Mobile Communications Chapter 9: Mobile Transport · PDF file... Mobile Transport Layer Prof...
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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 9.1 Mobile Communications Chapter 9: Mobile Transport Layer Motivation TCP-mechanisms Classical approaches Indirect TCP Snooping TCP Mobile TCP PEPs in general Additional optimizations Fast retransmit/recovery Transmission freezing Selective retransmission Transaction oriented TCP TCP for 2.5G/3G wireless
Transcript of Mobile Communications Chapter 9: Mobile Transport · PDF file... Mobile Transport Layer Prof...
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
w.jo
chen
schi
ller.
de/
MC
SS
029.
1
Mo
bile
Co
mm
un
icat
ion
s C
hap
ter
9: M
ob
ile T
ran
spo
rt L
ayer
Mot
ivat
ion
TC
P-m
echa
nism
sC
lass
ical
app
roac
hes
Indi
rect
TC
PS
noop
ing
TC
PM
obile
TC
PP
EP
sin
gen
eral
Add
ition
al o
ptim
izat
ions
Fas
t ret
rans
mit/
reco
very
Tra
nsm
issi
on fr
eezi
ngS
elec
tive
retr
ansm
issi
on
Tra
nsac
tion
orie
nted
TC
P
TC
P fo
r 2.
5G/3
G w
irele
ss
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
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chen
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ller.
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MC
SS
029.
2
Tra
nspo
rt L
ayer
E.g
. HT
TP
(us
ed b
y w
eb s
ervi
ces)
ty
pica
lly u
ses
TC
PR
elia
ble
tran
spor
t bet
wee
n cl
ient
an
d se
rver
req
uire
d
TC
PS
team
orie
nted
, not
tran
sact
ion
orie
nted
Net
wor
k fr
iend
ly: t
ime-
out
cong
estio
n sl
ow d
own
tran
smis
sion
Wel
l kno
wn
–T
CP
gue
sses
qui
te o
ften
wro
ng in
wire
less
and
mob
ile n
etw
orks
Pac
ket l
oss
due
to tr
ansm
issi
on
erro
rsP
acke
t los
s du
e to
cha
nge
of
netw
ork
Res
ult
Sev
ere
perf
orm
ance
deg
rada
tion
Clie
ntS
erve
r Con
nect
ion
setu
p
Dat
atr
ansm
issi
on
Con
nect
ion
rele
ase
TC
P S
YN
TC
P S
YN
/AC
K
TC
P A
CK
HT
TP
req
uest
HT
TP
res
pons
e
GP
RS
: 500
ms!
>15
sno
dat
a
Pro
f. D
r.-I
ng. J
oche
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chill
er, h
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MC
SS
029.
3
Mot
ivat
ion
I
Tra
nspo
rt p
roto
cols
typi
cally
des
igne
d fo
rF
ixed
end
-sys
tem
s
Fix
ed, w
ired
netw
orks
Res
earc
h ac
tiviti
esP
erfo
rman
ceC
onge
stio
n co
ntro
l
Effi
cien
t ret
rans
mis
sion
s
TC
P c
onge
stio
n co
ntro
lpa
cket
loss
in fi
xed
netw
orks
typi
cally
due
to (
tem
pora
ry)
over
load
si
tuat
ions
ro
uter
hav
e to
dis
card
pac
kets
as
soon
as
the
buffe
rs a
re fu
ll
TC
P r
ecog
nize
s co
nges
tion
only
indi
rect
via
mis
sing
ac
know
ledg
emen
ts, r
etra
nsm
issi
ons
unw
ise,
they
wou
ld o
nly
cont
ribut
e to
the
cong
estio
n an
d m
ake
it ev
en w
orse
slow
-sta
rt a
lgor
ithm
as
reac
tion
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
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ller.
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MC
SS
029.
