Latest trend in multi core architectures is to integrate heterogeneouscores on a single chip in order to achieve task and threadlevel parallelism, high performance and energy efficiency. Someexamples of heterogeneous multi cores processors include (Tegraby NVIDIA,Cell by IBM and Fusion by AMD). The goal of this thesis work is to design a heterogeneous (2x2)network on chip which can run different tasks in parallel on allthe four cores in the network. Development steps of heterogeneousnetwork on chip include integration of Leon3 -a soft core processorby AeroFlex Gaisler which conforms with IEEE 1754 (SPARCV8) architecture- at one of the nodes of a homogeneous networkon chip incorporating four NiosII/s cores -soft core processor byAltera.This integration involves replacing a NiosII/s processor fromone of the four nodes of the homogeneous network by Leon3 processor.To translate the signals between the resource to networkinterface of the node and the Leon3 processor an AMBA bus1 toAvalon bus2 signal translation wrapper was designed. All processorsin the network on chip communicate by message passing interface.To exploit the potential of heterogeneous network on chipthree applications including sparse LU factorization, nqueens andFibonacci numbers calculation were run on it. These applicationwere run on Leon3 SPARC which generated a number of tasks thatcan run in parallel on all cores of the network simultaneously. Thisparallel execution of nqueens and fibonacci numbers calculationhas resulted in speed up as compared to the serial execution ofthese applications on Leon3 SPARC only. Because of the limitedsize of the on chip memory available for the Leon3 processor, itwas not possible to run sparse LU factorization for bigger matrixsizes and this constraint has resulted in no speed up in case ofsparse LU factorization.

This thesis project’s goal is to enable undergraduate students to gain insight into media access and control protocols based upon carrying out laboratory experiments. The educational goal is to de-mystifying radio and other link and physical layer communication technologies as the students can follow packets from the higher layers down through the physical layer and back up again. The thesis fills the gap between the existing documentation for the Universal Software Radio Peripheral (USRP) resources and the knowledge of undergraduate students. This was necessary because the existing document is targeted at advanced audiences rather than undergraduates. This thesis describes the design and evolution of a workbench for students to experiment with a variety of media access and control protocols, much as Wireshark gives students the ability to watch network and higher layer protocols. Another motivation for this thesis is that an increasing number of communication networks use complex media access and control protocols and existing tools do not allow students to see the details of what is taking place in these protocols, except via simulation. Today an software defined radio and computer are affordable as laboratory equipment for an undergraduate course. Hence the time is ripe for the development of undergraduate laboratory course material using these tools. The thesis is targeted at (1) instructors of undergraduates who might use this work to develop their own lesson plans and course material and (2) students of physical and link layer protocols who want a practical tool for carrying out experiments in these layers. Hopefully by de-mystifying these lower layers and by making the USRP more approachable by undergraduate students we will encourage lots of students to view wireless network technology as being just as approachable as a wired Ethernet. Due to the widespread use of wireless communications technologies, there is a great need by industry for more graduates who can understand communication systems from the physical to the application layer - rather than the current situation where there is a hard boundary between the lower two layers and the upper layers. While there has been a lot of research concerning cross layer optimization, much of this is theoretical and not very approachable by students. A desired outcome of this thesis project is that undergraduate students will be able to understand tradeoffs at all layers of the protocol stack and not be limited to the upper layers. / Detta examensarbete har som mål att göra det möjligt för studenter att få inblick i tillgång till medierna och protokoll som grundar sig på att utföra laboratorieexperiment. Det pedagogiska målet är att de-mystifierande radio och annan länk och fysiska lagret kommunikationsteknik som studenterna kan följa paket från högre skikt ner genom det fysiska lagret och upp igen. Avhandlingen fyller gapet mellan den befintliga dokumentationen för Universal Software Radio Peripheral (usrp) resurser och kunskap om studerande. Detta var nödvändigt eftersom det befintliga dokument riktar sig till avancerade publik snarare än studenter. Denna avhandling beskriver utformningen och utvecklingen av en arbetsbänk för studenter att experimentera med olika tillgång till medierna och protokoll kontroll, mycket som Wireshark ger studenterna möjlighet att titta på nätet och högre skikt protokoll. Ett annat motiv för denna tes är att ett ökande antal kommunikationsnät använda komplicerade tillgång till medierna och protokoll kontroll och befintliga verktyg inte tillåter eleverna att se detaljer om vad som sker i dessa protokoll, utom via simulering. Idag en programvarustyrd radio och dator är överkomliga laboratorieutrustning för en grundutbildningskurs. Därför är tiden mogen för utvecklingen av grundutbildningen laborationer material med hjälp av dessa verktyg. Avhandlingen riktar sig till (1) instruktörer för studenter som kan använda detta arbete för att utveckla sin egen lektionsplanering och kursmaterial och (2) studenter på fysisk och länka protokoll skikt som vill ha ett praktiskt verktyg för att utföra experiment i dessa lager. Förhoppningsvis genom de-mystifierande de undre lagren och genom att göra usrp mer tillgänglig genom att studenter ska vi uppmuntra många elever att visa trådlös nätverksteknik vara lika lättillgänglig som ett ethernet. På grund av den utbredda användningen av trådlös kommunikationsteknik, finns ett stort behov från näringslivet för fler studenter som kan förstå kommunikationssystem från det fysiska till applikationslagret - i stället för den nuvarande situationen där det finns en hård gräns mellan de två lägre skikten och de övre skikten. Samtidigt som det har varit en hel del forskning om cross lager optimering, mycket av detta är teoretisk och inte särskilt tillgänglig av studenter. Ett önskat resultat med detta examensarbete är att studenter ska kunna förstå kompromisser på alla nivåer inom den protokollstack och inte vara begränsade till de övre skikten.

