<s>
In	O
IEEE	O
802	O
LAN/MAN	O
standards	O
,	O
the	O
medium	B-Protocol
access	I-Protocol
control	I-Protocol
(	O
MAC	O
,	O
also	O
called	O
media	B-Protocol
access	I-Protocol
control	I-Protocol
)	O
sublayer	O
is	O
the	O
layer	O
that	O
controls	O
the	O
hardware	O
responsible	O
for	O
interaction	O
with	O
the	O
wired	O
,	O
optical	O
or	O
wireless	O
transmission	O
medium	O
.	O
</s>
<s>
The	O
MAC	B-Protocol
sublayer	I-Protocol
and	O
the	O
logical	O
link	O
control	O
(	O
LLC	O
)	O
sublayer	O
together	O
make	O
up	O
the	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
.	O
</s>
<s>
The	O
LLC	O
provides	O
flow	O
control	O
and	O
multiplexing	B-Architecture
for	O
the	O
logical	O
link	O
(	O
i.e.	O
</s>
<s>
EtherType	B-Protocol
,	O
802.1Q	O
VLAN	O
tag	O
etc	O
)	O
,	O
while	O
the	O
MAC	O
provides	O
flow	O
control	O
and	O
multiplexing	B-Architecture
for	O
the	O
transmission	O
medium	O
.	O
</s>
<s>
These	O
two	O
sublayers	O
together	O
correspond	O
to	O
layer	B-Protocol
2	I-Protocol
of	O
the	O
OSI	O
model	O
.	O
</s>
<s>
Within	O
the	O
hierarchy	O
of	O
the	O
OSI	O
model	O
and	O
IEEE	O
802	O
standards	O
,	O
the	O
MAC	B-Protocol
sublayer	I-Protocol
provides	O
a	O
control	B-Application
abstraction	I-Application
of	O
the	O
physical	O
layer	O
such	O
that	O
the	O
complexities	O
of	O
physical	O
link	O
control	O
are	O
invisible	O
to	O
the	O
LLC	O
and	O
upper	O
layers	O
of	O
the	O
network	O
stack	O
.	O
</s>
<s>
In	O
turn	O
,	O
the	O
medium	B-Protocol
access	I-Protocol
control	I-Protocol
block	O
is	O
formally	O
connected	O
to	O
the	O
PHY	O
via	O
a	O
media-independent	B-Protocol
interface	I-Protocol
.	O
</s>
<s>
Although	O
the	O
MAC	O
block	O
is	O
today	O
typically	O
integrated	O
with	O
the	O
PHY	O
within	O
the	B-Algorithm
same	I-Algorithm
device	I-Algorithm
package	I-Algorithm
,	O
historically	O
any	O
MAC	O
could	O
be	O
used	O
with	O
any	O
PHY	O
,	O
independent	O
of	O
the	O
transmission	O
medium	O
.	O
</s>
<s>
When	O
sending	O
data	O
to	O
another	O
device	O
on	O
the	O
network	O
,	O
the	O
MAC	B-Protocol
sublayer	I-Protocol
encapsulates	O
higher-level	O
frames	O
into	O
frames	O
appropriate	O
for	O
the	O
transmission	O
medium	O
(	O
i.e.	O
</s>
<s>
the	O
MAC	O
adds	O
a	O
syncword	O
preamble	O
and	O
also	O
padding	O
if	O
necessary	O
)	O
,	O
adds	O
a	O
frame	B-Protocol
check	I-Protocol
sequence	I-Protocol
to	O
identify	O
transmission	O
errors	O
,	O
and	O
then	O
forwards	O
the	O
data	O
to	O
the	O
physical	O
layer	O
as	O
soon	O
as	O
the	O
appropriate	O
channel	O
access	O
method	O
permits	O
it	O
.	O
</s>
<s>
For	O
topologies	O
with	O
a	O
collision	B-Protocol
domain	I-Protocol
(	O
bus	O
,	O
ring	O
,	O
mesh	O
,	O
point-to-multipoint	O