4
Mot
ivat
ion
II
TC
P s
low
-sta
rt a
lgor
ithm
send
er c
alcu
late
s a
cong
estio
n w
indo
w fo
r a
rece
iver
star
t with
a c
onge
stio
n w
indo
w s
ize
equa
l to
one
segm
ent
expo
nent
ial i
ncre
ase
of th
e co
nges
tion
win
dow
up
to th
e co
nges
tion
thre
shol
d, th
en li
near
incr
ease
mis
sing
ack
now
ledg
emen
t cau
ses
the
redu
ctio
n of
the
cong
estio
n th
resh
old
to o
ne h
alf o
f the
cur
rent
con
gest
ion
win
dow
co
nges
tion
win
dow
sta
rts
agai
n w
ith o
ne s
egm
ent
TC
P fa
st r
etra
nsm
it/fa
st r
ecov
ery
TC
P s
ends
an
ackn
owle
dgem
ent o
nly
afte
r re
ceiv
ing
a pa
cket
if a
send
er r
ecei
ves
seve
ral a
ckno
wle
dgem
ents
for
the
sam
e pa
cket
, thi
s is
due
to a
gap
in r
ecei
ved
pack
ets
at th
e re
ceiv
erho
wev
er, t
he r
ecei
ver
got a
ll pa
cket
s up
to th
e ga
p an
d is
act
ually
re
ceiv
ing
pack
ets
ther
efor
e, p
acke
t los
s is
not
due
to c
onge
stio
n, c
ontin
ue w
ith
curr
ent c
onge
stio
n w
indo
w (
do n
ot u
se s
low
-sta
rt)
Pro
f. D
r.-I
ng. J
oche
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chill
er, h
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ller.
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MC
SS
029.
5
Influ
ence
s of
mob
ility
on
TC
P-m
echa
nism
s
TC
P a
ssum
es c
onge
stio
n if
pack
ets
are
drop
ped
typi
cally
wro
ng in
wire
less
net
wor
ks, h
ere
we
ofte
n ha
ve p
acke
t lo
ss d
ue to
tran
smis
sion
err
ors
furt
herm
ore,
mob
ility
itsel
f can
cau
se p
acke
t los
s, if
e.g
. a m
obile
no
de r
oam
s fr
om o
ne a
cces
s po
int (
e.g.
fore
ign
agen
t in
Mob
ile IP
) to
ano
ther
whi
le th
ere
are
still
pac
kets
in tr
ansi
t to
the
wro
ngac
cess
poi
nt a
nd fo
rwar
ding
is n
ot p
ossi
ble
The
per
form
ance
of a
n un
chan
ged
TC
P d
egra
des
seve
rely
how
ever
, TC
P c
anno
t be
chan
ged
fund
amen
tally
due
to th
e la
rge
base
of i
nsta
llatio
n in
the
fixed
net
wor
k, T
CP
for
mob
ility
has
to
rem
ain
com
patib
leth
e ba
sic
TC
P m
echa
nism
s ke
ep th
e w
hole
Inte
rnet
toge
ther
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
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chen
schi
ller.
de/
MC
SS
029.
6
Ear
ly a
ppro
ach:
Indi
rect
TC
P I
Indi
rect
TC
P o
r I-
TC
P s
egm
ents
the
conn
ectio
nno
cha
nges
to th
e T
CP
pro
toco
l for
hos
ts c
onne
cted
to th
e w
ired
Inte
rnet
, mill
ions
of c
ompu
ters
use
(va
riant
s of
) th
is p
roto
col
optim
ized
TC
P p
roto
col f
or m
obile
hos
tssp
littin
g of
the
TC
P c
onne
ctio
n at
, e.g
., th
e fo
reig
n ag
ent i
nto
2 T
CP
co
nnec
tions
, no
real
end
-to-
end
conn
ectio
n an
y lo
nger
host
s in
the
fixed
par
t of t
he n
et d
o no
t not
ice
the
char
acte
ristic
s of
th
e w
irele
ss p
art
mob
ile h
ost
acce
ss p
oint
(f
orei
gn a
gent
)„w
ired“
Inte
rnet
„wir
eles
s“ T
CP
stan
dar
d T
CP
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
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chen
schi
ller.
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MC
SS
029.
7
I-T
CP
soc
keta
nd s
tate
mig
ratio
n
mob
ile h
ost
acce
ss p
oint
2
Inte
rnet
acce
ss p
oint
1
sock
etm
igra
tion
and
stat
etr
ansf
er
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
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chen
schi
ller.