In recent years, Smart Grid (SG) is envisioned to be the next generation electric power system by replacing traditional power grid due to its advantage of using two way communications. To implement reliable SG wireless communication networks, IEEE introduced a new wireless standard (IEEE802.15.4g) for Smart Utility Networks (SUNs). However, SUN operates on 2.4 GHz unlicensed band which is overlapped with Wireless Local Area Networks (WLANs) that leads to coexistence in Smart Utility Networks. In this paper, the coexistence problem of SUN is addressed in terms of homogeneous and heterogeneous interferences. To mitigate the homogeneous interference, Contention Access Period (CAP) and Contention Free Period (CFP) of a super frame of IEEE 802.15.4g is used to access the channel using slotted CSMA/CA algorithm by modifying the Backoff Period (BP) and Clear Channel Assessment (CCA) period for different priority data. An analytical model is developed using Markov chain, through which we demonstrate the accuracy of the proposed model in terms of throughput, channel access delay, probability of successful transmission and collision for nodes with different priority data. Performance evaluation is further investigated by comparing the proposed scheme with the existing PA-MAC. A channel switching mechanism is explored to mitigate the heterogeneous interference by the prediction of Naive Bayes Classifier. Predicted result shows that proposed mechanism effectively mitigates the heterogeneous interference by choosing the non-overlapping and non-coexisting channel.

The focus of this research is to investigate the effects of bursts of errors and packet collisions on the performance of the medium access control (MAC) portion of the IEEE 802.11 wireless local area network (LAN) protocol.An important ingredient in rapid expansion of wireless networks is the seamless transition between wired and wireless systems. The IEEE standards group in charge of developing the widely used IEEE 802.3 LAN standard has developed the IEEE 802.11 wireless LAN standard. IEEE 802.11 remains hidden from the upper levels of the network, thus allowing a seamless transition between networks. The foundation protocol for the IEEE 802.11 standard, known as Distributed Foundation Wireless Medium Access Control (DFWMAC), operates at the MAC level of the Data Link Layer. The protocol bases its access control mechanism on a principle called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), which is an adaptation of the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol used by IEEE 802.3 standard. The collision avoidance scheme in CSMA/CA allows data packets to be transferred via the wireless medium with lower probability of packet collision. In a slotted multi-access wireless system, performance parameters are affected by the bit error rates on the communication channel. These errors occur as a result of noise introduced by the radio channel or data packet collisions. Collisions occur when two or more stations select the same time slot to transmit their data, thus causing corruption in data packets. In this research, a simulation model coded in Microsoft's Visual Basic programming environment is utilized to investigate the effects of bit errors and packet collisions on performance in CSMA/CA. Performance parameters used in this study include throughput, medium utilization, collisions and station data queue lengths. In the simulation model, error bursts in the communication channel are modeled using a simple Gilbert model with two states, good (G) and bad (B). State G is error free, thus errors can only occur while the model is in state B. Collisions are simulated by two or more stations starting to transmit data packets in the same time slot. Therefore, as the number of stations increases, more and more stations compete for the medium, resulting in an increase in the number of collisions. Collisions are also increased by the amount of traffic that each station introduces into the system. Station load is defined here as the number of data packets per unit time that are released by the higher network protocol layers.The results in Chapter 5 demonstrate that higher network throughput can be achieved when the aggregate load on the network is distributed. For example, 30 stations offering 20 kilobits per second (kbps) of load for a total of 600 kpbs, results in a network throughput of 585 kbps. However, three stations offering 200 kbps of load for a total of 600 kbps offered load, results in a network throughput of 486 kbps. The distributed load is serviced at a 17 percent higher rate. However, once the network becomes saturated at above 40 stations for this model, collisions will more than offset the performance gains produced by the distribution of load.Furthermore, reducing the packet size by 50 percent under an approximately 19.5 percent packet error rate results in a 12 percent gain in throughput. This is primarily due to higher utilization of the network by shorter packets. However, as the packet error rate is reduced, the performance gap between the two packet sizes is reduced. Once the errors are removed completely from the communications channel, the longer packets produce a higher throughput than the shorter packets. / Master of Science

