Price-Based Optimal Resource Allocation in Multi-Hop Wireless Networks

Recent advances in wireless communications and digital electronics have enabled rapid development of a variety of wireless network technologies. The undeniable popularity of wireless network is due to its ubiquity and convenience, which is appreciated by the users. In this dissertation, we study the problem of resource allocation in multihop wireless networks (so called ad hoc networks). A wireless ad hoc network consists of a collection of wireless nodes without a fixed infrastructure. Two wireless nodes communicate with each other directly, if they are within the transmission range of each other. Otherwise, the communication is achieved through the relays of intermediate nodes. Compared with traditional wireline networks, the unique characteristics of wireless networks pose fundamental challenges to the design of effective resource allocation algorithms that are optimal with respect to resource utilization and fair across different network flows. Particularly, the following issues of wireless networks need fresh treatment: (1) Interference of wireless communication. Flows not only contend at the same node (contention in the time domain), but also compete for shared channel if they are within the interference ranges of each other (contention in the spatial domain). (2) Multiple resource usage. Sending data from one wireless node to another needs to consume multiple resources, most notably wireless bandwidth and battery energy. (3) Autonomous communication entities. The wireless nodes usually belong to different autonomous entities. They may lack the incentive to contribute to the network functionality in a cooperative way. (4) Rate diversity. Wireless nodes can adaptively change the transmission bit rate based on perceived channel conditions. This leads to a wireless network with rate diversity, where competing flows within the interference range transmit at different rates. None of the existing resource allocation algorithms in wireless ad hoc networks have realistically considered end-to-end flows spanning multiple hops. Moreover, strategies proposed for wireline networks are not applicable in the context of wireless ad hoc network, due to its unique characteristics. In this dissertation, we propose a new price-based resource allocation framework in wireless ad hoc networks to achieve optimal resource utilization and fairness among competing end-to-end flows. We build our pricing framework on the notion of maximal cliques in wireless ad hoc networks, as compared to individual links in traditional wide-area wireline networks. Based on such a price-based theoretical framework, we present a two-tier iterative algorithm. Distributed across wireless nodes, the algorithm converges to a global network optimum with respect to resource allocations. Further, we present a price pair mechanism to coordinate multiple resource allocations, and to provide incentives simultaneously such that cooperation is promoted and the desired global optimal network operating point is reached by convergence with a fully decentralized self-optimizing algorithm. Such desired network-wide global optimum is characterized with the concept of Nash bargaining solution, which not only provides the Pareto optimal point for the network, but is also consistent with the fairness axioms of game theory. Finally, we present a channel aware price generation scheme to decompose the bit rate adjustment and the flow rate allocation. The allocation result achieves channel time fairness where user fairness and channel utilization is balanced. The major achievements of this dissertation are outlined as follows. It models a system-wide optimal operation point of a wireless network, and outlines the solution space of resource allocation in a multihop wireless network; It presents a price-based distributed resource allocation algorithm to achieve this global optimal point; It presents a low overhead implementation of the price-based resource allocation algorithm; It presents an incentive mechanism that enables the resource allocation algorithm when users are selfish

Contributions to Wireless multi-hop networks : Quality of Services and Security concerns

