Minimum power multicasting with delay bound constraints in Ad Hoc wireless networks

In this paper, we design a new heuristic for an important extension of the minimum power multicasting problem in ad hoc wireless networks. Assuming that each transmission takes a fixed amount of time, we impose constraints on the number of hops allowed to reach the destination nodes in the multicasting application. This setting would be applicable in time critical or real time applications, and the relative importance of the nodes may be indicated by these delay bounds. We design a filtered beam search procedure for solving this problem. The performance of our algorithm is demonstrated on numerous test cases by benchmarking it against an optimal algorithm in small problem instances, and against a modified version of the well-known Broadcast Incremental Power (BIP) algorithm 20 for relatively large problems

Genetic Algorithm for Effective Optimization of Delay Performance in Wireless Sensor Networks

شبكات الاستشعار اللاسلكية (WSNs) تلعب دورا هاما في العديد من التطبيقات في العالم الحقيقي مثل المراقبة. وتستخدم الشبكات اللاسلكية أيضا لنقل البيانات. في مثل هذه الحالات، هناك مشاكل مع شبكات محدودة الموارد. وتشمل هذه المشاكل التأخير في الاتصال وتقليل جودة الخدمة(QoS). توبولوجيا السيطرة يمكن أن تحل هذه المشكلة إلى حد ما. التأخير في الاداء و QoS  يحتاج إلى مزيد من التحسين لدعم العمليات المقصودة في الشبكات اللاسلكية.  وعند النظر في مفهوم عقدة التأخير من الممكن تحسين الأداء في مثل هذه الشبكات. في هذه الورقة اقترحنا تكوين التاخير قائم على الخوارزمية الجينية (GA) لتحسين أداء التأخير في WSN. وتحسب عقد التتابع المواضع المثلى باستخدام الخوارزمية المقترحة من أجل تحسين نوعية الخدمة وتقليل التأخير قدر الإمكان. نفذنا الخوارزمية باستخدام المحاكاة NS2. وكشفت النتائج أن النهج المقترح قادر على تحسين جودة الخدمة، والحد من التأخير إلى جانب تحسين أداء الشبكة من حيث الإنتاجية، وقدرة الشبكة وكفاءة الطاقة.Wireless sensor networks (WSNs) play an important role in many real-world applications like surveillance. Wireless networks are also used to have data transfer. In such cases, there are problems with  resourcece-constraintnednetworks. The problems include a delay in communication and reduction in Quality of Service (QoS). Topology control can solve this problem to some extent. However, the delay performance and QoS need to be improved further to support intended operations in wireless networks. When relay node concept is considered, it is possible to optimize performance in such networks. In this paper, we proposed a Genetic Algorithm (GA) based relay configuration for optimizing delay performance in WSN. Relay nodes compute optimal positions using the proposed algorithm so as to improve QoS and reduce delay as much as possible. We implemented the algorithm using NS2 simulations. The results revealed that the proposed approach is able to improve QoS, reduce delay besides improving network performance in terms of throughput, network capacity, and energy efficiency

Topology Control in Cooperative Ad Hoc Wireless Networks

AbstractCooperative communication (CC) is a technique that exploits spatial diversity allowing multiple nodes to cooperatively relay signals to the receiver so that it can combine the received signals to obtain the original message. CC can be combined with topology control to increase connectivity at the cost of a small increase in energy consumption. This work focuses on exploring CC to improve the connectivity with a sink node in ad hoc wireless networks. More precisely, this work proposes a new technique, named CoopSink, that combines CC and topology control techniques to increase connectivity to a sink node while ensuring energy-efficient routes. Simulation results show that connectivity and routing to the sink cost can be improved up to 6.8 and 2.3 times, respectively, when compared with other similar strategies

Flow Aggregation for Energy-Aware Ad-Hoc Wireless Networks Respecting QoS Provisions, Journal of Telecommunications and Information Technology, 2020, nr 1

Emerging communication technologies are now leading developers to design IT systems taking into count their energy-related considerations. Much research performed in the area of ad-hoc wireless networks tends to distribute the flows over all nodes of the network, which increases the amount of energy consumed by each node and reduces longevity of the network. To overcome these problems, this paper seeks to aggregate a set of flows within a number of nodes that is as low as possible in order to be capable of routing those flows. This proposal allows to maximize the number of network nodes that may be turned off. The proposed solution was formulated as an integer linear programming (ILP) problem using a set of energy and quality of service (QoS) constraints. This formulation minimizes the total energy consumed by the nodes to construct a topology network that is capable of meeting QoS requirement for a set flows inserted into the network. To evaluate the efficiency of the proposed model, a performance-based comparison was conducted with another routing model. The simulation results show that the proposed model offers better performance in terms of global energy consumption and network loa

QoS Routing in Wireless Mesh Networks

Wireless Mesh Networking is envisioned as an economically viable paradigm and a promising technology in providing wireless broadband services. The wireless mesh backbone consists of fixed mesh routers that interconnect different mesh clients to themselves and to the wireline backbone network. In order to approach the wireline servicing level and provide same or near QoS guarantees to different traffic flows, the wireless mesh backbone should be quality-of-service (QoS) aware. A key factor in designing protocols for a wireless mesh network (WMN) is to exploit its distinct characteristics, mainly immobility of mesh routers and less-constrained power consumption. In this work, we study the effect of varying the transmission power to achieve the required signal-to-interference noise ratio for each link and, at the same time, to maximize the number of simultaneously active links. We propose a QoS-aware routing framework by using transmission power control. The framework addresses both the link scheduling and QoS routing problems with a cross-layer design taking into consideration the spatial reuse of the network bandwidth. We formulate an optimization problem to find the optimal link schedule and use it as a fitness function in a genetic algorithm to find candidate routes. Using computer simulations, we show that by optimal power allocation the QoS constraints for the different traffic flows are met with more efficient bandwidth utilization than the minimum power allocations

