doc.: IEEE 802.11-09/0340r0 Submission Mar 2009 Brian Hart, Cisco Systems Slide 1 More Reliable GroupCast Proposal Presentation Date: 2009-03-01 Authors: Additional authors on next slide
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doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 1
More R
eliab
le Gro
up
Cast P
rop
osa
l Presen
tatio
n
Date: 2
009-0
3-0
1 A
uth
ors:
Ad
ditio
nal a
uth
ors o
n n
ext slid
e
doc.: IE
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 2
Au
thor L
ist (Con
t.)
doc.: IE
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 3
Ab
stract
Th
is pro
posa
l specifies th
e enh
an
cemen
ts to th
e 802.1
1
MA
C th
at en
ab
les imp
roved
link
reliab
ility fo
r gro
up
cast
au
dio
vid
eo strea
m tra
nsm
ission
.
doc.: IE
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Brian
Hart, C
isco S
ystem
s S
lide 4
Fea
tures
•T
hree A
ck p
olices to
sup
port th
e vario
us ty
pes o
f the ta
rget
ap
plica
tion
s an
d p
rovid
e the flex
ibility
to m
eet the n
eeds o
f d
ifferent sca
lab
ility a
nd
imp
lemen
tatio
n co
mp
lexity
–D
irected
–U
nso
licited retries
–B
lock
Ack
•C
om
patib
le to n
on
-802.1
1aa sta
tion
s –
Co
ncealm
ent o
f retried g
rou
p ad
dressed
frames
•E
xten
sion
of R
TS
/CT
S fo
r gro
up
ad
dressed
fram
e tran
smissio
n
pro
tection
–
Allev
iate the h
idd
en n
od
e and
OB
SS
pro
blem
by
reservin
g th
e med
ium
an
d p
rotectin
g th
e follo
win
g g
rou
p ad
dressed
frame tran
smissio
ns
•M
RG
-SP
Pow
er Man
agem
ent m
od
e to red
uce M
AC
deliv
ery
laten
cy fo
r gro
up
ad
dressed
stream
s –
Tran
smits th
e gro
up
add
ressed fram
es via E
DC
A w
ithin
Sch
edu
led
Serv
ice Perio
ds
doc.: IE
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Brian
Hart, C
isco S
ystem
s S
lide 5
MR
G S
ervice C
ap
ab
ility
•M
ore R
eliab
le Gro
up
cast (M
RG
) Serv
ice allo
ws a
non
-AP
ST
A to
req
uest g
reater relia
bility
for o
ne o
r more g
rou
p a
dd
ressed
stream
s
•T
wo lev
els of M
RG
cap
ab
ilities
–R
obust A
V S
treamin
g
•D
irected
•U
nso
licited retries
•R
etry co
ncealm
ent
•M
RG
-SP
pow
er man
agem
ent
–A
dvan
ced M
RG
•T
he ab
ov
e
•B
lock
Ack
–A
dv
ertised in
Ex
tend
ed C
apab
ilities info
rmatio
n elem
ent
doc.: IE
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Brian
Hart, C
isco S
ystem
s S
lide 6
MR
G S
ervice S
etup
MR
G R
equest
MR
G R
esponse
Exten
ded
AD
DB
A R
equest
Exten
ded
AD
DB
A R
esponse
Wh
en th
e ST
A
sup
port
Ad
van
ced M
RG
Unso
licited M
RG
Resp
onse (o
ptio
nal)
Non-A
P S
TA
A
P
Ack
Ack
Ack
Ack
Ack
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Brian
Hart, C
isco S
ystem
s S
lide 7
Rob
ust A
V S
tream
ing A
ction
Fra
mes
•R
ob
ust A
V S
tream
ing A
ction
Fra
mes
•M
RG
Req
uest F
ram
e
•M
RG
Resp
on
se Fra
me
Actio
n field
valu
e M
ean
ing
0
MR
G R
equest
1 M
RG
Resp
onse
2 –
255
Reserv
ed
Categ
ory
Actio
n D
ialo
g T
ok
en M
RG
Req
uest
Elem
ents
Octets
1 1
1 varia
ble
Categ
ory
Actio
n D
ialo
g T
ok
en M
RG
Resp
on
se
Elem
ents
Octets
1 1
1 varia
ble
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Brian
Hart, C
isco S
ystem
s S
lide 8
MR
G R
