Magister Scientiae - MSc / This thesis demonstrates that a situation-aware algorithm improves quality of service on small mesh networks running BATMAN-adv with some mobile nodes. BATMAN-adv is a proactive mesh routing protocol that counts beacons as a link quality metric. BATMAN-adv was modi ed to give more recently received beacons more weight, thereby calculating a more precise indication of the current state of a link that BATMAN-adv can use to forward packets. BATMAN-adv `original' was compared with a situation-aware version in two laboratory test beds with the same voice traffic profile on actual hardware with a realistic voice traffic profile; with controlled transmission rates and buffer sizes to simulate congestion. The second test bed included mesh potatoes, PCs and laptops as mobile nodes. BATMAN-adv achieved better jitter and packet loss than the situation-aware version in the initial, smaller test bed, and average throughput for both versions was almost identical. However, in the second slightly larger test bed, with additional mobile nodes, the situation-aware algorithm performed better than the original BATMAN-adv algorithm for all quality of service metrics, including throughput. Thus the thesis concludes that a situation-aware protocol offers a promising solution to address issues pertaining to mobility, congestion and scalability for voice traffic in mesh networks with mobile nodes. / South Africa

The tremendous growth in the development of wireless networking techniques attracts growing attention to this research area. The ease of development, low installation and maintenance costs and self healing abilities are some of the qualities that make the multi-hop wireless mesh network a promising solution for both - rural and urban environments. Examining the performance of such a network, depending on the external conditions and the applied routing protocol, is the main aim of this research. It is addressed in an empirical way, by performing repetitive multistage network simulations followed by a systematic analysis and a discussion. This research work resulted in the implementation of the experiment and analysis tools, a comprehensive assessment of the simulated routing protocols - DSDV, AODV, OLSR and HWMP, and numerous observations concerning the simulation tool. Among the major findings are: the suitability of protocols for wireless mesh networks, the comparison of rural and urban environments and the large impact of conditions such as propagation, density and scale of topology on the network performance. An unexpected but valuable outcome is the critical review of the ns network simulator. / Mobile number: +48 660144055

Mesh network is gaining importance as the next generation network for many high speed applications such as multimedia streaming. This is because it is easy and inexpensive to setup mesh networks with mobile and PDA devices and can be used as a private network. Hence research is active in the field of routing protocols and routing metrics to improve the mesh network performance. Though most of the protocols are evaluated based on simulation, we implemented protocols based on a few metrics like Expected Transmission Count (ETX) Per-hop Packet Pair Delay (Pkt Pair) and WCETT (Weighted Cumulative Expected Transmitted Time) to investigate the performance of the network through experiments. An advanced version of DSR protocol called LQSR (Link Quality Source Routing) protocol of Microsoft Research along with MCL (Mesh Connectivity Layer) allows multiple heterogeneous adapters to be used in mesh network. Since wireless adapters of 802.11a standard offer 12 non-interfering channels and 802.11b/g standard offer 3 non-interfering channels, using multiple adapters of different bands operating on non-interfering channels to improve capacity and robustness of mesh networks was also investigated. In this thesis we explore the possibility of increasing the coverage area of Wireless Mesh Networks (WMN) to enhance the capacity of WMN and minimize the problems due to interference. Theoretical achievable capacity to every node in a random static wireless ad-hoc network with ideal routing is known to be where n is the total number of nodes in the network. Therefore, with increasing number of nodes in a network, throughput drops significantly. Our measurements show that throughput in a single WMN for different path length is closer to the throughput with nodes across two WMNs of the same path length. We propose to interconnect the networks by using multiple wireless adapters in a gateway node configured with the SSID of the networks in operation. We exploit the DSR protocol feature of assigning locally unique interface indices to its adapters. Performance of a network depends heavily on the metrics used for routing packets. Different metrics were studied in the thesis by setting up a 10-node testbed with a combination of nodes with single and two radios. Testbed was partitioned into two networks with two gateway nodes. Performance of multi-radio performance with the above metrics was compared with baseline single radio nodes in the network with the same metric. It is found that multi-radio nodes out-perform single radio nodes in the multi-hop scenario. Also, operating multi-mesh networks using multiple interfaces configured to those networks in a gateway node increases the coverage area and robustness without loss of performance.

