Energy Efficient Multicast Algorithm for an Ad Hoc Network

In this paper, we propose an energy efficient multicast algorithm for an Ad hoc network. The network is configured by identifying the virtual node and its neighboring nodes to form a Directed Acyclic graph. The non interference links are identified by creating realization Indicator Function. The Scheduling unequal timeshares are computed for non interference links using realization indicator functions. The Network Coding is applied based on the incoming traffic and the different number of source nodes for packet delivery

A Probability Collectives Approach with a Feasibility-Based Rule for Constrained Optimization

This paper demonstrates an attempt to incorporate a simple and generic constraint handling technique to the Probability Collectives (PC) approach for solving constrained optimization problems. The approach of PC optimizes any complex system by decomposing it into smaller subsystems and further treats them in a distributed and decentralized way. These subsystems can be viewed as a Multi-Agent System with rational and self-interested agents optimizing their local goals. However, as there is no inherent constraint handling capability in the PC approach, a real challenge is to take into account constraints and at the same time make the agents work collectively avoiding the tragedy of commons to optimize the global/system objective. At the core of the PC optimization methodology are the concepts of Deterministic Annealing in Statistical Physics, Game Theory and Nash Equilibrium. Moreover, a rule-based procedure is incorporated to handle solutions based on the number of constraints violated and drive the convergence towards feasibility. Two specially developed cases of the Circle Packing Problem with known solutions are solved and the true optimum results are obtained at reasonable computational costs. The proposed algorithm is shown to be sufficiently robust, and strengths and weaknesses of the methodology are also discussed

Protocolo de encaminamiento con diseño intercapa para redes ad hoc inalámbricas

En este trabajo se propone y se evalúa un protocolo de encaminamiento para redes ad hoc que operen bajo el estándar IEEE 802.11. Este protocolo tiene el propósito de mejorar el desempeño de redes que requieren encaminamiento del tipo reactivo. El objetivo principal de esta propuesta es reducir la cantidad de mensajes de señalización que se generan en el proceso de búsqueda de rutas a través de nodos que retransmitan estos mensajes. La propuesta se basa en un diseño intercapa entre la capa de control de acceso al medio (MAC) y la capa de red. Para esto, se utiliza información de la ventana de contienda (que se genera en la capa MAC). Ésta se interpreta en la capa de red como una medida de la congestión que presenta un nodo. De esta forma, es posible identificar los nodos que presentan bajo nivel de ocupación y elegirlos para que retransmitan mensajes de solicitudes de ruta. La elección de estos nodos se realiza utilizando un umbral de decisión. Los resultados encontrados en la evaluación de desempeño del protocolo propuesto muestran que la cantidad de mensajes de señalización generados en el proceso de inundación (es decir, en la búsqueda de rutas) disminuyen considerablemente con respecto al estudio de un caso (AODV), manteniendo el mismo desempeño respecto a la cantidad de datos entregados al nodo destino. La evaluación del desempeño a nivel de la capa MAC mostró que la cantidad de colisiones que se presentan en los nodos disminuye hasta un 50% con respecto al protocolo AODV. También, se evaluó la efectividad del protocolo propuesto para encontrar rutas y se observó que la cantidad de rutas halladas entre un nodo fuente y nodo destino es menor a la que presenta el protocolo AODV. No obstante, la cantidad de paquetes de datos recibidos en el nodo destino no disminuye en gran medida con respecto al protocolo AODV, ya que con el uso del umbral de decisión, la red es capaz de optimizar sus recursos sin necesidad de comprometer la entrega de paquetes de datos entre nodos. A manera de conclusión y como trabajo a futuro se ha determinado que el uso de diferentes umbrales de decisión podría ayudar a una mejora del protocolo propuesto. Además, los diferentes umbrales de decisión se podrían adaptar a las condiciones de tráfico presentes en la red de forma dinámica

A cross-layer optimization framework for multicast in multi-hop wireless networks

Abstract — The optimal and distributed provisioning of high throughput in mesh networks is known as a fundamental but hard problem. The situation is exacerbated in a wireless setting due to the interference among local wireless transmissions. In this paper, we propose a cross-layer optimization framework for throughput maximization in wireless mesh networks, in which the data routing problem and the wireless medium contention problem are jointly optimized for multihop multicast. We show that the throughput maximization problem can be decomposed into two subproblems: a data routing subproblem at the network layer, and a power control subproblem at the physical layer with a set of Lagrangian dual variables coordinating interlayer coupling. Various effective solutions are discussed for each subproblem. We emphasize the network coding technique for multicast routing and a game theoretic method for interference management, for which efficient and distributed solutions are derived and illustrated. Finally, we show that the proposed framework can be extended to take into account physical-layer wireless multicast in mesh networks. Index Terms — Convex optimization, dual decomposition, mesh network, multicast routing, network coding, power allocation, game theory. I

A cross-layer optimization framework for multicast in multi-hop wireless networks

Abstract — Achieving optimal transmission throughput in data networks is known as a fundamental but hard problem. The situation is exacerbated in multi-hop wireless networks due to the interference among local wireless transmissions. In this paper, we propose a general modeling and solution framework for the throughput optimization problem in wireless networks. In our framework, data routing, wireless medium contention and network coding are jointly considered to achieve the optimal network performance. The primal-dual solution method in the framework represents a cross-layer optimization approach. It decomposes the original problem into data routing sub-problems at the network layer, and power allocation sub-problems at the physical layer. Various effective solutions are discussed for each sub-problem, verifying that our framework may handle the throughput optimization problem in an efficient and distributed fashion for a broad range of wireless network scenarios. I