Ce document résume mes travaux de recherche conduits au cours de ces 6 dernières années. Le principal sujet de recherche de mes contributions est la conception et l’évaluation des solutions pour les réseaux sans fil multi-sauts en particulier les réseaux mobiles adhoc (MANETs), les réseaux véhiculaires ad hoc (VANETs), et les réseaux de capteurs sans fil (WSNs). La question clé de mes travaux de recherche est la suivante : « comment assurer un transport des données e cace en termes de qualité de services (QoS), de ressources énergétiques, et de sécurité dans les réseaux sans fil multi-sauts? » Pour répondre à cette question, j’ai travaillé en particulier sur les couches MAC et réseau et utilisé une approche inter-couches.Les réseaux sans fil multi-sauts présentent plusieurs problèmes liés à la gestion des ressources et au transport des données capable de supporter un grand nombre de nœuds, et d’assurer un haut niveau de qualité de service et de sécurité.Dans les réseaux MANETs, l’absence d’infrastructure ne permet pas d’utiliser l’approche centralisée pour gérer le partage des ressources, comme l’accès au canal.Contrairement au WLAN (réseau sans fil avec infrastructure), dans les réseaux Ad hoc les nœuds voisins deviennent concurrents et il est di cile d’assurer l’équité et l’optimisation du débit. La norme IEEE802.11 ne prend pas en compte l’équité entre les nœuds dans le contexte des MANETs. Bien que cette norme propose di érents niveaux de transmission, elle ne précise pas comment allouer ces débits de manière e cace. En outre, les MANETs sont basés sur le concept de la coopération entre les nœuds pour former et gérer un réseau. Le manque de coopération entre les nœuds signifie l’absence de tout le réseau. C’est pourquoi, il est primordial de trouver des solutions pour les nœuds non-coopératifs ou égoïstes. Enfin, la communication sans fil multi-sauts peut participer à l’augmentation de la couverture radio. Les nœuds de bordure doivent coopérer pour transmettre les paquets des nœuds voisins qui se trouvent en dehors de la zone de couverture de la station de base.Dans les réseaux VANETs, la dissémination des données pour les applications de sureté est un vrai défi. Pour assurer une distribution rapide et globale des informations, la méthode de transmission utilisée est la di usion. Cette méthode présente plusieurs inconvénients : perte massive des données due aux collisions, absence de confirmation de réception des paquets, non maîtrise du délai de transmission, et redondance de l’information. De plus, les applications de sureté transmettent des informations critiques, dont la fiabilité et l’authenticité doivent être assurées.Dans les réseaux WSNs, la limitation des ressources (bande passante, mémoire, énergie, et capacité de calcul), ainsi que le lien sans fil et la mobilité rendent la conception d’un protocole de communication e cace di cile. Certaines applications nécessitent un taux important de ressources (débit, énergie, etc) ainsi que des services de sécurité, comme la confidentialité et l’intégrité des données et l’authentification mutuelle. Ces paramètres sont opposés et leur conciliation est un véritable défi. De plus, pour transmettre de l’information, certaines applications ont besoin de connaître la position des nœuds dans le réseau. Les techniques de localisation sou rent d’un manque de précision en particulier dans un environnement fermé (indoor), et ne permettent pas de localiser les nœuds dans un intervalle de temps limité. Enfin, la localisation des nœuds est nécessaire pour assurer le suivi d’objet communicant ou non. Le suivi d’objet est un processus gourmand en énergie, et requiert de la précision.Pour répondre à ces défis, nous avons proposé et évalué des solutions, présentées de la manière suivante : l’ensemble des contributions dédiées aux réseaux MANETs est présenté dans le deuxième chapitre. Le troisième chapitre décrit les solutions apportées dans le cadre des réseaux VANETs. Enfin, les contributions liées aux réseaux WSNs sont présentées dans le quatrième chapitre

