An Enhanced EDD QoS Scheduler for IEEE 802.11e WLAN - Advances in Computational Science and Engineering - page 54

(a) Modification of mSI

(b) The difference between expected and real time
when channel is idle

Fig. 5. SI allocation of the proposed scheduler

if( t exp − t cur ) > 0 ,
mSI new = mSI i − ( t exp − t cur )

(11)

otherwise ,
mSI new = mSI i

t i t i

where respectively denote the time when the data transmission

completed and the expected time when TXOP i finished in previous SI. mSI i

and

cur exp

new

is newly assigned mSI of QST A i .

4 Performance Evaluation of the Proposed Algorithm

In this section, in order to show the performance of our scheduler, we ran the
simulation using NS-2 [12].