

0.01 0.1 1 10

Data rate (Mbps)

100 1000

Range

ZigBee

802.15.4

Bluetooth

802.15.1

WiMax

IEEE 802.16

FIGURE 28.1 Wireless.technologies:.range.versus.data.rates.

TABLE 28.1 IEEE.802.11.Standards

Standard 802.11 802.11a 802.11b 802.11g 802.11n

Year 1997 1999 1999 2003 2009

Frequency 2.4

.GHz 5.GHz 2.4.GHz 2.4.GHz 2.4.GHz,.5.GHz

Max

.Data.Rate 2.Mbps 54.Mbps 11.Mbps 54.Mbps 600.Mbps

Modulation

.Type FHSS,.DSSS,.&.IR Orthogonal.FDM DSSS Orthogonal.FDM Orthogonal.FDM

Industrial Wireless Communications Security (IWCS)/C42 28-3

Encryption. transforms. data. from. a. readable. form. to. a. nonreadable. form. for. humans.. e. key.

length.is.an.indicator.for.the.strength.of.the.encryption.algorithm..Examples.of.encryption.algorithms.

include.RC4.(Rivest.Cypher.4),.Data.Encryption.Standard.(DES),.Triple-DES,.Blowsh,.International.

Data.Encryption.Algorithm.(IDEA),.Soware-Optimized.Encryption.Algorithm.(SEAL),.RSA.(Rivest.

Shamir.Adelman),.and.RC4..Encryption.prevents.eavesdropping.of.wirelessly.transmitted.data.

Radio

.communications.are.subject.to.jamming.regardless.of.the.form.of.wireless.signal..APs.monitor.

channel.quality.and.bit.rate.for.other.stations,.which.enables.the.detection.of.jamming..However,.unless.

APs.have.collaborative.soware.for.sharing.and.analyzing.this.information,.the.location.of.the.attacker.

cannot.be.identied.

Wireless

.signals.radiate.in.free.space.and.are.subject.to.interception..Wireless.laptop.computers.placed.

near.industrial.enterprises.can.intercept.WLAN.signals,.collect.sensitive.information,.and.potentially.

disrupt.the.network.

Hijacking

.a.wireless.channel.is.a.dicult.task.because.the.attacker.must.ensure.that.the.two.par-

ties

.cannot.communicate.with. one.another. [7].. e.two.users. must.be. out.of.wireless.range.or.be.

desynchronized.to.set.up.a.man.in.the.middle.(MITM).attack..In.an.MITM.attack,.the.attacker.must.

eavesdrop.on.both.users.and.impersonate.each.user.to.the.other..One.MITM.attack.approach.would.be.

to.jam.the.receiver.of.one.user.using.a.directional.antenna.while.receiving.the.transmitted.trac.from.

another.user.

28.2.2 Security Mechanisms

Security.mechanisms.and.protocols.are.necessary.to.maintain.the.secrecy.of.data.transmitted.through.

the.air.and.to.ensure.that.the.data.is.not.tampered.with..Since.the.introduction.of.802.11.WLAN,.new.

protocols.have.been.developed.as.insecurities.were.found.in.existing.deployed.protocols.(WEP,.WPA,.

WPA2,.TKIP,.CCMP,.and.WAPI)..A.survey.of.these.protocols.follows.

28.2.2.1

Wireless Encryption Protocol

.rst.security.mechanism.for.WiFi.is.the.wireless.encryption.protocol.(WEP),.which.requires.little.

computational.power..WEP.is.based.on.the.RC4.encryption.algorithm.and.is.not.as.sophisticated.as.the.

cryptographic.protocols.that.follow..Researchers.demonstrated.the.insecurity.of.WEP.within.the.rst.

few.years.of.its.deployment.[8].

WEP

.uses.a.symmetric.secret.key.cipher,.k,.and.an.initialization.vector,.IV,.to.generate.a.keystream.

(a.pseudorandom.sequence.of.bits).as.shown.in.Figure.28.2.

.decryption.key.is.identical.to.the.encryption.key.in.symmetric.key.algorithms..WEP.is.not.scal-

able

.due.to.a.lack.of.automatic.key.management.. e.key.is.either.64.or.128.bits..An.integrity.checksum.

is.computed.on.the.message/data.and.then.the.two.are.concatenated.to.create.a.plaintext.. e.keystream.

is.mathematically.combined.(Exclusive.OR).with.the.plaintext.to.create.a.ciphertext.. e.ciphertext.and.

IV.are.transmitted.between.a.sender.and.receiver.. e.receiver.uses.the.identical.secret.key.to.recover.

the.message.from.the.ciphertext..RC4.was.developed.in.1987.by.Ron.Rivest.of.RSA.Security.. e.process.

for.the.RC4.encryption.and.decryption.is.shown.in.Figure.28.3.

Plaintext

Ciphertext

Keystream

Plaintext XOR keystream

Message

RC4 (IV, k)

CRC|

FIGURE 28.2 Encrypted.WEP.frame.