<s>
Maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
is	O
a	O
procedure	O
for	O
scheduling	O
data	B-Protocol
packets	I-Protocol
in	O
a	O
packet-switched	B-Protocol
best-effort	O
network	O
,	O
typically	O
a	O
wireless	B-General_Concept
network	I-General_Concept
,	O
in	O
view	O
to	O
maximize	O
the	O
total	O
throughput	O
of	O
the	O
network	O
,	O
or	O
the	O
system	O
spectral	O
efficiency	O
in	O
a	O
wireless	B-General_Concept
network	I-General_Concept
.	O
</s>
<s>
In	O
advanced	O
packet	B-Protocol
radio	O
systems	O
,	O
for	O
example	O
the	O
HSDPA	O
3.5G	O
cellular	O
system	O
,	O
channel-dependent	O
scheduling	O
is	O
used	O
instead	O
of	O
FIFO	B-Operating_System
queuing	I-Operating_System
to	O
take	O
advantage	O
of	O
favourable	O
channel	O
conditions	O
to	O
make	O
best	O
use	O
of	O
available	O
radio	O
conditions	O
.	O
</s>
<s>
Maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
may	O
be	O
tempting	O
in	O
this	O
context	O
,	O
especially	O
in	O
simulations	O
where	O
throughput	O
of	O
various	O
schemes	O
are	O
compared	O
.	O
</s>
<s>
However	O
,	O
maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
is	O
normally	O
not	O
desirable	O
,	O
and	O
channel-dependent	O
scheduling	O
should	O
be	O
used	O
with	O
care	O
,	O
as	O
we	O
will	O
see	O
below	O
.	O
</s>
<s>
In	O
a	O
wireless	B-General_Concept
network	I-General_Concept
with	O
link	B-Protocol
adaptation	I-Protocol
,	O
and	O
without	O
co-channel	O
interference	O
from	O
nearby	O
wireless	B-General_Concept
networks	I-General_Concept
,	O
the	O
bit	O
rate	O
depends	O
heavily	O
on	O
the	O
carrier	O
to	O
noise	O
ratio	O
(	O
CNR	O
)	O
,	O
which	O
depends	O
on	O
the	O
attenuation	O
on	O
the	O
link	O
between	O
the	O
transmitter	O
and	O
receiver	O
,	O
i.e.	O
</s>
<s>
For	O
maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
,	O
links	O
that	O
are	O
affected	O
by	O
low	O
attenuation	O
should	O
be	O
considered	O
as	O
inexpensive	O
,	O
and	O
should	O
be	O
given	O
scheduling	O
priority	O
.	O
</s>
<s>
In	O
the	O
uplink	O
of	O
a	O
spread	B-Architecture
spectrum	I-Architecture
cellular	O
system	O
,	O
the	O
carrier-to-interference	O
ratio	O
(	O
CIR	O
)	O
is	O
held	O
constant	O
by	O
the	O
power	O
control	O
for	O
all	O
users	O
.	O
</s>
<s>
Consequently	O
,	O
for	O
maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
,	O
data	O
flows	O
that	O
suffer	O
from	O
high	O
path	O
loss	O
should	O
be	O
considered	O
as	O
the	O
most	O
expensive	O
,	O
also	O
in	O
this	O
case	O
.	O
</s>
<s>
In	O
wireless	B-General_Concept
network	I-General_Concept
with	O
fast	O
dynamic	B-Protocol
channel	I-Protocol
allocation	I-Protocol
(	O
DCA	O
)	O
,	O
on	O
a	O
packet-by-packet	O
or	O
slot-by-slot	O
basis	O
,	O
a	O
user	O
that	O
is	O
situated	O
in	O
the	O
overlap	O
between	O
the	O
coverage	O
areas	O
of	O
several	O
base	O
stations	O
would	O
cause	O
,	O
or	O
would	O
be	O
affected	O
by	O
,	O
interference	O
to/from	O
nearby	O
cells	O
.	O
</s>
<s>
If	O
there	O
are	O
large	O
differences	O
between	O
the	O
"	O
cost	O
"	O
of	O
each	O
data	O
flow	O
,	O
which	O
is	O
the	O
case	O
especially	O
in	O
wireless	B-General_Concept
networking	I-General_Concept
,	O
resources	O
may	O
be	O
assigned	O
to	O
only	O
one	O
or	O
very	O
few	O
data	O
flows	O
per	O
physical	O
channel	O
in	O
the	O
network	O
.	O
</s>
<s>
A	O
maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
policy	O
may	O
be	O
tempting	O
since	O
it	O
would	O
optimize	O
the	O
resource	O
utilization	O
in	O
a	O
given	O
network	O
,	O
but	O
it	O
would	O
not	O
be	O
likely	O
to	O
maximize	O
profit	O
for	O
the	O
network	O
operator	O
.	O
</s>
<s>
Proportional	B-Algorithm
fairness	I-Algorithm
would	O
result	O
in	O
lower	O
throughput	O
,	O
but	O
starvation	O
would	O
be	O
avoided	O
.	O
</s>
<s>
Max-min	B-Algorithm
fairness	I-Algorithm
would	O
result	O
in	O
even	O
lower	O
throughput	O
,	O
but	O
higher	O
level	O
of	O
fairness	B-Protocol
,	O
meaning	O
that	O
the	O
service	O
quality	O
that	O
each	O
data	O
flow	O
achieves	O
would	O
be	O
even	O
more	O
stable	O
.	O
</s>
<s>
Unlike	O
max-min	B-Algorithm
fair	I-Algorithm
scheduling	I-Algorithm
based	O
on	O
the	O
fair	B-Algorithm
queuing	I-Algorithm
or	O
round	B-Algorithm
robin	I-Algorithm
algorithms	O
,	O
a	O
maximum	B-Algorithm
throughput	I-Algorithm
scheduling	I-Algorithm
algorithm	O
relies	O
on	O
the	O
calculation	O
of	O
a	O
cost	O
function	O
,	O
which	O
in	O
wireless	B-General_Concept
networks	I-General_Concept
may	O
require	O
fast	O
and	O
truthful	O
measurement	O
of	O
the	O
path	O
loss	O
.	O
</s>
<s>
Proportional	B-Algorithm
fairness	I-Algorithm
based	O
on	O
weighted	B-Algorithm
fair	I-Algorithm
queuing	I-Algorithm
also	O
require	O
measurement	O
or	O
calculation	O
of	O
the	O
cost	O
function	O
.	O
</s>
