Tesis: "Congestion Detection and Notification"

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Rui, Zhu. "Moving Object Trajectory Based Intelligent Traffic Information Hub". Thesis, KTH, Geodesi och geoinformatik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134944.

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Congestion is a major problem in most metropolitan areas and given the increasingrate of urbanization it is likely to be an even more serious problem in the rapidlyexpanding mega cities. One possible method to combat congestion is to provide in-telligent trafﬁc management systems that can in a timely manner inform drivers aboutcurrent or predicted trafﬁc congestions that are relevant to them on their journeys. Thedetection of trafﬁc congestion and the determination of whom to send in advance no-tiﬁcations about the detected congestions is the objective of the present research. Byadopting a grid based discretization of space, the proposed system extracts and main-tains trafﬁc ﬂow statistics and mobility statistics from the grid based recent trajectoriesof moving objects, and captures periodical spatio-temporal changes in the trafﬁc ﬂowsand movements by managing statistics for relevant temporal domain projections, i.e.,hour-of-day and day-of-week. Then, the proposed system identiﬁes a directional con-gestion as a cell and its immediate neighbor, where the speed and ﬂow of the objectsthat have moved from the neighbor to the cell signiﬁcantly deviates from the histori-cal speed and ﬂow statistics. Subsequently, based on one of two notiﬁcation criteria,namely, Mobility Statistic Criterion (MSC) and Linear Movement Criterion (LMC),the system decides which objects are likely to be affected by the identiﬁed conges-tions and sends out notiﬁcations to the corresponding objects such that the numberof false negative (missed) and false positive (unnecessary) notiﬁcations is minimized.The thesis discusses the design and DBMS-based implementation of the proposedsystem. Empirical evaluations on realistically simulated trajectory data assess the ac-curacy of the methods and test the scalability of the system for varying input sizes andparameter settings. The accuracy assessment results show that the MSC based systemachieves an optimal performance with a true positive notiﬁcation rate of 0.67 and afalse positive notiﬁcation rate of 0.05 when min prob equals to 0.35, which is superiorto the performance of the LMC based system. The execution time of- and the spaceused by the system scales linearly with the input size (number of concurrently movingvehicles) and the methods mutually dependent parameters (grid resolution r and RTlength l) that jointly deﬁne a spatio-temporal resolution. Within the area of a large city (40km by 40km), assuming a 60km/h average vehicle speed, the system, runningon a commodity personal computer, can manage the described congestion detectionand three-minute-ahead notiﬁcation tasks within real-time requirements for 2000 and20000 concurrently moving vehicles for spatio-temporal resolutions (r=100m, l=19)and (r=2km, l=3), respectively.

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2

Zheng, Zici. "Adaptive explicit congestion notification (AECN) for heterogeneous flows". Link to electronic thesis, 2001. http://www.wpi.edu/Pubs/ETD/Available/etd-0502101-062544.

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3

Ahmed, Uvaiz. "Performance evaluation of explicit congestion notification method in IP networks ECN and BECN". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/MQ48467.pdf.

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4

Makkar, Rupinder Singh. "QoS control for IP networks, buffer management and backward explicit congestion notification (BECN)". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61021.pdf.

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5

Ahmed, Uvaiz Carleton University Dissertation Engineering Systems and Computer. "Performance evaluation of explicit congestion notification methods in IP networks ECN and BECN". Ottawa, 1999.

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6

Zetterlund, Samuel. "Blind swimmer detection and notification utilizing OpenCV on the Android platform". Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-25084.

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For a blind swimmer to be able to exercise in a swimming pool today, human assistance is required to notifying the swimmer in due time when and if she is too close to the edge. The purpose of this thesis was to see whether or not it is possible to replace and even improve the human intervention using a warning system built around a tablet mounted next to the pool edge. A secondary goal was to evaluate how suitable a tablet pc is for robotic applications. The system proposed utilizes a tablet’s built-in frontal facing camera, OpenCV as vision library, FM modules for the wireless warning system and is intended for the Android environment. Videos of the real scenario have been analyzed on a computer using OpenCV and a detection algorithm searching for the swimmer’s red swimming cap has been developed. Next, the algorithm was implemented on an Android tablet. The result obtained shows that it is perfectly possible to use a cheap tablet to accurately detect and notify the blind swimmer in due time when she is too close to the edge. If calibrated thoroughly, the likelihood of a missed detection is actually lower with this system as compared to human intervention, as humans can only warn the swimmer when she is above the water.

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7

Montojo, Villasanta Javier y Viñas Manuel Maqueda. "Congestion Identification in a Radio Access Transport Network". Thesis, KTH, Radio Systems Laboratory (RS Lab), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-142437.

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The convergence of mobile services and Internet has brought a radical change in mobile networks. An all IP network architecture, an evolution of the radio access transport network, is required to support new high-bandwidth services. Unfortunately, existing control mechanisms are insufficient to guarantee end users a high quality of experience. However, coordinating radio and transport network resources is expected to yield a more efficient solution. This thesis project investigates the interactions between the congestion avoidance protocols, explicit congestion notification, and the traffic engineering metrics for latency and bandwidth, when using Open Shortest Path First with traffic engineering (OSPF-TE) as a routing protocol. Using knowledge of these interactions, it is possible to identify the appearance of bottlenecks and to control the congestion in the transport links within a radio access transport network. Augmenting a topology map with the network’s current characteristics and reacting to evidence of potential congestion, further actions, such as handovers can be taken to ensure the users experience their expected quality of experience. The proposed method has been validated in a test bed. The results obtained from experiments and measurements in this test bed provide a clear picture of how the traffic flows in the network. Furthermore, the behavior of the network observed in these experiments, in terms of real-time performance and statistical analysis of metrics over a period of time, shows the efficiency of this proposed solution.
Tjänstekonvergensen av Internet- och mobila tjänster har medfört en radikal förändring i mobilnäten. En ”All IP” nätverksarkitektur, en utveckling av radios transportnät. Utvecklingen krävs för att stödja de nya bredbandiga tjänsterna. Tyvärr är befintliga kontrollmekanismer otillräckliga för att garantera användarens kvalitetsupplevelse. Med att samordna radio- och transportnätverkets resurser förväntar man sig en effektivare lösning. Detta examensarbete undersöker samspelet mellan protokoll för att undvika överlast, direkt indikation av överlast och trafikal statistik för fördröjning och bandbredd med trafikstyrning baserat på fördröjning och bandbredd , vid användning av Open Shortest Path First ( OSPF - TE ) som routingprotokoll. Med hjälp av information om dessa interaktioner, är det möjligt att identifiera uppkomsten av flaskhalsar och för att styra trafikstockningar i transportförbindelser inom ett radioaccess transportnät. En utökad topologikarta med nätverkets aktuella egenskaper kommer att reagera på en potentiell överbelastning. Ytterligare åtgärder, till exempel överlämningar, vidtas i mobilnätet för att säkerställa användarens upplevda kvalitet. Den föreslagna metoden har validerats i en testmiljö. Resultaten från experiment och mätningar i denna testmiljö ger en tydlig bild av hur trafikflödena framskrider i nätverket. Beteendet hos nätverket som observeras i dessa experiment, i termer av realtidsprestanda och statistisk analys av mätvärden över en tidsperiod, visar effektiviteten av denna föreslagna lösning.

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8

Goyal, Prateesh. "Elasticity detection : a building block for internet congestion control". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120404.

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Thesis: S.M. in Computer Science and Engineering, Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 61-64).
This thesis develops a technique to detect whether the cross traffic competing with a flow is elastic or not, and shows how to use the elasticity detector to improve congestion control. If the cross traffic is elastic, i.e., made up of flows like Cubic or NewReno that increase their rate when they perceive available bandwidth, then one should use a scheme that competes well with such traffic. Such a scheme will not be able to control delays because the cross traffic will not cooperate to maintain low delays. If, however, cross traffic is inelastic, then one can use a suitable delay-controlled algorithm. Our elasticity detector uses an asymmetric sinusoidal pulse pattern and estimates elasticity by computing the frequency response (FFT) of the cross traffic estimate; we have measured its accuracy to be over 90%. We present the design and evaluation of Nimbus, a congestion control protocol that uses the elasticity detector to switch between delay-control and TCP-competitive modes. Our results on emulated and real-world paths show that Nimbus achieves throughput comparable to or better than Cubic always, but with delays that are much lower when cross traffic is inelastic. Unlike BBR, Nimbus is fair to Cubic, and has significantly lower delay by 40-50 ms. Compared to Copa, which also switches between a delay-controlling and a TCP-competitive mode, Nimbus is more robust at correctly detecting the nature of cross traffic, and unlike Copa, it is usable by a variety of delay-based and TCP-competitive methods.
by Prateesh Goyal.
S.M. in Computer Science and Engineering

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9

Cai, Kan. "Interference mitigation and detection in wifi networks under congestion". Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53933.

