El despliegue de las redes celulares 3G/3.5G plantea un reto a las estrategias de planificación y optimización radio tradicionales. A diferencia de los sistemas 2G FDMA, cobertura y capacidad están estrechamente ligadas y deben ser tratadas conjuntamente. Además, están presentes nuevos y más sofisticados algoritmos de gestión de recursos radio (RRM) así como una concepción de red más flexible, con múltiples parámetros interdependientes con ajuste no trivial. Un nuevo paradigma de planificación radio aparece y la red se optimiza mediante complejos algoritmos ya sea estática o dinámicamente. Esta tesis doctoral supone una contribución a la optimización de las redes de acceso radio en sistemas 3G/3.5G. Varios aspectos susceptibles de mejorar la planificación han sido investigados y nuevos métodos, directrices y estrategias de análisis se proponen con el objetivo final de mejorar el rendimiento del sistema. También se han diseñado y estudiado mecanismos dinámicos que se encuentran en la frontera difusa entre la planificación y la RRM. La 1ª parte de la tesis trata la configuración de las estaciones base. El impacto de las potencias piloto, inclinación de antenas y sus interacciones con parámetros de soft handover son investigados. Se hace énfasis en los efectos más allá de los conocidos y se derivan reglas para su ajuste. A partir de los resultados, se propone una estrategia para su Planificación Automática. El objetivo final es encontrar una combinación tal que el tráfico sea ecualizado de manera efectiva entre las celdas e incrementar la capacidad del sistema. La técnica se basa en la metaheurística Simulated Annealing y es capaz de mejorar el rendimiento global de la red, representado por una función de coste con información sobre el factor de carga y sujeta a otras condiciones de calidad. La importancia de los requisitos que impone el UL, a menudo olvidados en propuestas anteriores, también se ha incluido y estudiado analíticamente. La reconfiguración de las base no es el único medio para modificar la cobertura de las celdas, en este sentido el estudio se amplía mediante la introducción de repetidores, que permiten la generación de celdas distribuidas. En este caso la planificación es más compleja debido a la aparición de nuevos efectos que no se daban en las redes clásicas 2G FDMA. La mayoría de los trabajos que tratan con repetidores tienden a ignorarlos. Por ello, la investigación se centró en el modelado y cuantificación de su impacto así como en derivar directrices de planificación. Se ha obtenido analíticamente la nueva expresión que define la región de admisión y se concluye que existe un compromiso entre capacidad y cobertura, analizado tanto teóricamente como mediante simulación. Ciertos parámetros presentan un impacto importante y se han estudiado para obtener reglas prácticas de ajuste. La variación de cobertura en la celda padre antes y después de la instalación de repetidores también ha sido modelada. Posteriormente, se propone una nueva metodología para analizar estos despliegues, teniendo en cuenta de manera realista los retardos de propagación y el comportamiento del receptor Rake. Esto permite un análisis superior con respecto a enfoques tradicionales que, en determinadas circunstancias, tienden a ofrecer cifras erróneamente optimistas. La última parte de la tesis da un paso más en la Planificación Automática y se proponen y validan 2 mecanismos dinámicos que permiten a la red reaccionar y auto-optimizarse frente a cambios en las condiciones de tráfico. El primero, basado en conclusiones anteriores, persigue detectar si uno de los enlaces presenta problemas de capacidad y, en caso afirmativo, favorecerlo para retrasar los mecanismos de control de congestión. Por último, se introduce la tecnología HSDPA y, después de analizar los recursos que deben ser compartidos con versiones previas de UMTS, se concluye que es deseable un sistema para la gestión dinámica del árbol de códigos OVSF. Se propone y valida un mecanismo que maximiza el throughput de las celdas, garantizando al mismo tiempo criterios de bloqueo y dropping. / The deployment of 3G/3.5G cellular networks challenges traditional radio planning and optimization strategies. Unlike FDMA based 2G systems, coverage and capacity are tightly coupled and must be treated as a whole. Besides new and more sophisticated Radio Resource Management (RRM) algorithms are present along with a more flexible network with many interdependent parameters, whose joint adjustment is not trivial. A new radio planning paradigm appears in which the radio network is optimized by means of complex algorithms both in a static and a dynamic way. This Ph.D. thesis provides a contribution to the radio network optimization of 3G/3.5G networks. Several issues to improve radio network planning have been investigated and new methods, guidelines and strategies of analysis have been proposed with the final objective of enhancing the wireless access network performance. Dynamic mechanisms being in the blurred line between radio planning and RRM are also devised and studied. The first part of this dissertation deals with the configuration of Base Stations (BSs) the impact of pilot powers, downtilt of antennas and interactions thereof with Soft Handover parameters are investigated. Effects beyond well-known facts are outlined and new planning guidelines are derived. Given the results, an Automatic Planning strategy is devised to automate the configuration of these parameters and to find a combination such as traffic is effectively equalized among cells and a higher capacity is achieved. The technique is based on the Simulated Annealing metaheuristic and is able to improve the global performance of the network, represented by a cost function containing information on the load factor and subject to other quality constraints. The importance of uplink (UL) requirements, usually missed by existent