Thèses sur le sujet « Call control »
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1
Vestmoen, Håkon. « Contex-Aware Call Control ». Thesis, Norwegian University of Science and Technology, Department of Telematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10071.
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Ho, Chi-Jui. « Call admission control in cellular networks ». Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15730.
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Dimitriou, Nikos. « Call admission control for multimedia CDMA ». Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/930/.
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Wiselyn, Jeyapaul Ebby. « GSM Voice Mail Service TDM Call Control ». Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-189242.
Texte intégralRésumé :
The Voice Mail Service (VMS) enables forwarding of calls to a dedicated Voice Mail Server (VMS) on behalf of the call receiving subscriber during certain conditions such as 'busy subscriber', 'no answer', 'always', etc. The standardization forum 3GPP has specified the Global System for Mobile communication (GSM) while the standardization forum ITU-T has specified the Integrated Services Digital Networks (ISDN) User Part (ISUP) call control protocol. Both of these standards rely on the use of Time Division Multiplex (TDM) as a media bearer and SS7 as signalling bearer, where both bearers require use of very expensive telecom-specific hardware. The thesis proposes the solution to use RTP as media bearer and IP as signalling bearer towards the handset in GSM and only use TDM as media bearer and SS7 as signalling bearer towards the VMS. The thesis demonstrates the feasibility and the advantages provided, by creating an implementation in Erlang/OTP and testing it to check if it confirms to the specification.
5
Cheung, Michael. « Call admission control in wireless communications networks ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/NQ53488.pdf.
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Naghavi, Nika. « Call admission control in wireless mesh networks ». Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/call-admission-control-in-wireless-mesh-networks(01d122ee-b6fe-4baa-b78c-9f5093136956).html.
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Efficiency in managing scarce wireless resources has been a major design obstacle in wireless mobile networks since its advent. A large body of work has been published on the subject in relation to the first two generation and third generation (3G) of wireless networks. However, these solutions are not readily applicable to the future IP based multi-hop wireless networks. Increased trend in the number of users accessing multimedia rich traffic, and the impacts of mobility management support mechanisms alongside the shared nature of backhaul nodes demand exploration of new avenues of resource management policies. In this thesis a set of schemes are proposed to address the issue of Call Admission Control (CAC) in future multi-hop IP based mobile networks. The first scheme is based on a joint CAC and route assignment design mechanism in Wireless Mesh Networks (WMNs) environment, addressing issues such as pricing policies, wireless resource constraints of the access and backhaul links as well as maximising network provider's revenue. Study's focus is then shifted towards CAC design in Mobility Agent (MA) based Proxy Mobile IPv6 (PMIPv6) networks. A novel class-based CAC mechanism was proposed with the aim of eliminating bottleneck effect at the MAs. To further improve the overall capacity of the network, in conjunction with the proposed CAC mechanism, a modified version of a previously proposed Route Optimisation (RO) scheme is implemented. The performance of the proposed schemes is investigated and analysed through extensive simulations. Comparative studies are then carried out to examine the network provider's total revenue gain in WMNs environment, total blocking probability and per class blocking probability in PMIPv6 networks.
7
Hossain, Firoz, et Abu-Shadat-Mohammad Sohab. « Mathematical Modelling of Call Admission Control in WCDMA Network ». Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2933.
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WCDMA is an interference limited multiple access technique .It is widely used in the 3rd generation mobile networks like UMTS. When a new call arrives in the system to get admission, it checks whether the call is admitted or not based on some parameters like signal to interference ratio (SIR), transmission power of the Node B and the air interface load .If the call is accepted this will increase some interference to the ongoing calls. This new interference would degrade the ongoing calls and this will also add some extra load which may also lead to the exceeding capacity. So that the system has to decide this admission policy in a systematic way that all the users should maintain their communication with guaranteed quality of service. This decision making algorithm belongs to the radio resource management functionalities of the Radio Network Controller (RNC) in a WCDMA based UMTS network. This thesis paper focuses on the mathematical representation of the call admission control in an interference based environment. There is also a comparative study with different methods.
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De, Alwis Priyan Mihira. « Call admission control and resource utilization in WCDMA networks ». Thesis, University of Canterbury. Electrical Engineering, 2005. http://hdl.handle.net/10092/9608.
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Unlike FDMA or TDMA systems, CDMA is interference limited and has a soft capcity that changes depending on the interference felt at the base station at a given time. Admitting a new call and user movement increases the interference level in the system. Therefore a robust Call Admission and Power Control Mechanism is needed. This thesis discusses the main approaches mentioned in the literature on Call Admission Control and Power Control and analyses two modern solutions, namely the QoS aware Power Control and Handoff Prioritization scheme introduced by [T. Rachidi, A. Y. Elbatji, M. Sebbane, and H. Bouzekri 2004] and the Received Power based simulation model discussed in [A. Capone and S. Redana 2001], in greater detail. Then we proceed to recommend improvements that are then tested in a MATLAB simulation environment. The recommended changes improve the overall dropping and handoff loss probabilities. The impact of the NRT overload mechanism discussed in [T. Rachidi, A. Y. Elbatji, M. Sebbane, and H. Bouzekri 2004] is also investigated. The investigations determined the optimum solution achievable with the NRT overload parameter settings.
As the final task, a discrete time dynamic feedback control system that aims to keep the dropping and handoff loss rates for RT services below a target value regardless of the traffic dynamics or the bandwidth requirements is designed. A simple Integral Feedback controller is chosen for this task because a controller that is capable of reducing steady state error is required. The controller is used for the NRT overload mechanism while the NRT error rate is left as best effort. The controller parameters are tuned using simulations and the final result is benchmarked against two algorithms that have fixed NRT overload parameters by simulating in environments under various Poisson call arrival rates and traffic loads. The NRT overload mechanism with our controller performed best by holding the RT error rate at the required target value while producing comparatively lower NRT error rates.
9
Foo, Yu Chiann. « Call admission control for high altitude platform station UMTS ». Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/689/.
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Rose, Ed. « Control, alienation, commitment and satisfaction amongst call centre workers ». Thesis, Liverpool John Moores University, 2009. http://researchonline.ljmu.ac.uk/5942/.
