Congestion control for transmission control protocol (TCP) over asynchronous transfer mode (ATM) networks

Performance of Transmission Control Protocol (TCP) connections in high-speed Asynchronous Transfer Model (ATM) networks is of great importance due to the widespread use of the TCP/IP protocol for data transfers and the increasing deployment of ATM networks. When TCP runs on top of ATM network, the TCP window based and ATM rate based congestion control mechanisms interact with each other. TCP performance may be degraded by the mismatch between the two mechanisms. We study the TCP performance over ATM networks with Unspecified Bit Rate (UBR) service and Available Bit Rate (ABR) service under various congestion control mechanisms by using simulation techniques, and propose a novel congestion control algorith, "Fair Intelligent Congestion Control", which significantly enhances the congestion control efficiency and improves the TCP performance over ATM networks

Satellite Networks: Architectures, Applications, and Technologies

Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

Quality of service over ATM networks

PhDAbstract not availabl

Optimization and Performance Analysis of High Speed Mobile Access Networks

The end-to-end performance evaluation of high speed broadband mobile access networks is the main focus of this work. Novel transport network adaptive flow control and enhanced congestion control algorithms are proposed, implemented, tested and validated using a comprehensive High speed packet Access (HSPA) system simulator. The simulation analysis confirms that the aforementioned algorithms are able to provide reliable and guaranteed services for both network operators and end users cost-effectively. Further, two novel analytical models one for congestion control and the other for the combined flow control and congestion control which are based on Markov chains are designed and developed to perform the aforementioned analysis efficiently compared to time consuming detailed system simulations. In addition, the effects of the Long Term Evolution (LTE) transport network (S1and X2 interfaces) on the end user performance are investigated and analysed by introducing a novel comprehensive MAC scheduling scheme and a novel transport service differentiation model

Reactive traffic control mechanisms for communication networks with self-similar bandwidth demands

Communication network architectures are in the process of being redesigned so that many different services are integrated within the same network. Due to this integration, traffic management algorithms need to balance the requirements of the traffic which the algorithms are directly controlling with Quality of Service (QoS) requirements of other classes of traffic which will be encountered in the network. Of particular interest is one class of traffic, termed elastic traffic, that responds to dynamic feedback from the network regarding the amount of available resources within the network. Examples of this type of traffic include the Available Bit Rate (ABR) service in Asynchronous Transfer Mode (ATM) networks and connections using Transmission Control Protocol (TCP) in the Internet. Both examples aim to utilise available bandwidth within a network. Reactive traffic management, like that which occurs in the ABR service and TCP, depends explicitly on the dynamic bandwidth requirements of other traffic which is currently using the network. In particular, there is significant evidence that a wide range of network traffic, including Ethernet, World Wide Web, Varible Bit Rate video and signalling traffic, is self-similar. The term self-similar refers to the particular characteristic of network traffic to remain bursty over a wide range of time scales. A closely associated characteristic of self-similar traffic is its long-range dependence (LRD), which refers to the significant correlations that occur with the traffic. By utilising these correlations, greater predictability of network traffic can be achieved, and hence the performance of reactive traffic management algorithms can be enhanced. A predictive rate control algorithm, called PERC (Predictive Explicit Rate Control), is proposed in this thesis which is targeted to the ABR service in ATM networks. By incorporating the LRD stochastic structure of background traffic, measurements of the bandwidth requirements of background traffic, and the delay associated with a particular ABR connection, a predictive algorithm is defined which provides explicit rate information that is conveyed to ABR sources. An enhancement to PERC is also described. This algorithm, called PERC+, uses previous control information to correct prediction errors that occur for connections with larger round-trip delay. These algorithms have been extensively analysed with regards to their network performance, and simulation results show that queue lengths and cell loss rates are significantly reduced when these algorithms are deployed. An adaptive version of PERC has also been developed using real-time parameter estimates of self-similar traffic. This has excellent performance compared with standard ABR rate control algorithms such as ERICA. Since PERC and its enhancement PERC+ have explicitly utilised the index of self-similarity, known as the Hurst parameter, the sensitivity of these algorithms to this parameter can be determined analytically. Research work described in this thesis shows that the algorithms have an asymmetric sensitivity to the Hurst parameter, with significant sensitivity in the region where the parameter is underestimated as being close to 0.5. Simulation results reveal the same bias in the performance of the algorithm with regards to the Hurst parameter. In contrast, PERC is insensitive to estimates of the mean, using the sample mean estimator, and estimates of the traffic variance, which is due to the algorithm primarily utilising the correlation structure of the traffic to predict future bandwidth requirements. Sensitivity analysis falls into the area of investigative research, but it naturally leads to the area of robust control, where algorithms are designed so that uncertainty in traffic parameter estimation or modelling can be accommodated. An alternative robust design approach, to the standard maximum entropy approach, is proposed in this thesis that uses the maximum likelihood function to develop the predictive rate controller. The likelihood function defines the proximity of a specific traffic model to the traffic data, and hence gives a measure of the performance of a chosen model. Maximising the likelihood function leads to optimising robust performance, and it is shown, through simulations, that the system performance is close to the optimal performance as compared with maximising the spectral entropy. There is still debate regarding the influence of LRD on network performance. This thesis also considers the question of the influence of LRD on traffic predictability, and demonstrates that predictive rate control algorithms that only use short-term correlations have close performance to algorithms that utilise long-term correlations. It is noted that predictors based on LRD still out-perform ones which use short-term correlations, but that there is Potential simplification in the design of predictors, since traffic predictability can be achieved using short-term correlations. This thesis forms a substantial contribution to the understanding of control in the case where self-similar processes form part of the overall system. Rather than doggedly pursuing self-similar control, a broader view has been taken where the performance of algorithms have been considered from a number of perspectives. A number of different research avenues lead on from this work, and these are outlined