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In IEEE 802.11, nodes regulate access to the airspace they share in a decentralized fashion using CSMA/CA. The goal of this approach is to share the common airspace fairly and efficiently without requiring centralized channel administration or direct coordination among peer nodes. However, it is well known that strong interference, as consequence of this de-centralized coordination scheme, can lead to extremely unfair network bandwidth allocation between competing devices. Interference detection and mitigation has posed great challenges. The cause of interference is complicated, involving many networking factors such as topology and traffic, and the interference relationship changes all the time. This thesis addresses these challenges by proposing a throttling based interference mitigation system (Shaper) and an online passive interference detection system (VOID). The main contribution of this thesis is to point out the correlated relationship between interference and congestion. First, this thesis provides a more thorough analysis on the impact of node topology, traffic type and signal strength on wireless performance. We came up with 9 UDP models and 10 TCP models just for two competing flow scenarios. The outcome of wireless interference can get harder to predict, however, as we introduce more factors into the interference model such as more competing nodes, sending rate, signal propagation model, etc. On the other hand, this thesis identifies the immediate cause to the unfair bandwidth distribution under interference: 802.11 network congestion. We observed and explained that all competing devices are able to perform well regardless of topology or traffic class, as long as there is sufficiently more bandwidth than the aggregate throughput demands. Therefore, we propose to trade the aggregate throughput to mitigate the impact of interference and prove its effectiveness through simulation and emulation. Finally, the key to successful addressing the interference is an accurate and fast interference detection mechanism and this thesis proposes such a system called VOID. It deploys the correlation between congestion and interference to infer the interference relationship from the ip-layer throughput variations. It is fast, accurate and more importantly, very easy to deploy in existing WiFi networks.
Science, Faculty of
Computer Science, Department of
Graduate

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10

Thorri, Sigurdsson Thorsteinn. "Road traffic congestion detection and tracking with Spark Streaming analytics". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254874.

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Road traffic congestion causes several problems. For instance, slow moving traffic in congested regions poses a safety hazard to vehicles approaching the congested region and increased commuting times lead to higher transportation costs and increased pollution.The work carried out in this thesis aims to detect and track road traffic congestion in real time. Real-time road congestion detection is important to allow for mechanisms to e.g. improve traffic safety by sending advanced warnings to drivers approaching a congested region and to mitigate congestion by controlling adaptive speed limits. In addition, the tracking of the evolution of congestion in time and space can be a valuable input to the development of the road network. Traffic sensors in Stockholm’s road network are represented as a directed weighted graph and the congestion detection problem is formulated as a streaming graph processing problem. The connected components algorithm and existing graph processing algorithms originally used for community detection in social network graphs are adapted for the task of road congestion detection. The results indicate that a congestion detection method based on the streaming connected components algorithm and the incremental Dengraph community detection algorithm can detect congestion with accuracy at best up to 94% for connected components and up to 88% for Dengraph. A method based on hierarchical clustering is able to detect congestion while missing details such as shockwaves, and the Louvain modularity algorithm for community detection fails to detect congested regions in the traffic sensor graph.Finally, the performance of the implemented streaming algorithms is evaluated with respect to the real-time requirements of the system, their throughput and memory footprint.
Vägtrafikstockningar orsakar flera problem. Till exempel utgör långsam trafik i överbelastade områden en säkerhetsrisk för fordon som närmar sig den överbelastade regionen och ökade pendeltider leder till ökade transportkostnader och ökad förorening.Arbetet i denna avhandling syftar till att upptäcka och spåra trafikstockningar i realtid. Detektering av vägtrafiken i realtid är viktigt för att möjliggöra mekanismer för att t.ex. förbättra trafiksäkerheten genom att skicka avancerade varningar till förare som närmar sig en överbelastad region och för att mildra trängsel genom att kontrollera adaptiva hastighetsgränser. Dessutom kan spårningen av trängselutveckling i tid och rum vara en värdefull inverkan på utvecklingen av vägnätet. Trafikavkännare i Stockholms vägnät representeras som en riktad vägd graf och problemet med överbelastningsdetektering är formulerat som ett problem med behandling av flödesgrafer. Den anslutna komponentalgoritmen och befintliga grafbehandlingsalgoritmer som ursprungligen användes för communitydetektering i sociala nätgravar är anpassade för uppgiften att detektera vägtäthet. Resultaten indikerar att en överbelastningsdetekteringsmetod baserad på den strömmande anslutna komponentalgoritmen och den inkrementella Dengraph communitydetekteringsalgoritmen kan upptäcka överbelastning med noggrannhet i bästa fall upp till 94% för anslutna komponenter och upp till 88% för Dengraph. En metod baserad på hierarkisk klustring kan detektera överbelastning men saknar detaljer som shockwaves, och Louvain modularitetsalgoritmen för communitydetektering misslyckas med att detektera överbelastade områden i trafiksensorns graf.Slutligen utvärderas prestandan hos de implementerade strömmalgoritmerna med hänsyn till systemets realtidskrav, deras genomströmning och minnesfotavtryck.

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11

Jarrett, Wayne O'Brian. "Congestion detection within multi-service TCP/IP networks using wavelets". Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1444757/.

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Using passive observation within the multi-service TCP/IP networking domain, we have developed a methodology that associates the frequency composition of composite traffic signals with the packet transmission mechanisms of TCP. At the core of our design is the Discrete Wavelet Transform (DWT), used to temporally localise the frequency variations of a signal. Our design exploits transmission mechanisms (including Fast Retransmit/Fast Recovery, Congestion Avoidance, Slow start, and Retransmission Timer Expiry with Exponential Back off.) that are activated in response to changes within this type of network environment. Manipulation of DWT output, combined with the use of novel heuristics permits shifts in the frequency spectrum of composite traffic signals to be directly associated with the former. Our methodology can be adapted to accommodate composite traffic signals that contain a substantial proportion of data originating from non-rate adaptive sources often associated with Long Range Dependence and Self Similarity (e.g. Pareto sources). We demonstrate the methodology in two ways. Firstly, it is used to design a congestion indicator tool that can operate with network control mechanisms that dissipate congestion. Secondly, using a queue management algorithm (Random Early Detection) as a candidate protocol, we show how our methodology can be adapted to produce a performance-monitoring tool. Our approach provides a solution that has both low operational and implementation intrusiveness with respect to existing network infrastructure. The methodology requires a single parameter (i.e. the arrival rate of traffic at a network node), which can be extracted from almost all network-forwarding devices. This simplifies implementation. Our study was performed within the context of fault management with design requirements and constraints arising from an in depth study of the Fault Management Systems (FMS) used by British Telecomm on regional UK networks up to February 2000.

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Ferrer, Pérez Joan Lluís. "DESIGN OF EFFICIENT PACKET MARKING-BASED CONGESTION MANAGEMENT TECHNIQUES FOR CLUSTER INTERCONNECTS". Doctoral thesis, Universitat Politècnica de València, 2012. http://hdl.handle.net/10251/18197.

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El crecimiento de los computadores paralelos basados en redes de altas prestaciones ha aumentado el interés y esfuerzo de la comunidad investigadora en desarrollar nuevas técnicas que permitan obtener el mejor rendimiento de estas redes. En particular, el desarrollo de nuevas técnicas que permitan un encaminamiento eficiente y que reduzcan la latencia de los paquetes, aumentando así la productividad de la red. Sin embargo, una alta tasa de utilización de la red podría conllevar el que se conoce como "congestión de red", el cual puede causar una degradación del rendimiento. El control de la congestión en redes multietapa es un problema importante que no está completamente resuelto. Con el fin de evitar la degradación del rendimiento de la red cuando aparece congestión, se han propuesto diferentes mecanismos para el control de la congestión. Muchos de estos mecanismos están basados en notificación explícita de la congestión. Para este propósito, los switches detectan congestión y dependiendo de la estrategia aplicada, los paquetes son marcados con la finalidad de advertir a los nodos origenes. Como respuesta, los nodos origenes aplican acciones correctivas para ajustar su tasa de inyección de paquetes. El propósito de esta tesis es analizar las diferentes estratégias de detección y corrección de la congestión en redes multietapa, y proponer nuevos mecanismos de control de la congestión encaminados a este tipo de redes sin descarte de paquetes. Las nuevas propuestas están basadas en una estrategia más refinada de marcaje de paquetes en combinación con un conjunto de acciones correctivas justas que harán al mecanismo capaz de controlar la congestión de manera efectiva con independencia del grado de congestión y de las condiciones de tráfico.
Ferrer Pérez, JL. (2012). DESIGN OF EFFICIENT PACKET MARKING-BASED CONGESTION MANAGEMENT TECHNIQUES FOR CLUSTER INTERCONNECTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/18197
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13

Brakmo, Lawrence Sivert. "End-to-end congestion detection and avoidance in wide area networks". Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282192.

