Simulation Based Topology Optimization in Wireless Sensor Network
Authors: Sharma Jeetu , Chauhan Reema Singh , Shukla Akanksha 
Published: May 2018

Background:
Wireless Sensor Network (WSN) is among the most promising technologies
that can be used to monitor crucial ambient conditions. WSNs are capable of effectively monitoring the
environmental parameters and any habitat necessary to be investigated. Sometimes, it is very important
to periodically monitor the critical environmental parameters such as humidity, temperature, soil moisture,
fire, volcanic eruptions, Tsunamis, seismic waves and many more to react proactively to save lives
and assets. This research work is an endeavor to present the importance and to determine the precise inter-
nodal distance required for distinct applications. The networks of the different terrain area and internodal
distance are deployed to evaluate and analyze the performance metrics such as a number of messages
received average end to end delay (secs), throughput (bps) and jitter (secs). The influence of varying
inter-nodal distance on the performance of WSN is determined to select the most appropriate value
of the distance between nodes in particular monitoring application. The patents related to the topology
based analysis of wireless nodes are reconsidered.

Methods:
The placement of nodes and inter-nodal distance significantly influences the operation and
performance of WSNs by diverging the ability of sensors to observe an event of interest and transmission
of information to data aggregation nodes (sink nodes). Moreover, effective sensor placement also
affects the resource management. The investigation of specific regions and habitats has peculiar constraints
of node placement and inter-nodal distance making it highly application specific. In this research
work, the intent is to monitor an entire area to attain optimum coverage to detect the occurrence
of a significant event. The node placement and inter-nodal distance can be classified on the basis of the
role played by the deployed nodes, like, placement of ordinary sensor nodes/Reduced Function Devices
(RFDs) and relay nodes/Full Function Devices (FFDs), respectively. The sensors are compatible with
IEEE 802.15.4/ZigBee protocol and application implemented is Constant Bit Rate (CBR) generator.
This paper analyzed and evaluated the influence of placement and inter-nodal distance of RFDs to the
data aggregation ability of sink node. The terrain area (m2) of different sensor networks deployed are
110×110, 200×200, 300×300, 400×400 and 500×500, respectively. The number of sensor nodes is
constant equal to 100 to evaluate their ability to provide optimum performance. The parameter internodal
distance is varied, keeping all other parameters constant to effectively evaluate its influence. The
simulations are carried out on QualNet 6.1 simulator.

Results:
The variation in inter-nodal distance significantly influences the performance metrics of the
network such as the number of messages received, average end to end delay, throughput and jitter. In
this paper, the distance between sensor nodes and terrain areas of grid topology is varied accordingly to
deduce that which value of the inter-nodal distance and network provides optimum performance. The
thorough evaluation of the simulation results presented that the inter-nodal distance of 30 m and terrain
area of 300×300 m2 has generated optimum performance by providing the highest number of messages
received (208) and highest throughput (2544.34 bps). It is also capable of providing minimum end to
end delay (14.45 secs) and lowest jitter (6.67 secs).

Conclusion:
The objective of this paper to determine the optimum inter-nodal distance and terrain area
of a WSN of 100 nodes is successfully achieved. It is analyzed and evaluated that the inter-nodal distance
of 30 m and terrain area of 300×300 m2 enhance and optimize the network performance significantly.