Contribution to resource management in cellular access networks with limited backhaul capacity

La interfaz radio de los sistemas de comunicaciones móviles es normalmente considerada como la única limitación de capacidad en la red de acceso radio. Sin embargo, a medida que se van desplegando nuevas y más eficientes interfaces radio, y de que el tráfico de datos y multimedia va en aumento, existe la creciente preocupación de que la infraestructura de transporte (backhaul) de la red celular pueda convertirse en el cuello de botella en algunos escenarios. En este contexto, la tesis se centra en el desarrollo de técnicas de gestión de recursos que consideran de manera conjunta la gestión de recursos en la interfaz radio y el backhaul. Esto conduce a un nuevo paradigma donde los recursos del backhaul se consideran no sólo en la etapa de dimensionamiento, sino que además son incluidos en la problemática de gestión de recursos. Sobre esta base, el primer objetivo de la tesis consiste en evaluar los requerimientos de capacidad en las redes de acceso radio que usan IP como tecnología de transporte, de acuerdo a las recientes tendencias de la arquitectura de red. En particular, se analiza el impacto que tiene una solución de transporte basada en IP sobre la capacidad de transporte necesaria para satisfacer los requisitos de calidad de servicio en la red de acceso. La evaluación se realiza en el contexto de la red de acceso radio de UMTS, donde se proporciona una caracterización detallada de la interfaz Iub. El análisis de requerimientos de capacidad se lleva a cabo para dos diferentes escenarios: canales dedicados y canales de alta velocidad. Posteriormente, con el objetivo de aprovechar totalmente los recursos disponibles en el acceso radio y el backhaul, esta tesis propone un marco de gestión conjunta de recursos donde la idea principal consiste en incorporar las métricas de la red de transporte dentro del problema de gestión de recursos. A fin de evaluar los beneficios del marco de gestión de recursos propuesto, esta tesis se centra en la evaluación del problema de asignación de base, como estrategia para distribuir el tráfico entre las estaciones base en función de los niveles de carga tanto en la interfaz radio como en el backhaul. Este problema se analiza inicialmente considerando una red de acceso radio genérica, mediante la definición de un modelo analítico basado en cadenas de Markov. Dicho modelo permite calcular la ganancia de capacidad que puede alcanzar la estrategia de asignación de base propuesta. Posteriormente, el análisis de la estrategia propuesta se extiende considerando tecnologías específicas de acceso radio. En particular, en el contexto de redes WCDMA se desarrolla un algoritmo de asignación de base basado en simulatedannealing cuyo objetivo es maximizar una función de utilidad que refleja el grado de satisfacción de las asignaciones respecto los recursos radio y transporte. Finalmente, esta tesis aborda el diseño y evaluación de un algoritmo de asignación de base para los futuros sistemas de banda ancha basados en OFDMA. En este caso, el problema de asignación de base se modela como un problema de optimización mediante el uso de un marco de funciones de utilidad y funciones de coste de recursos. El problema planteado, que considera que existen restricciones de recursos tanto en la interfaz radio como en el backhaul, es mapeado a un problema de optimización conocido como Multiple-Choice Multidimensional Knapsack Problem (MMKP). Posteriormente, se desarrolla un algoritmo de asignación de base heurístico, el cual es evaluado y comparado con esquemas de asignación basados exclusivamente en criterios radio. El algoritmo concebido se basa en el uso de los multiplicadores de Lagrange y está diseñado para aprovechar de manera simultánea el balanceo de carga en la intefaz radio y el backhaul.Postprint (published version

Wireless broadband access: WiMAX and beyond - Investigation of bandwidth request mechanisms under point-to-multipoint mode of WiMAX networks

The WiMAX standard specifies a metropolitan area broadband wireless access air interface. In order to support QoS for multimedia applications, various bandwidth request and scheduling mechanisms are suggested in WiMAX, in which a subscriber station can send request messages to a base station, and the base station can grant or reject the request according to the available radio resources. This article first compares two fundamental bandwidth request mechanisms specified in the standard, random access vs. polling under the point-to-multipoint mode, a mandatory transmission mode. Our results demonstrate that random access outperforms polling when the request rate is low. However, its performance degrades significantly when the channel is congested. Adaptive switching between random access and polling according to load can improve system performance. We also investigate the impact of channel noise on the random access request mechanism

Solution strategies of service fulfilment Operation Support Systems for Next Generation Networks