proposals, has been also included and analytically addressed. Reconfiguring BSs is not the only means to modify cell shapes, in this sense the study is extended by introducing repeaters, which allow generating distributed coverage areas. This is the context of the second part of the thesis. New effects not present in FDMA based 2G systems imply that the radio planning process becomes more complex. Most existent papers dealing with repeaters in WCDMA networks, ignore these effects or claim their irrelevance. That is why the research work was focused in modeling them, quantifying their impact and deriving radio planning guidelines to enhance the final performance of the radio access network. The new expression for the feasibility condition has been analytically obtained showing a tradeoff between capacity and coverage. This has been analyzed both theoretically and by means of simulations and the adjustment of several parameters which have a significant impact is discussed to derive practical rules of thumb. Variation on the coverage of the donor cell before and after installing repeaters is also modeled. Subsequently, it is proposed a new methodology to analyze WCDMA networks with repeaters deployment, considering realistically path delays and the behavior of Rake receivers. This allows an enhanced analysis with respect to traditional approaches which, under certain circumstances, tend to provide erroneously optimistic metrics. The final part of the dissertation goes one step further in Automatic Planning and two dynamic mechanisms are proposed and validated so that the network can react and self tune in front of changes in traffic conditions. The first one follows some previous conclusions and aims at detecting if one of the links has capacity problems and if so, favors it to delay congestion control actions. Finally, HSDPA technology is introduced and, after analyzing the resources to be shared with a previous release of UMTS, it is concluded that a system that dynamically manages the OVSF code tree is desired. A mechanism aiming at maximizing cell throughput while guaranteeing blocking and dropping criteria is proposed and validated.

The third generation, 3G, mobile telephone systems are designed for multimedia communication and will offer us similar services as in our stationary computers. This will involve large traffic loads, especially in the downlink direction, i.e. from base station to terminal. To improve the downlink capacity for packet data services a new concept is included in evolved 3G networks. The concept is called High Speed Data Packet Access, HSDPA, and provides peak bit rates of 14 Mbps. HSDPA uses a so-called best effort channel, i.e. it is developed for services that do not require guaranteed bit rates. The channel is divided in time between the users and a scheduling algorithm is used to allocate the channel among them. Streaming is a common technology for video transmission over the Internet and with 3G it is supposed to become popular also in our mobiles. Streaming generates lots of data traffic in the downlink direction and it would thus be satisfying to make use of the high bit rates HSDPA provides. The problem is that streaming requires reasonable stable bit rates, which is not guaranteed using HSDPA. The aim of this study is to modify the scheduling algorithms to prioritise streaming over web users and provide streaming Quality of Service, QoS. QoS is the ability to guarantee certain transmission characteristics. The results of the study show that it is hard to improve the streaming capacity by modifications of the scheduling. Of course, a consequence is that the web user throughput is decreased and to avoid this, new users have to be rejected by the admission control.The solution is to prioritise the streaming users both in the scheduling algorithm and in the admission control, i.e. when the system is nearly full new web users are rejected. By doing so the results are significantly improved.

In the standardized air interface for third generation mobile communication systems, WCDMA release 5, a concept called High Speed Downlink Packet Access (HSDPA) is introduced. HSDPA enables faster transmissions from base stations to mobile users by using a shared, high-capacity channel called the High-Speed Downlink Shared Channel (HS-DSCH) that is designed for best effort services. The HS-DSCH is developed for usage in the frequency band licensed for third generation communication systems. As the use of licensed frequency bands is costly it may be interesting to make use of the unlicensed frequency bands at 2.4 GHz and 5 GHz with higher interference and stricter regulations. Using HS- DSCH in unlicensed frequency bands would lead to smaller costs and a new kind of usage of the HS-DSCH. In order to transmit in unlicensed frequency bands, some requirements set up by the public authorities must be followed. This means that the maximum transmit power used by the HS-DSCH must be decreased and, on the 5 GHz frequency band, that features to avoid disturbing radar systems have to be implemented. The HS- DSCH has a bandwidth of 5 MHz. To use the available frequency spectra more efficiently, multiple carriers could be used. Wireless Local Area Networks (WLANs) are the most common way to transfer data in unlicensed frequency bands today. Assessments and simulations of WLAN and the HS-DSCH in unlicensed frequency bands show that WLAN can provide higher bitrates than the HS-DSCH for low loads. HS-DSCH can however provide a larger coverage per base station, and is more bandwidth effective than WLAN. Using a larger bandwidth is necessary for HS-DSCH to compete with WLAN, which uses a bandwidth approximately four times as large as the HS-DSCH bandwidth. The usage of the HS-DSCH in unlicensed frequency bands also has the advantage that the services provided by the third generation communication systems can be accessed easily.