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MC
SS
029.
8
Indi
rect
TC
P II
Adv
anta
ges
no c
hang
es in
the
fixed
net
wor
k ne
cess
ary,
no
chan
ges
for
the
host
s (T
CP
pro
toco
l) ne
cess
ary,
all
curr
ent o
ptim
izat
ions
to T
CP
stil
lwor
k
tran
smis
sion
err
ors
on th
e w
irele
ss li
nk d
o no
t pro
paga
te in
to th
e fix
ed
netw
ork
sim
ple
to c
ontr
ol, m
obile
TC
P is
use
d on
ly fo
r on
e ho
p be
twee
n, e
.g.,
a fo
reig
n ag
ent a
nd m
obile
hos
t
ther
efor
e, a
ver
y fa
st r
etra
nsm
issi
on o
f pac
kets
is p
ossi
ble,
the
shor
t de
lay
on th
e m
obile
hop
is k
now
n
Dis
adva
ntag
eslo
ss o
f end
-to-
end
sem
antic
s, a
n ac
know
ledg
emen
t to
a se
nder
doe
s no
w n
ot a
ny lo
nger
mea
n th
at a
rec
eive
r re
ally
got
a p
acke
t, fo
reig
n ag
ents
mig
ht c
rash
high
er la
tenc
y po
ssib
le d
ue to
buf
ferin
g of
dat
a w
ithin
the
fore
ign
agen
t and
forw
ardi
ng to
a n
ew fo
reig
n ag
ent
Pro
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ng. J
oche
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chill
er, h
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ller.
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MC
SS
029.
9
Ear
ly a
ppro
ach:
Sno
opin
g T
CP
I
„Tra
nspa
rent
“ ex
tens
ion
of T
CP
with
in th
e fo
reig
n ag
ent
buffe
ring
of p
acke
ts s
ent t
o th
e m
obile
hos
t
lost
pac
kets
on
the
wire
less
link
(bo
th d
irect
ions
!) w
ill b
e re
tran
smitt
ed im
med
iate
ly b
y th
e m
obile
hos
t or
fore
ign
agen
t, re
spec
tivel
y (s
o ca
lled
“loca
l” re
tran
smis
sion
)
the
fore
ign
agen
t the
refo
re “
snoo
ps”
the
pack
et fl
ow a
nd r
ecog
nize
s ac
know
ledg
emen
ts in
bot
h di
rect
ions
, it a
lso
filte
rs A
CK
s
chan
ges
of T
CP
onl
y w
ithin
the
fore
ign
agen
t
„wire
d“ In
tern
et
buffe
ring
of d
ata
end-
to-e
nd T
CP
con
nect
ion
loca
l ret
rans
mis
sion
corr
espo
nden
tho
stfo
reig
nag
ent
mob
ileho
st
snoo
ping
of A
CK
s
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
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chen
schi
ller.
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MC
SS
029.
10
Sno
opin
g T
CP
II
Dat
a tr
ansf
er to
the
mob
ile h
ost
FA
buf
fers
dat
a un
til it
rec
eive
s A
CK
of t
he M
H, F
A d
etec
ts p
acke
t lo
ss v
ia d
uplic
ated
AC
Ks
or ti
me-
out
fast
ret
rans
mis
sion
pos
sibl
e, tr
ansp
aren
t for
the
fixed
net
wor
k
Dat
a tr
ansf
er fr
om th
e m
obile
hos
tF
A d
etec
ts p
acke
t los
s on
the
wire
less
link
via
seq
uenc
e nu
mbe
rs,
FA
ans
wer
s di
rect
ly w
ith a
NA
CK
to th
e M
H
MH
can
now
ret
rans
mit
data
with
onl
y a
very
sho
rt d
elay
Inte
grat
ion
of th
e M
AC
laye
rM
AC
laye
r of
ten
has
sim
ilar
mec
hani
sms
to th
ose
of T
CP
thus
, the
MA
C la
yer
can
alre
ady
dete
ct d
uplic
ated
pac
kets
due
tore
tran
smis
sion
s an
d di
scar
d th
em
Pro
blem
ssn
oopi
ng T
CP
doe
s no
t iso
late
the
wire
less
link
as
good
as
I-T
CP
snoo
ping
mig
ht b
e us
eles
s de
pend
ing
on e
ncry
ptio
n sc
hem
es
Pro
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ng. J
oche
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er, h
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ller.