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As human dependence on wide area networks like the Internet increases, so does contention for the network's resources. This contention has noticeably affected the performance of these networks, reducing their usability. This dissertation addresses this problem in two ways. First, it describes TCP Vegas, a new implementation of TCP that is distinguished from current TCP implementations by containing a new congestion detection and avoidance mechanism. This mechanism was designed to work in currently available wide area networks and achieves between 37% and 71% better throughput on the Internet, with one-fifth to one-half the losses, as compared to the current implementation of TCP. Second, it describes x-Sim, a network simulator based on the x-kernel, that is able to simulate the topologies and traffic patterns of large scale networks. The usefulness of the simulator to analyze and debug network components is illustrated throughout this dissertation.

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RezaeiDivkolaei, Pouya. "DETECTION, CLASSIFICATION, AND LOCATION IDENTIFICATION OF TRAFFIC CONGESTION FROM TWITTER STREAM ANALYSIS". OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2257.

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Social media today is an important source of information about various events happening around the world. Among various social networking platforms, microtext based ones such as Twitter are of special interest as they are also a rich source of real-time events. In this thesis, our goal is to study the effectiveness of using Twitter as a social sensor for obtaining real-time information on road traffic conditions. Specifically, we focus on: i) identifying tweets that contain traffic event related information, ii) classify such tweets into six main groups of accident, fire, road construction, police activities, weather and others, iii) extract fine-grained location information about the traffic incident by analyzing tweet text. Our experimental results show that using Twitter as a social sensor for obtaining rich information about traffic events is indeed a promising approach. We show that we can correctly detect traffic related tweets with an accuracy of 81%. Moreover, the accuracy of correctly classifying traffic related tweets into one of the six categories is 97%. Lastly, our experimental results show that using only geo-tags of tweets is not sufficient for fine-grained localization of traffic incidents due to two reasons: i) a vast majority of traffic related tweets do not contain geo-tags, and ii) the location mentioned in the tweet text and the geo-tag of a tweet do not always agree. Such observations prove that fine-grained localization of traffic incidents from tweet must also include analysis of the tweet text using Natural Language Processing techniques.

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15

Anbaroglu, B. "Spatio-temporal clustering for non-recurrent traffic congestion detection on urban road networks". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1408826/.

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Non-Recurrent Congestion events (NRCs) frustrate commuters, companies and traffic operators because they cause unexpected delays. Most existing studies consider NRCs to be an outcome of incidents on motorways. The differences between motorways and urban road networks, and the fact that incidents are not the only cause of NRCs, limit the usefulness of existing automatic incident detection methods for identifying NRCs on an urban road network. This thesis contributes to the literature by developing an NRC detection methodology to support the accurate detection of NRCs on large urban road networks. To achieve this, substantially high Link Journey Time estimates (LJTs) on adjacent links that occur at the same time are clustered. Substantially high LJTs are defined in two different ways: (i) those LJTs that are greater than a threshold, (ii) those LJTs that belong to a statistically significant Space-Time Region (STR). These two different ways of defining the term ‘substantially high LJT’ lead to different NRC detection methods. To evaluate these methods, two novel criteria are proposed. The first criterion, high-confidence episodes, assesses to what extent substantially high LJTs that last for a minimum duration are detected. The second criterion, the Localisation Index, assesses to what extent detected NRCs could be related to incidents. The proposed NRC detection methodology is tested for London’s urban road network, which consists of 424 links. Different levels of travel demand are analysed in order to establish a complete understanding of the developed methodology. Optimum parameter settings of the two proposed NRC detection methods are determined by sensitivity analysis. Related to the first method, LJTs that are at least 40% higher than their expected values are found to maintain the best balance between the proposed evaluation criteria for detecting NRCs. Related to the second method, it is found that constructing STRs by considering temporal adjacencies rather than spatial adjacencies improves the performance of the method. These findings are applied in real life situations to demonstrate the advantages and limitations of the proposed NRC detection methods. Traffic operation centres could readily start using the proposed NRC detection methodology. In this way, traffic operators could be able to quantify the impact of incidents and develop effective NRC reduction strategies.

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Ghimire, Rajiv y Mustafa Noor. "Evaluation and Optimization of Quality of Service (QoS) In IP Based Networks". Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3920.

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The purpose of this thesis is to evaluate and analyze the performance of RED (Random Early Detection) algorithm and our proposed RED algorithm. As an active queue management RED has been considered an emerging issue in the last few years. Quality of service (QoS) is the latest issue in today’s internet world. The name QoS itself signifies that special treatment is given to the special traffic. With the passage of time the network traffic grew in an exponential way. With this, the end user failed to get the service for what they had paid and expected for. In order to overcome this problem, QoS within packet transmission came into discussion in internet world. RED is the active queue management system which randomly drops the packets whenever congestion occurs. It is one of the active queue management systems designed for achieving QoS. In order to deal with the existing problem or increase the performance of the existing algorithm, we tried to modify RED algorithm. Our purposed solution is able to minimize the problem of packet drop in a particular duration of time achieving the desired QoS. An experimental approach is used for the validation of the research hypothesis. Results show that the probability of packet dropping in our proposed RED algorithm during simulation scenarios significantly minimized by early calculating the probability value and then by calling the pushback mechanism according to that calculated probability value.
+46739567385(Rajiv), +46762125426(Mustafa)

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Khatri, Chandra P. "Real-time road traffic information detection through social media". Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53889.

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In current study, a mechanism to extract traffic related information such as congestion and incidents from textual data from the internet is proposed. The current source of data is Twitter, however, the same mechanism can be extended to any kind of text available on the internet. As the data being considered is extremely large in size automated models are developed to stream, download, and mine the data in real-time. Furthermore, if any tweet has traffic related information then the models should be able to infer and extract this data. To pursue this task, Artificial Intelligence, Machine Learning, and Natural Language Processing techniques are used. These models are designed in such a way that they are able to detect the traffic congestion and traffic incidents from the Twitter stream at any location. Currently, the data is collected only for United States. The data is collected for 85 days (50 complete and 35 partial) randomly sampled over the span of five months (September, 2014 to February, 2015) and a total of 120,000 geo-tagged traffic related tweets are extracted, while six million geo-tagged non-traffic related tweets are retrieved. The classification models for detection of traffic congestion and incidents are trained on this dataset. Furthermore, this data is also used for various kinds of spatial and temporal analysis. A mechanism to calculate level of traffic congestion, safety, and traffic perception for cities in U.S. is proposed. Traffic congestion and safety rankings for the various urban areas are obtained and then they are statistically validated with existing widely adopted rankings. Traffic perception depicts the attitude and perception of people towards the traffic. It is also seen that traffic related data when visualized spatially and temporally provides the same pattern as the actual traffic flows for various urban areas. When visualized at the city level, it is clearly visible that the flow of tweets is similar to flow of vehicles and that the traffic related tweets are representative of traffic within the cities. With all the findings in current study, it is shown that significant amount of traffic related information can be extracted from Twitter and other sources on internet. Furthermore, Twitter and these data sources are freely available and are not bound by spatial and temporal limitations. That is, wherever there is a user there is a potential for data.

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18

Qu, Yang. "Mixed Signal Detection, Estimation, and Modulation Classification". Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1576615989584971.

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Chuku, Ejike E. "Security and Performance Engineering of Scalable Cognitive Radio Networks. Sensing, Performance and Security Modelling and Analysis of ’Optimal’ Trade-offs for Detection of Attacks and Congestion Control in Scalable Cognitive Radio Networks". Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18448.