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Purpose: The purpose of the research for this thesis is to respond to the following research questions and to test the hypotheses which stem from the second research question. The research questions are: 1. What are the nature, relevance and extent of the application of the concepts and constructs of control, alienation, commitment and satisfaction within the call centre workplace? 2. What is the nature of the association between the concepts and constructs of control, alienation, commitment and satisfaction within the call centre workplace? Methodology and Research Design: A mixed method research design was devised, based upon piloted exploratory research. The main survey instrument was the questionnaire. The questionnaire responses were analysed and subject to confirmatory factor analysis. Findings: Ten hypotheses were tested and largely supported. The results demonstrate strong associations between the main constructs of control, alienation, commitment and satisfaction and also with their subsidiary constructs. Limitations and Implications: The main theoretical limitation of this research concerns both alienation and control. The exclusive focus upon control within the formalised workplace context of the call centre taken by the research is without reference to wider societal control relationships and structures, and as such could pose limitations in terms of generalising the research results. With regard to alienation, this research attempts to measure some alienation components in the tradition of Blauner (1964) and Seeman (1959), and hence poses the problem of whether reducing the alienation concept to measurable components is valid within the context of the wider discussion of alienation as an inherent societal condition, thereby leaving this research open to the charge of methodological reductivism. Originality and Value: The primary contribution to knowledge of this research lies in the consideration, empirical application, consolidation and relevance of the four central concepts of control, alienation, commitment and satisfaction as applied to call centre work and the call centre workplace, and to the attitudes and behaviour of CSRs.
11
Ma, Zhongjing 1975. « Call admission control and routing control in integrated communication networks via dynamic programming ». Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82615.
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The problems of Connection-oriented Networking Call Admission Control (CAC) and Routing Control (RC) in Integrated Networks are formulated as finite and infinite horizon finite-state Stochastic Dynamic Programs. In particular, Poisson Markovian communication networks are analysed in detail. Because of the complexity of communication networks and of the operation of some kind of communication networks, such as the Internet, by multi-agents, it is effectively impossible to obtain the optimal solutions. Currently it is reasonable to use decentralized aggregation methods to obtain sub-optimal solutions for CAC and RC communication problems. In this thesis, stochastic dynamic programming methods for the optimal control of such network are studied. The notion of a doubly stochastic network, which possesses Markovian aggregated dynamics, is introduced, this is exploited in the hierarchical stochastic control of such hierarchical networks.
12
Liu, Hui. « Dynamic call admission control under partial separation in ATM networks ». Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/8975.
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A dynamic call admission control scheme is proposed for ATM networks to support multiple Quality of Service (QoS) requirements. The scheme is based on the notion of partial separation. It divides the overall traffic flows into classes, within which each traffic source has similar QoS requirements, but may have different traffic characteristics, and the bandwidth of a link is dynamically allocated among the classes. A dynamic bandwidth allocation strategy is introduced. It achieves the goal of bandwidth allocation by optimizing a cost function defined as an estimate of the overall cell loss rate that would be generated by the total offered load. It is dynamic in the sense that the bandwidth allocation is adjusted each time when a connection requires for an acceptance or a leave. While optimizing the overall cell loss rate across classes, cell level constraint is satisfied for each class by deploying the cell loss rate estimate algorithm, proposed by H. Esaki in Connection Admission Control in ATM Networks. A simulation program is developed to validate the accuracy of the algorithm. Extensive numerical and simulation results are presented. Numerical search method is deployed to locate the optimal bandwidth assignment set. Numerical results are presented to evaluate the efficiency and adequacy of the CAC scheme.
13
Saintillan, Yves. « Performance evaluation of online call routing and admission control algorithms ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0005/MQ43558.pdf.
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Yang, Xu. « Call admission control in wireless networks using a neuroevolution algorithm ». Thesis, Queen Mary, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515513.
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Chevrollier, Nicolas. « Coexistence and call admission control in a heterogeneous wireless environment ». Evry, Institut national des télécommunications, 2006. http://www.theses.fr/2006TELE0011.
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In today’s digital world, various types of users, applications and wireless technologies interact to create a complex and heterogeneous environment. In this thesis, we address two issues introduced by the heterogeneity of the digital world. First, we evaluate the interference generated when multiple wireless technologies operate in close proximity. We develop two coexistence mechanisms to mitigate interference in the 2. 4 GHz frequency band: a scheduling scheme for Bluetooth devices known as bluetooth interference aware scheduling and a scheme based on Layer 2 triggered handovers. Second, we investigate how to integrate vertical handovers into call admission control algorithms in order to limit the communication disruption and quality of service discontinuity. We evaluate the impacts of those handovers in terms of packet loss and disruption latency, and develop two call admission control algorithms, namely the probabilistic call admission control and handover-based call admission control algorithms. The former is based on a probabilistic admission decision and the latter includes a bandwidth reservation policy along with preemptive handovers. Both aim at reducing the occurrence of hard handovers in a heterogeneous wireless environmentDans le monde digital qui nous entoure, différents types d'utilisateurs, d'applications et de technologies sans fil interagissent pour créer un environnement complexe et hétérogène. Le travail effectué dans cette thèse traite de problématiques introduites par le caractère hétérogène du monde digital. Le premier sujet d'étude s'attache à évaluer les interférences générées dans le bande de fréquence 2. 4 GHz lorsque plusieurs technologies sans fil opèrent en même temps dans un espace limité. Deux solutions sont proposées pour réduire ou éviter ces interférences. La première est un mécanisme d'ordonnancement des paquets au niveau de la couche MAC Bluetooth. La deuxième utilise des passages inter ou intra technologie déclenchés par des indicateurs de niveau 2. Le deuxième sujet d'étude s'attarde sur la mobilité verticale dans un environnement sans fil hétérogène. Les effets de cette mobilité sont évaluées sur le flux applicatif et la discontinuité de qualité de service que ces passages introduisent est analysée. Par la suite, deux algorithmes de contrôle d'admission qui prennent en compte le caractère néfaste de certains passages entre technologies sont proposés. Flexible et robuste, le premier repose sur une décision probabilistique d'admission dans une cellule WLAN. Le second utilise un système de réservation pondéré de bande passante et des passages préemptifs pour diminuer les nombres de passages de type "hard" et améliorer la qualité de service perçue par les utilisateurs
16
Mansingh, Suhas. « Call admission control for leaky bucket regulated traffic in ATM networks ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0026/MQ51616.pdf.
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Hartanto, Vincentius Felix. « User-network oriented call control and traffic management in B-ISDNs ». Thesis, University of Canterbury. Electrical and Electronic Engineering, 1994. http://hdl.handle.net/10092/5745.
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This thesis presents a framework for call control and traffic management in B-ISDNs. Unlike the conventional focus on network capabilities, this thesis proposes a novel user-network oriented approach. This approach allows user terminals to perform control functions and to make use of service-specific information, such as the nature of calls and the nature of information within connections of the calls, in order to reduce call establishment delay and to minimise the bandwidth required by the connections.
With B-ISDNs being expected to support general multiparty multimedia calls, a call control scheme is required to process such calls, and to establish and to manage the association among the parties (users) and the connections associated with each call. To this end, a hierarchical call control structure is proposed in this thesis. The structure allows the control functions to be carried out either by the network or by the user terminals depending on the level of terminal intelligence. The details of the call control structure along with the required signalling protocol are described. Examples of both simple and complex call establishments are provided in order to illustrate the proposed call control.