topologies	O
)	O
,	O
controlling	O
when	O
data	O
is	O
sent	O
and	O
when	O
to	O
wait	O
is	O
necessary	O
to	O
avoid	O
collisions	O
.	O
</s>
<s>
When	O
receiving	O
data	O
from	O
the	O
physical	O
layer	O
,	O
the	O
MAC	O
block	O
ensures	O
data	O
integrity	O
by	O
verifying	O
the	O
sender	O
's	O
frame	B-Protocol
check	I-Protocol
sequences	I-Protocol
,	O
and	O
strips	O
off	O
the	O
sender	O
's	O
preamble	O
and	O
padding	O
before	O
passing	O
the	O
data	O
up	O
to	O
the	O
higher	O
layers	O
.	O
</s>
<s>
According	O
to	O
IEEE	O
Std	O
802-2001	O
section	O
6.2.3	O
"	O
MAC	B-Protocol
sublayer	I-Protocol
"	O
,	O
the	O
primary	O
functions	O
performed	O
by	O
the	O
MAC	B-Protocol
layer	I-Protocol
are	O
:	O
</s>
<s>
The	O
local	O
network	O
addresses	O
used	O
in	O
IEEE	O
802	O
networks	O
and	O
FDDI	B-Protocol
networks	O
are	O
called	O
media	B-Protocol
access	I-Protocol
control	I-Protocol
addresses	O
;	O
they	O
are	O
based	O
on	O
the	O
addressing	O
scheme	O
that	O
was	O
used	O
in	O
early	O
Ethernet	O
implementations	O
.	O
</s>
<s>
This	O
makes	O
it	O
possible	O
for	O
frames	O
to	O
be	O
delivered	O
on	O
a	O
network	O
link	O
that	O
interconnects	O
hosts	O
by	O
some	O
combination	O
of	O
repeaters	O
,	O
hubs	B-Protocol
,	O
bridges	O
and	O
switches	O
,	O
but	O
not	O
by	O
network	B-Application
layer	I-Application
routers	B-Protocol
.	O
</s>
<s>
Thus	O
,	O
for	O
example	O
,	O
when	O
an	O
IP	B-Protocol
packet	O
reaches	O
its	O
destination	O
(	O
sub	O
)	O
network	O
,	O
the	O
destination	O
IP	B-Protocol
address	O
(	O
a	O
layer	B-Application
3	I-Application
or	O
network	B-Application
layer	I-Application
concept	O
)	O
is	O
resolved	O
with	O
the	O
Address	O
Resolution	O
Protocol	O
for	O
IPv4	B-Protocol
,	O
or	O
by	O
Neighbor	B-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
(	O
IPv6	O
)	O
into	O
the	O
MAC	O
address	O
(	O
a	O
layer	B-Protocol
2	I-Protocol
concept	O
)	O
of	O
the	O
destination	O
host	O
.	O
</s>
<s>
A	O
MAC	B-Protocol
layer	I-Protocol
is	O
not	O
required	O
in	O
full-duplex	O
point-to-point	B-Architecture
communication	I-Architecture
,	O
but	O
address	O
fields	O
are	O
included	O
in	O
some	O
point-to-point	B-Architecture
protocols	O
for	O
compatibility	O
reasons	O
.	O
</s>
<s>
The	O
channel	O
access	O
control	O
mechanisms	O
provided	O
by	O
the	O
MAC	B-Protocol
layer	I-Protocol
are	O
also	O
known	O
as	O
a	O
multiple	O
access	O
method	O
.	O
</s>
<s>
Examples	O
of	O
shared	O
physical	O
media	O
are	O
bus	B-Architecture
networks	I-Architecture
,	O
ring	B-Architecture
networks	I-Architecture
,	O
hub	B-Protocol
networks	O
,	O
wireless	B-General_Concept
networks	I-General_Concept
and	O
half-duplex	O
