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Impact of Time-based Fairness
Under the time-based fairness, our proposed definition of fairness, each node achieves an equal
share of channel occupancy time. Thus,
|
(11) |
Substituting Equation 11 in Equations 2 and 3,
|
(12) |
|
(13) |
Notice that R'(i) only depends on what node i can achieve under
the given conditions and the number of competing nodes. It does not
depend upon the data rates or packet sizes used by competing nodes.
Unlike R(I) shown in previous subsections, R'(I) is a simple
summation of each node's maximum achievable throughput when all
competing nodes use its data rate and packet size.
R'(I), and R(I) in Equations 7
and 10 will be equal if and only if all nodes in I
use the same data rate and packet size.
Table 2:
The experimentally achieved total throughput (or the baseline
throughput) of the two nodes simultaneously exchanging data at the same
data rate d and packet size s. Each node has a similar frame loss rate
of less than .
d ( Mbps) |
s (Byte) |
n = |I| |
|
11 |
1500 |
2 |
5.189 |
5.5 |
1500 |
2 |
3.327 |
2 |
1500 |
2 |
1.493 |
1 |
1500 |
2 |
0.806 |
|
Table 3:
Comparison of achieved throughputs (in Mbps) of four nodes,
each transmitting at 1, 2, 11 and 11 Mbps respectively, under RF and
TF. Note that R(n1) under TF is the same as what n1 would achieve if
all n2, n3 and n4 transmit at 1 Mbps.
Fairness |
R(n1) |
R(n2) |
R(n3) |
R(n4) |
Total |
Criteria |
(1) |
(2) |
(11) |
(11) |
|
RF |
0.436 |
0.436 |
0.436 |
0.436 |
1.742 |
TF |
0.202 |
0.373 |
1.30 |
1.30 |
3.175 |
|
Next: Examples
Up: Analysis
Previous: Impact of the AP
Godfrey Tan
2004-05-04