Study on Throughput of Network with Selfish Nodes Based on IEEE 802.15.4 - Advanced Research on Computer Education, Simulation and Modeling - page 413

2 CSMA/CA Mechanism Simulation

As open source network simulation software, NS2 provides strong support for simu-
lating and studying of wired and wireless networks. In the CSMA/CA mechanism, the
size of the CW affects nodes contend to the channel. The smaller the CW is, the more
opportunity to obtain channel resources.
In order to research the impact of selfish nodes on network, we design 5 groups of
simulation experiment.

2.1 Throughput Analysis

We simulate the network exists selfish nodes and does not exist selfish node. A super
frame has 16 intervals, and there are 21 nodes in the network, the No.0 node is desti-
nation node, and the No.1--20 nodes are source nodes. We adopt TCP protocol in
agent layer and FTP in the application layer and the packet size is 1500 bytes. The
structure of the network is illustrated in Fig. 2.

Fig. 2. Network topology

4

Throughput of Nodes

x 10

14

Ex is t Selfish node
all Common node

12

10

8

6

4

2

0

0 2 4 6 8 10 12 14 16 18 20

Node-id

Fig. 3. Thr o ughput of nodes