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Wireless Self-adaptive Ad hoc and Sensor Networks: Energy Efficiency and Spatial Reuse

Abstract : The need to maximize network lifetime in wireless ad hoc networks and especially in wireless sensor networks requires the use of energy efficient algorithms and protocols. Motivated by the fact that a node consumes the least energy when its radio is in sleep state, we achieve energy efficiency by scheduling nodes activity. Nodes are assigned time slots during which they can transmit and they can turn off their radio when they are neither ransmitting nor receiving. Compared to classical TDMA-based medium access scheme, spatial bandwidth use is optimized: non interfering nodes are able to share the same time slots, collisions are avoided and overhearing and interferences are reduced. In our work about time slots assignment, two cases are studied. First, when nodes require equal channel access, we use node coloring: Nodes having the same color do not interfere and a color is mapped to a time slot. In this context, we proposed the coloring algorithm OSERENA. Second, when nodes have heterogeneous traffic demands, we designed the traffic aware time slot assignment algorithm TRASA. In this algorithm, any node is assigned a number of slots proportional to its medium access time needs. We show that reducing the number of colors for OSERENA and the number of slots for TRASA increases the amount of energy saved and decreases data transmission delays. Unlike the majority of previous works, we generalize the definition of node coloring and slot allocation problems. Indeed, we set the maximum distance between two interfering nodes as a parameter of these problems. We prove that they are NP-complete, making heuristic approaches inevitable in practice. In addition to the energy resource scarcity, wireless ad hoc and sensor networks have many other constraints. A sensor is a tiny device with small amount of memory and storage space. Also, these networks are prone to the unreliability of wireless communications. That is why, a central directive of this thesis is to design self-adaptive solutions. This adaptivity concerns many aspects such as the mission given by the application, the heterogeneity of node traffic demands, the network density, the regularity of network topology, and the failure of wireless links. More precisely, we made the following contributions: (1) Using a cross layer with the application allows us to define two coloring modes: one adapted to general applications, and the second to data gathering applications. We prove that this adaptation reduces the coloring algorithm overhead. (2) TRASA is defined for data gathering applications while adapting to the heterogeneous numbers of packets to transmit. It allocates to each node a medium access time proportional to its traffic demand. (3) OSERENA scales for dense wireless networks; it uses a message whose size depends neither on the density nor on the number of nodes. Furthermore, compared to an existing coloring algorithm called SERENA, OSERENA reduces the amount of data stored by sensors. (4) We propose VCM, a coloring solution for grid wireless networks. This solution profits from the regularity of this topology and performs a periodic coloring by tiling a color pattern. (5) We enhance the robustness of the known algorithm SERENA to support unreliable links in data gathering applications: after topology changes, nodes can keep their initial colors without creating interferences. All these algorithms and protocols have been implemented and simulated on configurations of wireless networks. Furthermore, we participated in the OCARI project that targets wireless sensor networks in industrial environments. We collaborated to implement and integrate OSERENA in a real testbed of sensors coupled with a new version of the known energy efficient routing protocol EOLSR adapted to data gathering applications.
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https://tel.archives-ouvertes.fr/tel-00808651
Contributor : Ichrak Amdouni <>
Submitted on : Friday, April 5, 2013 - 6:33:37 PM
Last modification on : Wednesday, December 9, 2020 - 3:09:34 PM
Long-term archiving on: : Monday, April 3, 2017 - 1:12:27 AM

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  • HAL Id : tel-00808651, version 1

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Ichrak Amdouni. Wireless Self-adaptive Ad hoc and Sensor Networks: Energy Efficiency and Spatial Reuse. Networking and Internet Architecture [cs.NI]. Université Pierre et Marie Curie - Paris VI, 2013. English. ⟨tel-00808651⟩

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