Since the late 90's IP telephony, commonly referred to as Voice over IP (VoIP), has been presented as a revolution on communications enabling the possibility to converge historically separated voice and data networks, reducing costs, and integrating voice, data and video on applications. This paper presents a study over the standard VoIP protocols H.323, session initiation protocol (SIP), media gateway control protocol (MGCP), and H.248/Megaco. Given the fact that H.323 and SIP are more widespread than the others, we focus our study on them. For each of these protocols we describe and discuss its main capabilities, architecture, stack protocol, and characteristics. We also briefly point their technical limitations. Furthermore, we present the advanced multimedia system (AMS) project, a new system that aims to operate on Next Generation Networks (NGN) taking the advantage of its features, and it is viewed as the successor to H.323 and SIP.
{"title":"Past, Present and Future of IP Telephony","authors":"V. Soares, P. Neves, J.J.P. Rodrigues","doi":"10.1109/CTRQ.2008.12","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.12","url":null,"abstract":"Since the late 90's IP telephony, commonly referred to as Voice over IP (VoIP), has been presented as a revolution on communications enabling the possibility to converge historically separated voice and data networks, reducing costs, and integrating voice, data and video on applications. This paper presents a study over the standard VoIP protocols H.323, session initiation protocol (SIP), media gateway control protocol (MGCP), and H.248/Megaco. Given the fact that H.323 and SIP are more widespread than the others, we focus our study on them. For each of these protocols we describe and discuss its main capabilities, architecture, stack protocol, and characteristics. We also briefly point their technical limitations. Furthermore, we present the advanced multimedia system (AMS) project, a new system that aims to operate on Next Generation Networks (NGN) taking the advantage of its features, and it is viewed as the successor to H.323 and SIP.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123781986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Operations of vehicular ad hoc networks rely on the collaboration of participating nodes to route data for each other. This standard approach using a fixed set of nodes for each communication link cannot cope with high mobility due to a high frequency of link breaks. A recent approach based on virtual routers has been proposed to address this problem. In this new environment, virtual routers are used for forwarding data. The functionality of each virtual router is provided by the mobile devices currently within its spatial proximity. Since these routers do not move, the communication links are much more robust compared to those of the conventional techniques. In this paper, we investigate techniques to enforce collaboration among mobile devices in supporting the virtual router functionality. Simulation results based on various system configurations are given. They indicate that the proposed technique is effective.
{"title":"Cooperation Enforcement in Vehicular Networks","authors":"Y. H. Ho, A. H. Ho, G. Hamza-Lup, Kien A. Hua","doi":"10.1109/CTRQ.2008.25","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.25","url":null,"abstract":"Operations of vehicular ad hoc networks rely on the collaboration of participating nodes to route data for each other. This standard approach using a fixed set of nodes for each communication link cannot cope with high mobility due to a high frequency of link breaks. A recent approach based on virtual routers has been proposed to address this problem. In this new environment, virtual routers are used for forwarding data. The functionality of each virtual router is provided by the mobile devices currently within its spatial proximity. Since these routers do not move, the communication links are much more robust compared to those of the conventional techniques. In this paper, we investigate techniques to enforce collaboration among mobile devices in supporting the virtual router functionality. Simulation results based on various system configurations are given. They indicate that the proposed technique is effective.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"2009 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127332712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
TCP remains the protocol of choice for bulk data transfers over the Internet. A range of mathematical approaches were proposed to evaluate the performance of TCP, approaches validated through synthetic or endpoint controlled traffic, typically unsuitable for short-lived transfers or clients with unknown behaviour. This paper aims to overcome these problems by using a supervised adaptive learning approach to build the relationship between TCP performance and the influencing parameters. An earlier study indicated several advantages of the approach, as well as several issues, particularly related to the efficiency of the model on real traces. Comparison against the mathematical models showed that the proposed model provides more accurate estimates for real time traffic without losses, with tests results indicating that the average error of the connection duration, estimated using the proposed model, was 50% smaller than the value obtained using the mathematical approach.
{"title":"Neural Network Estimation of TCP Performance","authors":"Bogdan Ghita, S. Furnell","doi":"10.1109/CTRQ.2008.19","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.19","url":null,"abstract":"TCP remains the protocol of choice for bulk data transfers over the Internet. A range of mathematical approaches were proposed to evaluate the performance of TCP, approaches validated through synthetic or endpoint controlled traffic, typically unsuitable for short-lived transfers or clients with unknown behaviour. This paper aims to overcome these problems by using a supervised adaptive learning approach to build the relationship between TCP performance and the influencing parameters. An earlier study indicated several advantages of the approach, as well as several issues, particularly related to the efficiency of the model on real traces. Comparison against the mathematical models showed that the proposed model provides more accurate estimates for real time traffic without losses, with tests results indicating that the average error of the connection duration, estimated using the proposed model, was 50% smaller than the value obtained using the mathematical approach.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115435074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E.J. Rivera-Lara, R. Herrerias-Hernandez, J. A. Pérez-Díaz, C. F. Garcia-hernandez
Nowadays, it is very important to study the behavior of the wireless networks due to the variety of applications that make use of this technology. These applications frequently require a minimum QoS in order to work properly and guarantee a good service to the user. This paper aims to find a relationship between signal to noise ratio (SNR) and a 802.11g networkpsilas QoS in terms of latency, packet loss and jitter. It has been created a software tool that obtains different TCP parameters from a file which contains the data about the packet transfer between two nodes in the network. Wepsilave found an instable behavior during the test series because of the nature of wireless networks. Besides, wepsilave pointed out how the delay and the packet loss are affected as the SNR ratio decreases, while jitter has an exponential growth when the signal decreases from 19 to 11 dB. Wepsilave found that the optimal range for most of the real time applications (as VoIP) goes from 34-90 dB, at this range we can find a good QoS in the network performance.
