Analysis of Quality of Service in Wimax networks

Figure 5 NS-2 Simulation Example 
Sink Node 
Base Station 
Duplex wired connection 
Mobile Nodes 
Wireless link with traffic 

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After the simulation starts each node goes through basic registration procedure 
to get associated with the base station. So the traffic is started after some time to 
allow the mobile node to complete the registration. In the simulation, the traffic is 
started 15 seconds after the simulation is started. 
Figure 5 displays a typical example of the ns-2 setup. In the WiMAX module, 
the mobile nodes are created as MAC/802_16/SS nodes and the base station is created 
as MAC/802_16/BS node. When the mobile node is added to the base station, using 
“setflow” command the service flow is statically created. The types of service flows 
that are supported by the version 2.1 of the WiMAX modules are, BE, rtPS and UGS.
At this point, nrtPS and ertPS service flows are not supported. 
The TCL scripts were parameterized. The input parameters that were varied, 
for example, number of nodes in the simulation, was passed in as a parameter while 
running the simulation for easy execution. 
3.3 QoS Parameters 
QoS provisioning encompasses providing Quality of Service to the end user in 
terms of several generic parameters. The perceived quality of service can be 
quantitatively measured in terms of several parameters. In the analysis, the 
throughput, average delay, average jitter and packet loss were considered. 

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3.1.1. Throughput 
Throughput is a measure of the date rate (bits per second) generated by the 
application. Equation 1 shows the calculation for throughput TP, where PacketSize
i
is the packet size of the ith packet reaching the destination, PacketStart
o
is the time 
when the first packet left the source and PacketArrival
n
is the time when the last 
packet arrived. 
0
t
PacketStar
val
PacketArri
PacketSize
TP
n
i
i
−
=
∑