<s>
Radio	B-Protocol
resource	I-Protocol
management	I-Protocol
(	O
RRM	O
)	O
is	O
the	O
system	O
level	O
management	O
of	O
co-channel	O
interference	O
,	O
radio	O
resources	O
,	O
and	O
other	O
radio	O
transmission	O
characteristics	O
in	O
wireless	O
communication	O
systems	O
,	O
for	O
example	O
cellular	O
networks	O
,	O
wireless	B-Architecture
local	I-Architecture
area	I-Architecture
networks	I-Architecture
,	O
wireless	B-Architecture
sensor	I-Architecture
systems	O
,	O
and	O
radio	O
broadcasting	O
networks	O
.	O
</s>
<s>
RRM	O
involves	O
strategies	O
and	O
algorithms	O
for	O
controlling	O
parameters	O
such	O
as	O
transmit	O
power	O
,	O
user	O
allocation	O
,	O
beamforming	B-Algorithm
,	O
data	O
rates	O
,	O
handover	B-Protocol
criteria	O
,	O
modulation	B-Application
scheme	O
,	O
error	O
coding	O
scheme	O
,	O
etc	O
.	O
</s>
<s>
Traditional	O
telecommunications	O
research	O
and	O
education	O
often	O
dwell	O
on	O
channel	O
coding	O
and	O
source	B-General_Concept
coding	I-General_Concept
with	O
a	O
single	O
user	O
in	O
mind	O
,	O
but	O
when	O
several	O
users	O
and	O
adjacent	O
base	O
stations	O
share	O
the	O
same	O
frequency	O
channel	O
it	O
may	O
not	O
be	O
possible	O
to	O
achieve	O
the	O
maximum	O
channel	O
capacity	O
.	O
</s>
<s>
Efficient	O
dynamic	O
RRM	O
schemes	O
may	O
increase	O
the	O
system	O
spectral	O
efficiency	O
by	O
an	O
order	O
of	O
magnitude	O
,	O
which	O
often	O
is	O
considerably	O
more	O
than	O
what	O
is	O
possible	O
by	O
introducing	O
advanced	O
channel	O
coding	O
and	O
source	B-General_Concept
coding	I-General_Concept
schemes	O
.	O
</s>
<s>
RRM	O
is	O
especially	O
important	O
in	O
systems	O
limited	O
by	O
co-channel	O
interference	O
rather	O
than	O
by	O
noise	O
,	O
for	O
example	O
cellular	O
systems	O
and	O
broadcast	O
networks	O
homogeneously	O
covering	O
large	O
areas	O
,	O
and	O
wireless	B-General_Concept
networks	I-General_Concept
consisting	O
of	O
many	O
adjacent	O
access	B-Device
points	I-Device
that	O
may	O
reuse	O
the	O
same	O
channel	O
frequencies	O
.	O
</s>
<s>
The	O
cost	O
for	O
deploying	O
a	O
wireless	B-General_Concept
network	I-General_Concept
is	O
normally	O
dominated	O
by	O
base	O
station	O
sites	O
(	O
real	O
estate	O
costs	O
,	O
planning	O
,	O
maintenance	O
,	O
distribution	O
network	O
,	O
energy	O
,	O
etc	O
.	O
)	O
</s>
<s>
So	O
,	O
the	O
objective	O
of	O
radio	B-Protocol
resource	I-Protocol
management	I-Protocol
is	O
typically	O
to	O
maximize	O
the	O
system	O
spectral	O
efficiency	O
in	O
bit/s/Hz/area	O
unit	O
or	O
Erlang/MHz/site	O
,	O
under	O
some	O
kind	O
of	O
user	O
fairness	O
constraint	O
,	O
for	O
example	O
,	O
that	O
the	O
grade	O
of	O
service	O
should	O
be	O
above	O
a	O
certain	O
level	O
.	O
</s>
<s>
The	O
grade	O
of	O
service	O
is	O
also	O
affected	O
by	O
blocking	O
due	O
to	O
admission	O
control	O
,	O
scheduling	B-Operating_System
starvation	I-Operating_System
or	O
inability	O
to	O
guarantee	O
quality	O
of	O
service	O
that	O
is	O
requested	O
by	O
the	O
users	O
.	O
</s>
<s>
While	O
classical	O
radio	B-Protocol
resource	I-Protocol
managements	I-Protocol
primarily	O
considered	O
the	O
allocation	O
of	O
time	O
and	O
frequency	O
resources	O
(	O
with	O
fixed	O
spatial	O
reuse	O
patterns	O
)	O
,	O
recent	O
multi-user	B-Architecture
MIMO	I-Architecture
techniques	O
enables	O
adaptive	O
resource	O
management	O
also	O
in	O
the	O
spatial	O
domain	O
.	O
</s>
<s>
Frequency	B-Algorithm
allocation	I-Algorithm
band	B-Algorithm
plans	I-Algorithm
decided	O
by	O
standardization	O
bodies	O
,	O
by	O
national	O
frequency	O
authorities	O
and	O
in	O
frequency	O
resource	O
auctions	O
.	O
</s>
<s>
Static	O
RRM	O
schemes	O
are	O
used	O
in	O
many	O
traditional	O
wireless	O
systems	O
,	O
for	O
example	O
1G	O
and	O
2G	O
cellular	O
systems	O
,	O
in	O
today	O
's	O
wireless	B-Architecture
local	I-Architecture
area	I-Architecture
networks	I-Architecture
and	O
in	O
non-cellular	O
systems	O
,	O
for	O
example	O
broadcasting	O
systems	O
.	O
</s>
<s>
Some	O
schemes	O
are	O
centralized	O
,	O
where	O
several	O
base	O
stations	O
and	O
access	B-Device
points	I-Device
are	O
controlled	O
by	O
a	O
Radio	O
Network	O
Controller	O
(	O
RNC	O
)	O
.	O
</s>
<s>
Others	O
are	O
distributed	O
,	O
either	O
autonomous	O
algorithms	O
in	O
mobile	O
stations	O
,	O
base	O
stations	O
or	O
wireless	B-Device
access	I-Device
points	I-Device
,	O
or	O
coordinated	O
by	O
exchanging	O
information	O
among	O
these	O
stations	O
.	O
</s>
<s>
Inter-cell	O
radio	B-Protocol
resource	I-Protocol
management	I-Protocol
coordinates	O
resource	O
allocation	O
between	O
different	O
cell	O
sites	O
by	O
using	O
multi-user	B-Architecture
MIMO	I-Architecture
techniques	O
.	O
</s>
<s>
There	O
are	O
various	O
means	O
of	O
inter-cell	B-Protocol
interference	I-Protocol
coordination	I-Protocol
(	O
ICIC	O
)	O
already	O
defined	O
in	O
the	O
standard	O
.	O
</s>
<s>
Dynamic	B-Protocol
single-frequency	I-Protocol
networks	I-Protocol
,	O
coordinated	O
scheduling	O
,	O
multi-site	O
MIMO	O
or	O
joint	O
multi-cell	O
precoding	B-Protocol
are	O
other	O
examples	O
for	O
inter-cell	O
radio	B-Protocol
resource	I-Protocol
management	I-Protocol
.	O
</s>
