With the constant expansion of the industrial monitoring system, there is an urgent requirement to reduce investment and operating costs for the development of industrial communication technology. For industrial real-time monitoring systems, wireless technology can be used in a practical industrial production to take advantages of its flexibility and robustness. As wireless sensor networks have many advantages such as low investment costs, flexible structure and ease of transformation, it has become the focus with regards to industrial areas. THVRG is a routing algorithm that selects the routing path based on two-hop information. Since different information sensed by the sensors may have different requirements in order to reach the sink, a priority-based routing algorithm is required in order to adapt to this kind of situation. This thesis has proposed a priority routing algorithm based on the THVRG (Priority-based THVRG). In addition, a simulation of this algorithm was performed in OPNET. Finally, the report provides an evaluation of the proposed algorithm in industrial wireless sensor networks.

As the field of Delay Tolerant Networking continues to expand and receive more attention, a new class of routing algorithms have been proposed that are specifically tailored to perform in a network where no end to end paths between devices are assumed to exist. As the number of proposed routing algorithms has grown, it has become difficult to fully understand their similarities and differences. Although published results clearly show different performance results between algorithms, it can be difficult to pinpoint which of their characteristics are most responsible for their performance differences. This thesis proposes an architectural framework to define the underlying features that Delay Tolerant Network routing algorithms are composed of. Popular routing algorithms from research are discussed and shown to be compositions of the proposed architectural features, thereby validating the architecture itself. The architectural framework is also shown to be a useful guide to developing a modular and configurable simulation platform. Algorithms from literature were implemented as a composition of features, which can easily be modified and combined later to define and implement new algorithms. Better understanding the underlying structure and similarities between different routing algorithm approaches is key to truly analyzing their performance and obtaining a deep understanding of which components of an algorithm have the most influence, both positively and negatively, on the results. Armed with this knowledge, designers of Delay Tolerant Networks can more easily determine the proper composition of routing algorithm features to best fit their needs. / text

A mobile ad hoc network is a collection of wireless nodes, all of which may be mobile, that dynamically create a wireless network amongst them without using any infrastructure. Ad hoc wireless networks come into being solely by peer-to-peer interactions among their constituent mobile nodes, and it is only such interactions that are used to provide the necessary control and administrative functions supporting such networks. Mobile hosts are no longer just end systems; each node must be able to function as a router as well to relay packets generated by other nodes. As the nodes move in and out of range with respect to other nodes, including those that are operating as routers, the resulting topology changes must somehow be communicated to all other nodes as appropriate. In accommodating the communication needs of the user applications, the limited bandwidth of wireless channels and their generally hostile transmission characteristics impose additional constraints on how much administrative and control information may be exchanged, and how often. Ensuring effective routing is one of the greatest challenges for ad hoc networking. As a practice, ad hoc routing protocols make routing decisions based on individual node mobility even for applications such as disaster recovery, battlefield combat, conference room interactions, and collaborative computing etc. that are shown to follow a pattern. In this thesis we propose an algorithm that performs routing based on underlying mobility patterns. A mobility pattern aware routing algorithm is shown to have several distinct advantages such as: a more precise view of the entire network topology as the nodes move; a more precise view of the location of the individual nodes; ability to predict with reasonably accuracy the future locations of nodes; ability to switch over to an alternate route before a link is disrupted due to node movements. / Master of Science