Enhanced packet-data access is a trend in third generation mobile communication system. WCDMA Release 5 introduces HSDPA (High Speed Packet Data Access) with a brand new downlink transport channel HS-DSCH (High Speed Downlink Shared Channel) into 3GPP specification to provide greater capacity. HS-DSCH supports some new feature such as fast link adaptation, fast scheduling and fast HARQ (hybrid ARQ) so as to increase system performance. It efficiently improves power utilization, shortens retransmission time and increases system throughput. The focus for this thesis is implementation and simulation of HSDPA functionality with ns-2. There is some previous work has been done, such as EURANE. EURANE is an end to end extension which adds several HSDPA modules to ns-2. This paper addresses the analysis of HSDPA by simulating on HS-DSCH based on EURANE, and extends the power consumption on HS-DSCH.

Σε έναν κόσμο που αλλάζει με ταχύτατους ρυθμούς, που η γνώση σχεδόν διπλασιάζεται κάθε 10 χρόνια, η χρήση των κινητών δικτύων τρίτης γενιάς έχει αρχίσει να επεκτείνεται. Ειδικά σε μια χώρα όπως η Ελλάδα που η μορφολογία του εδάφους δεν επιτρέπει την χρησιμοποιήση των οπτικών ινών, η ασύρματη επικοινωνία αποκτά πολύ σημαντικό ρόλο. Το τελευταίο καιρό έχει επεκταθεί η χρήση των κινητών δικτύων 3ης γενιάς, που αντικαθιστούν τα προηγούμενα της 2ης γενιάς προσφέροντας στους χρήστες παραπάνω υπηρεσίες. Οι προηγμένες υπηρεσίες που παρέχονται σε ομάδες κινητών χρηστών είναι εφάμιλες με αυτές των συμβατικών ενσύρματων δικτύων όπως mobile internet, mobile streaming, mobile TV κ.α. Στην περίπτωση του ενσύρματου δικτύου είναι εύκολο να κατανοήσουμε ότι ο multicast αυτός μηχανισμός αποστέλνει τα δεδομένα μόνο μία φορα πάνω απο κάθε σύνδεσμο,που είναι τμήμα των μονοπατιών των προορισμών. Στα κινητά δίκτυα που έχουμε την MBMS υπηρεσία (Multimedia Broadcast / Multicast Service) που υποστηρίζει IP εφαρμογές πανεκπομπής (broadcact) και πολυεκπομπής (multicast) επιτρέποντας με αυτό τον τρόπο την παροχή υπηρεσιών υψηλού ρυθμού μετάδοσης σε πολλαπλούς χρήστες με οικονομικό τρόπο. Η multicast μετάδοση δεδομένων σε κινητά δίκτυα επικοινωνιών βρίσκεται ακόμη στο στάδιο των δοκιμών και της προτυποποίησης της. Ένας multicast μηχανισμός μεταδίδει τα δεδομένα μόνο μία φορά πάνω από κάθε ασύρματο σύνδεσμο που αποτελεί τμήμα των μονοπατιών προς τους προορισμούς-κινητούς χρήστες. Αντικείμενο στην προκείμενη διπλωματική εργασία είναι η μελέτη της τεχνολογιας hsdpa για την μετάδοση multicast δεδομένων σε δίκτυα κινητών επικοινωνών Τρίτης γενιάς .Οπου η σημαντικότερη πρόκληση που αντιμετωπίζει σήμερα η παγκόσμια αγορά κινητών τηλεπικοινωνιών είναι η παροχή νέων, ελκυστικών και διαδραστικών υπηρεσιών προς τους τελικούς χρήστες. Η τεχνολογία High Speed Packet Access (HSPA) αποτελεί τη φυσιολογική εξέλιξη του WCDMA προς αυτή την κατεύθυνση, η οποία πολλές φορές συναντάται και ως 3.5G ή 3G+, προκειμένου να δηλώσει την αναβάθμιση του 3G (UMTS) και ήδη έχει υιοθετηθεί από πολλά δίκτυα κινητής τηλεφωνίας ανά τον κόσμο. Η εισαγωγή του HSPA κρίθηκε απαραίτητη καθώς, στην πράξη, οι μέγιστοι ρυθμοί μετάδοσης για τα UMTS δίκτυα αποδείχθηκαν χαμηλοί για εφαρμογές πολυμέσων. Ουσιαστικά, το HSPA αποτελεί μία σημαντική αναβάθμιση των UMTS δικτύων προσφέροντας υψηλότερο εύρος ζώνης στους κινητούς χρήστες και αυξημένη χωρητικότητα για τους τηλεπικοινωνιακούς παρόχους με αποτέλεσμα την παροχή υπηρεσιών και εφαρμογών αυξημένης διαδραστικότητας. Η ορολογία HSPA αναφέρεται σε μία γενικότερη έννοια που υιοθετήθηκε από το UMTS Forum προκειμένου να τονίσει τις αναβαθμίσεις του UMTS Radio Interface στις εκδόσεις 5 και 6 του 3GPP στάνταρ. Η συμβολή της HSPA τεχνολογίας, προσεγγίζει μόνο το δίκτυο πρόσβασης, δηλαδή το UTRAN, χωρίς να επεμβαίνει καθόλου στη δομή και τη λειτουργικότητα του Core Network του UMTS. Πιο συγκεκριμένα, το HSPA αναφέρεται σε βελτιώσεις που πραγματοποιήθηκαν τόσο στον κατερχόμενο ασύρματο σύνδεσμο, μέσω του High Speed Downlink Packet Access (HSDPA) όσο και στον ανερχόμενο, μέσω του High Speed Uplink Packet Access (HSUPA). Αξίζει να αναφερθεί ότι τόσο το HSDPA όσο και το HSUPA μπορούν να υλοποιηθούν στο ίδιο εύρος ζώνης με το UMTS (των 5 MHz), γεγονός που επιτρέπει την παράλληλη λειτουργία τόσο του HSPA όσο και του κλασσικού UMTS. / Due to rapid growth of mobile communications technology, the demand for wireless multimedia communications thrives in today’s consumer and corporate market. The