Within each connection of a call, cell loss priority (CLP) can be used to identify cells having different loss probability requirements. Users can use CLP for tagging cells containing less essential information. Furthermore, we propose the possibility for users to police their traffic appropriately and to selectively tag any excess cells, considered expendable or else protected by end-to-end error recovery schemes, as being low priority; this avoids indiscriminate cell losses that would be caused by network usage of CLP.
Not all connections will allow tagging of cells. Therefore, based on the existence or absence of pretagged or low priority cells in a connection, we can distinguish two classes of connections, namely connections without pretagged cells (the class of pure connections) and connections with pretagged cells (the class of mixed connections). The traffic management framework for pure connections is very well established, but this is not the case for mixed connections. Therefore it is of the interest in this thesis to present a traffic management framework for mixed connections, which includes connection admission control, usage parameter control, as well as buffer management and scheduling policy.
Connection admission control algorithms, based upon a virtual bandwidth concept, involve a search for an equivalent bandwidth required by a connection. With mixed connections, there are two different QoS requirements. Existing methods which satisfy both requirements are either specific to some services, or time consuming, due to the required separate search for sufficient bandwidth to satisfy each QoS requirement. Considering these drawbacks, we propose two bandwidth allocation schemes in a homogeneous traffic environment and one scheme in a heterogeneous traffic environment. The methods require a single search for bandwidth and fully exploit the statistical dependency between the high and low priority traffic, and, as the result, allocate smaller bandwidth than previously proposed methods.
After a connection has been admitted, a usage parameter control or policing algorithm is required, to monitor and to control the traffic within the connection during the information transfer phase, in order to ensure that the negotiated traffic parameters are not exceeded. The leaky bucket algorithm is the basis for the most popular policing schemes. In order to make sense of the large number of leaky bucket schemes, two classifications are proposed. Most of the schemes cannot take into account the presence of pretagged cells in mixed connections. Therefore, in order to overcome this drawback, we propose four modifications to the original leaky bucket scheme. Comparative studies based on both analytical and simulation techniques show that the newly proposed leaky bucket schemes can offer better quality of service for high priority traffic than earlier proposed leaky bucket schemes.
The convergence within a network of high priority cells in pure connections and both high and low priority cells in mixed connections can lead to the interference between the cells in the sense that overload of low priority cells in a mixed connection can degrade not only the QoS of other mixed connections but also the QoS of pure connections. Therefore it is necessary for the network to implement a buffer management scheme to minimise such interference, while simultaneously trying to maximise the utilisation of network resources. A new buffer policy, called dual queues with limited cyclic service (DQCS), is developed and shown to achieve both objectives by both discrete-time performance analysis and simulation.
The thesis concludes with proposals of some novel schemes for further study in order to develop an overall call control and traffic management framework for B-ISDNs.
18
Zondervan, Quinton Y. « Increasing cross-domain call batching using promises and batched control structures ». Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36040.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 63-64).
by Quinton Y. Zondervan.
M.S.
19
Ramaswamy, Srinivasan. « Dynamic call admission control and quality-of-service regulation in ATM networks ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23061.pdf.
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Jacobs, Ashley. « Investigating call control using MGCP in conjuction with SIP and H.323 ». Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1006516.
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Telephony used to mean using a telephone to call another telephone on the Public Switched Telephone Network (PSTN), and data networks were used purely to allow computers to communicate. However, with the advent of the Internet, telephony services have been extended to run on data networks. Telephone calls within the IP network are known as Voice over IP. These calls are carried by a number of protocols, with the most popular ones currently being Session Initiation Protocol (SIP) and H.323. Calls can be made from the IP network to the PSTN and vice versa through the use of a gateway. The gateway translates the packets from the IP network to circuits on the PSTN and vice versa to facilitate calls between the two networks. Gateways have evolved and are now split into two entities using the master/slave architecture. The master is an intelligent Media Gateway Controller (MGC) that handles the call control and signalling. The slave is a "dumb" Media Gateway (MG) that handles the translation of the media. The current gateway control protocols in use are Megaco/H.248, MGCP and Skinny. These protocols have proved themselves on the edge of the network. Furthermore, since they communicate with the call signalling VoIP protocols as well as the PSTN, they have to be the lingua franca between the two networks. Within the VoIP network, the numbers of call signalling protocols make it difficult to communicate with each other and to create services. This research investigates the use of Gateway Control Protocols as the lowest common denominator between the call signalling protocols SIP and H.323. More specifically, it uses MGCP to investigate service creation. It also considers the use of MGCP as a protocol translator between SIP and H.323. A service was created using MGCP to allow H.323 endpoints to send Short Message Service (SMS) messages. This service was then extended with minimal effort to SIP endpoints. This service investigated MGCP’s ability to handle call control from the H.323 and SIP endpoints. An MGC was then successfully used to perform as a protocol translator between SIP and H.323.
21
Zhang, Meng. « The impact of mobility on call admission control and scheduling in wireless networks / ». View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20ZHANGM.
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Barnes, Alison Kate School of Industrial Relations & Organisational Behaviour UNSW. « 'The centre cannot hold' : resistance, accommodation and control in three Australian call centres ». Awarded by:University of New South Wales. School of Industrial Relations and Organisational Behaviour, 2005. http://handle.unsw.edu.au/1959.4/22026.
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Drawing upon case studies of three organisations operating six call centres in Australia, this thesis explores the manifestations and interplay of employee resistance and accommodation in response to five facets of employer control: electronic monitoring; repetitious work; emotional control; the built environment; and workplace flexibility. Accommodation refers to the ways workers protect themselves from and adapt to the pressures that make up their day-to-day experiences of work. Accommodation, unlike resistance, which implies opposition to control, may superficially resemble consent to control. I argue that resistance and accommodation are not polar opposites; rather they are both reflections of the conflict and tensions that lie at the heart of the employment relationship. At the study sites, employees utilised resistance and accommodation both separately and concurrently. An explanation of these seemingly contradictory responses and of the links among accommodation individual resistance and collective resistance lies in the concept of ???self???. In this thesis, ???self??? refers to workers??? perceptions of fairness, dignity and autonomy. I examine how these notions frame worker discontent and promote employee solidarity. ???Everyday resistance???, a concept first developed by Scott (1985) in relation to peasant struggles, is employed to highlight the existence of subterranean struggles in workplaces that otherwise appear to be harmonious. At the study sites, everyday resistance was a multi-faceted, widely employed strategy whose strength lay primarily in its immediate impact. There was, however, no necessary sequential development from accommodation, through everyday resistance to overt, formal forms of conflict. What was evident was that multiple responses to employer control could co-exist and inhibit or promote one another. But it was through organised collective resistance that more formalised gains were made and widely held grievances addressed. I suggest that, although everyday resistance may lay the groundwork for more formal struggles, one should not conclude that traditional collective resistance is ???genuine??? resistance and everyday resistance is simply a second-best prelude to it. Although conflict is always present, its intensity differs. If we are to understand the complexity of worker responses to managerial control, we need to expand the theoretical frameworks within which we analyse and interpret conflict.
