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Study on Throughput of Network with Selfish Nodes
Based on IEEE 802.15.4
Haiping Li, Jianlin Mao, Ning Guo, and Bin Zhang
Haiping Li, Kunming University of Science and Technology, 650000 Yunnan, China
lhping3@126.com
Abstract. CSMA/CA mechanism in 802.15.4 protocol provides a contention
mechanism and has been widely used in wireless sensor networks. But some
nodes may disobey the backoff algorithm and behave selfishly in order to ob-
tain more bandwidth share. In this paper, we study the selfish behavior of nodes
which minimize their BE (Backoff Exponent) once sense the channel state is
busy. Finally, NS2 is used to simulate the CSMA/CA mechanism and the simu-
lation result indicates that the network packet loss rate is decreased, the fairness
is affected and the throughput is reduced due to the introduction of selfish node.
Keywords: selfish node, CSMA/CA, NS2.
1 Introduction
Over the last few years, wireless sensor networks (WSN) develops very quickly . It
has become the predominant medium responsible for the wireless internet access in
many environments. WSN is constituted by a large number of low energy consump-
tion and small size sensing nodes, which are capable of dealing with data and identi-
fying the current network. Based on the above mentioned, WSN technology have
come to pervade every aspect of our lives, especially wireless remote monitoring
system. IEEE802.15.4 is a simple and low rate Media Access Control (MAC) stan-
dard, which is applied to the transducer and other low energy consumption equip-
ments. IEEE802.15.4 utilizes the contention based MAC based on CSMA/CA
(Carrier Sense Multiple Access/Collision Avoidance). Due to the advent of program-
mable radios, different MAC protocol parameters can be manipulated in various ways
to gain an unfair share of the wireless channel resources and that leads to the birth of
the selfish behavior. In practice, protocol parameters such as transmission power and
carrier sensing threshold can be easily adjusted [1].For example, a higher CCA
threshold can effectively disable carrier sensing. Thus, the selfish node gains more
transmission opportunities. The authors in [2] [3] propose a routing misbehavior. The
selfish nodes participate in the route discovery and maintenance processes but refuse
to forward data packets. Li Dan and Wu jianping[4] survey the recent research trends
in this area, and classify the research into three categories according to the working
steps of ALM protocols, that is ,the selfishness in maintenance of control structure,
the selfishness in collection of node information, and the selfishness in construction of
 
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