equ
est Elem
ent
•M
RG
Ack
Policy
Elem
ent
ID
Len
gth
G
rou
p
Ad
dress
MR
G
Ack
Policy
MR
G P
ow
er
Man
agem
ent
Mod
e
TS
PE
C
Elem
ent
Sch
edu
le
elemen
t
(op
tion
al)
Octets
1
1
6
1
1
57
0 o
r 14
Valu
e M
RG
Ack
Policy
No
tes
0 M
RG
-Serv
ice-Can
cel
1 M
RG
-Directed
2 M
RG
-Unso
licited-R
etry
3 M
RG
-Blo
ck-A
ck
4-2
55
Reserv
ed
•M
RG
Pow
er Man
agem
ent M
ode
Valu
e M
RG
Pow
er Man
agem
ent M
ode
No
tes
0 R
eserved
1 A
ll-Activ
e/Any-P
S o
r FM
S
2 M
RG
-SP
3-2
55
Reserv
ed
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009
Brian
Hart, C
isco S
ystem
s S
lide 9
MR
G R
espon
se elemen
t
Elem
ent ID
L
ength
G
roup
Address
MR
G A
ck
Policy
MR
G P
ow
er
Man
agem
ent
Mode (o
ptio
nal)
Sch
edu
le
Elem
ent
(optio
nal)
Octets
1
1
6
1
1
0 o
r 14
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009
Brian
Hart, C
isco S
ystem
s S
lide 1
0
Blo
ck A
ck A
ction
Fra
mes
Actio
n field
valu
es M
ean
ing
0
AD
DB
A R
equest
1
AD
DB
A R
esponse
2
DE
LB
A (E
xtend
ed)
3
Exten
ded
AD
DB
A R
equ
est
4
Exten
ded
AD
DB
A R
espon
se
5–255
Reserv
ed
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009
Brian
Hart, C
isco S
ystem
s S
lide 1
1
Exten
ded
AD
DB
A R
equ
est Fra
me
•E
xten
ded
Blo
ck A
ck P
ara
meter S
et field
Ord
er In
form
atio
n
1
Categ
ory
2
Actio
n
3
Dialo
g T
oken
4
Blo
ck A
ck P
arameter S
et
5
Blo
ck A
ck T
imeo
ut V
alue
6
Blo
ck A
ck S
tarting
Seq
uen
ce Co
ntro
l
7
Exten
ded
Blo
ck A
ck P
ara
meter S
et
8
AD
DB
A M
RG
Gro
up
Ad
dress
Bits
B0
B1 B
15
AD
DB
A M
RG
Gro
up A
ddress
Presen
t
Reserv
ed
Octets
----------------------------2 --------------------------
doc.: IE
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009
Brian
Hart, C
isco S
ystem
s S
lide 1
2
Exten
ded
AD
DB
A R
espon
se Fra
me
Ord
er In
form
atio
n
1
Categ
ory
2
Actio
n
3
Dialo
g T
oken
4
Statu
s Code
5
Blo
ck A
ck P
arameter S
et
6
Blo
ck A
ck T
imeo
ut V
alue
7
Exten
ded
Blo
ck A
ck P
ara
meter S
et
8
AD
DB
A M
RG
Gro
up
Ad
dress
doc.: IE
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Brian
Hart, C
isco S
ystem
s S
lide 1
3
DE
LB
A F
ram
e Form
at
•D
EL
BA
MR
G G
rou
p A
dd
ress is inclu
ded
if DE
LB
A M
RG
Gro
up
A
dd
ress Presen
t field is set
•D
EL
BA
Para
meter S
et
Ord
er In
form
atio
n
1
Categ
ory
2
Actio
n
3
DE
LB
A P
ara
meter S
et
4
Reaso
n C
ode
5
DE
LB
A M
RG
Gro
up
Ad
dress
Bits
B0 B
9
B10
B11
B12 B
15
Reserv
ed
DE
LB
A M
RG
Gro
up A
ddress
Presen
t
Initiato
r T
ID
Octets
----------------------------2 --------------------------
doc.: IE
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Brian
Hart, C
isco S
ystem
s S
lide 1
4
MR
G A
ck P
olicy
an
d P
ow
er Man
agem
ent
Mod
e Mod
ificatio
n
•T
he M
RG
AP
may u
pd
ate th
e ack
policy
an
d p
ow
er
man
agem
ent m
od
e by eith
er:
–T
ransm
itting
un
solicited
MR
G R
espo
nse fram
es ind
ivid
ually
addressed
to each
MR
G g
roup m
ember w
ith n
ew M
RG
ack p
olicy
and
po
wer m
anag
emen
t setting
,
or
–T
ransm
itting
an u
nso
licited M
RG
Resp
on
se frame in
gro
up
cast
addressed
to th
e MR
G g
roup ad
dress w
ith n
ew M
RG
ack p
olicy
and
po
wer m
anag
emen
t setting
.