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Yu, Sam Shaokai. « Performance analysis and call control procedures in high-speed multimedia personal wireless communications / ». Title page, abstract and contents only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phy936.pdf.
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Levine, David A. « Resource allocation, call admission, and media access control protocols for wireless multimedia networks ». Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/14766.
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Tsai, Ming-Ying, et 蔡明穎. « Call Admission Control in ATM Networks ». Thesis, 1995. http://ndltd.ncl.edu.tw/handle/18121525023789473329.
Texte intégralRésumé :
碩士國立交通大學
電信研究所
83
In this thesis, we mainly investigate the traffic control performed at the call setup phase in an ATM network loaded with heterogeneous sources. And this is what so called "Call Control". Under this topic, it is still divided into two categories:first, based on the numerical comparison results between the allowable number of connections from the exact analysis and that from the effective bandwidth method, here, we propose a new bandwidth allocation method for the call admission control to heterogeneous on-off sources in an infinite-buffer queueing system, which the network system accommodating the delay-tolerable but almost loss-free required sources. In the second part, we propose an optimum quantization scheme for the Markov-modulated sources in a bufferless fluid- flow model of an ATM network. Following the real-time computation algorithm for on-off sources proposed in \cite{duann}, with little modification, we extend the application to a more general source model, Markov-modulated sources. Furthermore, considering the quantization loss that might be caused under the computation algorithm in \cite{duann}, we suggest a policy for the sources to minimize the loss and achieve better utilization of link capacity.
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Hsu, Meng-Ta, et 許孟達. « Call Control for IP Multimedia Service ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/20711453160702572696.
Texte intégralRésumé :
博士國立交通大學
資訊科學與工程研究所
95
In recent years, there are many forces urging operators to provide the converged services. First, customers hope to enjoy unified services on different type of devices. Second, users want to have uniform services and contents regardless of the kind of underlying access network being used, such as WiFi, 3G, ethernet, WiMax, ADSL, or cable. Third, fixed network providers’ profit is reducing, so they must begin to look for the opportunities in wireless domain. And wireless operators’ speed of growth slows down, makes them begin to explore how to expand their markets. Finally, the competition between the fixed and wireless carriers will drive the network service toward convergence, and some successful cases of Internet telecommunications services such as Yahoo! Messenger and Skype, etc., make Internet Protocol (IP) applications take very important role during the process toward convergence. As consumers become increasingly mobile, they will demand wireless Internet access from everywhere. In keeping with these requirements of end users, IP Multimedia Subsystem (IMS) standards based on the 3GPP UMTS become more and more important. In the IMS system, we propose an integrated call agent of the converged VoIP network. We presente a simple, flexible framework for the interworking functions of VoIP protocols such as Media Gateway Control Protocol (MGCP), Session Initiation Protocol (SIP) and H.323 base on Intelligent Network (IN). In UMTS two-pass authentication, many steps in the General Packet Radio Service (GPRS) authentication and IMS authentication are duplicated. Therefore, we propose an one-pass authentication procedure, in which only the GPRS authentication procedure is performed. In the IMS network, the authentication is implicitly executed in the IMS registration. We formally prove that the IMS user is correctly authenticated, and the one-pass authentication saves up to 50% of the IMS registration/authentication traffic. In the service platform of IP multimedia services, we describe the design and implementation of a SIP-based VoIP call center with waiting time prediction. The SIP-based plug-in modular call center architecture and detailed message flows are elaborated. We propose two output measures and develop a discrete event simulation model to investigate the performance of the waiting time prediction algorithm for the call center. These research results presented in this dissertation can be viewed as a useful foundation for further study in call control for IP multimedia services and authentication.
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Vannucci, David Emmanuele. « Extended call control telecommunications web service ». Thesis, 2011. http://hdl.handle.net/10539/10678.
Texte intégralRésumé :
Internet based call control Web services enable telecommunications network operators to
offerWeb developers a simplified method of controlling telecommunication resources. Web
Services that expose telecommunication networks to third parties are highly abstracted.
This abstraction allows Web developers to create applications that provide call control
functionality without detailed knowledge of the underlying network. Functionality offered
by network operators is usually of a simple nature, and does not provide developers with
advanced call control functionality, similar to that found in operator services.
Advanced call control requires the Web application to have detailed knowledge of the state
of the telecommunication resources. In this research an Extended Call Control call model
and Extended Call Control Web service are developed and demonstrated to provide Web
applications with this knowledge.
To develop the Extended Call Control call model existing telecommunication call models
were analysed for components suitable for Web control. The Extended Call Control Web
service was developed using advanced call control use cases. The proof of concept successfully
demonstrates the use of the Extended Call Control Web service and the value of
the Extended Call Control call model in proving asynchronous Web based advanced call
control of telecommunications resources.
This research has developed a novel call model for Web based call control of telecommunications
networks. The Extended Call Control call model and API fulfils a fundamental
requirement for Web based advanced call control, namely knowledge of the state of the
underlying network and asynchronous control of those resources. This research facilitates
the development of advancedWeb applications controlling telecommunications calls within
the network which previously was limited by the knowledge of the network state. Telecommunication
service applications can be moved from tightly coupled systems within the
operators network to Web based applications within third party domains such as a Internet
based virtual private branch exchange or call centre.
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Tsai, Meng-Hsun, et 蔡孟勳. « A Study on IMS Call Control ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/40874621583583784746.
