Analysis of Quality of Service in Wimax networks

Figure 6 Throughput with number of nodes for BE service flow 
Service Flow Type: Best Effort (BE) 
Traffic Type: VOIP 
VOIP Codec: G.711 ((64kbps): 80 bytes frame, 160 bytes payload, 50 pkts per sec.) 

---

36
The throughput steadily increases as the number of nodes increase. This is 
expected behavior. As the number of nodes increase, so does the number of packets 
being transmitted. Each node is transmitting 160 byte packets at the rate of 50 packets 
per second as per the G.711 specifications. The packets are generated at the rate of 
64kbps. So for two nodes, the throughput is around 116 kbps. For 10 nodes, the value 
reaches around 519 kbps. This is because of the packet loss. The variation of percent 
packet loss is seen in Figure 7. 
Packet Loss %
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
2
4
6
8
10
Num ber of nodes
%
Figure 7 Packet Loss with number of nodes for BE service flow 
When number of nodes increase, the number of packets transferred increases.
These include data packets as well as control packets that are exchanged between the SS 
Service Flow Type: Best Effort (BE) 
Traffic Type: VOIP 
VOIP Codec: G.711 ((64kbps): 80 bytes frame, 160 bytes payload, 50 pkts per sec.) 

---

37
and BS. With increased traffic, the packet loss rate goes up from about less than 0.1 % 
for 2 nodes to up to 1.5 % for 10 nodes. 
Average Jitter
0.00E+00
5.00E-07
1.00E-06
1.50E-06
2.00E-06
2.50E-06
3.00E-06
3.50E-06
2
4
6
8
10
Number of nodes
S
eco
n
d