Mobile Ad hoc Networks (MANETs) are of great interest to researchers and have become very popular in the last few years. One of the great challenges is to provide a routing protocol that is capable of offering the shortest and most reliable path in a MANET in which users are moving continuously and have no base station to be used as a reference for their position. This thesis proposes some new routing protocols based on the angles (directions) of the adjacent mobile nodes and also the node density. In choosing the next node in forming a route, the neighbour node with the closest heading angle to that of the node of interest is selected, so the connection between the source and the destination consists of a series of nodes that are moving in approximately the same direction. The rationale behind this concept is to maintain the connection between the nodes as long as possible. This is in contrast to the well known hop count method, which does not consider the connection lifetime. We propose three enhancements and modifications of the Ad-hoc on demand distance vector (AODV) protocol that can find a suitable path between source and destination using combinations and prioritization of angle direction and hop count. Firstly, we consider that if there are multiple routing paths available, the path with the minimum hop count is selected and when the hop counts are the same the path with the best angle direction is selected. Secondly, if multiple routing paths are available the paths with the best angle direction are chosen but if the angles are the same (fall within the same specified segment), the path with minimum hop count is chosen. Thirdly, if there is more than one path available, we calculate the average of all the heading angles in every path and find the best one (lowest average) from the source to the destination. In MANETs, flooding is a popular message broadcasting technique so we also propose a new scheme for MANETS where the value of the rebroadcast packets for every host node is dynamically adjusted according to the number of its neighbouring nodes. A fixed probabilistic scheme algorithm that can dynamically adjust the rebroadcasting probability at a given node according to its ID is also proposed; Fixed probabilistic schemes are one of the solutions to reduce rebroadcasts and so alleviate the broadcast storm problem. Performance evaluation of the proposed schemes is conducted using the Global Mobile Information System (GloMoSim) network simulator and varying a number of important MANET parameters, including node speed, node density, number of nodes and number of packets, all using a Random Waypoint (RWP) mobility model. Finally, we measure and compare the performance of all the proposed approaches by evaluating them against the standard AODV routing protocol. The simulation results reveal that the proposed approaches give relatively comparable overall performance but which is better than AODV for almost all performance measures and scenarios examined.

The Quality of Service (QoS) is a profound concept which is gaining increasing attention in the Internet industry. Best-effort applications are now no longer acceptable in certain situations needing high bandwidth provisioning, low loss and streaming of multimedia applications. New emerging multimedia applications are requiring new levels of quality of services beyond those supported by best-effort networks. Quality of service routing is an essential part in any QoS architecture in communication networks. QoS routing aims to select a path among the many possible choices that has sufficient resources to accommodate the QoS requirements. QoS routing can significantly improve the network performance due to its awareness of the network QoS state. Most QoS routing algorithms require maintenance of the global network's state information to make routing decisions. Global state information needs to be periodically exchanged among routers since the efficiency of a routing algorithm depends on link-state information accuracy. However, most QoS routing algorithms suffer from scalability due to the high communication overhead and the high computation effort associated with maintaining accurate link state information and distributing global state information to each node in the network. The ultimate goal of this thesis is to contribute towards enhancing the scalability of QoS routing algorithms. Towards this goal, the thesis is focused on Localised QoS routing algorithms proposed to overcome the problems of using global network state information. Using such an approach, the source node makes routing decisions based on the local state information for each node in the path. Localised QoS routing algorithms avoid the problems associated in the global network state, like high communication and processing overheads. In Localised QoS routing algorithms each source node maintains a predetermined set of candidate paths for each destination and avoids the problems associated with the maintenance of a global network state by using locally collected flow statistics and flow blocking probabilities.