Energy efficient offloading techniques for heterogeneous networks

Mobile data offloading has been proposed as a solution for the network congestion problem that is continuously aggravating due to the increase in mobile data demand. The concept of offloading refers to the exploitation of network heterogeneity with the objective to mitigate the load of the cellular network infrastructure. In this thesis a multicast protocol for short range networks that exploits the characteristics of physical layer network coding is presented. In the proposed protocol, named CooPNC, a novel cooperative approach is provided that allows collision resolutions with the use of an indirect inter-network cooperation scheme. Through this scheme, a reliable multicast protocol for partially overlapping short range networks with low control overhead is provided. It is shown that with CooPNC, higher throughput and energy efficiency are achieved, while it presents lower delay compared to state-of-the-art multicast protocols. A detailed description of the proposed protocol is provided, with a simple scenario of overlapping networks and also for a generalised scalable scenario. Through mathematical analysis and simulations it is proved that CooPNC presents significant performance gains compared to other state-of-the-art multicast protocols for short range networks. In order to reveal the performance bounds of Physical Layer Network Coding, the so-called Cross Network is investigated under diverse Network Coding (NC) techniques. The impact of Medium Access Control (MAC) layer fairness on the throughput performance of the network is provided, for the cases of pure relaying, digital NC with and without overhearing and physical layer NC with and without overhearing. A comparison among these techniques is presented and the throughput bounds, caused by MAC layer limitations, are discussed. Furthermore, it is shown that significant coding gains are achieved with digital and physical layer NC and the energy efficiency performance of each NC case is presented, when applied on the Cross Network.In the second part of this thesis, the uplink offloading using IP Flow Mobility (IFOM) is also investigated. IFOM allows a LTE mobile User Equipment (UE) to maintain two concurrent data streams, one through LTE and the other through WiFi access technology, that presents uplink limitations due to the inherent fairness design of IEEE 802.11 DCF. To overcome these limitations, a weighted proportionally fair bandwidth allocation algorithm is proposed, regarding the data volume that is being offloaded through WiFi, in conjunction with a pricing-based rate allocation algorithm for the rest of the data volume needs of the UEs that are transmitted through the LTE uplink. With the proposed approach, the energy efficiency of the UEs is improved, and the offloaded data volume is increased under the concurrent use of access technologies that IFOM allows. In the weighted proportionally fair WiFi bandwidth allocation, both the different upload data needs of the UEs, along with their LTE spectrum efficiency are considered, and an access mechanism is proposed that improves the use of WiFi access in uplink offloading. In the LTE part, a two-stage pricing-based rate allocation is proposed, under both linear and exponential pricing approaches, with the objective to satisfy all offloading UEs regarding their LTE uplink access. The existence of a malicious UE is also considered that aims to exploit the WiFi bandwidth against its peers in order to upload less data through the energy demanding LTE uplink and a reputation based method is proposed to combat its selfish operation. This approach is theoretically analysed and its performance is evaluated, regarding the malicious and the truthful UEs in terms of energy efficiency. It is shown that while the malicious UE presents better energy efficiency before being detected, its performance is significantly degraded with the proposed reaction method.La derivación del tráfico de datos móviles (en inglés data offloading) ha sido propuesta como una solución al problema de la congestión de la red, un problema que empeora continuamente debido al incremento de la demanda de datos móviles. El concepto de offloading se entiende como la explotación de la heterogeneidad de la red con el objetivo de mitigar la carga de la infraestructura de las redes celulares. En esta tesis se presenta un protocolo multicast para redes de corto alcance (short range networks) que explota las características de la codificación de red en la capa física (physical layer network coding). En el protocolo propuesto, llamado CooPMC, se implementa una solución cooperativa que permite la resolución de colisiones mediante la utilización de un esquema indirecto de cooperación entre redes. Gracias a este esquema, se consigue un protocolo multicast fiable i con poco overhead de control para redes de corto alcance parcialmente solapadas. Se demuestra que el protocolo CooPNC consigue una mayor tasa de transmisión neta (throughput) y una mejor eficiencia energética, a la vez que el retardo se mantiene por debajo del obtenido con los protocolos multicast del estado del arte. La tesis ofrece una descripción detallada del protocolo propuesto, tanto para un escenario simple de redes solapadas como también para un escenario general escalable. Se demuestra mediante análisis matemático y simulaciones que CooPNC ofrece mejoras significativas en comparación con los protocolos multicast para redes de corto alcance del estado del arte. Con el objetivo de encontrar los límites de la codificación de red en la capa física (physical layer network coding), se estudia el llamado Cross Network bajo distintas técnicas de Network Coding (NC). Se proporciona el impacto de la equidad (fairness) de la capa de control de acceso al medio (Medium Access Control, MAC), para los casos de repetidor puro (pure relaying), NC digital con y sin escucha del medio, y NC en la capa física con y sin escucha del medio. En la segunda parte de la tesis se investiga el offloading en el enlace ascendente mediante IP Flow Mobility (IFOM). El IFOM permite a los usuarios móviles de LTE mantener dos flujos de datos concurrentes, uno a través de LTE y el otro a través de la tecnología de acceso WiFi, que presenta limitaciones en el enlace ascendente debido a la equidad (fairness) inherente del diseño de IEEE 802.11 DCF. Para superar estas limitaciones, se propone un algoritmo proporcional ponderado de asignación de banda para el volumen de datos derivado a través de WiFi, junto con un algoritmo de asignación de tasa de transmisión basado en pricing para el volumen de datos del enlace ascendente de LTE. Con la solución propuesta, se mejora la eficiencia energética de los usuarios móviles, y se incrementa el volumen de datos que se pueden derivar gracias a la utilización concurrente de tecnologías de acceso que permite IFOM. En el algoritmo proporcional ponderado de asignación de banda de WiFi, se toman en consideración tanto las distintas necesidades de los usuarios en el enlace ascendente como su eficiencia espectral en LTE, y se propone un mecanismo de acceso que mejora el uso de WiFi para el tráfico derivado en el enlace ascendente. En cuanto a la parte de LTE, se propone un algoritmo en dos etapas de asignación de tasa de transmisión basada en pricing (con propuestas de pricing exponencial y lineal) con el objetivo de satisfacer el enlace ascendente de los usuarios en LTE. También se contempla la existencia de usuarios maliciosos, que pretenden utilizar el ancho de banda WiFi contra sus iguales para transmitir menos datos a través del enlace ascendente de LTE (menos eficiente energéticamente). Para ello se propone un método basado en la reputación que combate el funcionamiento egoísta (selfish).Postprint (published version