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A Cognitive Radio Network (CRN) is a technology that allows unlicensed users to utilise licensed spectrum by detecting an idle band through sensing. How- ever, most research studies on CRNs have been carried out without considering the impact of sensing on the performance and security of CRNs. Sensing is essential for secondary users (SUs) to get hold of free band without interfering with the signal generated by primary users (PUs). However, excessive sensing time for the detection of free spectrum for SUs as well as extended periods of CRNs in an insecure state have adverse effects on network performance. Moreover, a CRN is very vulnerable to attacks as a result of its wireless nature and other unique characteristics such as spectrum sensing and sharing. These attacks may attempt to eavesdrop or modify the contents of packets being transmitted and they could also deny legitimate users the opportunity to use the band, leading to underutilization of the spectrum space. In this context, it is often challenging to differentiate between networks under Denial of Service (DoS) attacks from those networks experiencing congestion. This thesis employs a novel Stochastic Activity Network (SAN) model as an effective analytic tool to represent and study sensing vs performance vs security trade-offs in CRNs. Specifically, an investigation is carried out focusing on sensing vs security vs performance trade-offs, leading to the optimization of the spectrum band’s usage. Moreover, consideration is given either when a CRN experiencing congestion and or it is under attack. Consequently, the data delivery ratio (PDR) is employed to determine if the network is under DoS attack or experiencing congestion. In this context, packet loss probability, queue length and throughput of the transmitter are often used to measure the PDR with reference to interarrival times of PUs. Furthermore, this thesis takes into consideration the impact of scalability on the performance of the CRN. Due to the unpredictable nature of PUsactivities on the spectrum, it is imperative for SUs to swiftly utilize the band as soon as it becomes available. Unfortunately, the CRN models proposed in literature are static and unable to respond effectively to changes in service demands. To this end, a numerical simulation experiment is carried out to determine the impact of scalability towards the enhancement of nodal CRN sensing, security and performance. Atthe instant the band becomes idle and there are requests by SUs waiting for encryption and transmission, additional resources are dynamically released in order to largely utilize the spectrum space before the reappearance of PUs. These additional resources make the same service provision, such as encryption and intrusion detection, as the initial resources. To this end,SAN model is proposed in order to investigate the impact of scalability on the performance of CRN. Typical numerical simulation experiments are carried out, based on the application of the Mobius Petri Net Package to determine the performance of scalable CRNs (SCRNs) in comparison with unscalable CRNs (UCRNs) and associated interpretations are made.

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20

Olaleye, Olufunke I. "Symbiotic Audio Communication on Interactive Transport". Kent State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=kent1176438067.

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21

Movsesyan, Aleksandr. "Reliable Ethernet". DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/602.

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Networks within data centers, such as connections between servers and disk arrays, need lossless flow control allowing all packets to move quickly through the network to reach their destination. This paper proposes a new algorithm for congestion control to satisfy the needs of such networks and to answer the question: Is it possible to provide circuit-less reliability and flow control in an Ethernet network? TCP uses an end-to-end congestion control algorithm, which is based on end-to-end round trip time (RTT). Therefore its flow control and error detection/correction approach is dependent on end-to-end RTT. Other approaches utilize specialized data link layer networks such as InfiniBand and Fibre Channel to provide network reliability. The algorithm proposed in this thesis builds on the ubiquitous Ethernet protocol to provide reliability at the data link layer without the overhead and cost of the specialized networks or the delay induced by TCP’s end-to-end approach. This approach requires modifications to the Ethernet switches to implement a back pressure based flow control algorithm. This back pressure algorithm utilizes a modified version of the Random Early Detection (RED) algorithm to detect congestion. Our simulation results show that the algorithm can quickly recover from congestion and that the average latency of the network is close to the average latency when no congestion is present. With correct threshold and alpha values, buffer sizes in the network and on the source nodes can be kept small to allow little needed additional hardware to implement the system.

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22

Swaro, James E. "A Heuristic-Based Approach to Real-Time TCP State and Retransmission Analysis". Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1448030769.

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23

Elfstadius, Martin y Daniel Gecer. "Method to Detect and Measure Potential Market Power Caused by Transmission Network Congestions on Electricity Markets". Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12133.

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This thesis is based on studies of the deregulated electricity markets located in the United States of America. The problem statement of the thesis evolved continuously throughout our initial period of research. Focus was finally put on monitoring and detection of potential market power caused by congestion in the transmission network. The existence of market power is a serious concern in today’s electric energy markets. A system that monitors the trading is needed and much research and many proposals on how to deal with this problem have been introduced over the years. We focus on some of these approaches and develop an approach of our own, which we call “Monopolistic Energy Calculation”. We adopt the idea to identify participants with the ability to raise prices without losing market share. An ability that should not be present on a competitive market. We take this idea further by identifying participants with the ability to make considerable price raises without losing all market shares. We propose a way to calculate the remaining market shares (Monopolistic Energy Levels) after a large price raise. These calculated levels of energy, that are only deliverable by a certain participant or by a certain group of participants, are caused by the active congestions in the network.

The approach detects the amounts of these energy levels and the location in the network at which they are present. This is a prospective method if used with a prediction of the following day’s demand, which is regularly available with high accuracy. The method can also be used for monitoring purposes to identify critical situations in real-time. The method is implemented and two sets of simulations are done in which we explain and evaluate the approach. The results are promising and the correlation between “Monopolistic Energy” and market power is confirmed.

Detta examensarbete är baserat på studier av de deregulerade electricitsmarknaderna i USA. Problemformuleringen var i början av detta arbete inte definitiv, utan utvecklades under en längre inledande fas av forskningsarbete. Slutligen kunde vi faställa att detektion av potentiell marknadskraft på elektricitetsmarknaden, orsakat av överbelastningar i transmissionnätverket, var av särskilt intresse. Ett system som övervakar handeln och förekomster av orättvisor orsakat av detta är nödvändigt. Det har de senaste åren gjorts mycket forskning inom detta område. Baserat på denna forskning utvecklades sedan ett eget förslag, som vi kallar ”Monopolistic Energy Calculations”. Vissa tidigare förslag på hur problemet kan angripas blev av särskilt intresse. En idé från dessa var att identifiera marknadsaktörer med förmågan att höja priser utan att förlora marknadsandelar, en icke önskvärd egenskap hos aktörer då en konkurrenskraftig marknad är eftertraktad.

Vi tar denna idé ett steg längre genom att identifiera marknadsaktörer med förmågan att höja priser signifikant utan att förlora alla marknadsandelar. Vi föreslår ett sätt att beräkna dessa energinivåer som endast är möjliga att levereras av en eller ett fåtal särskilda aktörer, som direkt följd av de aktiva stockningarna i nätverket, under antagandet av en inelastisk efterfrågan. Vi föreslår ett sätt att beräkna de återstående marknadsandelarna (Monopolistic Energy Levels) efter en stor prishöjning. Vår metod beräknar mängden av denna energi och var i nätverket dessa mängder förekommer. Denna metod kan sia om framtida problem om en estimering av morgondagens efterfråga används. Sådana estimeringar görs idag

regelbundet med hög träffsäkerhet. Metoden kan även användas i realtid för upptäckt av kritiska marknadssituationer. Simuleringar av detta görs som förklarar vår lösning och utvärderar den. Resultaten är lovande och korrelationen mellan ”Monopolistisk Energi” och marknadskraft är bekräftade.

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24

Ayran, Orhan. "Reliable Real-time Video Communication In Wireless Sensor Networks". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608233/index.pdf.

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Many wireless sensor network (WSN) applications require efficient multimedia communication capabilities. However, the existing communication protocols in the literature mainly aim to achieve energy efficiency and reliability objectives and do not address the multimedia communication challenges in WSN. In this thesis, comprehensive performance evaluation of the existing transport protocols is performed and it has been shown that the existing proposals achieve very poor performance in terms of large set of metrics such as packet delivery rate, end-to-end packet delay, bandwidth and energy efficiency, frame peak signal-to-noise ratio (PSNR), delay-bounded frame PSNR, frame delivery probability, frame end-to-end delay and jitter. Based on these results, an energy-efficient real-time and reliable video sensor communication protocol (VSCP) is introduced for WSN. VSCP estimates video quality perceived by sink using lost segments of video frames and aims to maintain the overall reliability at a given level with minimum energy expenditure. Source data rates are adjusted in a quality adaptable manner according to the network conditions and the overall reliability computed by sink. QSC (quality scalable coding) encoding technique is used to produce a nearly constant quality video at a given maximum data rate during adjustment of source data rates. Performance evaluations show that VSCP protocol significantly outperforms the existing proposals in terms of multimedia communication performance metrics in WSN.

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25

Abdel-Jaber, Hussein F. "Performance Modelling and Evaluation of Active Queue Management Techniques in Communication Networks. The development and performance evaluation of some new active queue management methods for internet congestion control based on fuzzy logic and random early detection using discrete-time queueing analysis and simulation". Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4261.