Quality of Service (QoS) routing considered as one of the major components of the QoS framework in communication networks. The concept of QoS routing has emerged from the fact that routers direct traffic from source to destination, depending on data types, network constraints and requirements to achieve network performance efficiency. It has been introduced to administer, monitor and improve the performance of computer networks. Many QoS routing algorithms are used to maximize network performance by balancing traffic distributed over multiple paths. Its major components include bandwidth, delay, jitter, cost, and loss probability in order to measure the end users' requirements, optimize network resource usage and balance traffic load. The majority of existing QoS algorithms require the maintenance of the global network state information and use it to make routing decisions. The global QoS network state needs to be exchanged periodically among routers since the efficiency of a routing algorithm depends on the accuracy of link-state information. However, most of QoS routing algorithms suffer from scalability problems, because of the high communication overhead and the high computation effort associated with marinating and distributing the global state information to each node in the network. The goal of this thesis is to contribute to enhancing the scalability of QoS routing algorithms. Motivated by this, the thesis is focused on localized QoS routing that is proposed to achieve QoS guarantees and overcome the problems of using global network state information such as high communication overhead caused by frequent state information updates, inaccuracy of link-state information for large QoS state update intervals and the route oscillating due to the view of state information. Using such an approach, the source node makes its own routing decisions based on the information that is local to each node in the path. Localized QoS routing does not need the global network state to be exchanged among network nodes because it infers the network state and avoids all the problems associated with it, like high communication and processing overheads and oscillating behaviour. In localized QoS routing each source node is required to first determine a set of candidate paths to each possible destination. In this thesis we have developed localized QoS routing algorithms that select a path based on its quality to satisfy the connection requirements. In the first part of the thesis a localized routing algorithm has been developed that relies on the average residual bandwidth that each path can support to make routing decisions. In the second part of the thesis, we have developed a localized delay-based QoS routing (DBR) algorithm which relies on a delay constraint that each path satisfies to make routing decisions. We also modify credit-based routing (CBR) so that this uses delay instead of bandwidth. Finally, we have developed a localized QoS routing algorithm for routing in two levels of a hierarchal network and this relies on residual bandwidth to make routing decisions in a hierarchical network like the internet. We have compared the performance of the proposed localized routing algorithms with other localized and global QoS routing algorithms under different ranges of workloads, system parameters and network topologies. Simulation results have indicated that the proposed algorithms indeed outperform algorithms that use the basics of schemes that currently operate on the internet, even for a small update interval of link state. The proposed algorithms have also reduced the routing overhead significantly and utilize network resources efficiently.

Localised QoS routing is a relatively new, alternative and viable approach to solve the problems of traditional QoS routing algorithms which use global state information resulting in the imposition of a large communication overhead and route flapping. They make use of a localised view of the network QoS state in source nodes to select paths and route flows to destination nodes. Proportional Sticky Routing (PSR) and Credit Based Routing (CBR) have been proposed as localised QoS routing schemes and these can offer comparable performances. However, since network state information for a specific path is only updated when the path is used, PSR and CBR operate with decision criteria that are often stale for paths that are used infrequently. The aim of this thesis is to focus on localised QoS routing and contribute to enhancing the scalability of QoS routing algorithms. In this thesis we have developed three new localised QoS routing schemes which are called Score Based QoS Routing (SBR), Bandwidth Based QoS Routing (BBR) and Delay Based Routing (DBR). In some of these schemes, the path setup procedure is distributed and uses the current network state to make decisions thus avoiding problems of staleness. The methods also avoid any complicated calculations. Both SBR and BBR use bandwidth as the QoS metric and mean delay is used as the QoS metric in DBR. Extensive simulations are applied to compare the performance of our proposed algorithms with CBR and the global Dijkstra's algorithm for different update intervals of link state, different network topologies and using different flow arrival distributions under a wide range of traffic loads. It is demonstrated by simulation that the three proposed algorithms offer a superior performance under comparable conditions to the other localised and global algorithms.