Au cours des dernières années, l’utilisation des téléphones portables et tablettes s’est vue croitre de façon significative. De plus, la disponibilité et l’ubiquité de l’accès sans fil a permis de créer un environnement dans lequel les utilisateurs partout où ils sont accèdent en tout temps à des services se trouvant dans le cloud. Cet environnement appelé cloud sans fil consomme une quantité d’énergie significative et est responsable d’émissions considérables en carbone. Cette consommation massive d’énergie et émissions en carbone deviennent un problème majeur dans le secteur des technologies de la communication. Dans ce contexte, nous nous intéressons dans cette thèse à la réduction de la consommation d’énergie et des empreintes en carbone des réseaux d’accès de type mesh et réseaux de campus ainsi que les data centers des infrastructures cloud. Dans la première partie, nous nous intéressons aux réseaux mesh de type TDMA. Nous proposons des solutions pour le problème de routage et ordonnancement des liens qui permettent de réduire la consommation d’énergie dans le réseau. Nous étendons par la suite cette approche pour les réseaux de campus dans un contexte compatible avec le paradigme SDN. Dans la deuxième partie, nous nous intéressons à la réduction de la consommation l’énergie et des empreintes en carbone des infrastructures cloud distribuées, avec des couts variables de l’électricité et d’émission en carbone. Nous proposons des approches d’optimisations dans deux cas de figures : le cas d’un fournisseur cloud souhaitant réduire ses couts et dans le cas où les utilisateurs cloud spécifient des contraintes en carbone sous forme de Green SLA. / Over the last decade, there has been an increasing use of personal wireless devices, such as laptops, smartphones and tablets. The widespread availability of wireless access created an environment in which anywhere at anytime users access data and services hosted in cloud infrastructures. However, such wireless cloud network consumes a non-negligible amount of energy and generates a considerable amount of carbon, which is becoming a major concern in IT industry. In this context, we address the problem of reducing energy consumption and carbon footprint, as well as building green infrastructures in the two different parts of the wireless cloud: (i) wireless access networks including wireless mesh and campus networks, and (ii) data centers in a cloud infrastructure. In the first part of the thesis, we present an energy-efficient framework for joint routing and link scheduling in multihop TDMA-based wireless networks. At a later stage, we extended this framework to cover campus networks using the emerging Software Defined Networking (SDN) paradigm. In the second part of this thesis, we address the problem of reducing energy consumption and carbon footprint of cloud infrastructures. Specifically, we propose optimization approaches for reducing the energy costs and carbon emissions of a cloud provider owning distributed infrastructures of data centers with variable electricity prices and carbon emissions in two different setups: the case of a cloud provider trying to reduce its carbon emissions and operational costs as well as the case where green constraints are specified by the cloud consumers in the form of Green SLAs.

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Excessive droughts on the African continent have caused the Swedish Meteorological and Hydrological Institute to launch a program of gathering data in hopes of producing models for rainfalls and droughts. A sensor capable of gathering such data has already been chosen, however there remains the problem of conveniently retrieving data from each of the sensors spread over a large area of land. To accomplish this goal, a small, cheap and efficient wireless capable module would need to be used. A possible candidate is the new WiFi-module from Espress if designated ESP8266. It is an extremely cheap and versatile wireless SoC that is able to perform the task of a wireless communications adapter for the sensor unit. The point of this thesis is to investigate the suitability of IEEE 802.11 for the task, and produce a piece of firmware for the ESP8266. The firmware shall enable it to be attached to a sensor and operate as a wireless mesh node in a self-organizing WLAN sensor network, enabling data retrieval via WiFi multi-hop deliveries.