Texte intégralRésumé :
博士國立交通大學
資訊科學與工程研究所
98
Universal Mobile Telecommunications System (UMTS) is one of the major standards for the third generation (3G) mobile telecommunications. In UMTS, the core network consists of two service domains: the circuit-switched (CS) and the packet-switched (PS) domains. To integrate with the Internet, the Third Generation Partnership Project (3GPP) proposed the IP Multimedia Core Network Subsystem (IMS) in the PS domain to provide Internet services through the Voice over Internet Protocol (VoIP) technology. In integration of UMTS and Internet, call control has become one of the most fundamental issues in telecommunications. As IMS evolves, more new call control features are supported. This dissertation investigates how the IMS call control affects three major applications: emergency call, Push-to-talk over Cellular (PoC), and Voice Call Continuity (VCC). IMS emergency call provides the capability for the emergency center to track the caller's location through a polling procedure. The problems of existing mechanism include mis-tracking and redundant query. We study the performance of location tracking in the IMS, and then propose the Active Location Reporting (ALR) scheme which reports the caller's location in real time without redundant query. PoC provides a "walkie-talkie"-like group communication method. The speak permission is arbitrated through a talk burst control mechanism. We implement a prototype in the IMS and study the performance of the talk burst control mechanism. Our study indicates that by including the buffer mechanism for PoC (where an ungranted request can be buffered in the queue, and may be granted later), more than twice clients can be supported while maintaining the same granting probability of a request. VCC allows a user to switch from one domain to another during a call. Domain transfer may produce a large number of message exchanges and resource reservation that result in long switching latency. To resolve this issue, we propose the Bearer Reservation with Preemption (BRP) scheme in the IMS to support fast domain transfer. Our study indicates that when the user behavior (either in terms of call holding time or movement pattern) is more irregular, the advantage of the BRP scheme becomes more significant. We also develop analytic models and simulation experiments to investigate the effects of input parameters. Our study provides suggestions to set up the parameters for mobile operations. Numerical experiments indicate that the proposed schemes significantly improve the performance of IMS call control.
29
Lo, Yu-Shun, et 羅友舜. « Multicast Congestion Control Strategy based on Call Admission Control ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/50978700387936967876.
Texte intégralRésumé :
碩士國立中正大學
通訊工程研究所
90
In Multicast Congestion Control research, “drop-to-zero” is a well-known problem. It means a slower receiver slows down faster receiver in the same multicast group. This is because the sender has to adapt its rate or window size to the slowest path, so that a multicast group performance could be dropped. In this paper, we propose that a call admission control (CAC) scheme manage receivers in multicast group to handle “drop-to-zero” problem and improve multicast performance. For this purpose, we integrate multicast congestion control protocol with CAC scheme and utilize the group member’s network information obtained from multicast congestion control protocol to calculate group reward. The basic idea is two-fold. First, the sender can observe the group performance in accordance with calculated group reward. Second, the sender can decide the permission that receiver ask for to join the multicast group in accordance with group reward. We expect to improve group performance and get better group reward and use simulation to analyze CAC scheme of group performance, member counts and group reward. We will show our CAC scheme can effectively drop slower receivers in multicast group and serve the majority of group receivers. The multicast group can build up the group performance and group reward to resolve “drop-to-zero” problem.
30
Shi, YuFei. « ATM traffic generation and Call Admission Control ». 1998. http://hdl.handle.net/1993/19409.
Texte intégral
31
Lee, Byeongcheol. « Call graph correction using control flow constraints ». Thesis, 2006. http://hdl.handle.net/2152/30457.
Texte intégralRésumé :
Dynamic optimizers for object-oriented languages collect a variety of profile data to drive optimization decisions. In particular, the dynamic call graph (DCG) informs key structural optimizations such as which methods to optimize and how to optimize them. Unfortunately, current low-overhead call-stack hardware and software sampling methods are subject to sampling bias, which loses accuracy of 40 to 50% when compared with a perfect call graph. This paper introduces DCG correction, a novel approach that uses static and dynamic control-flow graphs (CFGs) to improve DCG accuracy. We introduce the static frequency dominator (FDOM) relation, which extends the dominator relation on the CFG to capture relative execution frequencies and expose static constraints on DCG edges, which we use to correct DCG edge frequencies. Using conservation of flow principles, we further show how to use dynamic CFG basic block profiles to correct DCG edge frequencies intraprocedurally and interprocedurally. We implement and evaluate DCG correction in Jikes RVM on the SPEC JVM98 and DaCapo benchmarks. Default DCG sampling attains an average accuracy of 52-59% compared with perfect, whereas FDOM correction improves average accuracy to 64-68%, while adding 0.2% average overhead. The dynamic correction raises accuracy to 85% on average, while adding 1.2% average overhead. We then provide dynamically corrected DCGs to the inliner with mixed results -1% average degradations and improvements across a variety of configurations. However, prior work shows that increased DCG accuracy in production VMs has benefits. We believe that high-accuracy DCGs will become more important in the future as the complexity and modularity of object-oriented programs increases.
32
Cheng, Sheng-Wang, et 鄭昇旺. « Call Admission Control for Information Retrieval Service ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70877032143772809821.
Texte intégralRésumé :
碩士中華大學
資訊工程學系碩士班
93
The thesis is a research of call admission control (CAC) for information retrieval service. A CAC Model called "Constant Bit Rate and Port Based Bandwidth Reservation" (CBR-PBBR) was proposed in this thesis to guarantee the Quality of Service and try to enhance the performance of transmission. For the data flow to be transmitted on the architecture of Integrated Service or Differentiated Service, if the bandwidth request and the total size of the data flow are known, we can use the CAC Model of CBR-PBBR to transmit it. We hope this CAC model is to be efficient, economic and predictable on QOS. The model of CBR-PBBR will be suitable to the real time and interactive transmission. An example is VoIP. But the flows which with greatly variable request to bandwidth or unable to be restricted the transmission time will not be applicable. These flows need to be transformed into a constant bit rate transmission first if they can be. As for the non-real time or non-interactive Transmission, the model of CBR-PBBR still can be used because of the feature that transmission is easy to be transformed into a fixed size data flow. This is for the guarantee of QOS of SLA (service level agreement) or avoiding the network congestion. According to the discussion and simulation in the thesis, we can find the model of CBR-PBBR has better perfomance than UBR (non-CAC) transmission when the network is congested. In the points of average queue length, average transmission time to every packet and packet drop rate, the model of CBR-PBBR has good simulation result. Keywords : Call Admission Control, Bandwidth Reservation, CBR-PBBR, Quality of Service, Integrated Service, Differentiated Service
33
Su-Chih, Kao, et 高蘇志. « Call Admission Control/Congestion Control in WCDMA with Bursty Multimedia Traffic ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/30893653808263610388.
Texte intégralRésumé :
碩士國立臺灣科技大學
電機工程系
90
The third generation wireless communication system is expected to provide an efficient method that allows anybody to conduct multimedia communication in any place at any time. Different services usually have different transmission characteristics and quality of service requirements. Therefore, how to design an efficient media access control protocol is an important issue in terms of performance of wireless communication system. We consider wireless communication systems supporting video, voice and data services, where call admission control (CAC) is used to guarantee that existing and new connections can have enough resource to maintain QoS at the connection level; and congestion control is used to guarantee QoS at the packet level. The call admission control adopted in the thesis is a simple threshold scheme, i.e., the number of voice terminals in use can not exceed the threshold. The congestion control used is dynamic reservation assignment, and thus the capacity of real-time traffic and channel utilization can be improved. Via computer simulation, we make use of proper Markovian models for studying the performance measures of video traffic and voice traffic respectively, and studying the data average message delay of data traffic with different data message arrival process, e.g., Poisson message arrival process and self-similar message arrival process. We also study the effects of different system parameter on video packet loss probability, voice packet loss probability, voice call blocking probability, and data average message delay.
