Simulation Based Topology Optimization in Wireless Sensor Network

Abstract

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.