Variable power transmission in highly Mobile Ad-Hoc Networks

Mobile Ad Hoc Networks pose challenges in terms of power control, due to their fixed transmission power, the mobility of nodes and a constantly changing topology. High levels of power are needed in wireless networks, particularly for routing. As a result of the increase in the number of communication devices being used, there is the challenge of increased density within these networks, and a need to extend the battery life of communication devices. In order to address this challenge, this thesis presents the development of a new protocol (Dynamic Power AODV), which is an enhancement of the Ad Hoc On Demand Distance Vector (AODV) protocol. The new protocol dynamically adjusts the transmission power based on the range, which depends on node density. This thesis provides a systematic evaluation of the performance of DP-AODV, in a high speed and high density environment, in comparison with three other routing protocols. The experiments demonstrated that DP-AODV performed better than two of the protocols in all scenarios. As compared to the third protocol (AOMDV), DP-AODV gave better performance results for throughput and Power Consumption, but AOMDV performed better in terms of Packet Delivery Fraction rate and End-to-End Delay in some cases

Conception des réseaux maillés sans fil à multiples-radios multiples-canaux

Généralement, les problèmes de conception de réseaux consistent à sélectionner les arcs et les sommets d’un graphe G de sorte que la fonction coût est optimisée et l’ensemble de contraintes impliquant les liens et les sommets dans G sont respectées. Une modification dans le critère d’optimisation et/ou dans l’ensemble de contraintes mène à une nouvelle représentation d’un problème différent. Dans cette thèse, nous nous intéressons au problème de conception d’infrastructure de réseaux maillés sans fil (WMN- Wireless Mesh Network en Anglais) où nous montrons que la conception de tels réseaux se transforme d’un problème d’optimisation standard (la fonction coût est optimisée) à un problème d’optimisation à plusieurs objectifs, pour tenir en compte de nombreux aspects, souvent contradictoires, mais néanmoins incontournables dans la réalité. Cette thèse, composée de trois volets, propose de nouveaux modèles et algorithmes pour la conception de WMNs où rien n’est connu à l’ avance. Le premiervolet est consacré à l’optimisation simultanée de deux objectifs équitablement importants : le coût et la performance du réseau en termes de débit. Trois modèles bi-objectifs qui se différent principalement par l’approche utilisée pour maximiser la performance du réseau sont proposés, résolus et comparés. Le deuxième volet traite le problème de placement de passerelles vu son impact sur la performance et l’extensibilité du réseau. La notion de contraintes de sauts (hop constraints) est introduite dans la conception du réseau pour limiter le délai de transmission. Un nouvel algorithme basé sur une approche de groupage est proposé afin de trouver les positions stratégiques des passerelles qui favorisent l’extensibilité du réseau et augmentent sa performance sans augmenter considérablement le coût total de son installation. Le dernier volet adresse le problème de fiabilité du réseau dans la présence de pannes simples. Prévoir l’installation des composants redondants lors de la phase de conception peut garantir des communications fiables, mais au détriment du coût et de la performance du réseau. Un nouvel algorithme, basé sur l’approche théorique de décomposition en oreilles afin d’installer le minimum nombre de routeurs additionnels pour tolérer les pannes simples, est développé. Afin de résoudre les modèles proposés pour des réseaux de taille réelle, un algorithme évolutionnaire (méta-heuristique), inspiré de la nature, est développé. Finalement, les méthodes et modèles proposés on été évalués par des simulations empiriques et d’événements discrets.Generally, network design problems consist of selecting links and vertices of a graph G so that a cost function is optimized and all constraints involving links and the vertices in G are met. A change in the criterion of optimization and/or the set of constraints leads to a new representation of a different problem. In this thesis, we consider the problem of designing infrastructure Wireless Mesh Networks (WMNs) where we show that the design of such networks becomes an optimization problem with multiple objectives instead of a standard optimization problem (a cost function is optimized) to take into account many aspects, often contradictory, but nevertheless essential in the reality. This thesis, composed of three parts, introduces new models and algorithms for designing WMNs from scratch. The first part is devoted to the simultaneous optimization of two equally important objectives: cost and network performance in terms of throughput. Three bi-objective models which differ mainly by the approach used to maximize network performance are proposed, solved and compared. The second part deals with the problem of gateways placement, given its impact on network performance and scalability. The concept of hop constraints is introduced into the network design to reduce the transmission delay. A novel algorithm based on a clustering approach is also proposed to find the strategic positions of gateways that support network scalability and increase its performance without significantly increasing the cost of installation. The final section addresses the problem of reliability in the presence of single failures. Allowing the installation of redundant components in the design phase can ensure reliable communications, but at the expense of cost and network performance. A new algorithm is developed based on the theoretical approach of "ear decomposition" to install the minimum number of additional routers to tolerate single failures. In order to solve the proposed models for real-size networks, an evolutionary algorithm (meta-heuristics), inspired from nature, is developed. Finally, the proposed models and methods have been evaluated through empirical and discrete events based simulations