need to evolve multimedia applications and services is at a critical point given the proliferation and integration of wireless systems. Consequently, there is a great interest in using the IP-based networks to provide multimedia services. One of the most important areas in which the issues are being debated, is the development of standards for the Universal Mobile Telecommunications System (UMTS). UMTS constitutes the third generation (3G) of cellular wireless networks which aims to provide high-speed data access along with real time voice calls. Wireless data is one of the major boosters of wireless communications and one of the main motivations of the next generation standards. Through the 3G mobile networks, the mobile users have the opportunity to run applications and realize services that offered until today only by wired networks. Such broadband services are mobile Internet, mobile TV, mobile gaming, mobile streaming, video calls etc. High Speed Packet Access (HSPA) constitutes a significant step towards the so-called Mobile Broadband. HSPA supports both downlink and uplink communication through the HSDPA and HSUPA channels, respectively. HSPA promises the provision of enhanced end-users’ experience with a wide range of novel, interactive applications, faster performance and reduced delays. Furthermore, from the operators’ prism, HSPA ensures improved network performance, increased capacity and higher coverage. Multimedia Broadcast Multicast Service (MBMS) is a novel framework, extending the existing UMTS infrastructure that constitutes a significant step towards the so-called Mobile Broadband. MBMS is intended to efficiently use network and radio resources, both in the core network and, most importantly, in the air interface of UMTS Terrestrial Radio Access Network (UTRAN), where the bottleneck is placed to a large group of users. Actually, MBMS is a point-to-multipoint service in which data is transmitted from a single source entity to multiple destinations, allowing the networks resources to be shared. MBMS is an efficient way to support the plethora of the emerging wireless multimedia and application services such as IP Video Conferencing, Streaming Video by supporting both broadcast and multicast transmission modes. Long Term Evolution (LTE) will stretch the performance of 3G systems with improved coverage and system capacity, as well as increased data rates and reduced latency. LTE also provides a tight integration between unicast and multicast/broadcast MBMS transport bearers. Moreover, it also takes 3G-MBMS one step further to provide highly efficient multi-cell broadcast. By transmitting not only identical signals from multiple cell sites (with identical coding and modulation), but also synchronize the transmission timing between cells, the signal at the mobile terminal will appear exactly as a signal transmitted from a single cell site and subject to multi-path propagation. There is a growing demand for wireless data applications, which although face low penetration today, are expected to gain high interest in future mobile networks. These applications actually reflect a modern, future way of communication among mobile users. For instance, mobile TV is expected to be a ‘killer’ application for 3G’s. Such mobile TV services include streaming live TV (news, weather forecasts etc.) and streaming video (such as video clips). All the above constitute a series of some indicative emerging applications that necessitate advanced transmission techniques. However, increased improvements have to be made both in the uplink and downlink transmission and in better radio resource management, in order to meet future demands and provide rich multimedia services to large users’ population. In addition, several obstacles, mainly regarding the interoperability and ubiquitous access between different access technologies and services, have to be overcome (thus leading to 4G). The main target of this dissertation is the study of power control issues, the development and the performance evaluation of an efficient power scheme for the provision of broadband, multicast services and applications to mobile users. This will be effectively implemented through the efficient use of MBMS and HSPA technologies in both 3G and its evolution LTE. An important aspect of this work is the investigation of the selection of the most efficient radio bearer for