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Since the field of computer networks has rapidly grown in the last two decades, congestion control of traffic loads within networks has become a high priority. Congestion occurs in network routers when the number of incoming packets exceeds the available network resources, such as buffer space and bandwidth allocation. This may result in a poor network performance with reference to average packet queueing delay, packet loss rate and throughput. To enhance the performance when the network becomes congested, several different active queue management (AQM) methods have been proposed and some of these are discussed in this thesis. Specifically, these AQM methods are surveyed in detail and their strengths and limitations are highlighted. A comparison is conducted between five known AQM methods, Random Early Detection (RED), Gentle Random Early Detection (GRED), Adaptive Random Early Detection (ARED), Dynamic Random Early Drop (DRED) and BLUE, based on several performance measures, including mean queue length, throughput, average queueing delay, overflow packet loss probability, packet dropping probability and the total of overflow loss and dropping probabilities for packets, with the aim of identifying which AQM method gives the most satisfactory results of the performance measures. This thesis presents a new AQM approach based on the RED algorithm that determines and controls the congested router buffers in an early stage. This approach is called Dynamic RED (REDD), which stabilises the average queue length between minimum and maximum threshold positions at a certain level called the target level to prevent building up the queues in the router buffers. A comparison is made between the proposed REDD, RED and ARED approaches regarding the above performance measures. Moreover, three methods based on RED and fuzzy logic are proposed to control the congested router buffers incipiently. These methods are named REDD1, REDD2, and REDD3 and their performances are also compared with RED using the above performance measures to identify which method achieves the most satisfactory results. Furthermore, a set of discrete-time queue analytical models are developed based on the following approaches: RED, GRED, DRED and BLUE, to detect the congestion at router buffers in an early stage. The proposed analytical models use the instantaneous queue length as a congestion measure to capture short term changes in the input and prevent packet loss due to overflow. The proposed analytical models are experimentally compared with their corresponding AQM simulations with reference to the above performance measures to identify which approach gives the most satisfactory results. The simulations for RED, GRED, ARED, DRED, BLUE, REDD, REDD1, REDD2 and REDD3 are run ten times, each time with a change of seed and the results of each run are used to obtain mean values, variance, standard deviation and 95% confidence intervals. The performance measures are calculated based on data collected only after the system has reached a steady state. After extensive experimentation, the results show that the proposed REDD, REDD1, REDD2 and REDD3 algorithms and some of the proposed analytical models such as DRED-Alpha, RED and GRED models offer somewhat better results of mean queue length and average queueing delay than these achieved by RED and its variants when the values of packet arrival probability are greater than the value of packet departure probability, i.e. in a congestion situation. This suggests that when traffic is largely of a non bursty nature, instantaneous queue length might be a better congestion measure to use rather than the average queue length as in the more traditional models.

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26

Gungor, Vehbi Cagri. "Real-Time and Reliable Communication in Wireless Sensor and Actor Networks". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16366.

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Wireless Sensor and Actor Networks (WSANs) are composed of heterogeneous nodes referred to as sensors and actors. Sensors are low-cost, low-power, multi-functional devices that communicate untethered in short distances. Actors collect and process sensor data and perform appropriate actions on the environment. Hence, actors are resource-rich devices equipped with higher processing and transmission capabilities, and longer battery life. In WSANs, the collaborative operation of the sensors enables the distributed sensing of a physical phenomenon. After sensors detect an event in the deployment field, the event data is distributively processed and transmitted to the actors, which gather, process, and eventually reconstruct the event data. WSANs can be considered a distributed control system designed to react to sensor information with an effective and timely action. For this reason, in WSANs it is important to provide real-time coordination and communication to guarantee timely execution of the right actions. The energy efficiency of the networking protocols is also a major concern, since sensors are resource-constrained devices. Hence, the unique characteristics and challenges coupled with the limitations of wireless environments call for novel networking protocols for WSANs. The objective of this research is to develop new communication protocols to support real-time and reliable event data delivery with minimum energy consumption in WSANs. The proposed solutions dynamically adjust their protocol configurations to adapt to the heterogeneous characteristics of WSANs. Specifically, the interactions between contention resolution and congestion control mechanisms as well as the physical layer effects in WSANs are investigated. Next, a real-time and reliable transport protocol is proposed to achieve reliable and timely event detection with congestion avoidance in WSANs. In addition, a resource-aware and link-quality-based routing protocol is presented to address energy limitations and link quality variations in WSANs. Finally, the electric utility automation applications of WSANs are presented and the propagation characteristics of wireless channel in different utility environments are investigated.

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27

Joshi, Raoul y Per Sundström. "WCDMA Cell Load Control in a High-speed Train Scenario : Development of Proactive Load Control Strategies". Thesis, Linköpings universitet, Kommunikationssystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-84635.

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Load control design is one of the major cornerstones of radio resource management in today's UMTS networks. A WCDMA cell's ability to utilize available spectrum efficiently, maintain system stability and deliver minimum quality of service (QoS) requirements to in-cell users builds on the algorithms employed to manage the load. Admission control (AC) and congestion control (CC) are the two foremost techniques used for regulating the load, and differing environments will place varying requirements on the AC and CC schemes to optimize the QoS for the entire radio network. This thesis studies a real-life situation where cells are put under strenuous conditions, investigates the degrading effects a high-speed train has on the cell's ability to maintain acceptable levels of QoS, and proposes methods for mitigating these effects. The scenario is studied with regard to voice traffic where the limiting radio resource is downlink power. CC schemes that take levels of fairness into account between on-board train users and outdoor users are proposed and evaluated through simulation. Methods to anticipatorily adapt radio resource management (RRM) in a cell to prepare for a train is proposed and evaluated through simulation. A method to detect a high-speed train in a cell, and the users on it, is outlined and motivated but not simulated. Simulation results are promising but not conclusive. The suggested CC schemes show a surprising tendency towards an increase in congestion avoidance performance. Proactive RRM shows a significant increase in QoS for on-board users. No negative effects to users in the macro environment is noticed, with regard to the studied metrics.

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28

Lopez, Pacheco Dino Martín. "Propositions pour une version robuste et inter-operable d' eXpliciit Control Protocol dans des réseaux hétérogènes à haut débit". Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2008. http://tel.archives-ouvertes.fr/tel-00295072.

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Les protocoles de contrôle de congestion ont pour but d'autoriser un partage équitable des ressources entre les utilisateurs et d'éviter la congestion dans les réseaux de communications. Dans cette thèse, nous avons commencé par comparer la performance des différents protocoles dans des modèles de réseaux qui intègrent la notion de variation de bande passante produit par l'agrégation/désagrégation des flux ainsi que la présence des mécanismes fournissant de la Qualité du Service.

Ainsi, nous avons montré que ce sont les protocoles basés sur l'assistance de routeurs fournissant aux émetteurs un taux d'émission explicite (``Explicit Rate Notification'' - ERN) partagent mieux les ressources du réseaux entre les utilisateurs et évitent mieux la congestion que les protocoles de bout-en-bout (comme les protocoles basés sur TCP). Cependant, l'absence d'inter-opérabilité des protocoles ERN avec les routeurs non-ERN (par exemple, les routeurs DropTail) et les protocoles de congestion de bout-en-bout (comme TCP), empêche leur mise en place dans les réseaux actuels.

Pour résoudre les problèmes d'inter-opérabilité des protocoles ERN avec des routeurs non-ERN, nous avons proposé des stratégies et des mécanismes capables de détecter les groupes des routeurs non-ERN entre deux routeurs ERN, d'estimer la bande passante minimale disponible à l'intérieur de ces groupes, et de créer des routeurs virtuels qui remplacent chaque groupe de routeurs non-ERN par un routeur ERN.

Nous avons également proposé un système d'équité intra-protocolaire entre les protocoles ERN et les protocoles de bout-en-bout. Avec notre solution, les routeurs ERN dans une première étape estiment les besoins en terme de bande passante des flux ERN et non-ERN puis, dans une deuxième étape, limitent le débit des flux non-ERN en rejetant leurs paquets avec une probabilité qui dépend des résultats de la première étape.

Le succès des protocoles ERN est basé sur l'information de rétroalimentation, calculée par les routeurs, et renvoyée par les récepteurs aux émetteurs. Nous avons montré que les protocoles ERN deviennent instables face aux pertes de l'information de rétroalimentation dans des environnements hétérogènes et à bande passante variable. Dans ce cadre là, nous avons proposé une nouvelle architecture qui améliore la robustesse des protocoles ERN, ainsi que la réactivité des émetteurs.

Toutes nos propositions, applicables sur d'autres protocoles ERN, ont été expérimentées et validées sur le protocole eXplicit Control Protocol (XCP). Ainsi, nous avons montré que nos solutions surmontent les défis concernant les problèmes d'inter-opérabilité des protocoles ERN dans un grand nombre des scénarios et de topologies.

De cette façon, nous avons développé les bases pour bénéficier d'un protocole ERN capable d'être déployé dans des réseaux hétérogènes à grand produit bande passante - délai où le transfert de grande quantité des données est nécessaire, tels que les réseaux de grilles (ex. GÉANT).

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29

"A multi-objective particle swarm optimized fuzzy logic congestion detection and dual explicit notification mechanism for IP networks". Thesis, 2006. http://hdl.handle.net/10413/2237.

