Analysis of Quality of Service in Wimax networks

in bytes 
Packet Rate 
in packets/sec 
G.711 64 160 50 
G.729 8 20 50 
G.729.2 8 
30 33 
G.723 6.3 30 26 
G.723.2 5.3 
30 
22 
These codecs are defined by the ITU. As can be seen, G.711 codec has the 
highest throughput with higher payload and higher packet rate. It uses Pulse code 
modulation (PCM) of voice frequencies and uses simple compression to result in 64 kbps.
On the other hand G.723.2 is a codec which has the lowest throughput with smaller 
packet size and smallest packet rate.
For each of the codes, number of nodes with the VOIP traffic was varied from 2, 
4, 6, 8 and 10. This experiment was repeated for the following service flows which are 
defined by IEEE 802.16e standard: 
1.
BE: Best Effort 
2.
rtPS: Real Time Polling Service 
3.
UGS- Unsolicited Grant Service 
Note that simulation did not support ertPS (Enhanced Real Time Polling Service) 
and nrtPS (Non Real Time Polling Service). 

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In the following sections 4.1.1 to 4.1.3 results for G.711 codec are presented. The 
patterns observed in all the other codecs were very similar. Instead of presenting all the 
results for other codecs, a comparative analysis is done in section 4.2.4. 
4.1.1 Results for VOIP traffic over Best Effort Service Flow 
In the first case the VOIP traffic is setup over Best Effort (BE) service flow.
Figure 6 to Figure 9 displays the variation of throughput, percentage packet loss, average 
jitter, and average delay as the number of nodes increase from 2 to 10.
Thoughput (kbps)
0
100
200
300
400
500
600
2
4
6
8
10
Num ber of nodes
kb
p
s