the transmission of MBMS multicast data. MBMS services can be provided in each cell by either multiple Point to Point (PTP) channels or by a single Point to Multipoint (PTM) channel. PTM transmission uses a single channel reaching down to the cell edge, which conveys identical traffic. On the other hand, PTP transmission uses dedicated channel allocated to each user, which conveys identical content. Obviously, a decision has to be made on the threshold between these two approaches. Therefore, improvements of the currently existing Counting Mechanism in MBMS will be studied. Although relative research work in this field considers the need for a power-based Counting Mechanism and not a UE-based Counting Mechanism, the case of HSDPA usage in such a power mechanism could be further investigated, taking also into account the availability of multi-mode cells. This could lead to an optimal scheme for the MBMS Counting Mechanism. The fundamental selection criterion of channel type is the amount of base station power required to transmit to a group of users. To this direction, the role of power control in the MBMS multicast transmission in UMTS is studied and analysed. A power control scheme for the efficient radio bearer selection in MBMS is then proposed. The choice of the most efficient transport channel in terms of power consumption is a key point for the MBMS since a wrong transport channel selection for the transmission of the MBMS data could result to a significant decrease in the total capacity of the system. Various UMTS transport channels are examined for the transmission of the multicast data and a new algorithm is proposed for the more efficient usage of power resources in the base station

La demanda de servicios móviles de alta velocidad en Chile ha experimentado un crecimiento explosivo en los últimos años. Para la toma de dediciones el operador de red necesita conocer la capacidad disponible o necesaria en el acceso de estas redes. El objetivo general de este trabajo es entregar un modelo que permita aproximar la capacidad de una celda 3.5G entendida como el número máximo de usuarios simultáneos. Se deben considerar los recursos disponibles en ella, las condiciones de transmisión e imponer restricciones de servicio esperado. La hipótesis corresponde a que la calidad del canal de transmisión, medida por el parámetro denominado CQI (Channel Quality Indicator), es la principal condicionante de la capacidad. Los datos reales de ésta variable tienen un comportamiento que se ajusta bien a la distribución de probabilidades llamada Extreme Value (EV). Esta distribución tiene dos parámetros:  que corresponde a la localización y  que indica la dispersión. El modelo desarrollado en este trabajo se basa en el esquema round robin con el que se simula el envío de datos por la interfaz aérea entre una radio base y un cierto número de terminales móviles. A cada uno de ellos se le asigna aleatoriamente un valor de CQI con una probabilidad de asignación dada por la distribución EV. Usando tablas de mapeo de CQI se determina la tasa de transferencia de bits que tiene cada uno de los terminales en un TTI (Transmission Time Interval) de 2ms, calculándose una tasa promedio después de 1 segundo. El procedimiento se repite 10 minutos obteniéndose una distribución para las muestras de velocidades de transferencia. Sobre ésta distribución se aplica el criterio de servicio deseado, correspondiente a que el 95% de las muestras estén por sobre una tasa de transferencia de bits mínima. Se observa que a mayor número de terminales, menores son las tasas de transferencia. Entonces se irá aumentando la cantidad de terminales hasta que no se cumpla la condición de servicio, con lo que se habrá alcanzado la capacidad máxima de usuarios simultáneos en la celda. Con las simulaciones se confirma que a una mayor calidad de canal (mayor ) y a un menor grado de dispersión (menor ), mayor es la capacidad de la celda. Se entregan tablas para ciertas combinaciones de () que permiten una rápida aproximación a la cantidad máxima de usuarios según la simulación. Como trabajos futuros se sugieren: agregar como entrada a la simulación algún modelo de comportamiento de tráfico para aproximar mejor la capacidad de una celda; estudiar otros algoritmos de asignación (scheduler) y estudiar el posible efecto de modificación de la distribución de CQI al agregar gradualmente más usuarios.