The demand for ubiquitous networks has pushed the designs of networks all the way. The requirement for access point to be integrated into IEEE 802.3 standard and other networks has always been a sore point in the limitation of wireless coverage of IEEE 802.11 standard networks. Wireless Mesh Network (WMN) is expected to be the future of the next generation wireless network. It is experiencing a fast growing development due to its attractive features which includes high reliable connectivity, easy deployment, self healing, self configuring, flexible network expansion etc. Hence the mobility of the WMN nodes has been of paramount importance, which would make it independent of wired infrastructure and flexible interoperability with various networks and devices. The requirements like mobility, transparency etc. have led to the amendment of the WMN standard by the Institute of Electronics and Electrical Engineering (IEEE) 802.11 Working Group (WG), Task Group (TG) “S. The IEEE 802.11s standard tackles these issues by its operation on layer 2 of Open Systems Interconnection (OSI) reference model and creates a transparent IEEE 802 broadcast domain that supports any higher layer protocol. In our work we give the evaluation of the upcoming IEEE 802.11s standard based on its features some of which include routing at layer 2 and medium access control to enable its design and implementation in the existing mesh frame work of Communication Research Labs (CRL) using the proposed IEEE 802.11s routing protocols with focus on RA-OLSR and HWMP. We concentrate on how to integrate these features into the existing CRL’s C-CORE which runs other layer 3 routing protocols and complex functions as Application Programming Interface (API) modules. The implementation of the IEEE 802.11s standard creates major challenges as we have to create a roadmap on integrating the new wireless kernel interfaces like the nl80211, cfg80211 and the Wireless Extension (Wext) into the CRL’s C-CORE framework for communication between user space and kernel space, especially taking into consideration of the existing HAL and madwifi wireless drivers of the CRL’s framework. To support the evaluation of the features like the layer 2 routing and the modified MAC performance, we compare results of the CRL’s real time mesh network test with our simulation result of the IEEE 802.11s standard using the Qualnet 4.5 simulator with focus on the basic network parameters like delay, jitter and throughput. The comparison shows that the CRL’s network has higher throughput running its existing layer 3 protocols. The analysis also proves that the 802.11s is flexible, scalable and efficient in delivering multi hop capabilities to clients that cannot afford the deployment time or the cost for wired networks that use access points. With the complete integration, of the 802.11s standard specifications the CRL’s C-CORE framework can be much more capable of supporting more diverse network scenario deployments. / +46-736318897

Avec les progrès dans les communications sans fil, le réseau maillé sans fils (WMN) est apparu comme une solution à la couverture et à la capacité limitée des réseaux d'infrastructure. Un WMN est un réseau ad-hoc multi-sauts dans lequel les routeurs participants acheminent le trafic pour le compte de tiers. Malgré les avantages et l'efficacité accrue de nombreuses applications, plusieurs problèmes doivent encore être résolus, notamment des facteurs critiques influant sur les performances des WMNs tels que l'évolutivité, la stabilité de la connectivité réseau, la qualité de service, la sécurité et les problèmes d'interférence. Face à ce défi, cette thèse explore une nouvelle approche des réseaux, à savoir le concept de réseau défini par logiciel (SDN). Dans une configuration SDN, l'intelligence située au niveau des périphériques réseau est déplacée dans une entité centrale communément appelée le contrôleur SDN. Dans cette architecture, le contrôleur SDN prend toutes les décisions et dicte à chaque périphérique réseau comment router les flux de données. Dans cette thèse, l'accent est mis sur l'évaluation des améliorations de la gestion de réseau que SDN pourrait apporter aux WMNs. En particulier, nous avons analysé et déterminé le type de granularité de contrôle SDN envisageable pour ce type de réseaux ainsi que les solutions techniques permettant de mettre en œuvre ce concept pour de meilleures performances. / With advances in wireless communications, Wireless Mesh Network (WMN) has emerged as one solution to the limited coverage and capacity of infrastructure networks. A WMN is a multihop ad-hoc network where participating routers forward traffic on behalf of others. Despite the advantages and increased efficiency in many applications, several challenges still need to be solved and especially critical factors influencing the performance of WMNs such as scalability, network connectivity steadiness, Quality of Service (QoS), security, and interference problems. In the face of this challenge, this thesis explores a new approach for networks, namely the concept of Software-Defined Network (SDN). In an SDN configuration, the intelligence located at network devices level is moved within a central entity commonly referred to as the SDN controller. In this architecture, the SDN controller takes all decisions and dictates to each network device how to route data flows. In this thesis, the focus is on evaluating network management improvements that SDN could make in WMNs. Particularly, we analyzed and determined what kind of SDN control granularity that could be envisaged for this type of networks as well as the technical solutions to implement this concept for better performance.