A aplicação de redes sem fio vem crescendo consideravelmente nos últimos anos. Protocolos baseados nesta tecnologia estão sendo desenvolvidos para uma grande variedade de aplicações. A confiabilidade é um dos principais requisitos dos protocolos de comunicação nos ambientes industriais. Interferências, ambiente ruidoso e o grande risco das aplicações industriais que são monitoradas são fatores que elevam os níveis de exigência no que se refere à confiabilidade, redundância e segurança do protocolo. O protocolo WirelessHART é um padrão de comunicação sem fio desenvolvido especificamente para monitoramento e controle de processos com os requisitos necessários para ser utilizado em ambientes industriais. A norma do WirelessHART define diversos aspectos técnicos a serem utilizados no desenvolvimento de algoritmos. Os algoritmos de roteamento e escalonamento de mensagens são de grande relevância para o cumprimento dos requisitos temporais, de confiabilidade e segurança. Requisitos de roteamento e escalonamento são especificados, porém, os algoritmos a serem utilizados não são definidos. O objetivo nessa dissertação é analisar alguns dos principais algoritmos que tem sido propostos especificamente para o protocolo WirelessHART e apresentar um conjunto capaz de ser aplicado nesse protocolo. Análises e comparações entre os algoritmos são realizadas proporcionando um estudo aprofundado sobre seus impactos no desempenho do protocolo. / The application of wireless networks has grown considerably in recent years. Protocols based on this technology are being developed for a great variety of applications. Reliability is one of the main requirements for communication protocols in industrial environments. Interferences, noisy environment and high risk processes that are monitored are factors that increase the levels of requirements in terms of reliability, redundancy and security of the protocol. The WirelessHART protocol is a wireless communication standard specifically designed for process monitoring and control applications with the necessary requirements for to be used in industrial environments. The WirelessHART standard defines several technical aspects to be used in the development of the algorithms. The algorithms of routing and scheduling messages are highly relevant to meeting the timing requirements of reliability and safety. Routing and scheduling strategies are specified, however, the routing and scheduling algorithms are not defined for use. The goal of this dissertation is to analyze some of the main algorithms that have been proposed specifically for the WirelessHART protocol and to present a set able to be applied in this protocol. Analyzes and comparisons between algorithms are realized by providing a detailed study of their impacts on the protocol performance.

<p>There is a seemingly endless miniaturization of electronic components, which has enabled designers to build sophisticated computing structureson silicon chips. Consequently, electronic systems are continuously improving with new and more advanced functionalities. Design complexity ofthese Systems on Chip (SoC) is reduced by the use of pre-designed cores. However, several problems related to the interconnection of coresremain. Network on Chip (NoC) is a new SoC design paradigm, which targets the interconnect problems using classical network concepts. Still,SoC cores show large variance in size and functionality, whereas several NoC benefits relate to regularity and homogeneity.</p><p>This thesis studies some network aspects which are characteristic to NoC systems. One is the issue of area wastage in NoC due to cores of varioussizes. We elaborate on using oversized regions in regular mesh NoC and identify several new design possibilities. Adverse effects of regions oncommunication are outlined and evaluated by simulation.</p><p>Deadlock freedom is an important region issue, since it affects both the usability and performance of routing algorithms. The concept of faultyblocks, used in deadlock free fault-tolerant routing algorithms has similarities with rectangular regions. We have improved and adopted one suchalgorithm to provide deadlock free routing in NoC with regions. This work also offers a methodology for designing topology agnostic, deadlockfree, highly adaptive application specific routing algorithms. The methodology exploits information about communication among tasks of anapplication. This is used in the analysis of deadlock freedom, such that fewer deadlock preventing routing restrictions are required.</p><p>A comparative study of the two proposed routing algorithms shows that the application specific algorithm gives significantly higher performance.But, the fault-tolerant algorithm may be preferred for systems requiring support for general communication. Several extensions to our work areproposed, for example in areas such as core mapping and efficient routing algorithms. The region concept can be extended for supporting reuse ofa pre-designed NoC as a component in a larger hierarchical NoC.</p>

Στόχος της εργασίας είναι να εμβαθύνει πάνω στο σημαντικό θέμα της ποιότητας υπηρεσίας, εξειδικεύοντας το θέμα για τα ATM switches. Μελετά τους αλγορίθμους που εφαρμόζονται ή λειτουργούν σε θεωρητικό επίπεδο για τα ATM switches και τον τρόπο που επηρεάζουν τις διάφορες παραμέτρους του QoS. Για το λόγο αυτό ορισμένοι αλγόριθμοι εφαρμόζονται σε εξομοιωτή δικτύων και με βάση τη συμπεριφορά τους εκτιμάται η επίδραση των διαφόρων αλγορίθμων στην απόδοση και τη συμπεριφορά των δικτύων. / This research examines closely the important issue of quality of service, specializing the issue on ATM switches. It examines the algorithms that are applied or used on theoretical level on ATM switches and the way they affect the QoS parameters. For this reason some algorithms are applied on a network simulator and according the network’s behavior we estimate the effect of different algorithms on networks’ performance and behavior.