Στην εν λόγω εργασία, έγινε μια προσπάθεια καταγραφής του τεχνολογικού τοπίου της τηλεπικοινωνιακής αγοράς, με έμφαση την διαλειτουργικότητα μεταξύ των Δικτύων Κινητής Τηλεφωνίας και των Ασύρματων Δικτύων Δεδομένων και των σχετικών αλλαγών που έχει επιφέρει αυτή η διαλειτουργικότητα, τόσο στις παρεχόμενες υπηρεσίες, όσο και στα εφαρμοζόμενα επιχειρηματικά μοντέλα από πλευράς εταιρειών της συγκεκριμένης αγοράς. Στα πλαίσια αυτής της προσπάθειας, χρειάστηκε να πραγματοποιηθεί μια λεπτομερής καταγραφή των τεχνολογικών εξελίξεων, σε επίπεδο τεχνικών προδιαγραφών και προτύπων, στις παραπάνω δύο κατηγορίες δικτύων, ώστε να καταλήξουμε σε εκείνα τα πρότυπα που πλέον μπορούν να οδηγήσουν στην υλοποίηση δικτύων τα οποία θα χαρακτηρίζονται από τα παρακάτω: • θα είναι ενοποιημένα ώστε οι διαφορετικές τεχνολογικές πλατφόρμες των εταιρειών να λειτουργούν απρόσκοπτα, • θα χαρακτηρίζονται από χαμηλό κόστος, • ο τελικός χρήστης θα μπορεί να είναι συνεχώς συνδεδεμένος με κάποιο δίκτυο ασύρματης πρόσβασης και να απολαμβάνει τις υπηρεσίες που επιθυμεί, οποτεδήποτε και οπουδήποτε. Η δομή της διπλωματικής εργασίας ακολουθεί τον προαναφερθέντα τρόπο σκέψης. Στο 1ο Κεφάλαιο γίνεται μια σύντομη παρουσίαση του στόχου σε επίπεδο τεχνολογιών αλλά και υπηρεσιών, δηλαδή των αναμενόμενων αποτελεσμάτων αυτών των δικτύων νέας γενιάς, στα οποία έχουμε συνηθίσει να αναφερόμαστε ως δίκτυα 4G (4th Generation) ή δίκτυα B3G (Beyond 3G) ή τέλος ως All – IP ασύρματα δίκτυα. Στο 2ο Κεφάλαιο, γίνεται μια λεπτομερής παρουσίαση των Δικτύων Κινητής Τηλεφωνίας από τις πρώτες τους εκδοχές (1G) έως τις πλέον σύγχρονες (3.5G) που έχουν εμφανιστεί μέχρι σήμερα. Αναλύονται τόσο οι γενιές των δικτύων όσο και τα χρησιμοποιούμενα πρότυπα, σε επίπεδο αρχιτεκτονικής όσο και σε επίπεδο πρωτοκόλλων. Στη συνέχεια του κεφαλαίου υπάρχει η τεχνική περιγραφή των επικρατέστερων δικτύων κινητής τηλεφωνίας, σήμερα, δηλαδή των GSM, GPRS και UMTS, ενώ στο τέλος του κεφαλαίου υπάρχει μια σύντομη περιγραφή της διαδικασίας intersystem handover μεταξύ των GSM και UMTS. Στο 3ο Κεφάλαιο, περνάμε πλέον στα Ασύρματα Δίκτυα Δεδομένων. Γίνεται μια εκτενής περιγραφή των προτύπων που έχουν καθοριστεί και συγκεκριμένα στα πρότυπα IEEE 802.15 Wireless Personal Area Networks (WPANs) με κυριότερους εκφραστές τα δίκτυα βασιζόμενα σε Bluetooth και IrDA, το πρότυπο IEEE 802.11 Wireless Local Area Networks (WLANs) με σημαντικότερος εκπροσώπους τα WiFi και HyperLan/2, το πρότυπο IEEE 802.16 Wireless Metropolitan Area Networks (WMANs) ή αλλιώς γνωστότερο ως WiMAX και τέλος το πρότυπο IEEE 802.20 Wireless Wide Area Networks (WWANs) ή διαφορετικά Mobile Broadband Wireless Access (MWBA) το οποίο είναι υπό διερεύνηση ακόμα και φιλοδοξεί να αποτελέσει το ασύρματο ανάλογο της τεχνολογίας xDSL, καθώς θα προσφέρει ασύρματες ευρυζωνικές υπηρεσίες. Στο 4ο Κεφάλαιο παρουσιάζονται μεθοδολογίες υλοποίησης του integration μεταξύ δικτύων των δύο κατηγοριών και συγκεκριμένα παραδείγματα διαλειτουργικότητας, όπως μεταξύ GPRS ή UMTS και WLANs ή μεταξύ UMTS και WiMAX. Γίνεται εκτενής συζήτηση γύρω από τα προβλήματα που θα πρέπει να αντιμετωπιστούν, όπως η εξασφάλιση ανεκτού επιπέδου QoS, οι μηχανισμοί για handover μεταξύ των δικτύων, η διαχείριση της κινητικότητας των χρηστών και των τερματικών και δίνονται παραδείγματα δημιουργίας ενοποιημένων δικτύων, τόσο με τη τεχνική της χαλαρής όσο και με την τεχνική της ισχυρής ζεύξης. Στο τελευταίο τμήμα του Κεφαλαίου, γίνεται μια εκτενής αναφορά στις αρχιτεκτονικές διασύνδεσης ετερογενών δικτύων με IP δίκτυα κορμού, τα γνωστά All – IP networks. Ιδιαίτερη έμφαση δίνεται στους μηχανισμούς πραγματοποίησης των handovers βάσει πολιτικών (policy based) και η χρήση τεχνικών για micromobility και macromobility σε σχέση με την κινητικότητα των τερματικών. Το 5ο Κεφάλαιο αφορά τις εφαρμογές και υλοποιήσεις ασυρμάτων δικτύων δεδομένων στον Ελληνικό χώρο, στα πλαίσια του Επιχειρησιακού Προγράμματος «Κοινωνία της Πληροφορίας» και πιο συγκεκριμένα τα «Εξοπλισμός και δικτύωση σε όλες τις βαθμίδες της εκπαίδευσης», «Ασύρματα Ευρυζωνικά Δίκτυα ΟΤΑ»και «Μητροπολιτικά Ευρυζωνικά Δίκτυα Οπτικών