doc.: IE
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Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 1
5
MR
G S
ervice T
eard
ow
n
•T
o ca
ncel a
MR
G a
greem
ent b
etween
a n
on
-AP
ST
A a
nd
an
AP
, eith
er –
Non-A
P S
TA
sends an
MR
G R
equest fram
e with
the A
ck P
olicy
set to
MR
G-S
ervice-C
ancel
or
–A
P tran
smits an
indiv
idually
addressed
MR
G R
esponse fram
e with
the
Ack
Po
licy set to
MR
G-S
ervice-C
ancel.
•A
P m
ay
can
cel the M
RG
service fo
r an
MR
G strea
m b
y eith
er –
transm
itting a series o
f indiv
idually
addressed
MR
G R
esponse fram
es w
ith th
e Ack
Policy
set to M
RG
-Serv
ice-Can
cel to each
non-A
P S
TA
g
rou
p m
emb
er
or
–tran
smittin
g a g
roup ad
dressed
MR
G R
esponse fram
e with
the A
ck P
olicy
set to
MR
G-S
ervice-C
ancel.
•S
uch
can
cellatio
n sh
all a
lso ca
use th
e Blo
ck A
ck a
greem
ent to
be
can
celled.
doc.: IE
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 1
6
MR
G-D
irected A
ck
•S
imila
r to D
MS
, bu
t
–W
ork
with
MR
G-S
P p
ow
er man
agem
ent
–E
nab
le AP
to sw
itch to
oth
er Ack
po
licies
•T
ran
smit g
rou
p a
dd
ressed M
SD
Us a
s ind
ivid
ually
ad
dressed
fram
es to a
MR
G g
rou
p m
emb
er in a
n A
-
MS
DU
fram
e form
at
•L
ow
efficiency
, not a
scala
ble so
lutio
n, h
igh
dela
y, b
ut
pro
vid
es best relia
bility
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 1
7
MR
G-U
nso
licited-R
etry •
Tra
nsm
it each
MS
DU
mu
ltiple tim
es, sub
ject to th
e
lifetime lim
it.
–R
etransm
itted fram
es sent w
ith th
e RA
set to th
e MR
G
Co
ncealm
ent ad
dress (n
ext slid
e) to av
oid
du
plicated
frames at
non-8
02.1
1aa S
TA
s
–W
hen
retransm
itting an
MP
DU
, for all retran
smissio
ns, th
e AP
shall in
vo
ke its b
acko
ff pro
cedu
re.
•L
ow
efficiency
, scala
ble so
lutio
n, d
elay d
epen
ds o
n
imp
lemen
tatio
n, p
rovid
es limited
reliab
ility
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Brian
Hart, C
isco S
ystem
s S
lide 1
8
Con
cealm
ent o
f MR
G T
ran
smissio
ns
•P
reven
ts du
plica
te gro
up
ad
dressed
fram
es from
bein
g
passed
up
the M
AC
-SA
P o
f MR
G-in
cap
ab
le ST
As
•M
SD
Us retra
nsm
itted v
ia th
e MR
G-U
nso
licited-R
etry
or M
RG
-Blo
ck-A
ck A
ck p
olicies sh
all b
e sent in
an
A-
MS
DU
fram
e form
at w
ith th
e RA
set to th
e MR
G
Con
cealm
en
t address
–T
o-b
e-assigned
-by-A
NA
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ission
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Brian
Hart, C
isco S
ystem
s S
lide 1
9
MR
G-B
lock
-Ack
•E
xten
d th
e Blo
ck A
ck m
echan
ism to
gro
up
cast.
