Cryptography Reference
In-Depth Information
In conclusion, the need for mobility in WSN is application dependent. For exam-
ple, in applications that measure temperature, humidity, sound, or light in an enclosed
area, there is no need to have mobile sensors or a mobile sink. However, for monitoring
a moving object in a battlefield environment, or in monitoring endangered species,
there is a need for mobile sensors in the network, for efficient tracking of the object.
In such scenarios, it has been observed that the use of mobile relays helps increase the
lifetime of a WSN.
7.2.7 Network Heterogeneity
Early research on sensor networks focused on homogenous network architectures
(Section 1.3.1). However, recently there has been an increase in the popularity of
heterogeneous sensor networks (Section 1.3.2) because of their ability to significantly
increase the lifetime and reliability of the system. A usual heterogeneous sensor net-
work consists of a large number of low-cost nodes for the sensing operation and a
few resource-abundant nodes that primarily perform data filtering, aggregation, and
transport operations. Although heterogeneous networks have gained precedence over
homogenous networks, the efficient realization of heterogeneity in a sensor network
requires prior systematic planning for placing these heterogeneous resources in a
resource-aware manner (Yarvis et al. 2005).
7.3 Related Work
The LEACH protocol (discussed in Section 7.2.3.1) has been one of the most promis-
ing cluster-based architectures. However, it makes a broad assumption that every ordi-
nary node can easily reach the sink. In addition, ordinary or leaf nodes send the sensed
data to their respective cluster heads in order to save energy, which then aggregates the
data and sends the aggregation to the sink.
To increase the overall energy efficiency of the sensor network, LEACH randomly
rotates cluster heads among all sensor nodes in the network, in a timely fashion.
Following the idea of LEACH, a number of protocols have been presented, such as
Power-Efficient Gathering in Sensor Information Systems (PEGASIS) (Lindsey and
Raghavendra 2002), and Power Efficient and Adaptive Clustering Hierarchy Protocol
for wireless sensor networks (PEACH) (Yia et al. 2007), which use a similar concept as
LEACH. Because traditional privacy protection cannot solve security vulnerability in
WSNs, some security protocols have been proposed for WSNs, e.g., Security Protocols
for Sensor Network (SPINS) (Perrig et al. 2002). Adding security to LEACH-like
protocols is challenging because its dynamic clustering makes key-distribution solu-
tions for node-to-node trust relationships messy and inadequate. There are some secure
routing protocols based on LEACH-like protocols, such as SecLEACH (Oliveira et al.
2007) and grid-based secure LEACH (GS-LEACH) (Banerjee et al. 2007) However,
most of them are applying symmetric key-management schemes, which increase the
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