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MC
SS
029.
11
Ear
ly a
ppro
ach:
Mob
ile T
CP
Spe
cial
han
dlin
g of
leng
thy
and/
or fr
eque
nt d
isco
nnec
tions
M-T
CP
spl
its a
s I-
TC
P d
oes
unm
odifi
ed T
CP
fixe
d ne
twor
k to
sup
ervi
sory
hos
t (S
H)
optim
ized
TC
P S
H to
MH
Sup
ervi
sory
hos
tno
cac
hing
, no
retr
ansm
issi
on
mon
itors
all
pack
ets,
if d
isco
nnec
tion
dete
cted
set s
ende
r w
indo
w s
ize
to 0
send
er a
utom
atic
ally
goe
s in
to p
ersi
sten
t mod
e
old
or n
ew S
H r
eope
n th
e w
indo
w
Adv
anta
ges
mai
ntai
ns s
eman
tics,
sup
port
s di
scon
nect
ion,
no
buffe
r fo
rwar
ding
Dis
adva
ntag
eslo
ss o
n w
irele
ss li
nk p
ropa
gate
d in
to fi
xed
netw
ork
adap
ted
TC
P o
n w
irele
ss li
nk
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
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chen
schi
ller.
de/
MC
SS
029.
12
Fas
t ret
rans
mit/
fast
rec
over
y
Cha
nge
of fo
reig
n ag
ent o
ften
resu
lts in
pac
ket l
oss
TC
P r
eact
s w
ith s
low
-sta
rt a
lthou
gh th
ere
is n
o co
nges
tion
For
ced
fast
ret
rans
mit
as s
oon
as th
e m
obile
hos
t has
reg
iste
red
with
a n
ew fo
reig
n ag
ent,
the
MH
sen
ds d
uplic
ated
ack
now
ledg
emen
ts o
n pu
rpos
e
this
forc
es th
e fa
st r
etra
nsm
it m
ode
at th
e co
mm
unic
atio
n pa
rtne
rs
addi
tiona
lly, t
he T
CP
on
the
MH
is fo
rced
to c
ontin
ue s
endi
ng w
ith
the
actu
al w
indo
w s
ize
and
not t
o go
into
slo
w-s
tart
afte
r re
gist
ratio
n
Adv
anta
gesi
mpl
e ch
ange
s re
sult
in s
igni
fican
t hig
her
perf
orm
ance
Dis
adva
ntag
efu
rthe
r m
ix o
f IP
and
TC
P, n
o tr
ansp
aren
t app
roac
h
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
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w.jo
chen
schi
ller.
de/
MC
SS
029.
13
Tra
nsm
issi
on/ti
me-
out f
reez
ing
Mob
ile h
osts
can
be
disc
onne
cted
for
a lo
nger
tim
eno
pac
ket e
xcha
nge
poss
ible
, e.g
., in
a tu
nnel
, dis
conn
ectio
n du
e to
ove
rload
ed c
ells
or
mux
. with
hig
her
prio
rity
traf
fic
TC
P d
isco
nnec
ts a
fter
time-
out c
ompl
etel
y
TC
P fr
eezi
ngM
AC
laye
r is
ofte
n ab
le to
det
ect i
nter
rupt
ion
in a
dvan
ce
MA
C c
an in
form
TC
P la
yer
of u
pcom
ing
loss
of c
onne
ctio
nT
CP
sto
ps s
endi
ng, b
ut d
oes
now
not
ass
ume
a co
nges
ted
link
MA
C la
yer
sign
als
agai
n if
reco
nnec
ted
Adv
anta
gesc
hem
e is
inde
pend
ent o
f dat
a
Dis
adva
ntag
eT
CP
on
mob
ile h
ost h
as to
be
chan
ged,
mec
hani
sm d
epen
ds o
n M
AC
laye
r
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
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chen
schi
ller.
de/
MC
SS
029.