•O
nly
sup
port im
med
iate b
lock
ack
policy
•T
he ex
tent o
f efficiency
, dela
y a
nd
reliab
ility p
rovid
ed
are flex
ible a
nd
dep
end
ent o
n im
plem
enta
tion
, scala
ble.
doc.: IE
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 2
0
MR
G B
lock
Ack
Req
with
Imm
edia
te Blo
ck A
ck P
olicy
•M
RG
BA
R In
form
atio
n field
in M
RG
Blo
ckA
ckR
eq co
nta
ins a
list of
MR
G g
rou
p m
emb
ers from
wh
ich th
is Blo
ckA
ckR
eq is req
uestin
g a
B
lock
Ack
respon
se.
•T
he M
RG
gro
up
mem
bers in
the list sh
all sen
d th
eir Blo
ckA
ck in
the
ord
er that th
ey a
re specified
in th
e MR
G B
AR
Info
rmatio
n field
.
MR
G A
P
Blo
ck
AckR
eq
MR
G g
rou
p m
em
ber 1
MR
G g
rou
p m
em
ber 2
MR
G g
rou
p m
em
ber 3
Data
D
ata
Blo
ck
Ack
Not in
clu
ded in
the M
RG
BA
R
Info
rmatio
n fie
ld
Blo
ck
Ack
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 2
1
MR
G B
lock
Ack
Req
Fra
me
•S
end
to M
RG
gro
up
ad
dress
•In
clud
e MR
G B
AR
Info
rmatio
n
Fra
me
Contro
l D
ura
tion
/ID
RA
TA
F
CS
B
AR
C
ontro
l B
AR
In
form
atio
n
MR
G B
AR
In
form
atio
n
MR
G B
AR
Bitm
ap
Contro
l M
RG
BA
R P
artia
l B
itmap
Octets: 2
2
6
6
2
V
ariable
Variab
le 4
MR
G B
AR
Info
rmatio
n
Length
Octets: 1
1
V
ariable
MA
C H
eader
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009
Brian
Hart, C
isco S
ystem
s S
lide 2
2
MR
G B
lock
Ack
Fra
me
Fram
e
Contro
l D
uratio
n/ID
R
A
TA
FC
S
BA
Contro
l
BA
Info
rmatio
n
MR
G G
roup
Address
BA
Ack
Policy
M
ulti-
TID
Com
pressed
Bitm
ap
MR
G
Reserv
ed
TID
_IN
FO
B0
B1
B2
B3
B4
B11
B12
B15
Octets: 2
2
6
6
2
V
ariable
6
4
MA
C H
eader
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 2
3
Collisio
n A
void
ing P
roced
ure
•M
RG
AP
ma
y select
on
e MR
G g
rou
p
mem
ber a
nd
use o
ne
RT
S/C
TS
or o
ther
pro
tection
meth
od
to
set NA
V to
pro
tect the
follo
win
g g
rou
p
ad
dressed
fram
e tra
nsm
ission
.
AP
1
ST
A1
ST
A2
ST
A3
AP
3
ST
A7
ST
A8
ST
A9
Back
off
AP
1
ST
A1
ST
A2
ST
A3
Pro
tected M
RG
TX
OP
Pro
tection
Stag
eM
RG
Tx S
tage
MR
G D
ata Fram
es
CTS
RTS
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ission
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009
Brian
Hart, C
isco S
ystem
s S
lide 2
4
MR
G-S
P
•A
n A
P a
dvertises th
e MR
G serv
ice perio
ds in
MR
G
Resp
on
se elemen
t
–C
on
tain S
ched
ule elem
ent (sch
edu
le info
, service start tim
e,
service in
terval, sp
ecification
interv
al)
–N
on-A
P S
TA
gro
up m
ember sh
all wak
es up at th
e service start
time
–T
he S
ervice P
eriod en
ds w
hen
the A
P tran
smits th
e QoS
gro
up
add
ressed fram
e with
the E
OS
P b
it set to 1
.
•S
hall n
ot b
e tran
smitted
simu
ltan
eou
sly v
ia th
e MR
G-
SP
an
d eith
er the A
ll-Activ
e/An
y-P
S o
r FM
S P
ow
er
Man
agem
ent m
od
es.