Ινών ΟΤΑ» και ουσιαστικά αποτελούν παραδείγματα και υλοποιήσεις διασύνδεσης WiFi, WiMAX και IP backbone δικτύων όπως το ΣΥΖΕΥΞΙΣ με δυνατότητες για παροχή VoIP. / In this thesis, an effort of presenting the technological landscape of the telecommunication market takes place, with focus on the interoperability between the Mobile Telephony Networks and the Wireless Data Networks and the relative changes that have evolved through this interoperability, both regarding the provided services and the applied business models by the enterprises of the specific market. Within the frames of this effort, a detailed recording of technological developments is realised, in terms of technical specifications and standards, in the two aforementioned categories of networks, so as to conclude to those standards that are utilized by the next generation networks (4G) which will be: • Networks that will be unified so as the different technological platforms will function smoothly. • Networks that will be characterized by low cost of deployment. • The end user will be continuously connected with a wireless access network, enjoying the preferred services anywhere and anytime. The master thesis structure follows the aforementioned methodology. The 1st Chapter includes a short presentation of expected results, both in terms of technologies and services for next generation networks, which we usually refer to as 4G networks (4th Generation) or B3G networks (Beyond 3G) or finally as All - IP wireless networks (AIPN). In the 2nd Chapter, a detailed presentation of Mobile Telephony Networks takes place, from their first versions (1G) until the most modern (3.5G) that have been presented up to today. The analysis includes both the various generations of networks and the used standards, in terms of modulation and multiplexing techniques. The rest of the chapter focuses on the technical description of the prevailing networks, GSM, GPRS and UMTS, while the chapter ends with a short description of intersystem handover processes between GSM and UMTS. Τhe 3rd Chapter, includes an extensive description of the Wireless Data Networks standards such as: IEEE 802.15 Wireless Personal Area Networks (WPANs) with main representatives networks based on Bluetooth and IrDA, standard IEEE 802.11 Wireless Local Area Networks (WLANs) mainly represented by WiFi and HyperLan/2, IEEE 802.16 Wireless Metropolitan Area Networks (WMANs) standard, widely known as WiMax and finally the IEEE 802.20 Wireless Wide Area Networks (WWANs) standard, namely Mobile Broadband Wireless Access (MWBA) that is still under development and aspires to constitutes the wireless version of the xDSL technology, since it aims to provide wireless broadband services. In the 4th Chapter methodologies for integrating the two types of networks, are presented along with examples of interoperability between GPRS / UMTS and WLANs or between UMTS and WiMAX. Extensive discussion around the problems that should be faced, as the guarantee of bearable QoS level, the mechanisms for handover between the networks and the management of mobility of users and terminals, is held. Moreover, examples of integrated networks with both loose and tight coupling methodologies are presented. The last section of the chapter concerns a detailed description of architectures for interconnecting heterogeneous wireless networks over IP – based backhaul networks, namely All – IP networks, with special focus on policy based handover mechanisms and techniques for managing micromobility and macromobility issues. The 5th Chapter concerns the changes taking place in the telecommunications market deriving from the technological progress in the subject of heterogeneous wireless networks interconnection. New service packets are created, as a result of new business plans that are drawn up by the big telecommunications organizations. Finally, we present the developments in the Greek market and subsidised projects from Information Society AE, via which wireless networks have been materialised, with aim to promote Broadband Services.