Optimisation de la capacité et de la consommation énergétique dans les réseaux maillés sans fil

Les réseaux maillés sans fil sont une solution efficace, de plus en plus mise en œuvre en tant qu infrastructure, pour interconnecter les stations d accès des réseaux radio. Ces réseaux doivent absorber une croissance très forte du trafic généré par les terminaux de nouvelle génération. Cependant, l augmentation du prix de l énergie, ainsi que les préoccupations écologiques et sanitaires, poussent à s intéresser à la minimisation de la consommation énergétique de ces réseaux. Ces travaux de thèse s inscrivent dans les problématiques d optimisation de la capacité et de la minimisation de la consommation énergétique globale des réseaux radio maillés. Nous définissons la capacité d un réseau comme la quantité de trafic que le réseau peut supporter par unité de temps. Ces travaux s articulent autour de quatre axes. Tout d abord, nous abordons le problème d amélioration de la capacité des réseaux radio maillés de type WIFI où l accès au médium radio se base sur le protocole d accès CSMA/CA. Nous mettons en lumière, les facteurs déterminants qui impactent la capacité du réseau, et l existence d un goulot d étranglement qui limite cette capacité du réseau. Ensuite, nous proposons une architecture de communication basée sur l utilisation conjointe de CSMA/CA et de TDMA afin de résoudre ce problème de goulot d étranglement. Dans la deuxième partie de cette thèse, nous nous intéressons aux réseaux maillés sans fil basés sur un partage des ressources temps-fréquence. Afin de calculer des bornes théoriques sur les performances du réseau, nous développons des modèles d optimisation basés sur la programmation linéaire et la technique de génération de colonnes. Ces modèles d optimisation intègrent un modèle d interférence SINR avec contrôle de puissance continue et variation de taux de transmission. Ils permettent, en particulier, de calculer une configuration optimale du réseau qui maximise la capacité ou minimise la consommation d énergie. Ensuite, dans le troisième axe de recherche, nous étudions en détail le compromis entre la capacité du réseau et la consommation énergétique. Nous mettons en évidence plusieurs résultats d ingénierie nécessaires pour un fonctionnement optimal d un réseau maillé sans fil. Enfin, nous nous focalisons sur les réseaux cellulaires hétérogènes. Nous proposons des outils d optimisation calculant une configuration optimale des stations de base qui maximise la capacité du réseau avec une consommation efficace d énergie. Ensuite, afin d économiser l énergie, nous proposons une heuristique calculant un ordonnancement des stations et leur mise en mode d endormissement partiel selon deux stratégies différentes, nommées LAFS et MAFS.Wireless mesh networks (WMN) are a promising solution to support high data rate and increase the capacity provided to users, e.g. for meeting the requirements of mobile multimedia applications. However, the rapid growth of traffic load generated by the terminals is accompanied by an unsustainable increase of energy consumption, which becomes a hot societal and economical challenges. This thesis relates to the problem of the optimization of network capacity and energy consumption of wireless mesh networks. The network capacity is defined as the maximum achievable total traffic in the network per unit time. This thesis is divided into four main parts. First, we address the problem of improvement of the capacity of 802.11 wireless mesh networks. We highlight some insensible properties and deterministic factors of the capacity, while it is directly related to a bottleneck problem. Then, we propose a joint TDMA/CSMA scheduling strategy for solving the bottleneck issue in the network. Second, we focus on broadband wireless mesh networks based on time-frequency resource management. In order to get theoretical bounds on the network performances, we formulate optimization models based on linear programming and column generation algorithm. These models lead to compute an optimal offline configuration which maximizes the network capacity with low energy consumption. A realistic SINR model of the physical layer allows the nodes to perform continuous power control and use a discrete set of data rates. Third, we use the optimization models to provide practical engineering insights on WMN. We briefly study the tradeoff between network capacity and energy consumption using a realistic physical layer and SINR interference model. Finally, we focus on capacity and energy optimization for heterogeneous cellular networks. We develop, first, optimization tools to calculate an optimal configuration of the network that maximizes the network capacity with low energy consumption. We second propose a heuristic algorithm that calculates a scheduling and partial sleeping of base stations in two different strategies, called LAFS and MAFS.VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF

Integrated Scheduling and Beam Steering for Spatial Reuse

This document describes an approach to integrating antenna selection and control into a time-division MAC scheduling process. I argue that through such integration it is possible to achieve greater spatial reuse and interference mitigation than by solving the two problems separately. Without coupling between the MAC scheduling and physical antenna configuration processes, a \u22chicken-and-egg\u22 problem exists: If antenna decisions are made before scheduling, they cannot be optimized for the communication that will actually occur. If, on the other hand, the scheduling decisions are made first, the scheduler cannot know what the actual interference and communications properties of the network will be. This dissertation presents algorithms for optimal spatial reuse TDMA scheduling with reconfigurable antennas. I present and solve the joint beam steering and scheduling problem for spatial reuse TDMA and describe an implemented system based on the algorithms developed. The algorithms described achieve up to a 600% speedup over TDMA in the experiments performed. This is based on using an optimization decomposition approach to arrive at a working distributed protocol which is equivalent to the original problem statement while also producing optimal solutions in an amount of time that is at worst linear in the size of the input. This is, to the best of my knowledge, the first actually implemented STDMA scheduling system based on dual decomposition. This dissertation identifies and briefly address some of the challenges that arise in taking such a system from theory to reality