Meteor - The 'MisbEhavior deTEctor and enfORcer': A protocol to mitigate routing misbehaviour under mobile ad-hoc networks

Master'sMASTER OF ENGINEERIN

Fair relay selection in wireless rural networks using game theory

Access to Internet is the key to facilitate the economic growth and development of the rural communities and to bridge the digital-divide between the urban and rural population. The traditional broadband access technologies are not always suitable for the rural areas due to their difficult topography and sparsely populated communities. Specialized relay stations can be deployed to extend the coverage of a wireless rural network but they come with an inherited increase in the infrastructural cost. An alternative is to utilize the in-range users as relays to enhance the coverage range of the wireless rural network. In this thesis, the in-range ordinary users termed as primary users (PUs) are used to act as relays for the out-of-range users called the secondary users (SUs). Two relay selection solutions, the Fair Battery Power Consumption (FBPC) algorithm and the Credit based Fair Relay Selection (CF-RS) protocol have been proposed with the aim of providing fair chance to every PU to assist the SUs, thus resulting in fair utilization of battery power of all relays along with the coverage extension. The FBPC algorithm uses the concept of proportional fairness as the relay selection criterion. However, if only proportionally fair consumption of battery power is taken as the relay selection parameter, the FBPC algorithm may result in selecting relays with poor channel conditions. The rural network may also consist of selfish PUs which need to be incentivized to use their resources for the SUs. The CF-RS protocol is developed which takes into account both the achievable data rate and consumption of battery power for selection of a relay. The CF-RS protocol is formulated using Stackelberg game which employs a credit-based incentive mechanism to motivate the self-interested PUs to help the SUs by providing instantaneous as well as long term benefit to the PUs. A basic network model consisting of PUs and SUs has been simulated and the performance of the FBPC algorithm and the CF-RS protocol have been evaluated in terms of data rate and utility achievable at the SUs, dissipation of battery power of the PUs and Jain’s fairness index to determine fairness in utilization of battery power. The results obtained show that the FBPC algorithm achieves approximately 100% fairness for utilization of battery power of relays but compromises the data rate attainable by the SUs. Thus the FBPC algorithm shall be viewed as a trade-off between the fair battery power dissipation of relays and the data rate achievable by the SUs. Whereas, the CF-RS protocol provides 55% better utility and longer service time to the SUs without harming the attainable data rate and achieves 80% fairness. When the CF-RS protocol is used for relay selection, it is advantageous even for the self-interested users to participate in the relaying process to earn some benefit to utilize it when needed to buy assistance from other users