Les réseaux véhiculaires font l’objet de recherches actives aussi bien dans le domaine des réseaux que dans celui des transports. Le potentiel des réseaux véhiculaires à fournir des services comme l’information sur le trafic en temps réel ou sur les accidents font de cette technologie un domaine de recherche très important. Ces réseaux peuvent comporter des communications véhicule-à-véhicule (V2V), véhicule-à-infrastructure (V2I), ou une combinaison des deux. La norme IEEE 1609.4 est la spécification multicanal pour l’IEEE802.11p/WAVE des réseaux véhiculaires (VANETs). Elle utilise sept canaux, l'un étant un canal de contrôle (CCH) qui est écouté par les équipements de façon périodique, et les six autres canaux sont utilisés comme canaux de service (SCH). Elle définit également une division du temps en alternance entre les intervalles CCH et les intervalles SCH. L’objet de cette thèse de doctorat est d’évaluer les performances des réseaux VANETs dans le cas des communications véhiculaires sans infrastructure, et au niveau des couches inférieures du standard 802.11p. Dans la première partie, nous proposons une approche MAC d’allocation multicanal opportuniste dans un contexte sans infrastructure. Cette approche est conforme à la norme IEEE1609.4 -2010 de l'architecture WAVE pour un fonctionnement multicanal, et elle est conçue pour des applications de services de données (non urgentes), tout en assurant la transmission des messages de sécurité routière et des paquets de contrôle. Pour maintenir la qualité de service des deux types de messages (urgents et non-urgents) en exploitant la capacité du canal, deux solutions sont proposées. Dans la deuxième partie, lorsque le véhicule sélectionne son canal et contrôle son alternance temporelle entre CCH et SCH, il commence à transmettre ses paquets, en particulier sur le canal CCH, lesquels ont une durée de péremption. Nous présentons une approche visant à minimiser les collisions des émetteurs tout en évitant la contention de début d’intervalle, en particulier dans un contexte de densité élevée de véhicules. Même si les mécanismes proposés ci-dessus diminuent le taux de collision, il n’est pas possible de les supprimer complètement. Dans la troisième partie, nous traitons le problème des collisions entre les paquets diffusés sur le CCH, en particulier quand la charge des messages transmis dépasse la capacité du canal. Pour cela, nous proposons un nouveau mécanisme de codage réseau analogique adapté à la modulation QPSK pour les messages diffusés sur le CCH. Dans cette approche des symboles connus sont envoyés avant d'envoyer les paquets pour estimer les paramètres du canal et une solution explicite est utilisée pour inverser le système de la superposition de deux paquets / Vehicular networks are the subject of active research in the field of networks as well as transport. The potential for vehicular networks to provide services such as traffic information in real time or accident makes this technology a very important research domain. These networks may support vehicle-to-vehicle communications (V2V), vehicle-to-infrastructure (V2I), or a combination of both. The IEEE 1609.4 is the specification of multichannel operations for IEEE802 .11p/WAVE vehicular networks (VANETs). It uses seven channels; one being a control channel (CCH) which is listened periodically by the vehicles and the other six channels are used as service channels (SCH). It also defines a time division between alternating CCH and SCH intervals. The purpose of this thesis is to evaluate the performance of VANETs in the case of vehicular communications without infrastructure, and at the lower layers of IEEE 802.11p standard. In the first part, we propose an opportunistic multichannel MAC allocation in an environment without infrastructure. This approach is consistent with the standard IEEE1609.4 -2010/WAVE for a multi-channel operation, and it is designed for data services applications (non-urgent), while ensuring the transmission of road safety messages and control packets. To maintain the quality of service of the two types of messages (urgent and non-urgent) by exploiting the channel capacity, two solutions are proposed. In the second part, when the vehicle selects its channel and controls its temporal alternation between CCH and SCH, it starts transmitting its packets, particularly on the CCH, which have an expiration time. We present an approach to minimize collisions between transmitters while avoiding contention at the beginning of CCH interval, especially in a context of high vehicular density. Although the mechanisms proposed above reduce the collision rate, it is not possible to completely remove these collisions. In the third part, we address the problem of collisions between broadcast packets on the CCH, especially when the load of transmitted messages exceeds the channel capacity. For this purpose, we propose a new analog network coding mechanism adapted to QPSK modulation for broadcast messages on the CCH. In this approach, known symbols are sent before sending the packets to estimate the channel parameters and an explicit solution is used to reverse the system of the superposition of two packets