14
Sel
ectiv
e re
tran
smis
sion
TC
P a
ckno
wle
dgem
ents
are
ofte
n cu
mul
ativ
eA
CK
n a
ckno
wle
dges
cor
rect
and
in-s
eque
nce
rece
ipt o
f pac
kets
up
to n
if si
ngle
pac
kets
are
mis
sing
qui
te o
ften
a w
hole
pac
ket s
eque
nce
begi
nnin
g at
the
gap
has
to b
e re
tran
smitt
ed (
go-b
ack-
n), t
hus
was
ting
band
wid
th
Sel
ectiv
e re
tran
smis
sion
as
one
solu
tion
RF
C20
18 a
llow
s fo
r ac
know
ledg
emen
ts o
f sin
gle
pack
ets,
not
onl
y ac
know
ledg
emen
ts o
f in-
sequ
ence
pac
ket s
trea
ms
with
out g
aps
send
er c
an n
ow r
etra
nsm
it on
ly th
e m
issi
ng p
acke
ts
Adv
anta
gem
uch
high
er e
ffici
ency
Dis
adva
ntag
em
ore
com
plex
sof
twar
e in
a r
ecei
ver,
mor
e bu
ffer
need
ed a
t the
re
ceiv
er
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
w.jo
chen
schi
ller.
de/
MC
SS
029.
15
Tra
nsac
tion
orie
nted
TC
P
TC
P p
hase
sco
nnec
tion
setu
p, d
ata
tran
smis
sion
, con
nect
ion
rele
ase
usin
g 3-
way
-han
dsha
ke n
eeds
3 p
acke
ts fo
r se
tup
and
rele
ase,
re
spec
tivel
yth
us, e
ven
shor
t mes
sage
s ne
ed a
min
imum
of 7
pac
kets
!
Tra
nsac
tion
orie
nted
TC
PR
FC
1644
, T-T
CP
, des
crib
es a
TC
P v
ersi
on to
avo
id th
is o
verh
ead
conn
ectio
n se
tup,
dat
a tr
ansf
er a
nd c
onne
ctio
n re
leas
e ca
n be
co
mbi
ned
thus
, onl
y 2
or 3
pac
kets
are
nee
ded
Adv
anta
geef
ficie
ncy
Dis
adva
ntag
ere
quire
s ch
ange
d T
CP
mob
ility
not
long
er tr
ansp
aren
t
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
w.jo
chen
schi
ller.
de/
MC
SS
029.
16
Com
paris
on o
f diff
eren
t app
roac
hes
for
a “m
obile
” T
CP
Ap
pro
ach
Mec
han
ism
Ad
van
tag
esD
isad
van
tag
esIn
dire
ct T
CP
split
s T
CP
con
nect
ion
into
two
conn
ectio
nsis
olat
ion
of w
irele
sslin
k, s
impl
elo
ss o
f TC
P s
eman
tics,
high
er la
tenc
y at
hand
over
Sno
opin
g T
CP
“sno
ops”
dat
a an
dac
know
ledg
emen
ts, l
ocal
retr
ansm
issi
on
tran
spar
ent f
or e
nd-t
o-en
d co
nnec
tion,
MA
Cin
tegr
atio
n po
ssib
le
prob
lem
atic
with
encr
yptio
n, b
ad is
olat
ion
of w
irele
ss li
nkM
-TC
Psp
lits
TC
P c
onne
ctio
n,ch
okes
sen
der
via
win
dow
siz
e
Mai
ntai
ns e
nd-t
o-en
dse
man
tics,
han
dles
long
term
and
freq
uent
disc
onne
ctio
ns
Bad
isol
atio
n of
wire
less
link,
pro
cess
ing
over
head
due
toba
ndw
idth
man
agem
ent
Fas
t ret
rans
mit/
fast
rec
over
yav
oids
slo
w-s
tart
afte
rro
amin
gsi
mpl
e an
d ef
ficie
ntm
ixed
laye
rs, n
ottr
ansp
aren
tT
rans
mis
sion
/tim
e-ou
t fre
ezin
gfr
eeze
s T
CP
sta
te a
tdi
scon
nect
, res
umes
afte
r re
conn
ectio
n
inde
pend
ent o
f con
tent
or e
ncry
ptio
n, w
orks
for
long
er in
terr
upts
chan
ges
in T
CP
requ
ired,
MA
Cde
pend
ant
Sel
ectiv
ere
tran
smis
sion
retr
ansm
it on
ly lo
st d
ata
very
effi
cien
tsl
ight
ly m
ore
com
plex
rece
iver
sof
twar
e, m
ore
buffe
r ne
eded
Tra
nsac
tion
orie
nted
TC
Pco
mbi
ne c
onne
ctio
nse
tup/
rele
ase
and
data
tran
smis
sion
Effi
cien
t for
cer
tain
appl
icat
ions
chan
ges
in T
CP
requ
ired,
not
tran
spar
ent
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
w.jo
chen
schi
ller.