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 2
5
Back
up
Slid
es
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 2
6
Com
plex
ities of S
equ
ence C
ou
nter
•M
echan
ism 1
(mech
1): o
ne seq
uen
ce cou
nter fo
r all
gro
up
cast tra
ffic, non
-QoS
fram
es, an
d m
an
agem
ent
fram
es
–A
s per to
day
•M
echan
ism 2
(mech
2): o
ne seq
uen
ce cou
nter p
er gro
up
ad
dressed
stream
•In
the n
ext 4
slides w
e show
the p
ros a
nd
con
s of ea
ch
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 2
7
Mech
1 - C
on
s
•If th
ere is 1 seq
# co
un
ter for a
ll GA
fram
es yet o
ne B
A a
greem
ent p
er GA
, an
d th
e AP
tra
nsm
its mu
ltiple G
A strea
ms (o
r mgm
t fram
es or n
on
-QoS
fram
es), then
the R
X d
oes n
ot
kn
ow
wh
ether th
e holes it h
as in
its BA
bitm
ap
are d
ue to
missin
g fra
mes in
the 1
1aa G
A
stream
or o
ther fra
mes. T
he R
X m
ust h
old
on
to th
e pack
ets un
til: –
Wo
rkaro
un
d 1
: New
frames cau
se its BA
win
do
w to
adv
ance, so
that th
e old
est frames can
be released
up
the
MA
C-S
AP
. Pro
blem
: guaran
teed larg
e delay
s; delay
s are unbounded
if new
pack
ets arrive slo
wly
[U
naccep
table]
–W
ork
around 2
: AP
sends u
nicast B
AR
frames reg
ularly
to ad
van
ce the B
A w
indow
in clien
ts. The A
P h
as ad
ditio
nal p
rocessin
g to
match
ho
les again
st each 1
1aa G
A stream
as on
ly it k
no
ws w
hich
are gen
uin
e ho
les and
wh
ich are n
ot. U
p to
a lifetime lim
it, the A
P retries th
e missin
g p
ackets, sen
din
g a u
nicast B
AR
and
gettin
g a
BA
. If there are h
oles fro
m o
ther p
ackets o
r the lifetim
e limit is ex
ceeded
, the A
P h
as to p
erform
an ad
ditio
nal
BA
R/B
A ex
chan
ge to
get th
e client to
release bu
ffered p
ackets u
p th
e MA
C-S
AP
. An
d th
is add
ition
al BA
R/B
A
need
s to h
appen
with
each g
roup m
ember, ev
en fo
r gro
ups w
ith 1
0-2
0-1
00 m
embers (e.g
. the b
road
cast gro
up)
and so
this scales p
oorly
.
–W
ork
arou
nd
3: S
ame as 2
excep
t that th
e BA
Rs are sen
t GA
, and
the B
AR
sched
ules th
e BA
s imm
ediately
afterw
ards. T
he A
P can
transm
it a GA
BA
R w
ith an
empty
BA
sched
ule if th
e AP
only
wish
es to ad
van
ce the
BA
win
dow
of th
e gro
up. T
his is a n
ew B
AR
form
at, and req
uires n
ew A
DD
BA
.request/resp
onse fo
rmats also
.
•In
pro
cessing B
As, th
e AP
mu
st keep
track
of th
e holes p
er GA
stream
•In
ord
er to red
uce th
e need
for a
n a
dd
ition
al B
AR
to a
dvan
ce the B
A w
ind
ow
in clien
ts, the A
P
shou
ld seq
uen
ce fram
es for o
ne G
A a
nd
its exch
an
ges o
f BA
R a
nd
BA
s befo
re send
ing fra
mes
for a
noth
er GA
•R
epair req
uests (N
AC
Ks) a
re challen
gin
g/im
possib
le, since a
client d
etecting a
missin
g
sequ
ence n
um
ber ca
nn
ot a
scribe th
at to
a m
issing M
SD
U fo
r a G
A o
f interest.