34
Shen, Wen-hsing, et 沈紋興. « A Novel Service Policy with Call Admission Control for the SIP-based Call Control Agent over DiffServ-based MPLS Network ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/74288225435730873633.
Texte intégralRésumé :
碩士國立中正大學
電機工程研究所
94
The development of Internet is growing rapidly. High speed network and quality of service (QoS) have become the main trend. How to increase the network transmission rate and guarantee QoS are two important issues. Based on these two major requirements, the Diffserv/MPLS network was established. In the Diffserv/MPLS network, the multimedia services will support Content-Aware Secured and QoS. In the multimedia services, we use SIP protocol to signal sessions and set up the SIP proxy server for the central administration component of the multimedia transmitted architecture. For the DiffServ/MPLS network environment, call control agent (CCA) will be integrated with SIP server and a novel service policy with call admission control (CAC) for call control agent will be implemented. In the SLA contract between VoIP service provider (CCA) and network provider (NRB), it provides for maximum reservation bandwidth and minimum reservation bandwidth in the L-LSP. The goals of adding service policy is increasing the utilization of bandwidth and decreasing the call blocking probability.
35
Lu, We-Ran, et 盧尉然. « Call Admission Control Scheme in Wireless Mobile Network ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/fd98ep.
Texte intégralRésumé :
碩士銘傳大學
資訊傳播工程學系碩士班
92
The purpose of future telecommunications networks is to provide multiple services with together. To support various combined multiple services with quality of service (QoS) requirement in these wireless networks, the call admission control (CAC) plays an important role in resource management. We propose a novel call admission control scheme with buffer to guarantee QoS for both new calls and handoff calls. The queuing model is developed to estimate the threshold, which determines the channels dedicated to the handoff calls. In addition, the proposed scheme adopts the pseudo channel to improve the dropping rate of handoff calls, and employs a new mechanism to partially allocate channels for new calls when the channel occupancy is higher than threshold in order to refine the blocking rate. From the simulation, the proposed scheme significantly improves the dropping rate and the blocking rate in comparison with the existing methods
36
Tsai, Chi-lin, et 蔡其琳. « Utility-based Call Admission Control in Cellular Networks ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/97518327320338479568.
Texte intégralRésumé :
碩士國立臺灣科技大學
電機工程系
102
The demand for cellular mobile services is rapidly growing. When the demand for bandwidth exceeds the supply, congestion will occur so that the QoS of users degrades and the revenue is reduced. Hence, it is important to use the limited bandwidth in the most efficient way. Call Admission Control (CAC) is a strategy to control the number of users into the networks to achieve congestion reduction. Nevertheless, only CAC cannot provide incentives to the users to use the network resources rationally and efficiently. One of the common approaches to deal with the problem is congestion pricing, where the behavior of users are affected by changing the charged price. In this work, we study how to maximize the utility by combining call admission control and congestion price in cellular networks. It is assumed that the utility is a function of the weighted blocking probability, which is a weighted sum of the new call blocking probability and the handoff failure probability. We consider two scenarios: single-cell and multi-cell. In single-cell scenarios, the handoff call arrival rate is assumed to be independent of the new call arrival rate. In multi-cell scenarios, the handoff call arrival rate depends on the new call arrival rate and other system parameters. On the other hand, the handoff call droppings are assumed to be less acceptable than new call blockings. Therefore, some guard channels may be reserved for handoff calls exclusively. We propose a utility-based CAC which adopts a higher congestion price when the channel occupancy exceeds a threshold. We derive the analytical models for the systems considered. An iterative algorithm is developed to find the steady state probability distribution and the performance measures of interest. The performance measures of interest are the new call blocking probability, the handoff failure probability, the give-up probability, the weighted blocking probability, the aggregate utility, and revenue. We study the effect of various system parameters on different performance measures. For comparison, we also present the performance of the traditional schemes with or without congestion price. Last but not least, the computer simulation is used to verify the accuracy of the analytical results.
37
Wu, Lin-Yi, et 吳怜儀. « Design of Call Control and Authentication for UMTS ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/96258831581964816754.
Texte intégralRésumé :
博士國立交通大學
資訊科學與工程研究所
94
Universal Mobile Telecommunication System (UMTS) is an integrated solution for multimedia and data services with wide area coverage. UMTS is developed towards large system capacity, high data transmission, and customized services with quality of services. The UMTS all-IP architecture can be horizontally partitioned into four layers: radio network layer, UMTS core network, IP Multimedia Subsystem (IMS), application layer. In this dissertation, we discuss design issues of each layer. In the radio network layer, UMTS and WLAN interworking extends the UMTS services to the WLAN coverage, and the UMTS subscribers can acquire services with better quality through WLAN. We propose WLAN-based GPRS Support Node (WGSN), which is a loosely-coupled architecture satisfying Scenario 3 features in 3GPP TS 22.934. A push mechanism is implemented in WGSN to connect the MS-terminated call where the Voice over IP (VoIP) client in the callee is not activated. In the UMTS authentication, the Authentication Vector (AV) usage mechanism is used to reduce the signaling traffic between the SGSN and the HSS/AuC. However the AV usage mechanism also consumes extra storage at the SGSN. Therefore, we propose analytic and simulation models to investigate the performance of the AV usage mechanism. In UMTS two-pass authentication, many steps in the GPRS authentication and IMS authentication are duplicated. Therefore, we propose an one-pass authentication procedure, in which only the GPRS authentication procedure is performed. In the IMS network, the authentication is implicitly executed in the IMS registration. We formally prove that the IMS user is correctly authenticated, and the one-pass authentication saves up to 50% of the IMS registration/authentication traffic. In the application layer, we implement the Push to Talk over Cellular (PoC) on the Open Service Access (OSA) platform. We focus on the design and implementation of the PoC client. The detailed architecture and message flows are described. These research results presented in this dissertation can be viewed as a useful foundation for further study in UMTS call control and authentication.
38
Kevin et 劉文周. « A Call Admission Control Design for Transport Network ». Thesis, 2000. http://ndltd.ncl.edu.tw/handle/94515929656162805855.
Texte intégralRésumé :
碩士國立清華大學
工業工程與工程管理學系
88
This thesis proposes a call admission control scheme based on a method of estimating cell loss quality for individual bursty traffic source. The estimate is expressed in terms of virtual cell lose probability for decreasing the influence of the optimization problems of the buffer size. The role of call admission control in high-speed networks is to maintain the network utilization at high level, while ensuring that the quality of service requirement of the individual calls are met. We use the term convolution call admission control to achieve the high level of network utilization by increasing the user connection numbers. Meanwhile we consider the Markov Decision Process﹙MDP﹚for developing the routing table. As we know the MDP will decide the available virtual path route that will maximize the expectation of networks revenue.
