# ETC: Energy-Driven Tree Construction in Wireless Sensor Networks

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Panayiotis Andreou, Jul 29, 2015 Available from:-
- "Our approach to creating a routing tree with inner-corona balance is motivated by the observation that if every node in the network had the same number of children then the routing tree would be perfectly balanced. This is the idea behind the ETC algorithm proposed by Andreou et al. [18], described in Section 3. The problem is that in a shortest path routing tree constructed over a uniformly distributed network, it is impossible for all nodes to have the same number of children. Macedo analysed the average number of children per parent in such a routing tree and found that the number varies with the corona number [22]. "

##### Article: DECOR: Distributed Construction of Load Balanced Routing Trees for Many to One Sensor Networks

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**ABSTRACT:**Many sensor networks suffer from the energy hole problem which is a special case of load imbalance caused by the funnelling effect of many sensor nodes transmitting their data to a single, central sink. In order to mitigate the problem, a balanced routing tree is often required and this can be constructed with either a centralised or distributed algorithm. Distributed solutions are typically less effective but are significantly cheaper than centralised solutions in terms of communication overhead and they scale better for the same reason. In this paper we propose a novel distributed algorithm for the construction of a load balanced routing tree. Our proposed solution, Degree Constrained Routing, is unique in that it aims to maximise global balance during construction rather that relying on rebalancing an arbitrary tree or only maximising local balance. The underlying principle is that if all nodes adopt the same number of children as each other while the routing tree grows, then the final tree will be globally balanced. Simulation results show that our algorithm can produce trees with improved balance which results in lifetimes increased by up to 80% compared to the next best distributed algorithm.Ad Hoc Networks 05/2014; 16. DOI:10.1016/j.adhoc.2013.12.014 · 1.94 Impact Factor -
- "This happens because our algorithm looks for candidates only in the intersection of its extended floods, whereas GIG looks for candidates inside the whole union of its floods. Below the x-axis the group of [0] [1] [2] [3] [4] candidate is broken down just to show the distribution for our algorithm. "

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**ABSTRACT:**In this paper, we focus the attention on the operator placement problem in Wireless Sensor Networks (WSN). This problem is very relevant for in-network query processing over WSN, where query routing trees are decomposed into three sub-components that must be processed at query time, namely operator tree, operator placement assignment scheme and routing scheme. In particular, the operator placement assignment defines on which node of the network each (query) operator will be hosted and executed. Hence, operator placement plays a key role in the context of query optimization issues in WSN research. In line with this main motivation, in this paper we present an optimal distributed algorithm to adapt the placement of a single operator in high communication cost networks, such as a wireless sensor network. Our parameter-free algorithm finds the optimal node to host the operator with minimum communication cost overhead. Three techniques, proposed here, make this feature possible: (1) identifying the special, and most frequent case, where no flooding is needed, otherwise (2) limitation of the neighborhood to be flooded and (3) variable speed flooding and eves-dropping. When no flooding is needed the communication cost overhead for adapting the operator placement is negligible. In addition, our algorithm does not require any extra communication cost while the query is executed. In our experiments we show that for the rest of cases our algorithm saves 30%–85% of the energy compared to previously proposed techniques. To our knowledge this is the first optimal and distributed algorithm to solve the 1-median (Fermat node) problem. A comprehensive experimental evaluation and the proposal of two solutions that are capable of dealing with adaptive properties of the operator placement problem, which is an innovative perspective of research in this scientific field, represent two further contributions of our research.Journal of Computer and System Sciences 05/2013; 79(3):349–368. DOI:10.1016/j.jcss.2012.09.013 · 1.09 Impact Factor -
- "The resultant tree is called a minimum balanced tree (MBT) and its depth is provably minimal. A different approach is adopted by Andreou et al. [4]. "

##### Conference Paper: Trading latency for load balancing in many-to-one wireless networks

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**ABSTRACT:**Wireless networks that combine a many-to-one traffic flow with multi-hop communication suffer from a funnelling effect that inevitably overburdens nodes closer to the base station. In sensor networks this is known as the energy hole problem. A routing protocol that constructs a shortest path tree exacerbates this problem by leaving some of the most critical nodes with more descendants than others and hence more relaying work to do. In this paper we propose a novel, fully distributed tree construction algorithm for building a load-balanced tree. Our algorithm, Degree Constrained Routing (DECOR), trades off latency for load balancing. We simulated the algorithm using a sensor network as an example. The results show that a small increase in latency, of less than 10%, can be sacrificed for a larger increase in balance of up to 80%. The lifetime of a sensor network using DECOR can be extended by up to 150% compared to the next best algorithm.Wireless Telecommunications Symposium (WTS), 2012; 01/2012