Traffic Profiles and Performance Modelling of Heterogeneous Networks

This thesis considers the analysis and study of short and long-term traffic patterns of heterogeneous networks. A large number of traffic profiles from different locations and network environments have been determined. The result of the analysis of these patterns has led to a new parameter, namely the 'application signature'. It was found that these signatures manifest themselves in various granularities over time, and are usually unique to an application, permanent virtual circuit (PVC), user or service. The differentiation of the application signatures into different categories creates a foundation for short and long-term management of networks. The thesis therefore looks from the micro and macro perspective on traffic management, covering both aspects. The long-term traffic patterns have been used to develop a novel methodology for network planning and design. As the size and complexity of interconnected systems grow steadily, usually covering different time zones, geographical and political areas, a new methodology has been developed as part of this thesis. A part of the methodology is a new overbooking mechanism, which stands in contrast to existing overbooking methods created by companies like Bell Labs. The new overbooking provides companies with cheaper network design and higher average throughput. In addition, new requirements like risk factors have been incorporated into the methodology, which lay historically outside the design process. A large network service provider has implemented the overbooking mechanism into their network planning process, enabling practical evaluation. The other aspect of the thesis looks at short-term traffic patterns, to analyse how congestion can be controlled. Reoccurring short-term traffic patterns, the application signatures, have been used for this research to develop the "packet train model" further. Through this research a new congestion control mechanism was created to investigate how the application signatures and the "extended packet train model" could be used. To validate the results, a software simulation has been written that executes the proprietary congestion mechanism and the new mechanism for comparison. Application signatures for the TCP/IP protocols have been applied in the simulation and the results are displayed and discussed in the thesis. The findings show the effects that frame relay congestion control mechanisms have on TCP/IP, where the re-sending of segments, buffer allocation, delay and throughput are compared. The results prove that application signatures can be used effectively to enhance existing congestion control mechanisms.AT&T (UK) Ltd, Englan

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Tohoku University加藤寧課

Dimensioning mobile WiMAX in the access and core network : a case study

Existing broadband wireless technologies such as evolving 3G and WiFi have enjoyed widespread adoption but are far from offering the flexibility in deployment and high data rates. Mobile WiMAX, an emerging broadband wireless technology promises to bring a new experience to mobile broadband services by offering users high data rates and efficient network access techniques. This thesis work provides a technical description of mobile WiMAX and compares its technical capabilities with the existing technologies such as WiFi and 3G. The work continues further on dimensioning mobile WiMAX in the access and core network. In the access network, we determine the number of base stations required to cover a given metropolitan area, explore their configurations, and perform frequency selection. In the core network we dimension the interfaces, and nodes involved. From the study we will show that WiMAX provides the operator with the antenna configurations options of high capacities, large cell coverage area, and a wide selection of QoS classes. The study will also show that the data density requirements of customers, resulting from the capacity analysis are fulfilled by properly dimensioning the elements in the access and core network