Overview of UMTS network evolution through radio and transmission feature validation

This project is based on several UMTS network feature validation with the aim to provide an end-to-end in-depth knowledge overview gained in parallel in the areas of radio network mobility processes (cell camping and inter-system handover), Quality of Service improvement for HSPA data users and transport network evolution towards the All-IP era.Hardware and software validation is a key step in the relationship between the mobile network operator and the vendor. Through this verification process, while executing that functionality or testing a specific hardware, the difference between the actual result and expected result can be better understood and, in turn, this in-depth knowledge acquisition is translated into a tailored usage of the product in the operator’s live network. As a result, validation helps in building a better product as per the customer’s requirement and helps satisfying their needs, which positively impacts in the future evolution of the vendor product roadmap implementation process for a specific customer. This project is based on several Universal Mobile Telecommunication Services (UMTS) network feature validation with the aim to provide an end-to-end in-depth knowledge overview gained in parallel in the areas of radio network mobility processes (cell camping and inter-system handover), Quality of Service improvement for High Speed Downlink Packet Access (HSPA) data users and transport network evolution towards the All-IP era.Las campañas de validación hardware y software son un paso clave en las relaciones comerciales establecidas entre un operador de telecomunicaciones y su proveedor de equipos de red. Durante los procesos de certificación, mientras se ejecuta una funcionalidad software o se valida un determinado hardware, se obtiene un conocimiento profundo de la diferencia entre el resultado obtenido y el esperado, repercutiendo directamente en un uso a medida de dicha funcionalidad o hardware en la propia red del cliente. Como consecuencia de lo anterior, podemos aseverar que los procesos de validación permiten en gran medida al proveedor adaptarse mejor a los requerimientos del cliente, ayudando a satisfacer realmente sus necesidades. Esto implica directamente un impacto positivo en la futura evolución del portfolio que el fabricante ofrece a un determinado cliente. Este proyecto está basado en la validación de diferentes funcionalidades de red UMTS, cuyo objetivo es proporcionar un conocimiento global de distintos aspectos que conforman el funcionamiento de una red de telecomunicaciones 3G, como son los procesos de movilidad de acceso radio (acampado de red y handover inter-sistema), las mejoras en la calidad de servicio para usuarios de datos HSPA y la convergencia de la red de transporte hacia la era IP.Els processos de validació hardware i software són un punt clau en les relacions comercials establertes entre un operador de telecomunicaciones i el proveïdor d'equipament de la xarxa. En el transcurs dels processos de certificació, a la mateixa vegada que s'executa una funcionalitat software o es valida un determinat hardware, s'obtenen grans coneixements respecte la diferència entre el resultat obtingut i l'esperat, que són d'aplicació directa a l'hora d'establir un ús adpatat a la xarxa del client. En conseqüència, podem asseverar que les campanyes de validació permeten en gran mesura al proveïdor adaptar-se millor als requeriments del client, ajudant a satisfer realment les seves necessitats. Això implica directament un impacte positiu en la futura evol.lució del portfoli que el fabricant ofereix a un determinat client. Aquest projecte es basa en la presentació d'un procès de validació de diferents funcionalitats relacionades amb la xarxa UMTS, amb l'objectiu de proporcionar un coneixement global de la varietat d'aspectes que conformen el funcionament d'una xarxa de telecomunicacions 3G, com són els processos de mobilitat en accès radio (acampat de l'usuari i handover inter-sistema), millores en la qualitat de servei per a usuaris de dades HSPA i la convergència de la xarxa de transport cap a l'era IP

