Joint routing, gateway selection, scheduling and power management optimization in wireless mesh networks

Ankara : The Department of Industrial Engineering and the Graduate School of Engineering and Science of Bilkent University, 2011.Thesis (Master's) -- Bilkent University, 2011.Includes bibliographical references leaves 57-58.The third generation (3G) wireless communications technology delivers user traffic in a single step to the wired network via base station; therefore it requires all base stations to be connected to the wired network. On the other hand, in the fourth generation (4G) communication systems, it is planned to have the base stations set up so that they can deliver each other’s traffic to a small number of base stations equipped with wired connections. In order to improve system resiliency against failures, a mesh structure is preferred. The most important issue in Wireless Mesh Networks (WMN) is that the signals that are simultaneously transmitted on the same frequency channel can interfere with each other to become incomprehensible at the receiver end. It is possible to operate the links at different times or at different frequencies, but this also lowers capacity usage. In this thesis, we tackle the planning problems of WMN, using 802.16 (Wi-MAX) protocol, such as deploying a given number of gateway nodes along with operational problems such as routing, management of power used by nodes and scheduling while maximizing the minimum service level provided. The WMN under consideration has identical routers with fixed locations and the demand of each router is known. In order to be able to apply our results to real systems, we work with optimization models based on realistic assumptions such as physical interference and single path routing. We propose heuristic methods to obtain optimal or near optimal solutions in reasonable time. The models are applied to some cities in Istanbul and Ankara provinces.Uzunlar, OnurM.S

Point-to-Point Traffic in Wireless Mesh Networks

Although most work on Wireless Mesh Networks (WMNs) has focused on traffic flowing in and out of the network via gateways, traffic within the WMN may also be significant in many environments. This point-to-point (P2P) traffic between the nodes within WMN can be handled in different ways, particularly in WMNs containing multiple gateways. The approach used affects the performance of both the P2P flows and other traffic in the network. This work studies the impact of handling P2P traffic in the presence of gateways and gateway traffic. Through mathematical analysis of the resulting traffic patterns, along with extensive simulations, the need to route P2P traffic appropriately is demonstrated. While direct routing yields considerable performance improvements in small networks, it can actually decrease capacity in larger networks. Consequently, we extend the Hybrid Wireless Mesh Protocol (HWMP) proposed in IEEE 802.11s by adding two new message types to obtain more information useful for choosing the best route. Through simulations on different networks, HWMP shows better average delivery ratio and end-to-end delay than the original gateway-based and the P2P routing mechanisms in the simulation settings

Efficient Use of Partially Overlapping Channels in WMNs

There has been growing interest in using Wireless Mesh Networks (WMNs) because of their advantages such as easier to scale up and self-organization. We instigate whether increasing the number of available channels through the use of Partially Overlapping Channels (POCs) is always useful for improving the Quality of Service (QoS) of WMNs namely the throughput or delay. For the purpose of this thesis, we design a set of algorithms for: i) Channel assignment; ii) Transmission Configurations (TCs) which is a set of links with the ability of sending data simultaneously; iii) power control; and iv) delivery of packets to their destination in order to take advantage of POCs in WMNs. We evaluate our proposed algorithms by a comprehensive set of numerical experiments. Numerical experiments indicate that using POCs leads not only to increase throughput of networks, but also it can decrease delay of packet delivery

Radio Planning and Management of Energy-Efficient Wireless Access Networks

RÉSUMÉ Dans les dernières années, le secteur des Technologies de l'Information et de la Communication (TIC) a transformé la façon dont nous vivons: il joue un rôle principal sur le développement économique et la productivité, en offrant des services innovants qui sont devenus partie intégrante de la vie quotidienne. En raison de ce phénomène, l'effet des technologies de l'information et de la communication sur le réchauffement climatique ne peut plus être ignoré. Le concept des TIC Vertes (ou Green ICT, en anglais) est né dans le but de stimuler la recherche vers des solutions respectueuses de l'environnement et économes en énergie. Étant une partie important des TIC, les réseaux de télécommunication connaissent une croissance en plein essor. Les contraintes de qualité de service et de capacité sont les principaux responsables de l'augmentation de la consommation d'énergie; en particulier, une grande partie de la facture d'électricité des opérateurs de réseaux est due aux exigences élevées de puissance des stations de base sans fil, qui ont été identifiées comme les composantes les plus énergivores des réseaux. Jusqu'à présent, l'industrie de la communication mobile s'est essentiellement concentrée sur le développement de terminaux mobiles à faible consommation d'énergie afin d'attirer un plus grand nombre de clients et, par conséquent, d'augmenter les profits des opérateurs; en revanche, le monde de la recherche étudie la question de l'efficacité énergétique d'un point de vue plus large. En plus des études sur dispositifs et protocoles économes en puissance, des travaux plus récents ont abordé la problème du design et du fonctionnement éco-énergétiques dans les infrastructures de réseaux câblés et sans fil. De nombreux aspects de la planification et gestion des réseaux verts ont été explorés. Cependant, les deux problèmes n'ont jamais été liés et abordés à la fois, en négligeant le fait que l'efficacité d'une gestion de réseau à faible consommation d'énergie dépend en grande partie des décisions prises dans la phase de design.----------ABSTRACT In the last years, the ICT sector has transformed the way we live. Consistently delivering innovative products and services, the ICT assumed a primary role on economic development and productivity, becoming an integral part of everyday life. However, due to their wide and constantly increasing diffusion, the effect of information and communication technologies on global warming can no longer be ignored. The concept of Green ICT has originated with the aim of building awareness of this, thus boosting the research toward environmentally sustainable, energy-efficient technologies and solutions. As an important part of the ICT, telecommunication networks are experiencing a booming growth. Capacity issues and quality of service constraints are some of the main concerns that contribute to raise the power consumption. In particular, a large portion of the electricity bill results from the high power requirements of wireless base stations, which have been proved to be the most energy-hungry network components. Up to now, the mobile communication industry has focused mostly on the development of power-efficient mobile terminals, so as to attract a higher number of customers and consequently increase the operators' profits; on the other hand, the research world has been investigating energy efficiency from a wider point of view. Besides studies on power-efficient devices and protocols, more recent works addressed the problem of energy-aware design and operation in wired and wireless network infrastructures. Many aspects and challenges of green network planning and management have been explored; nevertheless, the two problems have never been linked and tackled at the same time, neglecting the fact that an effective power-efficient network operation largely depends on the decisions taken in the design phase. The research presented in this doctoral thesis aims at filling this gap by developing an optimization framework that jointly considers the design and operation of wireless networks. The proposed joint planning and energy management problem (JPEM) strives to prove that, when cell sleeping is adopted as network management technique, the level of flexibility offered by the installed topology strongly improves the system capability to adapt to the varying traffic load. By minimizing the trade-off between capital expenditures (CapEx) related to the network deployment and operational expenditures (OpEx) calculated over the network lifetime, the model finds the most energy-efficient network topology while meeting the capital investment limitations imposed by the mobile operator