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The Internet has experienced a tremendous growth over the past two decades and with that growth have come severe congestion problems. Research efforts to alleviate the congestion problem can broadly be classified into three groups: Cl) Router based congestion detection; (2) Generation and transmission of congestion notification signal to the traffic sources; (3) End-to-end algorithms which control the flow of traffic between the end hosts. This dissertation has largely addressed the first two groups which are basically router initiated. Router based congestion detection mechanisms, commonly known as Active Queue Management (AQM), can be classified into two groups: conventional mathematical analytical techniques and fuzzy logic based techniques. Research has shown that fuzzy logic techniques are more effective and robust compared to the conventional techniques because they do not rely on the availability of a precise mathematical model of Internet. They use linguistic knowledge and are, therefore, better placed to handle the complexities associated with the non-linearity and dynamics of the Internet. In spite of all these developments, there still exists ample room for improvement because, practically, there has been a slow deployment of AQM mechanisms. In the first part of this dissertation, we study the major AQM schemes in both the conventional and the fuzzy logic domain in order to uncover the problems that have hampered their deployment in practical implementations. Based on the findings from this study, we model the Internet congestion problem as a multi-objective problem. We propose a Fuzzy Logic Congestion Detection (FLCD) which synergistically combines the good characteristics of the fuzzy approaches with those of the conventional approaches. We design the membership functions (MFs) of the FLCD algorithm automatically by using Multi-objective Particle Swarm Optimization (MOPSO), a population based stochastic optimization algorithm. This enables the FLCD algorithm to achieve optimal performance on all the major objectives of Internet congestion control. The FLCD algorithm is compared with the basic Fuzzy Logic AQM and the Random Explicit Marking (REM) algorithms on a best effort network. Simulation results show that the FLCD algorithm provides high link utilization whilst maintaining lower jitter and packet loss. It also exhibits higher fairness and stability compared to its basic variant and REM. We extend this concept to Proportional Differentiated Services network environment where the FLCD algorithm outperforms the traditional Weighted RED algorithm. We also propose self learning and organization structures which enable the FLCD algorithm to achieve a more stable queue, lower packet losses and UDP traffic delay in dynamic traffic environments on both wired and wireless networks. In the second part of this dissertation, we present the congestion notification mechanisms which have been proposed for wired and satellite networks. We propose an FLCD based dual explicit congestion notification algorithm which combines the merits of the Explicit Congestion Notification (ECN) and the Backward Explicit Congestion Notification (BECN) mechanisms. In this proposal, the ECN mechanism is invoked based on the packet marking probability while the BECN mechanism is invoked based on the BECN parameter which helps to ensure that BECN is invoked only when congestion is severe. Motivated by the fact that TCP reacts to tbe congestion notification signal only once during a round trip time (RTT), we propose an RTT based BECN decay function. This reduces the invocation of the BECN mechanism and resultantly the generation of reverse traffic during an RTT. Compared to the traditional explicit notification mechanisms, simulation results show that the new approach exhibits lower packet loss rates and higher queue stability on wired networks. It also exhibits lower packet loss rates, higher good-put and link utilization on satellite networks. We also observe that the BECN decay function reduces reverse traffic significantly on both wired and satellite networks while ensuring that performance remains virtually the same as in the algorithm without BECN traffic reduction.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.

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Huang, Chia-Yu y 黃嘉佑. "qtECN – An Improved Explicit Congestion Notification Algorithm". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/21745296779867025114.

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碩士
國立中興大學
資訊科學與工程學系
96
ECN (Explicit Congestion Notification) is an active queue management scheme for network routers. The purpose of this protocol is mainly aimed at solving the problem of queue management and relieving the congestion phenomenon on the network. Compared with the traditional method that drops packets when buffer is full, ECN could improve the network performance by noticing the TCP sender to reduce its sending rate in advance, i.e., before the congestion really happened on the network. However, in ECN algorithm, TCP sender could only invoke the same mechanism as that when it encounters a packet loss event and thus have the sending rate excessively reduced. In addition, the rule of ECN marking/dropping packets in routers will cause the transmission throughput and delay to compete with each other. 　　In this thesis, we propose an improved ECN algorithm, named qtECN (Quantitatively Explicit Congestion Notification). The qtECN algorithm is based on the original design of ECN but modifies the rule that ECN uses for packets marking and dropping. Besides, qtECN adds additional information in the randomly marked packets to inform the TCP sender of the loading of the congested router, so the TCP sender could adjust its sending rate accordingly. The experimental results show that qtECN has a better performance at goodput, packet loss rate and delay jitter with acceptable transmission delay. In addition, packets’ dropping due to full queue is nearly zero when using qtECN. It means qtECN is more suitable for wired-wireless hybrid network than any other existing AQM schemes. In summary, applying the design of qtECN could make the performance of network further improved when unavoidable congestion happened in the router.

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Devkota, Prajjwal Prasad. "Performance of Quantized Congestion Notification in TCP Incast in Data Centers". Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7852.

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This thesis analyzes the performance of Quantized Congestion Notification (QCN) during data access from clustered servers in data centers. The reasons why QCN does not perform adequately in these situations are examined and several modifications are proposed to the protocol to improve its performance in these scenarios. The causes of QCN performance degradation are traced to flow rate variability, and it is shown that adaptive sampling at the switch and adaptive self-increase of flow rates at the QCN rate limiter significantly enhance QCN performance in a TCP Incast setup. The performance of QCN is compared against TCP modifications in a heterogeneous environment, and it is shown that modifications to QCN yield better performance. Finally, the performance of QCN with the proposed modifications is compared with that of unmodified QCN in other workloads to show that the modifications do not negatively affect QCN performance in general.

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32

Hsueh, Yuan-Yun y 薛元昀. "Smartphone with Fall-detection and Emergency Notification". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/23211389637573307841.

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碩士
臺灣大學
資訊工程學研究所
98
Abstract People can fall at any age, if older people or patients fall too often when there is nobody to look after them and because of delays in medical treatment, there could be serious consequences. In the case of women who suffer violence, there will certainly be a significant change in body posture, or even a fall. When the police are carrying out dangerous duties, they may be attacked by offenders, and knocked down. When fire fighters are at the scene of a raging fire, they may fall because of the rapidly changing and highly dangerous environment. In terms of the several situations of falling described above, it is very dangerous if people lose consciousness, or they are unable to recover from the state of falling themselves. If this happens, specific persons should be notified, such as family, colleagues, friends, and they should be asked to assist the parties as soon as possible. Since mobile phones have already become an essential part of modern life, this thesis proposes currently using and having expansionary Smartphones of the future, with a built-in accelerometer to judge whether or not the users have fallen. Because it has excellent communication functions, after detecting and examining users’ fall, it can send Short Message Service (SMS), automated answer incoming calls, automated voice calls or automated 3G video calls to inform the personnel who have been set up in advance. If the user is outdoors, it can also add Global Positioning System (GPS) information to care-givers, so that the user can obtain relief as soon as possible when losing consciousness and capacity. The function developed in this thesis can also be used for dementia, to determine whether or not people have walked outside, and then use the GPS to get their position, to find them in order to reduce the risk of getting lost. Keywords: fall, Smartphone, accelerometer, communication, global positioning system, dementia

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33

Gonçalves, Jóni Ramiro Pires. "Vehicle's Interior Presence Detection and Notification System". Dissertação, 2018. https://repositorio-aberto.up.pt/handle/10216/114138.

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This thesis aims to present both a solution analysis and potential implementation to prevent in-car infants' deaths, capitalizing on low-cost technologies that can easily be integrated on the vehicle or are already a part of it.The circumstances that lead to this outcome can be narrowed down to parent's carelessness, whether they left the child unattended because of a short time stop to do groceries that turned out too long, or simply because it was forgotten after bringing such groceries home first.As part of the state of art, several possible systems were considered, culminating in a system idealization incorporating two approaches as inputs - a motion sensor and a camera - while notifying the driver via SMS.In order to study the advantages a division was made, resulting in a low-cost approach, which utilizes the motion sensor and other that is anticipated to be more reliable consisting in human detection through vision algorithms. While the integrated system is idealized to optimally recognize the presence of children inside the vehicle, the performed studies premise a potential stand-alone application.Throughout this study it is noted the low-cost implementation limitations due to the sensor requiring movement to acknowledge that there is someone present, while the use of a camera can recognize infants whether or not moving. At the same time, vision algorithm improvement becomes even more reliable overtime, as well as the car electronics, with cameras being used for several other issues such as driver drowsiness detection, mitigating cost constraints. It is hoped that this thesis serves as both a solution and solution catalyst since it is not limited to this application, being able to prevent cars from being stolen or burglar's break-in to surprise an unware driver, although it's main focus is to present a reliable detection and notification system that allows in-car infant casualties decrease, turning such deaths into deliberate crimes.