{"title":"Analysis of the Relationship between QoS and SNR for an 802.11g WLAN","authors":"E.J. Rivera-Lara, R. Herrerias-Hernandez, J. A. Pérez-Díaz, C. F. Garcia-hernandez","doi":"10.1109/CTRQ.2008.18","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.18","url":null,"abstract":"Nowadays, it is very important to study the behavior of the wireless networks due to the variety of applications that make use of this technology. These applications frequently require a minimum QoS in order to work properly and guarantee a good service to the user. This paper aims to find a relationship between signal to noise ratio (SNR) and a 802.11g networkpsilas QoS in terms of latency, packet loss and jitter. It has been created a software tool that obtains different TCP parameters from a file which contains the data about the packet transfer between two nodes in the network. Wepsilave found an instable behavior during the test series because of the nature of wireless networks. Besides, wepsilave pointed out how the delay and the packet loss are affected as the SNR ratio decreases, while jitter has an exponential growth when the signal decreases from 19 to 11 dB. Wepsilave found that the optimal range for most of the real time applications (as VoIP) goes from 34-90 dB, at this range we can find a good QoS in the network performance.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114391036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a new robust congestion control strategy is proposed for a multi-services architecture, namely a Differentiated-Services (DiffServ) network. In virtue of their robustness capabilities, Sliding Mode-based Variable Structure Control (SM-VSC) techniques are utilized to design our proposed controller on the basis of an inaccurate/uncertain Fluid Flow Model (FFM). Developed for an interconnected network as a hop-by-hop distributed control scheme, the proposed algorithm is shown to achieve the desired performance specifications and requirements. Moreover, the error dynamics of the overall time delay dependent network is analytically shown to be L2 stable.
{"title":"A Distributed Congestion Control Strategy for Differentiated-Services Network","authors":"K. Bouyoucef, Khashayar Khorasani","doi":"10.1109/CTRQ.2008.13","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.13","url":null,"abstract":"In this paper, a new robust congestion control strategy is proposed for a multi-services architecture, namely a Differentiated-Services (DiffServ) network. In virtue of their robustness capabilities, Sliding Mode-based Variable Structure Control (SM-VSC) techniques are utilized to design our proposed controller on the basis of an inaccurate/uncertain Fluid Flow Model (FFM). Developed for an interconnected network as a hop-by-hop distributed control scheme, the proposed algorithm is shown to achieve the desired performance specifications and requirements. Moreover, the error dynamics of the overall time delay dependent network is analytically shown to be L2 stable.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114644145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HyTrace is a hybrid system providing stable paths between mobile ad hoc nodes. The ad hoc network thereby is organized in clusters where the cluster heads maintain uplinks to a backbone network. The backbone keeps track of available clusters and stable connection between them. The backbone also inter-links different network partitions thus increasing the reliability of the whole system. The underlying Weighted Cluster Path Discovery algorithm still keeps working in settings where no backbone network is available. Broadcasting as well as message exchange between arbitrary nodes is used to further motivate the usefulness of the system.
{"title":"HyTrace Backbone-Assisted Path Discovery in Hybrid Networks","authors":"A. Andronache, S. Rothkugel","doi":"10.1109/CTRQ.2008.16","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.16","url":null,"abstract":"HyTrace is a hybrid system providing stable paths between mobile ad hoc nodes. The ad hoc network thereby is organized in clusters where the cluster heads maintain uplinks to a backbone network. The backbone keeps track of available clusters and stable connection between them. The backbone also inter-links different network partitions thus increasing the reliability of the whole system. The underlying Weighted Cluster Path Discovery algorithm still keeps working in settings where no backbone network is available. Broadcasting as well as message exchange between arbitrary nodes is used to further motivate the usefulness of the system.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133650833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The transmission control protocol (TCP) uses a sliding window in order to enforce flow control. The receiver advertises its available buffer space to the sender, which cannot transmit more data than the advertised space. Transmitted data is first copied from application buffers into TCP buffers and from there it is sent through the network. In this paper we propose a model which characterizes the senderpsilas behavior throughout the duration of a TCP conversation. The model is suitable in the case of powerful, but variably loaded senders, slow receivers, fast connections and moderate amounts of data transmitted. For this model we present an O(nldrlog2n) algorithm which computes the minimum processing time spent by the sender, if the window sizes advertised by the receiver and the senderpsilas load are known in advance. The solution is based on an algorithmic framework for the segment tree data structure, which we introduce in this paper.
{"title":"Optimal Offline TCP Sender Buffer Management Strategy","authors":"M. Andreica, N. Tapus","doi":"10.1109/CTRQ.2008.11","DOIUrl":"https://doi.org/10.1109/CTRQ.2008.11","url":null,"abstract":"The transmission control protocol (TCP) uses a sliding window in order to enforce flow control. The receiver advertises its available buffer space to the sender, which cannot transmit more data than the advertised space. Transmitted data is first copied from application buffers into TCP buffers and from there it is sent through the network. In this paper we propose a model which characterizes the senderpsilas behavior throughout the duration of a TCP conversation. The model is suitable in the case of powerful, but variably loaded senders, slow receivers, fast connections and moderate amounts of data transmitted. For this model we present an O(nldrlog2n) algorithm which computes the minimum processing time spent by the sender, if the window sizes advertised by the receiver and the senderpsilas load are known in advance. The solution is based on an algorithmic framework for the segment tree data structure, which we introduce in this paper.","PeriodicalId":117329,"journal":{"name":"2008 International Conference on Communication Theory, Reliability, and Quality of Service","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114760802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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