39
Chen, Yuon-Haan, et 陳詠翰. « Fuzzy Call Admission Control in a CDMA Cellular ». Thesis, 2000. http://ndltd.ncl.edu.tw/handle/22631464888768636198.
Texte intégralRésumé :
碩士國立交通大學
電信工程系
88
Multiuser detection (MUD) is a very popular topic in recent years. Its impressive increase in capacity has caused that more and more latest wireless code division multiple access (CDMA) systems adopt this new technology. A lot of methods to implement the MUD were proposed and most of them tried to upgrade their performances and make them more feasible. The capacity limit, however, still exists due to other cells' multiple access interference (MAI) in a cellular system. As a result, a call admission control (CAC) scheme is required to control the number of voice users when using MUD. In this thesis, we first make a survey of the major types of MUDs and make comparisons among them, such as the important concepts, the performances, and the complexities, etc. Then we propose a fuzzy CAC using uplink MUD of successive interference cancellation (SIC), which has lower complexity and more advantages under the fading channel and imperfect power control. The fuzzy CAC considers both intra-cell and inter-cell MAI and it provides more accurate management of capacity than conventional (SIR-based) CAC in the CDMA cellular system.
40
Lai, Chich-Feng, et 賴志峰. « Fuzzy Call Admission Control for CDMA Cellular Systems ». Thesis, 2000. http://ndltd.ncl.edu.tw/handle/41798463949346212630.
Texte intégralRésumé :
碩士國立中央大學
資訊工程研究所
88
Recently, the wireless personal communication system grows very fast and the CDMA has become the key technology for multiple accesses in the third generation wireless communication systems. Unlike conventional FDMA and TDMA systems, the capacity of CDMA is limited by the interference. Moreover, it is difficult to make call admission decisions under the wireless network conditions that are varying with the terrain and location. Therefore, a new call admission control policy is proposed to adapt to the changing network conditions for CDMA networks. Due to the fuzzy logic control has the capability to make decisions under ill-defined network environment, a call admission control policy using fuzzy logic control for CDMA networks is proposed in the thesis. The fuzzy rule set and the membership functions are obtained by using genetic algorithms to achieve the near-optimal solution. Simulation results show that, as the system load increases, the proposed CAC policy still can guarantee the dropping probability of handoff calls not beyond a pre-determined value and thus the quality of communications for handoff calls is offered.
41
Duann, Shii-Tyng, et 段喜亭. « A Call Admission Control Scheme for ATM Networks ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/23279709478319432340.
Texte intégralRésumé :
碩士國立交通大學
電信研究所
81
This thesis proposes a new CAC scheme for ATM networks based on both long-term time averaged and instantaneous cell probabilities for global and individual bursty traffic The long-term time averaged cell loss probability is defined on a logically bufferless fluid flow traffic model. This investigates mainly the relation between bursty layer traffic cell loss probability. The overload period and underload period aggregated traffic are also discussed. Based on the model, relation between the average length of an underload period global cell loss probability is derived. The average length of underload period can also be used as a criterion for admission control because it is equivalent to global cell probability. In addition to long-term time averaged cell probability, we also analyze the instantaneous cell probability, considering the dynamic nature of the traffic, when a network is subject to an admission control. The proposed CAC procedure is divided into two sub-procedures. One called Preliminary CAC (PCAC) procedure designed based on long-term time averaged quality, another Advanced CAC (ACAC) procedure is designed based on quality. An on-line evaluation method is used to implement PCAC procedure, and a table look-up method is used to the ACAC procedure for real-time operation. The operation of proposed CAC scheme requires only two traffic parameters: peak and mean rates. The most important advantage the proposed procedure is that it can be performed in real time.
42
Wang, Wei-Tin, et 王偉廷. « IEEE 802.11e Performance Analysis and Call Admission Control ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/65878468373122836062.
Texte intégralRésumé :
碩士國立成功大學
電腦與通信工程研究所
93
We investigate the performance of the emerging IEEE 802.11e standard by introducing a novel analytical model for the enhanced distributed coordination function (EDCF). The EDCF is modeled as a Markov chain which encapsulates AIFS (arbitrary inter-frame spacing), the minimum backoff window size, retry limit, freezing mechanism in backoff, different packet size. Saturation throughputs and saturation delays of different priority classes are derived based on the proposed model. The influences of different parameters like AIFS and packet size on the EDCF service differential schemes are demonstrated analytically. IEEE 802.11e EDCF aims at supporting relative service differentiation in the MAC layer. However, the backoff mechanism may cause huge packet delay and jitter. In order to guarantee quality of service for voice and video flows, we propose an ABR-QoS control scheme integrated with a measurement-based admission control scheme for the IEEE 802.11e enhanced distributed channel access. In the proposed admission control strategy, the access point makes bandwidth reservations according to individual real-time source’s requirement, while the ABR-QoS control mechanism based on a dynamic adjustment of the IEEE 802.11e EDCA parameters. The performances of the proposed scheme are extensively investigated by simulations. Simulation results show that, with the proposed ABR-QoS control and the admission control scheme, real-time multimedia traffic obtains great quality of service while the channel capacity is fully ultilized.
43
Sigwele, Tshiamo, Prashant Pillai et Yim Fun Hu. « Call admission control in cloud radio access networks ». 2014. http://hdl.handle.net/10454/10791.
Texte intégralRésumé :
NoOver the past decade, wireless communications has experienced tremendous growth, and this growth is likely to multiply in the near future. The proliferation of mobile users and an ever increasing demand for multimedia services has resulted in greater capacity requirements. Radio frequency spectrum is scarce and cannot meet this ever increasing demand and the required Quality of Service (QoS) will no longer be achieved if efficient Radio Resource Management (RRM) solutions are not found. Conventional Radio Access Networks (RAN) have standalone Base Stations (BS) with capacity preconfigured for peak loads. These RANs have high call blocking and dropping rates since BSs resources cannot be shared. Cloud based RANs (C-RAN) have been proposed as a cost and energy efficient way of meeting high capacity demand of future wireless access networks by consolidating BSs to the cloud. Instead of relying on rejection of new call requests due to limited BS resources, C-RAN takes benefit of the cloud elasticity, which allows dynamic provisioning of cloud BS resources. This paper presents a novel C-RAN Call Admission Control (C-RAN CAC) to ensure Grade of Service (GoS) by improving blocking probability and improvement of call waiting times. Call blocking probability, call average waiting time and system utilization are used to evaluate the performance of the proposed CAC algorithm.
44
Chiu, Chin-Lien, et 邱進連. « Joint call admission control/congestion control for wireless integrated voice/data networks ». Thesis, 2001. http://ndltd.ncl.edu.tw/handle/53527107919468149937.
