New Methods of Quality of Service Assurance in Data Networks

Dizertační práce je zaměřena na výzkum v oblasti technologií pro zajištění kvality služeb v datových sítích. Moderní komunikační sítě se v dnešní době již neobejdou bez kvalitního nástroje pro poskytování odlišného zacházení různým třídám provozu. Jak studie ukázaly, v současnosti nejpoužívanější QoS mechanizmus v datových sítích je technologie diferencovaných služeb. Stěžejní částí práce je návrh nového QoS systému, který nabízí řešení jednoho z hlavních problémů technologie DiffServ. Nedostatkem tohoto mechanizmu je chybějící spolupráce mezi koncovou stanicí a hraničním prvkem DiffServ domény. Navržený systém proto nabízí síťové aplikaci možnost podílet se na procesu zajištění požadované úrovně kvality služby tím, že sama nastaví hodnotu DSCP v hlavičce svých paketů. Základem tohoto systému je znalost konfigurace technologie DiffServ na hraničním směrovači. Za tímto účelem používá koncová stanice protokol SNMP, pomocí kterého vyčítá potřebné konfigurační informace z MIB databáze síťového prvku. Navržený QoS systém byl ověřen v simulačních podmínkách. Výsledky simulací ukázaly, že navržený systém představuje efektivní řešení zmíněného problému technologie DiffServ, což dává dobrý předpoklad pro jeho úspěšné nasazení v reálných podmínkách.The doctoral thesis is focused on a research in the area of the quality-of-service support technologies in data networks. The current modern communication networks cannot operate correctly without an effective tool allowing differentiated treatment for various network traffic classes. Looking at the current trends in this area it turns out that the technology of Differentiated services is currently the most widely used mechanism for QoS assurance in data networks. The major part of this doctoral thesis concerns the design of a novel QoS system which offers a solution for one of the main problems of DiffServ technology. This disadvantage lies in the missing cooperation between the end station and edge node of the DiffServ domain. To overcome this limitation the system proposed introduces an improvement which enables the user application to actively participate in the resource reservation process by direct configuration of the DSCP value in the IP header of its own packets. This functionality is based on the identification of DiffServ configuration parameters available in the edge router. To retrieve the information required from network component the well-known SNMP protocol has been chosen, which has direct access to the components’s configuration stored in the MIB database. On the basis of this theoretical proposal several simulation scenarios have been created and analysed. The results show that the system designed presents an efficient solution for the mentioned problem of DiffServ. They also give good assumptions for the successful implementation of this system into a real environment.

Real-time bandwidth encapsulation for IP/MPLS Protection Switching

Bandwidth reservation and bandwidth allocation are needed to guarantee the protection of voice traffic during network failure. Since voice calls have a time constraint of 50 ms within which the traffic must be recovered, a real-time bandwidth management scheme is required. Such bandwidth allocation scheme that prioritizes voice traffic will ensure that the voice traffic is guaranteed the necessary bandwidth during the network failure. Additionally, a mechanism is also required to provide the bandwidth to voice traffic when the reserved bandwidth is insufficient to accommodate voice traffic. This mechanism must be able to utilise the working bandwidth or bandwidth reserved for lower priority applications and allocate it to the voice traffic when a network failure occurs

Accepting the challenges of IP-based UMTS radio access network evolution scenarios

The tendency in future mobile Radio Access Networks (RANs) consists in an increase of new and Internet Protocol (IP)-based services with strict requirements regarding bandwidth and Quality of Service (QoS) and in a dominance of packet data traffic in future mobile networks. Existing mobile networks (e.g. Universal Mobile Telecommunications System (UMTS) Release 99 (R99)), which are designed assuming a predominance of circuit switched traffic, are not suitable to efficiently carry IP traffic under consideration of the hierarchical and centralistic network structure of existing mobile networks, the coupling of user and control plane and the strict delay requirements in the RAN. Consequently, an architecture evolution of mobile RANs with regard to their network architecture has to take place. Within the cooperation of Lucent Technologies and the University of Duisburg-Essen in the project IPonAir, funded by the German Ministry for Education and Research (Bundesministerium für Bildung und Forschung (BMBF)), and within the work carried out for this thesis, a flexible, efficient and toolsupported approach was developed that allows for an evaluation of future mobile RANs with regard to signaling performance. This approach provides decision support to the designer of future mobile networks in a very early design phase. The evaluation approach comprises a methodology for eventdriven simulation of signaling sequences, depicted in the form of Message Sequence Charts (MSCs), as well as a toolkit – both, i.e. the simulation methodology as well as the toolkit, enable an optimization as well as an assessment of future mobile RANs with regard to signaling performance as well as a comparison with the UMTS R99 as a reference architecture. In the thesis on hand, the above mentioned evaluation approach is presented in detail. Moreover, the approach is applied to potential evolution scenarios of mobile RANs. On the one hand these RAN evolution scenarios are optimized with regard to signaling performance. On the other hand the RAN evolution scenarios are compared to the UMTS R99 reference architecture with regard to their signaling performance behavior

Performance evaluation of information and communications technology infrastructure for smart distribution network applications

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.Current electrical networks require secure, scalable and cost-effective Information and Communications Technology (ICT) solutions to facilitate the novel functionalities required by Smart Grids. Countries around the globe are investigating alternative energy sources to mitigate the current energy crisis and environmental issues experienced by many countries due to global warming, rapid growth of population, inefficient energy management, dwindling fossil fuel resources, etc. Therefore, alternative or renewable energy sources, such as wind, solar, hydro, combined heat and power, etc., are required to mitigate such a crisis and such sources will also need to be integrated in to the power grid in a distributed manner. Such distributed energy sources are mainly connected to the distribution networks and introduce huge challenges to the distribution network operator (DNO). Many of these challenges cannot be dealt with effectively using existing network operation mechanisms therefore the research and development of novel ICT solutions to support smart distribution network operation is required. This research investigated suitable ICT solutions to enable the Smart Grid to tackle these challenges and proposes ICT infrastructure models that can be used for simulation studies in order to investigate cost-effective, scalable and secure solutions for the DNOs. Initially, a Quality of Service (QoS) monitoring test-bed was proposed to evaluate the performance of bandwidth intensive applications, such as smart meter data transmission. Simulation studies for different communication technologies, cellular and Power Line Communication (PLC), were also carried out and the simulation models were verified using experimental test results. Finally, the modelling and analysis of smart metering infrastructure was carried out using simulation and extensive studies were performed to evaluate the data transmission rate performance for different configurations of smart meters and concentrators