ارائه مدل مناسب براي ترافيك انباشته VoIP

چكيده انگليسي :

66 Represent a Proper Model for Aggregated VoIP Traffic Zahra Dashti Z dashti@ec iut ac ir Date of Submission 2011 10 23 Department of Electrical and Computer Engineering Isfahan University of Technology Iran Isfahan 84156 83111 Degree M Sc Language Farsi Supervisor Mahdi Mahdavi m mahdavi@cc iut ac ir Advisor Masood Reza Hashemi hashemim@cc iut ac ir Abstract One of the most important services of today s communication networks is voice service Voice overInternet Protocol VoIP or internet telephony is the technology to transport voice packets over internetinstead of using traditional PSTN Packet Switching Transmission Network VoIP traffic also containsconnections that are machine to machine transactions such as faxes point of sale credit card chargeverifications and computer connections to the Internet Transmitting voice over internet is the necessity ofmodern applications which combine voice and data VoIP system has many options of configurations Normally a VoIP system includes encoder such as G 711 G 728 G 729 G 723 1 and packetizer RTP RTCP in the sender part the internet and depacketizer and decoder in the receiver part There are a numberof benefits of Voice over Internet Protocol which underlines the importance of VoIP reduced communicationcost the use of the integrated IP infrastructure participating in a multimedia application VoIP can alsoutilize the advantages of packet switched networks as high network utilization while keeping the quality ofcircuit switched networks However the best effort nature of IP networks can not guarantee the requirementsof delay sensitive voice traffic VoIP network management is needed to support Quality of service QoS forVoIP applications QoS requirements for voice are more stringent than for the other applications Voice is areal time application Speech to be intelligible needs special treatment So QoS standards for VoIP trafficare set for voice The design and performance analysis of VoIP QoS techniques requires adequate trafficmodels which is the target of this thesis Although good traffic models for unitary VoIP applications do exist the simulation of thousands of connections is very slow making simulation studies very heavy Aggregatetraffic models are needed to achieve faster simulations without losing accuracy In this thesis we characterizethe superposition of VoIP applications There have been many attempts to model a single voice over IPstream and their aggregation and there are also well explored theories on circuit switched telephonenetworks This thesis wants to expose a way how to combine these approaches to have a proper model foraggregate voice over IP traffic on a network Aggregate traffic models are essential in performanceevaluation studies on large scale networks However simple aggregate traffic models are needed to enhancesimulation efficiency and allow analytical QoS evaluation This thesis presents a characterization study ofVoIP aggregated traffic In this thesis we propose a method to simulate the aggregated traffic of a number ofOn Off traffic sources by a reduced equivalent set that will produce the same traffic characteristics On Offtraffic source models are used extensively to model the source traffic in the Internet However when trafficfrom a large number of sources is to be simulated it becomes computationally prohibitive to generate eachsource separately In such a case a reduced set of aggregated models would be needed if it can generate thesame traffic intensity and traffic characteristics An approach based on matching the first and second orderstatistics of the original aggregate to reduce the number of traffic generators is presented in this thesis withsome simulation results Keywords VoIP Traffic Aggregate Traffic Modeling Traffic Modeling On Off Source

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ارائه مدل مناسب براي ترافيك انباشته VoIP

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