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34

Gonçalves, Jóni Ramiro Pires. "Vehicle's Interior Presence Detection and Notification System". Master's thesis, 2018. https://repositorio-aberto.up.pt/handle/10216/114138.

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This thesis aims to present both a solution analysis and potential implementation to prevent in-car infants' deaths, capitalizing on low-cost technologies that can easily be integrated on the vehicle or are already a part of it.The circumstances that lead to this outcome can be narrowed down to parent's carelessness, whether they left the child unattended because of a short time stop to do groceries that turned out too long, or simply because it was forgotten after bringing such groceries home first.As part of the state of art, several possible systems were considered, culminating in a system idealization incorporating two approaches as inputs - a motion sensor and a camera - while notifying the driver via SMS.In order to study the advantages a division was made, resulting in a low-cost approach, which utilizes the motion sensor and other that is anticipated to be more reliable consisting in human detection through vision algorithms. While the integrated system is idealized to optimally recognize the presence of children inside the vehicle, the performed studies premise a potential stand-alone application.Throughout this study it is noted the low-cost implementation limitations due to the sensor requiring movement to acknowledge that there is someone present, while the use of a camera can recognize infants whether or not moving. At the same time, vision algorithm improvement becomes even more reliable overtime, as well as the car electronics, with cameras being used for several other issues such as driver drowsiness detection, mitigating cost constraints. It is hoped that this thesis serves as both a solution and solution catalyst since it is not limited to this application, being able to prevent cars from being stolen or burglar's break-in to surprise an unware driver, although it's main focus is to present a reliable detection and notification system that allows in-car infant casualties decrease, turning such deaths into deliberate crimes.

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35

CiWeiLin y 林奇緯. "Gas-type fire detection and immediate notification system". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/36970417874955704282.

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碩士
國立勤益科技大學
電子工程系
103
Fires are difficult to avoid, so if fast or immediately fled the scene of the fire the fire scene for emergency fire fighting process, to increase the chances of survival of the people and reduce the loss of finance. Occurred during each field of fire, will go through growing, exuberant and recession of the flame, therefore certain combustible substance has a close relationship. And the vast majority of the combustible substances, both containing carbon (C), hydrogen (H) element, because in the combustion process, the carbon, hydrogen and oxygen (O2) do engage, will produce products of incomplete combustion, such as carbon dioxide ( CO2), and incomplete combustion products such as carbon monoxide (CO) and other toxic gases. It can be seen, carbon dioxide and carbon monoxide during combustion flame is the material inevitably produce, so if in front of flame into the strong (the fire), the use of modern gas sensor technology (Nondispersive Infrared Detector, NDIR) for carbon dioxide and go carbon monoxide do synchronous analysis possibilities warning fires, and then with, under the concept of modern society to have one, and make the most rapid notified via App of the system, so that people make an immediate response to avoid greater losses .

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36

Peng, Shi-Jia y 彭士家. "Botnet Victim Detection and Notification based on Openflow Switch". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/58225684182753417397.

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碩士
國立中央大學
資訊工程研究所
98
Over the years, the network developed quickly and constantly. Because the rise of trade networks, data on the network become more and more important. Unfortunately, the rise of internet crime became a big problem at the same time such as Botnet. Botnet have hidden attackers, and the characteristics of high flexibility, but also an ability to control multiple computers. This paper describes the IRC-based botnet. First, we explain the botnet behavior and the hard to solve problems for security officer. Then we introduced the NetFPGA card developed by the Stanford University and explained the openflow project features and advantages. These devices are used as a linux gateway to be an efficient firewall. This paper use the NetFPGA card and openflow network project designed by Stanford University to detect bot in the botnet. Assume that normal users browser web everyday, we use openflow switch redirect the bot traffic to a particular page that show the warning information. Then through the network disconnected strategy, we try to let the user know the necessity and urgency.

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37

Shih, Sheng-Kai y 施勝凱. "An Automated Framework for Malware Detection and Infection Notification". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/08722226388600641506.

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碩士
國立交通大學
資訊科學與工程研究所
102
With the progress of Internet, the number of Internet connected devices has increased sharply. The rapid expansion of network also leads to the expansion of botnet, which have become a serious threat to the Internet. Botnets are formed by many compromised computers, which can be used by bot master to steal data or to participate in Distributer Denial of Services (DDoS) attacks. This paper proposed a framework to restrain the spread of botnet. Our framework is implemented on plug-in Internet Explorer and is designed for alarm computer owners. We have built three defend lines against the botnet expansion. First, we detect the web-based malwares and malicious URLs to reduce to risk of being infected. Also, the collected malicious sources will send to the malware database for further analyze. Second, the DNS protocol is usually utilized in botnet to provide the command and control (C\&;C) server with flexibility and strength. We monitor the DNS traffics to examine if target computers have been a bot. Last, we improve the current infection notification flow with our framework. The current notification flow is cumbersome and involves with a lot of manual works. We reduce the notification time from 2 or 3 days to 15 minutes. With these defending approaches, we can effective restrain the scale of botnet.

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38

Liu, Chun-Hung y 劉鈞鴻. "The Implementation of Automatic Pipeline Breakage Detection and Notification System". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/24r82t.

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碩士
國立臺北科技大學
土木與防災研究所
95
Cut off roads, collapsed buildings, and trapped residents tend to happen when large earthquakes strike. Pipe damage causes no water for conflagrations, rendering drastic disasters even more desperate. Advancements in communication and sensor technologies make it possible to detect the location of damaged pipelines. To examine this application and its effectiveness, the thesis has built a water delivery network in laboratory, simulated the damages to the network caused by earthquakes, and used wireless sensor network to monitor vibrations of pipes. Computer system is used to calculate the vibration data to identify the location of possible damaged pipes. A comprehensive system is then developed for automatic detection, notification, and display of the location of damaged pipelines, utilizing short message service (SMS) to inform and instruct concerned parties and J2ME program to search and locate rescue resources available near the accident scene. Information collected by the system can be expected to provide valuable and timely references for urgent decision-making by being posted real time on Google Earth and Google Map.

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39

Loureiro, Pedro Fernando Quintas. "Automatic traffic congestion detection using uncontrolled video sources". Dissertação, 2009. http://hdl.handle.net/10216/58176.

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40

Loureiro, Pedro Fernando Quintas. "Automatic traffic congestion detection using uncontrolled video sources". Master's thesis, 2009. http://hdl.handle.net/10216/58176.

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41

Wang, Chenqi y 汪晨騏. "Real-Time Traffic Congestion Detection with Vehicle Moving Patterns". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/91312831337959519782.

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碩士
國立臺灣大學
資訊工程學研究所
103
Traffic congestion in urban areas is a severe problem in many cities around the world. Existing solutions require data from a considerably large number of vehicles on the same road to accurately detect traffic congestion of a particular road. We notice that the behaviors of vehicles in congested and noncongested states are discriminable, thus we present a novel approach to detect the traffic states using motion patterns of an individual vehicle in real-time without any other preliminary knowledge. Specifically, only a smart phone is needed to predict the traffic state in our system. The biggest advantage of such an approach is that the system can function properly even if there are only a smaller number of vehicles equipped with the system, which is usually the case at the early stage of the deployment of a vehicle-to-vehicle (V2V) network or a large-scale intelligent transportation system. In our solution, machine learning mechanisms are utilized to classify the traffic state by extracting the motion behaviors of a vehicle. Our model development utilizes highly accurate vehicle traces collected at several real-world intersections with LIDAR. In implementation, we use KNN algorithm to determine the traffic state by comparing the real-world GPS trace with our collected traces. Since the length of traces will be different according to different road segments, we utilize dynamic time warping (DTW) mechanism to calculate the distance. Evaluation results show that, with only data from an individual vehicle, our classification model can achieve a promising 90% precision

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42

Lin, Wei-Chung y 林偉正. "An Improved Random Early Detection (RED) Algorithm for Congestion Control". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/16896950377494718155.

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碩士
國立中興大學
資訊科學系所
95
Many proposals have been adopted in controlling the congestions in the routers, including Random Early Detection (RED) and Drop-tail, and have shown to improve the loss rate, throughput, fairness, etc. of the network. Although RED algorithm is designed for TCP for a active queue management, we found that when comes to dropping the packets, it treats packets equally, ignoring the effect of the the size of the packets. This results in higher loss rate of packets and lower throughput for smaller packets. In this thesis, we propose to improve the original RED algorithm by differentiating packet sizes and devise RED_average algorithm and further improved PS_average algorithm. We then use ns-2 to simulate the performance of the aforementioned three algorithm.based on three MTU sizes. The results showed that if we take the factor of the packet size into consideration, the RED_average algorithm has a better loss rate and throughput. The PS_average, which takes the average packet size into consideration to adjust the intended loss rate for smaller packates, has a even further improved performance. We have shown that by the above two new algorithms, a better balance for the loss rate for all packets can be achieved, and thus improved utilization of the network resources.