Mobile telecommunications belong to one of the fields which still evolves and it is expected that in the future they are going to offer great benefit to the whole world. This work focuses on current and future development of mobile Internet connection in the Czech Republic. At first the technologies used to provide mobile Internet connection are described and compared and then the situation (in terms of technologies and mobile operators) in the Czech market is outlined and its possible evolution in the near future is presented. Furthermore, the tarifs of mobile operators are compared with those in place two years ago. The strengths and weaknesses of the current mobile Internet connection are evaluated based on the conducted questionnaire survey. The latest results are then analyzed and compared with the results from a previous survey conducted in 2007 as part of a bachelor's thesis, which has been further extended in this mater's thesis.

Cette thèse est dédiée à l'étude des systèmes de communications pour application aux services vidéo fournis par les réseaux radio mobiles. Ce travail met l'accent sur les systèmes point à multipoints et propose plusieurs améliorations : Dans un premier temps, on définit un système qui combine le décodage robuste aux retransmissions ARQ, et ce de telle façon à réduire le nombre de retransmissions tout en gardant le même niveau de qualité. Contrairement aux systèmes actuels (avec ou sans retransmissions), ce systèmes offre également la possibilité de choisir le compromis débit/qualité via un paramètre du système. Par la suite, on considère les sytèmes de transmission d'une vidéo scalable vers plusieurs terminaux. Des extensions des systèmes Go-Back-N (GBN) Automatic Repeat reQuest (ARQ) et Selective Repeat (SR) ARQ sont étudiées et comparées à un nouveau système. On montre que ce dernier limite les besoins de bufferisation au niveau du terminal récepteur tout en ayant des performances optimales (en termes de quantité de données transmises avec succès sur une période donnée). Finalement, on montre que même sous une contrainte débit on peut utiliser les retransmissions dans les communications point à multipoints à condition de ne pas dépasser une certaine limite sur le nombre d'utilisateurs. Si l'utilisation des retransmissions ARQ est introduite dans les sytèmes de Multicast/Broadcast 3GPP et/ou WiMAX, le système pourra garantir une qualité nominale à un certain nombre d'utilisateurs, ce qui n'est pas le cas des systèmes de Multicast/Broadcast actuels.

Research Doctorate - Doctor of Philosophy (PhD) / The Radio Access Network (RAN) accounts for the major proportion of the UMTS system operating cost. Transmission from radio base station sites contributes a larger part of the RAN operating costs. Selection of suitable transport technologies and proper allocation of network resources are vital from an operator cost optimisation and the Quality of Experience (QoE) points of view. This thesis extensively investigated the performance of a RAN to support multimedia traffic on a HSDPA air interface. Transport network layer of a future RAN could be based on a number of transport protocols such as ATM, IP and Ethernet. With the increasing traffic volume and diversity the efficiencies of IP and Ethernet based RAN could increases significantly due to the use of larger payloads and simpler resource allocation techniques. Also, on IP and Ethernet based links relatively fewer overhead bits are transmitted compared to an ATM based link. Both the IP and Ethernet based links appear to perform better under heavy traffic load conditions. An IP based link could perform better than an Ethernet based link when an IP header compression technique is used. An Ethernet based link is an alternative transport technique for the UTRAN transport network due to its flexibility, economy and bandwidth efficiency. The HSDPA (High Speed Downlink Packet Access) is considered to be one of the initial evolutionary steps to enhance the data rate, and QoS of downlink data and multimedia services for the evolved UMTS network. It can provide high data rate up to 28.8 Mbps on the downlink shared channel using the packet access technique. A HSDPA network can dynamically adjust a connection data rate to match radio conditions to ensure the highest possible data rate for different type of traffic. Inappropriate RAN capacity allocation could lead to low radio resource or RAN resource utilizations. In this thesis, a Markov chain based analytical model has been developed to study the interaction between the air interface and the RAN for a HSDPA network. The analytical model was used to study interactions of RAN transport protocols, flow control techniques and the air interface transmission conditions. Further a simulation model was developed to investigate the relationship between the HSDPA air interface and its RAN parameters. Another important issue in the HSDPA network design is the scheduling algorithm used at the Node-B. A scheduling algorithm plays a key role in allocating a RAN’s network resources. Impacts of scheduling algorithms are studied in this work using a simulation model. Based on the study of the HSDPA air interface and its RAN parameter interactions this work has developed an adaptive resource management algorithm, which uses the measured air interface information to allocate the corresponding connection data rate on the Iub link. The developed algorithm reduces RAN resource requirements while increasing the air interface resource utilization and QoS of connections.