A new charging scheme for ATM based on QoS

PhDNew services are emerging rapidly within the world of telecommunications. Charging strategies that were appropriate for individual transfer capabilities are no longer appropriate for an integrated broadband communications network. There is currently a range of technologies (such as cable television, telephony and narrow band ISDN) for the different services in use and a limited number of charging schemes are applicable for each of the underlying technologies irrespective of the services used over it. Difficulties arise when a wide range of services has to be supported on the same integrated technology such as asynchronous transfer mode (ATM); in such cases the type of service in use and the impact it has on the network becomes much more important. The subject of this thesis, therefore, is the charging strategies for integrated broadband communications networks. That is, the identification of the requirements associated with ATM charging schemes and the proposal of a new approach to charging for ATM called the “quality of service based charging scheme”. Charging for ATM is influenced by three important components: the type and content of a service being offered; the type of customer using the services; and the traffic characteristics belonging to the application supporting the services. The first two issues will largely be dependent on the business and regulatory requirements of the operators. The last item, and an essential one for ATM, is the bridge between technology and business; how are the resources used by a service quantified? Charging that is based on resource usage at the network level was the prime focus of the research reported here. With the proposed charging scheme, a distinction is first made between the four different ATM transfer capabilities that will support various services and the different quality of service requirements that may be applicable to each of them. Then, resources are distributed among buffers set-up to support the combination of these transfer capabilities and quality of services. The buffers are dimensioned according to the M/D/1/K and the ND/D/1 queuing analysis to determine the buffer efficiency and quality of service requirements. This dimensioning provides the basis for fixing the price per unit of resource and time. The actual resource used by a connection is based on the volume of cells transmitted or peak cell rate allocation in combination with traffic shapers if appropriate. Shapers are also dimensioned using the quality of service parameters. Since the buffer 4 efficiency is dependent on the quality of service requirements, users (customers) of ATM networks buy quality of service. The actual price of a connection is further subjected to a number of transformations based on the size of the resource purchased, the time of the day at which a connection is made, and the geographical locality of the destination switch. It is demonstrated that the proposed charging scheme meets all the requirements of customers and of network operators. In addition the result of the comparison of the new scheme with a number of existing, prominent, ATM charging schemes is presented, showing that the performance of the proposed scheme is better in terms of meeting the expectations of both the customers and the network operators

Results of the SURFnet4 management project 1997

This technical report bundles the five reports that were written for two SURFnet4 projects in 1997. Each report discusses a different research aspect of the SURFnet4 ATM network. The topics are 1) the Architecture of a ATM PVC Management Tool, 2) Reporting on the Use of the ATM Network, 3) SVCs in a Production Environment, 4) Quality of Service Measures, 5) Operation and Maintenance (OAM)

IP and ATM - current evolution for integrated services

Current and future applications make use of different technologies as voice, data, and video. Consequently network technologies need to support them. For many years, the ATM based Broadband-ISDN has generally been regarded as the ultimate networking technology, which can integrate voice, data, and video services. With the recent tremendous growth of the Internet and the reluctant deployment of public ATM networks, the future development of ATM seems to be less clear than it used to be. In the past IP provided (and was though to provide) only best effort services, thus, despite its world wide diffution, was not considered as a network solution for multimedia application. Currently many of the IETF working groups work on areas related to integrated services, and IP is also proposing itself as networking technology for supporting voice, data, and video services. This paper give a technical overview on the competing integrated services network solutions, such as IP, ATM and the different available and emerging technologies on how to run IP over ATM, and tries to identify their potential and shortcomings