de/
MC
SS
029.
17
TC
P Im
prov
emen
ts I
Initi
al r
esea
rch
wor
kIn
dire
ct T
CP
, Sno
op T
CP
, M-T
CP
, T/T
CP
, SA
CK
, T
rans
mis
sion
/tim
e-ou
t fre
ezin
g, …
TC
P o
ver
2.5/
3G w
irele
ss n
etw
orks
Fin
e tu
ning
toda
y’s
TC
P
Lear
n to
live
with
Dat
a ra
tes:
64
kbit/
s up
, 115
-384
kbi
t/s d
own;
asy
mm
etry
: 3-6
, but
als
o up
to 1
000
(bro
adca
st s
yste
ms)
, per
iodi
c al
loca
tion/
rele
ase
of c
hann
els
Hig
h la
tenc
y, h
igh
jitte
r, p
acke
t los
s
Sug
gest
ions
Larg
e (in
itial
) se
ndin
g w
indo
ws,
larg
e m
axim
um tr
ansf
er u
nit,
sele
ctiv
e ac
know
ledg
emen
t, ex
plic
it co
nges
tion
notif
icat
ion,
tim
e st
amp,
no
head
er c
ompr
essi
on
Alre
ady
in u
sei-m
ode
runn
ing
over
FO
MA
WA
P 2
.0 (
“TC
P w
ith w
irele
ss p
rofil
e”)
pR
TT
MSS
BW
**93.0
≤
•m
ax. T
CP
Ban
dWid
th•
Max
. Seg
men
t Siz
e•
Rou
nd T
rip T
ime
•lo
ss p
roba
bilit
y
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
w.jo
chen
schi
ller.
de/
MC
SS
029.
18
TC
P Im
prov
emen
ts II
Per
form
ance
enh
anci
ng p
roxi
es (
PE
P, R
FC
313
5)T
rans
port
laye
rLo
cal r
etra
nsm
issi
ons
and
ackn
owle
dgem
ents
Add
ition
ally
on
the
appl
icat
ion
laye
rC
onte
nt fi
lterin
g, c
ompr
essi
on, p
ictu
re d
owns
calin
g
E.g
., In
tern
et/W
AP
gat
eway
sW
eb s
ervi
ce g
atew
ays?
Big
pro
blem
: bre
aks
end-
to-e
nd s
eman
tics
Dis
able
s us
e of
IP s
ecur
ityC
hoos
e be
twee
n P
EP
and
sec
urity
!
Mor
e op
en is
sues
RF
C 3
150
(slo
w li
nks)
Rec
omm
ends
hea
der
com
pres
sion
, no
times
tam
p
RF
C 3
155
(link
s w
ith e
rror
s)S
tate
s th
at e
xplic
it co
nges
tion
notif
icat
ion
cann
ot b
e us
ed
In c
ontr
ast t
o 2.
5G/3
G r
ecom
men
datio
ns!
Mob
ile s
yste
m
PE
P
Com
m. p
artn
er
wire
less
Inte
rnet
Pro
f. D
r.-I
ng. J
oche
n S
chill
er, h
ttp://
ww
w.jo
chen
schi
ller.
de/
MC
SS
029.
19
Mob
ile
syst
emP
EP
Com
mun
icat
ion
part
ner
wire
less
Inte
rnet