The aim of this thesis is to design and implement modules for wireless sensor network ZigBee. These modules could communicate together and share information about measured values. The network will be managed by coordinator of network, which will process data from sensor modules and will decide about next steps around the network.

Proporciona los pasos y procedimientos para acceder al recurso IEEE Xplore.

Broadband wireless access (BWA) is a promising emerging technology. In the past, most BWA systems were based on proprietary implementations. The Institute of Electrical and Electronics Engineers (IEEE) 802.16 task group recently standardized the physical (PHY) and medium-access control (MAC) layers for BWA systems. To operate in a wide range of physical channel conditions, the standard defines a robust and flexible PHY. A wide range of modulation and coding schemes are defined. While the standard provides a framework for implementing link adaptation, it does not define how exactly adaptation algorithms should be developed. This thesis develops a link adaptation algorithm for the IEEE 802.16 standard's WirelessMAN air interface. This algorithm attempts to minimize the end-to-end delay in the system by selecting the optimal PHY burst profile on the air interface. The IEEE 802.16 standard recommends measuring C/(N+I) at the receiver to initiate a change in the burst profile, based on the comparison of the instantaneous the C/(N+I) with preset C/(N+I) thresholds. This research determines the C/(N+I) thresholds for the standard specified channel Type 1. To determine the precise C/(N+I) thresholds, the end-to-end(ETE) delay performance of IEEE 802.16 is studied for different PHY burst profiles at varying signal-to-noise ratio values. Based on these performance results, we demonstrate that link layer ETE delay does not reflect the physical channel condition and is therefore not suitable for use as the criterion for the determination of the C/(N+I) thresholds. The IEEE 802.16 standard specifies that ARQ should not be implemented at the MAC layer. Our results demonstrate that this design decision renders the link layer metrics incapable of use in the link adaptation algorithm. Transmission Control Protocol (TCP) delay is identified as a suitable metric to serve as the link quality indicator. Our results show that buffering and retransmissions at the transport layer cause ETE TCP delay to rise exponentially below certain SNR values. We use TCP delay as the criterion to determine the SNR entry and exit thresholds for each of the PHY burst profiles. We present a simple link adaptation algorithm that attempts to minimize the end-to-end TCP delay based on the measured signal-to-noise ratio (SNR). The effects of Internet latency, TCP's performance enhancement features and network traffic on the adaptation algorithm are also studied. Our results show that delay in the Internet can considerably affect the C/(N+I) thresholds used in the LA algorithm. We also show that the load on the network also impacts the C/(N+I) thresholds significantly. We demonstrate that it is essential to characterize Internet delays and network load correctly, while developing the LA algorithm. We also demonstrate that TCP's performance enhancement features do not have a significant impact on TCP delays over lossy wireless links. / Master of Science

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第24267号 / 情博第811号 / 新制||情||136(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 原田 博司, 教授 梅野 健, 准教授 山本 高至 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DGAM

Internet of Things (IoT) has drawn much attention in recent years. With IoT, physical world entities get connected through internet. IoT is used currently in various applications, such as environmental monitoring, control systems, farming, home automation, security and surveillance systems etc. The aim of this research is to design a low-cost, energy-efficient, reliable and scalable embedded application for the smart greenhouse monitoring system. The IoT based system designed in this thesis uses various sensors to measure the air and soil quality parameters in the greenhouse, and monitor real-time data online using web-server and mobile phone based applications. A ZigBee based wireless sensor network is implemented to transport various sensory data to the gateway. Among other contributions, the designed system develops a new routing algorithm by introducing a confirmed delivery of packets and re-routing features. We also introduced an efficient cost metric for making routing decisions within WSN using hops count, and simple bi-directional link quality estimator using PRR and current battery voltage of neighbor nodes. We also verified the stability of the system by conducting various performance tests. The system is equipped with data analytic functions for the online examination of the data. The designed system adopts event-based triggering and data aggregation methods to reduce the number of transmissions, and develops a new algorithm for such purpose. The web-server and mobile applications have user interface to display the output of the data analytic services, warning, control operations and give access to query data of the user's interest.