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 2
8
Mech
1 - P
ros
•N
o a
dd
ition
al seq
# co
un
ter requ
ired w
ithin
the A
P
•N
o p
ossib
ility o
f du
plica
te removal in
legacy
clients ca
usin
g sid
e-effects (e.g
. an
imp
lemen
tatio
n th
at d
oes d
up
licate rem
oval b
efore
gro
up
ad
dress filterin
g still d
oes n
ot o
ver-rem
ove fra
mes)
•A
llow
s fram
es sent v
ia th
e legacy
No-A
ck/N
o-R
etry A
ck p
olicy
to
be reu
sed a
s initia
l tran
smissio
ns (m
uch
less overh
ead
in m
ixed
cells)
•T
he req
uirem
ent fo
r regu
lar B
AR
s an
d B
As to
all S
TA
s seems lik
e a h
ack
, an
d a
hack
that w
ou
ld sta
y w
ith 8
02.1
1 ev
er afterw
ard
s, ev
en in
an
all-8
02.1
1aa w
orld
. Yet th
e overh
ead
of th
e hack
is still lik
ely less th
an
the o
verh
ead
of tra
nsm
itting th
e gro
up
ad
dress
stream
twice, so
the lo
ng term
pain
is mod
est bu
t the sh
ort term
b
enefits a
re hig
h.
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 2
9
Mech
2 - P
ros
•S
imp
le BA
beh
avio
r: holes a
re imm
edia
tely v
isible to
AP
an
d
client a
s missin
g p
ack
ets –
no
extra laten
cy
–n
o ex
tra BA
Rs n
eeded
to u
pd
ate the B
A b
itmap
win
do
w
•S
hou
ld b
e com
patib
le with
legacy
du
plica
te removal if g
rou
p
ad
dress filterin
g o
ccurs b
efore d
up
licate rem
oval.
–F
rom
802.1
1:2
007, th
ere is near silen
ce as to w
hich
hap
pen
s first. Only
in
the u
nm
aintain
ed A
nn
ex C
, for u
nicast, is th
ere is add
ress filtering
on
p
90
6 th
en d
up
remo
val later o
n p
90
8. F
or m
ulticast, th
ere is filtering
on
p
90
6 y
et no
du
p rem
ov
al at all on
p9
08
. Bu
t that w
ou
ld b
e the p
lace for it,
so it lo
ok
s mu
ch lik
e du
p rem
ov
al after add
ress filtering
is the n
om
inal
imp
lemen
tation
.
•In
the lo
ng term
, wh
en a
ll dev
ices in a
gro
up
are 1
1aa-en
ab
led,
there is n
o a
dd
ition
al o
verh
ead
from
du
plica
te stream
s or ex
tra
BA
Rs
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 3
0
Mech
2 - C
on
s
•S
epara
te seq# co
un
ter for leg
acy
(No A
ck/N
o R
etry) G
A fra
mes
an
d fo
r each
GA
stream
are d
ifferent, so
correla
tion
betw
een th
e tw
o strea
ms is im
possib
le.
–If a B
SS
has b
oth
kin
ds o
f clients fo
r a GA
stream, th
e stream n
eeds to
be
sent tw
ice: via N
o A
ck/N
o R
etry an
d v
ia 11
aa, and
the N
o A
ck/N
o R
etry
frames d
on
't assist the reliab
ility o
f the 1
1aa stream
(yet th
is is still better
than
MC
2U
C fo
r 2 clien
ts)
•S
hou
ld b
e com
patib
le with
legacy
du
plica
te removal (if g
rou
p
ad
dress filterin
g o
ccurs b
efore d
up
licate rem
oval, a
s per th
e n
om
inal im
plem
enta
tion
describ
ed u
nd
er "P
ros"
), yet n
ot
gu
ara
nteed
.
•E
xtra
seq# co
un
ters need
ed w
ithin
AP
s
•D
up
licate d
etection
requ
ires the R
X to
main
tain
a ca
che o
f <
Ad
dress1
, TID
, seq#>
for G
A strea
ms o
f interest
doc.: IE
EE
802.11
-09/0
340r0
Subm
ission
Mar 2
009
Brian
Hart, C
isco S
ystem
s S
lide 3
1
Seq
uen
ce Cou
nter S
um
mary
•M
ech1 (o
ne seq
uen
ce cou
nter fo
r all g
rou
pca
st traffic,
non
-QoS
fram
es, an
d m
an
agem
ent fra
mes) u
sing
Work
aro
un
d 3
seems to
have th
e low
est nea
r-term
overh
ead
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