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43

LI-CHUAN, KUO y 郭禮銓. "Implementation of a Fall-Detection and Location Notification Module Based on MSP430 Microcontroller". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/e45bbt.

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碩士
聖約翰科技大學
電機工程系碩士班
104
Due to the aging population in Taiwan, the care for elderly persons is getting more and more demanding. In Taiwan, one out of five elderly persons has a fall experience and falls become the most common cause in accidental death for elderly persons. It is quite helpful if it is able to detect a fall of the elderly person and immediately send a notification to his family member or the police where he falls. In the thesisthe implementation of a fall detection and location notification module is proposed based on the low power consumption and low costMSP430 micro-controller together with aninertial measurement unit (IMU) and Bluetooth 4.0 module. The whole set is embeddedinto a 3D printed wearable buckle to estimate the wearer’swaistgestures, which has the advantage that the module is immune to interference from limb movements and may result in higher fall detection accuracy. The fall detection algorithm is implemented mainly according to the waist gesture and the acceleration history measured by the IMU. Roughly speaking, if the declination angle of the waist gesture is large enough and the integration of 0.2 second time history of theaccelerationmagnitude is over a predefined threshold, then a fall is detected. Through a series of experiments, the proposed algorithm achieves a sensitivity and specificity of 91.8% and 98.5%. An Android App is also developed as the human interface of the proposed module. The App receivessensor data via Bluetooth 4.0 transceiverand presents the gesture of wearer with a 3D animation using OpenGL. When a fall is detected, the App will show a text alter together with an audio alarm. When the wearer has fallen over a period of time without return back to the normal gesture, the App will send a short message to the family memberwith a link to the Google map indicating where the wearer is located.

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44

JENG, SHIANG y 鄭翔. "Vehicle Child Life Detection and Notification Rescue System based on NB-IoT Architecture". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9g57zw.

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碩士
聖約翰科技大學
資訊與通訊系碩士班
107
In recent years, people have become obedient due to the increasing pressure of life. Many children have heat died in the car due to the negligence of their parents. It has been known so far that the occurrence of human tragedies has not been interrupted. In order to improve this situation, this study developed a safety notification system for children in the car. The system uses a number of sensors to utilize the Arduino single-chip microcontroller actively communicate users via Bluetooth and NB-IoT transmissions, to reduce the tragedy of forgetting children in the car. With the PIR human body infrared sensor and the FSR pressure sensor, it is possible to determine whether a child is riding in the car and designed to bring the rescue function after the active notification. When the mobile terminal does not respond within the time limit, the coordinate address is sent through the preset number for assistance, and the carbon dioxide sensor and the temperature sensor are used to evaluate the safety of the interior environment, thereby actively opening (closing) the window or starting the engine and the air conditioning system. At the same time, there also have In-car volume monitoring and off-board voice broadcast alarm for help. In addition, the vehicle power supply monitors the voltage at any time through the Arduino single-chip microcontroller to ensure the normal operation of the system.

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45

Liu, Xiaoming. "End-to-End Single-rate Multicast Congestion Detection Using Support Vector Machines". Thesis, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_2372_1262895664.

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IP multicast is an efficient mechanism for simultaneously transmitting bulk data to multiple receivers. Many applications can benefit from multicast, such as audio and videoconferencing, multi-player games, multimedia broadcasting, distance education, and data replication. For either technical or policy reasons, IP multicast still has not yet been deployed in today&rsquo
s Internet. Congestion is one of the most important issues impeding the development and deployment of IP multicast and multicast applications.

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46

Liu, Yi-Hsueh y 劉宜學. "The Study of a Congestion-Based DDoS Attack Detection in Wireless Mesh Networks". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/58932870960342391453.

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碩士
國立臺灣科技大學
電子工程系
95
In recent years, distributed denial of service (DDoS) attacks pose an immense threat to wired networks, and this threat will also be serious in wireless mesh networks (WMNs). However, most of current defense mechanisms in wired networks can not be suited to defend against congestion-based DDoS attacks in WMNs. In this paper, we present an anomaly detection scheme working on each mesh router for congestion-based DDoS attacks in WMNs. We define two metrics named NodeCondition and RangeCondition to extract the features, and detect abnormal behaviors according to the outlier detection result based on Gaussian mixture model (GMM) by analyzing the values of these metrics to make intrusion decisions. Then we identify abnormal routers (victims and malicious-sources) within the neighborhood based on sequential hypothesis testing. Through a series of experiments using traces from ns-2 simulations, we show that our scheme is suited to detect congestion-based DDoS attacks and its overall performance is excellent in WMNs.

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47

Hsu, Shu-Hao y 許書豪. "Adaptive Congestion Detection Scheme According to Burst Assembly State for TCP Over OBS Networks". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/r4x3d8.

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碩士
國立彰化師範大學
資訊工程學系
106
With the rapid development of science and technology, the network user's bandwidth demand is increasing. As a result, optical networks that can provide large network bandwidth are becoming increasingly important. Optical Burst Switching (OBS) is an optical switching technology which can be a key factor to reach all-optical networks and be more practical than Optical Circuit Switching (OCS) and Optical Packet Switching (OPS). However, in a OBS network packet losses could occur even at low traffic load situation due to its bufferless nature. This will significantly reduce the performance of TCP. Therefore, how to distinguish a packet loss is caused by network congestion or random contention is a critical and important issue for TCP over OBS networks. In this thesis, we propose a new loss-based TCP, ATABA-TCP, which is suitable for OBS networks. We make OBS edge nodes plus a mark on packet to notify TCP sender of burst assembly state. A TCP sender may utilize this information to estimate the current network load. When a TCP sender detects packet losses, the congestion window size (CWND) can be appropriately adjusted based on the frequency of the packet loss event and the current network load level. Through the simulation results in nOBS, we can find that ATABA-TCP achieves better performance than that of SAIMD.

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48

Cheng, Yuan-Cheng y 鄭元正. "The Study on the Versatile Traffic Control System with the Detection of Intersections Congestion". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/09341256433020707640.

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碩士
國立東華大學
電機工程學系
92
With the growth in Taiwan’s economy, the amount of vehicles increased year by year. Although the authorities pushed ahead with considerable public works in transportation, the boosting number of automobiles still heavily contributed to the traffic problem in urban area. For the purpose of utility in present communications to be efficient, most researcher focus on the phase control of intersections that mainly compose road system. This thesis proposed a Versatile Traffic Control System (VTCS) based on Petri Net and Queueing Theory instead of adopting stationary period to analyze instantaneous traffic flows. Under congestion, VTCS can automatically infer better strategy for all parameters of traffic signal control to improve the movement of single intersection. The determination of traffic congestion in VTCS could be not objective by basing on the number of vehicle over two third of road capacity on single link. Therefore, for acquiring more objective conclusion we proposed IVTCS (Intelligent Versatile Traffic Control System). We know that the traffic is obviously a complex system, and it can’t be expressed as explicit mathematical equation or model. Hence, IVTCS adapts fuzzy theory and approaches the way of human being’s reasoning to making decision on uncertain conditions and improve the shortcoming of VTCS. Simulations on IVTCS and VTCS showed that in traffic control on intersection the former attain more efficient performance than the latter. So are compared with traditional stationary traffic control, we also got reasonable results to prove that adapting IVTCS is sensible than others.

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49

Liu, Jia-Ge y 劉佳格. "Detection of Congestion in Crowds Based on Estimating the Number of People with Human Feature and Behavior". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/67352757721715514953.

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碩士
國立臺灣科技大學
電子工程系
105
Abnormal event detection is a challenging and emerging task in the field of the surveillance systems. Crowd congestion is an especially hot topic. When the count of people exceeds the capacity of the space, some tragedies would happen (eg., stampedes ). The proposed method comprises the approach of counting people and the estimation of crowd capacity threshold to detect the congestion. The least squares linear regression model is used to map the four human features into the number of people. Moreover, the crowd capacity threshold is obtained by reconstruction of space and theory of Edward [26], a famous anthropologist. According to the measurement of the NTUST2017 database, our method achieves the accuracy of 92% for detection of congestion.

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50

Mutwol, Lawrence [Verfasser]. "A novel method of early detection of congestion in heart failure using bioimpedance on a pig model / von Lawrence Mutwol". 2010. http://d-nb.info/1010576607/34.

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