Doctor of Philosophy

dissertationWe are seeing an extensive proliferation of wireless devices including various types and forms of sensor nodes that are increasingly becoming ingrained in our daily lives. There has been a significant growth in wireless devices capabilities as well. This proliferation and rapid growth of wireless devices and their capabilities has led to the development of many distributed sensing and computing applications. In this dissertation, we propose and evaluate novel, efficient approaches for localization and computation offloading that harness distributed sensing and computing in wireless networks. In a significant part of this dissertation, we exploit distributed sensing to create efficient localization applications. First, using the sensing power of a set of Radio frequency (RF) sensors, we propose energy efficient approaches for target tracking application. Second, leveraging the sensing power of a distributed set of existing wireless devices, e.g., smartphones, internet-of-things devices, laptops, and modems, etc., we propose a novel approach to locate spectrum offenders. Third, we build efficient sampling approaches to select mobile sensing devices required for spectrum offenders localization. We also enhance our sampling approaches to take into account selfish behaviors of mobile devices. Finally, we investigate an attack on location privacy where the location of people moving inside a private area can be inferred using the radio characteristics of wireless links that are leaked by legitimate transmitters deployed inside the private area, and develop the first solution to mitigate this attack. While we focus on harnessing distributed sensing for localization in a big part of this dissertation, in the remaining part of this dissertation, we harness the computing power of nearby wireless devices for a computation offloading application. Specially, we propose a multidimensional auction for allocating the tasks of a job among nearby mobile devices based on their computational capabilities and also the cost of computation at these devices with the goal of reducing the overall job completion time and being beneficial to all the parties involved

Game theoretic approaches to cooperation in wireless networks

Ph.DDOCTOR OF PHILOSOPH

Cooperative Internet access using heterogeneous wireless networks

Ph.DDOCTOR OF PHILOSOPH

Naming and discovery in networks : architecture and economics

In less than three decades, the Internet was transformed from a research network available to the academic community into an international communication infrastructure. Despite its tremendous success, there is a growing consensus in the research community that the Internet has architectural limitations that need to be addressed in a effort to design a future Internet. Among the main technical limitations are the lack of mobility support, and the lack of security and trust. The Internet, and particularly TCP/IP, identifies endpoints using a location/routing identifier, the IP address. Coupling the endpoint identifier to the location identifier hinders mobility and poorly identifies the actual endpoint. On the other hand, the lack of security has been attributed to limitations in both the network and the endpoint. Authentication for example is one of the main concerns in the architecture and is hard to implement partly due to lack of identity support. The general problem that this dissertation is concerned with is that of designing a future Internet. Towards this end, we focus on two specific sub-problems. The first problem is the lack of a framework for thinking about architectures and their design implications. It was obvious after surveying the literature that the majority of the architectural work remains idiosyncratic and descriptions of network architectures are mostly idiomatic. This has led to the overloading of architectural terms, and to the emergence of a large body of network architecture proposals with no clear understanding of their cross similarities, compatibility points, their unique properties, and architectural performance and soundness. On the other hand, the second problem concerns the limitations of traditional naming and discovery schemes in terms of service differentiation and economic incentives. One of the recurring themes in the community is the need to separate an entity\u27s identifier from its locator to enhance mobility and security. Separation of identifier and locator is a widely accepted design principle for a future Internet. Separation however requires a process to translate from the identifier to the locator when discovering a network path to some identified entity. We refer to this process as identifier-based discovery, or simply discovery, and we recognize two limitations that are inherent in the design of traditional discovery schemes. The first limitation is the homogeneity of the service where all entities are assumed to have the same discovery performance requirements. The second limitation is the inherent incentive mismatch as it relates to sharing the cost of discovery. This dissertation addresses both subproblems, the architectural framework as well as the naming and discovery limitations