Texte intégralRésumé :
碩士國立臺灣科技大學
電機工程系
89
The next generation wireless personal communication is expected to provide an efficient method that allows anybody to conduct multimedia communication in any place at any time. Different traffics usually have different transmission characteristics and quality of service requirements. Therefore, how to design an efficient media access control protocol is an important issue in terms of performance of wireless communication system. We consider wireless communication systems supporting both voice and data services, where call admission control (CAC) is used to guarantee that existing and new connections can have enough resource to maintain QoS at the connection level; and congestion control is used to guarantee QoS at the cell level. The call admission control adopted in the thesis is a simple threshold scheme, i.e., the number of voice terminals in use can not exceed the threshold. The congestion control used is D-TDMA/PRPTS, where data request packets can be transmitted in a minislot only if no voice request packets have already started at the same minislot. Therefore, collisions between voice request packets and data request packets can be avoided, the voice packet loss probability is reduced, and thus the capacity of voice terminals and channel utilization can be improved. Furthermore, to avoid excessive delay due to minislot contention, voice request packet is dropped if it can not succeed in the frame at which it originates. We study the effect of voice interarrival time and voice threshold on voice packet loss probability, voice call blocking probability, data packet average delay, and channel utilization. With a Markovian model, the voice packet loss probability, voice blocking probability and channel utilization of voice traffics are derived, and the analytical results are verified with the simulation results. Due to the mathematical complexity, for integrated voice/data scenarios, computer simulation is used to evaluate the effect of proposed CAC and congestion control on the performance measures of both voice and data traffics.
45
Chen, Tsung-Chin, et 陳宗群. « A Ratio-Based Call Admission Control for ATM networks ». Thesis, 2001. http://ndltd.ncl.edu.tw/handle/18458921551342480773.
Texte intégralRésumé :
碩士國立中山大學
電機工程學系研究所
89
We propose a novel call admission control which makes use of ratio-based traffic measurement to estimate the required bandwidth when a new call is issued. Existing approaches fail to estimate properly the required bandwidth. To alleviate the problem, we calculate the ratio between the measured mean rate and the mean rate declared by UPC parameters. The ratio and the target cell loss rate are used to estimate the required bandwidth to make decision if a new call is accepted or rejected. Because of more accurate estimation of required bandwidth, our method can provide a better control on quality of service.
46
Hung-Erh, Huang, et 黃宏二. « A Study of Wireless Dynamic Call Admission Control Mechanism ». Thesis, 2003. http://ndltd.ncl.edu.tw/handle/10933613392825547657.
Texte intégralRésumé :
碩士國防管理學院
國防資訊研究所
91
Abstract In the field of wireless mobile communication, the performance of base stations is crucial to the quality of communication, the quality of service for base stations will be measured by the new calls block rate and hand off calls drop rate. When the integral demand of the base stations is greater than the total channel span, hand off calls and new calls will not be available due to the congestion of base stations. Therefore, the kernel of the question lies in the efficiency of utilizing the precious channel resources. This research has set its goal on raising the frequency in using the channels of base stations through “Call Admission Control” (CAC). From the view point of the distribution of channel resources, we categorize the wireless communication environment into two approaches, namely “Fixed Channel Allocation” and “Dynamic Channel Allocation”. Then we introduce the “Setting In Advance” and “Random Early Detection Mechanism” respectively into these two approaches to simulate the operations of the base stations. From the result of simulation, both the cut off rate of new calls and that of the hand off calls, we can compare these two mechanisms and thus raise the performance of the base stations.
47
Chung, Yu-Fen, et 鍾玉芬. « Call Admission Control with Neural network in ATM networks ». Thesis, 2000. http://ndltd.ncl.edu.tw/handle/84887464996173855331.
Texte intégralRésumé :
碩士義守大學
資訊工程學系
89
Asynchronous Transfer Mode (ATM) netowrks is an essential technology for integrating multimedia services in high-speed networks and recommended by International Telecommunications Union (ITU) for broadband integrated services digital networks (B-ISDN). It provides different quality of services (QoS) for different types of traffic sources with widely varying traffic characteristics. In order to guarantee the QoS requirements and to achieve high network utilization, it is necessary to implement a call admission controller. In this thesis, we investigate a CAC algorithm with neural network first. Owing to the self-learning capacity, the neural networks can be trained to fit the uncertainty of the traffic source. However, increasing the inputs result in increasing the complexity of the neural network. We think that different types of inputs can be processed separately, such as network status and traffic characteristics. Therefore, we increase the inputs of neural networks to promote its ability. Secondly, we propose a CAC scheme with two algorithms, named B&WCAC. In many literatures, they always apply only one algorithm to implement CAC. In ATM networks, we think it can adopt more than one algorithm to implement CAC scheme according to different types of traffic sources. We expect that it can be more precise and efficient for CAC by dividing traffic sources and algorithms into two types, black and white.
48
Yeh, Chih-Hsiang. « Call Admission Control for VoIP in IEEE 802.11 WLANs ». 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-3008200714485700.
Texte intégral
49
Yeh, Chih-Hsiang, et 葉志祥. « Call Admission Control for VoIP in IEEE 802.11 WLANs ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/78164127982022930515.
Texte intégralRésumé :
碩士臺灣大學
電機工程學研究所
95
Voice over Internet Protocol (VoIP) is no longer only feasible in wired networks, but also applicable through wireless networks as prevalence of wireless networks grows with the technology maturity and rising demand. While making a VoIP call over WiFi wireless networks is applicable, this is not a service with guaranteed quality. With limited bandwidth, an overloaded AP may cause wireless users to experience delayed packets, high packet loss rate, and even low throughput. IEEE 802.11 wireless Local Area Network (WLAN) was originally designed only for data traffic transmission, and therefore deficiency in real-time traffic transmission, such as VoIP applications, is inevitable. Not being able to timely transmit real-time packets not only fails to meet the demand of users, but also increases unnecessary loading in the wireless network. Industries and academies have made lots of efforts on providing QoS for real-time voice traffic which usually coexists with other classes of traffic. In this thesis, a call admission control mechanism is proposed which not only timely monitors the wireless networks, but also dynamically adjusts the number of admissible clients to wireless networks. New VoIP users not only know the network condition before entering it, but also accurately predict transmission quality through sending probing packets. With the mechanism, existing VoIP users in the wireless networks have their service protected, and potential VoIP users can expect good quality of service once admitted.
50
Chien-An, Chen. « Multi-Criteria Call Admission Control in IEEE 802.11 WLAN for Multi-Criteria Call Admission Control in IEEE 802.11 WLAN for Distributed Access Point Selection ». 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0009-0112200611284515.
Texte intégral