Browsing by Subject "Network lifetime improvement"
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Item Open Access Coordinated movement of multiple mobile sinks in a wireless sensor network for improved lifetime(SpringerOpen, 2015) Koç, M.; Korpeoglu, I.Sink mobility is one of the most effective solutions for improving lifetime and has been widely investigated for the last decade. Algorithms for single-sink mobility are not directly applied to the multiple-sink case due to the latter’s specific challenges. Most of the approaches proposed in the literature use mathematical programming techniques to solve the multiple-sink mobility problem. However, doing so leads to higher complexities when traffic flow information for any possible sink-site combinations is included in the model. In this paper, we propose two algorithms that do not consider all possible sink-site combinations to determine migration points. We first present a centralized movement algorithm that uses an energy-cost matrix for a user-defined threshold number of combinations to coordinate multiple-sink movement. We also give a distributed algorithm that does not use any prior network information and has a low message exchange overhead. Our simulations show that the centralized algorithm gives better network lifetime performance compared to previously proposed MinDiff-RE, random movement, and static-sink algorithms. Our distributed algorithm has a lower network lifetime than centralized algorithms; sinks travel significantly less than in all the other schemes.Item Open Access Energy-efficient sink mobility algorithms for wireless sensor networks(Bilkent University, 2015-09) Koç, MetinA wireless sensor network consists of a large number of tiny sensor nodes which are capable of sensing an environment and sending the collected data to a sink node. For most scenarios, sensor nodes are powered with irreplaceable batteries and this dramatically limits the lifetime of the network, especially due to overloading of the sensor nodes neighboring sink node. Such nodes need to forward more traffic than other nodes in the network. Moving sink node and in this way distributing forwarding-load evenly among sensor nodes is one of the important techniques for improving lifetime of sensor networks. We propose different mobility algorithms for single-sink and multiple-sink mobility problem to efficiently move sink nodes through a predefined set of sink sites. We first provide packet-load and energy-load based sink mobility algorithms, called PLMA and ELMA, in which node-load parameters are incorporated into a table and this table is used to determine which sink site to visit in each round. We also give an integer programming model to get optimal results and do benchmarking. Since routing topology is an important component of sink mobility schemes, we also propose centralized and distributed routing topology construction algorithms to further increase network lifetime. Additionally, we propose an adaptive energy-load based sink movement algorithm, called A-ELMA, which does not require an initial training phase to learn about network topology. It incrementally constructs and updates energy-load table each time it visits a site location. Finally, besides proposing algorithms for single-sink mobility problem, we also propose two different algorithms for multiple-sink mobility problem. Our Multiple Sink Movement Algorithm (MSMA) is a centralized algorithm and effectively limits the sink site combinations to reduce computation and communication overhead in scheduling sink movements without harming network lifetime significantly. Our Prevent and Move Away (PMA) algorithm is a fully distributed algorithm and does not require topology information to be collected. It selects sites based on remaining energy values and distance metrics. We evaluated our algorithms and compared them to some basic approaches in the literature by conducting extensive simulation experiments. Our simulation results show that our algorithms can perform better than some other alternatives in terms of network lifetime, latency and travel distance. We also identify under which conditions our algorithms perform better for each of these metrics. We observed that our algorithms provide simple-to-use, efficient, and effective solutions for single- and multiple-sink mobility problems in wireless sensor networks.Item Open Access Traffic-and energy-load-based sink mobility algorithms for wireless sensor networks(Inderscience Enterprises Ltd., 2017) Koç M.; Korpeoglu, I.Moving the sink node is an effective solution for improving the lifetime of wireless sensor networks (WSNs). This paper provides another solution to the sink mobility problem in WSNs by incorporating node-load parameters into a matrix based on alternative sink positions and using this matrix to determine the next sink site to visit in each round.We first present a packet-load based sink movement algorithm that considers how many packets each node would receive and transmit for each different sink position. We extend this algorithm by also considering the distances the packets are transmitted, and in this manner obtain an energy-load based algorithm. We also provide an integer programming (IP) model to compute the optimal results. Our extensive simulations show that our packet-and energy-load based algorithms significantly improve network lifetime without introducing much overhead and only remain around 5% behind the optimal solution. Copyright © 2017 Inderscience Enterprises Ltd.