Faculty Publications
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Item Approximation algorithm for receiver interference problem in dual power Wireless Sensor Networks(Springer Verlag service@springer.de, 2019) Shetty D, D.; Lakshmi, M.P.The problem of assigning power levels to the nodes of a wireless sensor network from a given a set of two power levels is called Dual power management problem and the underlying network is called Dual power network. We consider the problem of minimizing the maximum receiver interference of such a network. The interference disrupts the communication and forces the data packets to be retransmitted. The motivation is to conserve the energy by minimizing the interference and maintaining the connectivity of the dual power network. Receiver interference problem is proved to be NP-hard. In this paper, an approximation algorithm is derived for minimizing the maximum receiver interference of a dual power network by utilizing the approximation algorithm for Dual Power Management Problem. The proposed algorithm is supported by the simulation results. We term this problem as Dual Power Receiver Interference Problem and show that it is NP-complete using a polynomial time reduction from Degree Constrained Minimum Spanning Tree problem. We also prove the NP-completeness of Dual Power Management Problem by a polynomial reduction from Vertex Cover Problem. © 2019, Korean Society for Computational and Applied Mathematics.Item Optimal algorithm for minimizing interference with two power levels in wireless sensor networks(Engineering and Technology Publishing, 2019) Lakshmi, M.P.; Shetty D, D.Interference is a major hindrance to the communication in wireless sensor networks which needs to be optimized in order to minimize the total power consumption of the network. A sensor node in a WSN is assigned certain transmission range for sensing and transmission of data. If the transmission between any two nodes is affected by a third node, then it leads to interference. Sender interference of a node in WSN is the number of nodes that lie within the transmission range of that vertex. The receiver interference of a node x is the number of other nodes which include x in their transmission range. In recent days WSNs are operated by a discrete set of power levels in which a limited number of power levels are available which can be assigned to a node. The problem of minimizing the maximum sender interference of a WSN using only two power levels is studied in this paper. An optimal algorithm is presented in this paper which assigns transmission power to the sensor nodes of a given network such that the maximum sender interference is minimized and it results in a connected topology. An algorithm for receiver interference is also proposed using a similar concept, and an extensive simulation is performed to compare the maximum sender and receiver interference for the same instances. © 2019 Journal of Communications.Item Approximation algorithms for minimum power k backbone node r-connected subgraph problem in wireless sensor networks(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2020) Shetty D, P.; Lakshmi, M.P.The minimum power assignment problem in a Wireless Sensor Network (WSN) is to assign transmission range to the nodes of the network with specified connectivity constraints minimizing the total power. This problem is termed as Strong Minimum Energy Topology (SMET) problem. Fault tolerance addresses the issue of a node or link failure in a WSN. So, with an objective of achieving high connectivity, we consider SMET problem with an additional property, i.e., the resultant network must satisfy the property of two or high connectivity. Minimum Power r-Connected Subgraph (MPrCS) problem is to contrive an r-connected network with minimum power. Minimum Power 2-Connected Subgraph (MP2CS) problem is proved to be NP-hard. Minimum Power k Backbone node r-Connected Subgraph (MPkBrCS) problem is a special case of MPrCS problem, which seeks a power assignment satisfying r-connectivity with k backbone nodes. We study MPkBrCS problem for k backbone nodes, r-connectivity and derive the approximation ratios. We also propose an algorithm of approximation ratio n+2 2, for Minimum Power k Backbone node 3-Connected Subgraph (MPkB3CS) problem for k = 2 that runs in O(n4) time and generalize for the case r = k + 1 for any k and r. © 2020 World Scientific Publishing Company.