point-to-point	B-Architecture
links	O
.	O
</s>
<s>
The	O
multiple	O
access	O
method	O
may	O
detect	O
or	O
avoid	O
data	O
packet	O
collisions	O
if	O
a	O
packet	O
mode	O
contention	O
based	O
channel	O
access	O
method	O
is	O
used	O
,	O
or	O
reserve	O
resources	O
to	O
establish	O
a	O
logical	O
channel	O
if	O
a	O
circuit-switched	B-Protocol
or	O
channelization-based	O
channel	O
access	O
method	O
is	O
used	O
.	O
</s>
<s>
The	O
channel	O
access	O
control	O
mechanism	O
relies	O
on	O
a	O
physical	O
layer	O
multiplex	B-Architecture
scheme	O
.	O
</s>
<s>
This	O
mechanism	O
is	O
only	O
utilized	O
within	O
a	O
network	O
collision	B-Protocol
domain	I-Protocol
,	O
for	O
example	O
an	O
Ethernet	O
bus	B-Architecture
network	I-Architecture
or	O
a	O
hub-based	O
star	O
topology	O
network	O
.	O
</s>
<s>
An	O
Ethernet	O
network	O
may	O
be	O
divided	O
into	O
several	O
collision	B-Protocol
domains	I-Protocol
,	O
interconnected	O
by	O
bridges	O
and	O
switches	O
.	O
</s>
<s>
A	O
multiple	O
access	O
method	O
is	O
not	O
required	O
in	O
a	O
switched	O
full-duplex	O
network	O
,	O
such	O
as	O
today	O
's	O
switched	B-Protocol
Ethernet	I-Protocol
networks	O
,	O
but	O
is	O
often	O
available	O
in	O
the	O
equipment	O
for	O
compatibility	O
reasons	O
.	O
</s>
<s>
Use	O
of	O
directional	O
antennas	O
and	O
millimeter-wave	O
communication	O
in	O
a	O
wireless	B-General_Concept
personal	I-General_Concept
area	I-General_Concept
network	I-General_Concept
increases	O
the	O
probability	O
of	O
concurrent	O
scheduling	O
of	O
non‐interfering	O
transmissions	O
in	O
a	O
localized	O
area	O
,	O
which	O
results	O
in	O
an	O
immense	O
increase	O
in	O
network	O
throughput	O
.	O
</s>
<s>
Cellular	O
networks	O
,	O
such	O
as	O
GSM	O
,	O
UMTS	B-Protocol
or	O
LTE	O
networks	O
,	O
also	O
use	O
a	O
MAC	B-Protocol
layer	I-Protocol
.	O
</s>
<s>
The	O
MAC	B-Protocol
protocol	I-Protocol
in	O
cellular	O
networks	O
is	O
designed	O
to	O
maximize	O
the	O
utilization	O
of	O
the	O
expensive	O
licensed	O
spectrum	O
.	O
</s>
<s>
The	O
air	O
interface	O
of	O
a	O
cellular	O
network	O
is	O
at	O
layers	O
1	O
and	O
2	O
of	O
the	O
OSI	O
model	O
;	O
at	O
layer	B-Protocol
2	I-Protocol
,	O
it	O
is	O
divided	O
into	O
multiple	O
protocol	O
layers	O
.	O
</s>
<s>
In	O
UMTS	B-Protocol
and	O
LTE	O
,	O
those	O
protocols	O
are	O
the	O
Packet	O
Data	O
Convergence	O
Protocol	O
(	O
PDCP	O
)	O
,	O
the	O
Radio	O
Link	O
Control	O
(	O
RLC	O
)	O
protocol	O
,	O
and	O
the	O
MAC	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
The	O
MAC	B-Protocol
protocol	I-Protocol
is	O
specified	O
by	O
3GPP	O
in	O
TS	O
25.321	O
for	O
UMTS	B-Protocol
,	O
TS	O
36.321	O
for	O
LTE	O
and	O
TS	O
38.321	O
for	O
5G	O
.	O
</s>