This thesis presents the work of a master degree project in mechatronics by two students from The Royal Institute of Technology. The project was carried out during spring 2017 in collaboration with Bosch Rexroth Mellansel as part of their desire to improve their operations. It is also in line with the Bosch Groups ambition to lead the development within Industry 4.0. The aim was to investigate the information need on a discrete manufacturing process and how radio-frequency identification (RFID) can be used to cover that need. The background research was made with qualitative methods using a literature review on relevant areas and a case study of Bosch Rexroth Mellansel. A discrete event simulation was created to confirm the possibilities of an RFID tracking system. It acted as a target for what the developed demonstrator should fulfil and was realised through a system of four wireless nodes connected in a mesh network. The plant in Mellansel partially implemented a Bosch standardised RFID system in parallel with the development of the demonstrator, which enabled a comparison of the two systems. The results show that from a tag event, which gives information on what, where and when, it is possible to, in real time, analyse and visualise valuable key performance indicators for a production process. It is also possible to use the data to automate transactions in an enterprise resource system which removes non-value adding activities from an operator while also ensuring consistency in the reporting procedure. The results indicate that benefits can be achieved. However, this requires further quantitative analysis before it can be fully confirmed and be used to push the development of Industry 4.0 forward. / Denna rapport presenterar ett examensarbete inom mekatronik av två studenter från Kungliga Tekniska Högskolan. Projektet genomfördes under våren 2017 i samarbete med Bosch Rexroth Mellansel som en del av deras strävan att förbättra sin verksamhet. Det ligger också i linje med Bosch koncernens ambition att leda utvecklingen inom Industri 4.0. Syftet var att undersöka informationsbehovet hos en diskret tillverkningsprocess och hur radio-frequency identification (RFID) kan användas för att täcka detta behov. Bakgrundsstudien gjordes med kvalitativa metoder som litteraturstudie inom relevanta områden och en fallstudie av en produktionsprocess inom Bosch Rexroth Mellansel. En simulering av produktionsprocessen skapades för att bekräfta möjligheterna av att använda ett RFID system för spårning av objekt. Den fungerade som ett mål för vad den utvecklade demonstratorn skulle uppfylla och realiserades genom en prototyp bestående av fyra trådlösa noder samlade i ett mesh nätverk. Parallellt med utvecklingen av demonstratorn gemomförde fabriken i Mellansel en del-implementering av en Bosch-standardiserad RFID lösning, vilket möjliggjorde en jämförelse av de två systemen. Resultaten visar att det från en avläsning av en tag, som ger information om vad, var och när, så är möjligt att i realtid analysera och visualisera värdefulla nyckeltal för en produktionsprocess. Det är också möjligt att använda data för att automatisera transaktioner i ett affärssystem som tar bort icke värdeskapande aktiviteter för operatören och samtidigt säkerställer en standardiserad rapporteringsprocess. Resultaten visar att fördelar kan uppnås men kräver ytterligare kvantitativ analys innan de kan bekräftas till fullo och användas för att driva utvecklingen av Industri 4.0 framåt.