Topology Control Algorithm considering Antenna Radiation Pattern in Three-Dimensional Wireless Sensor Networks

Topology control is a key issue of wireless sensor network to reduce energy consumption and communication collision. Topology control algorithms in three-dimensional space have been proposed by modifying existing two-dimensional algorithms. These algorithms are based on the theoretical assumption that transmission power is radiated equally to the all directions by using isotropic antenna model. However, isotropic antenna does not exist, which is hypothetical antenna to compare the real antenna performance. In the real network, dipole antenna is applied, and because of the radiation pattern, performance of topology control algorithm is degraded. We proposed local remapping algorithm to solve the problem and applied it to existing topology control algorithms. Simulation results show that our algorithm increases performance of existing algorithms and reduces power consumption

A Simple Proof of the Entropy Inequality

The purpose of this is to give a simple proof to the entropy inequality. In order to do so, a simple lemma is states, then the inequality is proved

Self Organization and Self Maintenance of Mobile Ad Hoc Networks through Dynamic Topology Control

One way in which wireless nodes can organize themselves into anad hoc network is to execute a topology control protocol, which is designed to build a network satisfying specific properties. A number of basic topology control protocols exist and have been extensively analyzed. Unfortunately, most of these protocols are designed primarily for static networks and the protocol designerssimply advise that the protocols should be repeated periodically to deal with failures, mobility, and other sources of dynamism. However, continuously maintaining a network topology with basic connectivity properties is a fundamental requirement for overall network dependability. Current approaches consider failures only as an afterthought or take a static fault tolerance approach, which results in extremely high energy usage and low hroughput. In addition, most of the existing topology control protocols assume that transmission poweris a continuous variable and, therefore, nodes can choose an arbitrary power value between some minimum and maximum powers. However, wireless network interfaces with dynamic transmission power control permit the power to be set to oneof a discrete number of possible values. This simple restriction complicates the design of the topology control protocol substantially. In this paper, we present a set of topology control protocols, which work with discrete power levels and forwhich we specify a version that deals specifically with dynamic networks that experience failures, mobility, and other dynamic conditions. Our protocols are also novel in the sense that they are the first to consider explicit coordination betweenneighboring nodes, which results in more efficient power settings. In this paper, we present the design of these topology control protocols, and we report on extensive simulations to evaluate them and compare their performance against existing protocols. The results demonstrate that our protocols produce very similartopologies as the best protocols that assume power is a continuous variable, while having very low communication cost and seamlessly handling failures and mobility

Power optimization for connectivity problems

Abstract. Given a graph with costs on the edges, the power of a node is the maximum cost of an edge leaving it, and the power of the graph is the sum of the powers of the nodes of this graph. Motivated by applications in wireless multi-hop networks, we consider four fundamental problems under the power minimization criteria: the Min-Power b-Edge-Cover problem (MPb-EC) where the goal is to find a min-power subgraph so that thedegreeofeverynodev is at least some given integer b(v), the Min-Power k-node Connected Spanning Subgraph problem (MPk-CSS), Min-Power k-edge Connected Spanning Subgraph problem (MPk-ECSS), and finally the Min-Power k-Edge-Disjoint Paths problem in directed graphs (MPk-EDP). We give an O(log 4 n)-approximation algorithm for MPb-EC. This gives an O(log 4 n)-approximation algorithm for MPk-CSS for most values of k, improving the best previously known O(k)-approximation guarantee. In contrast, we obtain an O ( √ n) approximation algorithm for MPk-ECSS, and for its variant in directed graphs (i.e., MPk-EDP), we establish the following inapproximability threshold: MPk-EDP cannot be approximated within O(2 log1−ε n) for any fixed ε>0, unless NP-hard problems can be solved in quasi-polynomial time.