Suomalainen operatiivisten tukijärjestelmien toimittaja tarjoaa ratkaisuja palvelujen aktivointiin, verkkoresurssien hallintaan ja laskutustietojen keruuseen. Nämä ratkaisut ovat pääosin käytössä langattomissa verkoissa. Tässä tutkimuksessa arvioidaan kyseisten ratkaisujen soveltuvuutta palvelutoimitusprosessien automatisointiin tulevaisuuden verkkoympäristöissä. Tarkastelun kohteena ovat runko- ja pääsyverkkojen kiinteät teknologiat, joiden suosio saavuttaa huippunsa seuraavan 5-10 vuoden aikana. Näissä verkoissa palvelujen, kuten yritys-VPN:n tai kuluttajan laajakaistan, aktivointi vaatii monimutkaisen toimitusprosessin, jonka tueksi tarvitaan ensiluokkaista tukijärjestelmää. Teknologiakatsauksen jälkeen tutkimuksessa verrataan viitteellistä tuoteportfoliota saatavilla oleviin operatiivisten tukijärjestelmien arkkitehtuurisiin viitekehyksiin, ja analysoidaan sen soveltuvuus tulevaisuuden verkkoympäristöjen palvelutoimitusprosessin automatisointiin. Myös palvelutoimitusprosessien automatisointiin soveltuvien tukijärjestelmien markkinatilanne arvioidaan, ja tämän perusteella tutkitaan optimaalisinta sovellusstrategiaa. Lopulta voidaan päätellä, että tuoteportfoliolle parhaiten soveltuvin sovellusalue on kuluttajan laajakaistan, ja siihen liittyvien kehittyneempien IP-palveluiden palvelutoimitusprosessien automatisointi.A Finnish Operation Support Systems (OSS) vendor provides solutions for service activation, network inventory and event mediation. These solutions have mostly been deployed in mobile environments. In this thesis it will be studied how feasible it is to use similar solutions for service fulfilment in Next Generation Networks (NGN). NGN is a broad term that describes some key architectural evolutions in telecommunication core and access networks that will be deployed over the next 5 to 10 years. In these networks service, e.g. Triple Play or Virtual Private Network (VPN), activations require an extensive service fulfilment process that must be supported by first-class OSS. After introducing the NGN technologies, the research compares a reference product portfolio to available service fulfilment frameworks and evaluates the applicability. The study analyses the current state of service fulfilment OSS markets and evaluates various solution strategies. Eventually it will be concluded that the most interesting and adequate solution scenario is residential broadband, including value-added IP services

Mobile Broadband Possibilities considering the Arrival of IEEE 802.16m & LTE with an Emphasis on South Asia

This paper intends to look deeper into finding an ideal mobile broadband solution. Special stress has been put in the South Asian region through some comparative analysis. Proving their competency in numerous aspects, WiMAX and LTE already have already made a strong position in telecommunication industry. Both WiMAX and LTE are 4G technologies designed to move data rather than voice having IP networks based on OFDM technology. So, they aren't like typical technological rivals as of GSM and CDMA. But still a gesture of hostility seems to outburst long before the stable commercial launch of LTE. In this paper various aspects of WiMAX and LTE for deployment have been analyzed. Again, we tried to make every possible consideration with respect to south Asia i.e. how mass people of this region may be benefited. As a result, it might be regarded as a good source in case of making major BWA deployment decisions in this region. Besides these, it also opens the path for further research and in depth thinking in this issue.Comment: IEEE Publication format, ISSN 1947 5500, http://sites.google.com/site/ijcsis

Dynamic bandwidth management with service differentiation over ethernet passive optical networks

Ethernet passive optical networks (EPONs) address the first mile of the communication infrastructure between the service provider central offices and the customer sites. As a low-cost, high speed technology, EPONs are deemed as the solution to the bottleneck problem of the broadband access network. A major feature of EPONs is the utility of a shared upstream channel among the end users. Only a single optical network unit (GNU) may transmit during a timeslot to avoid data collisions. In order to provide diverse quality of service (QoS), the bandwidth management of the upstream channel is essential for the successful implementation of EPONs, and thus, an efficient medium access control is required to facilitate statistical multiplexing among local traffics. This dissertation addresses the upstream bandwidth allocation over EPONs. An efficient mechanism, i.e., limited sharing with traffic prediction (LSTP), has been proposed to arbitrate the upstream bandwidth among ONUs. The MultiPoint Control Protocol (MPCP) messages, which are stipulated by the IEEE 802.3ah Ethernet in the First Mile (EFM) Task Force, are adopted by LSTP to facilitate the dynamic bandwidth negotiation between an GNU and the OLT. The bandwidth requirement of an ONU includes the already enqueued frames and the predicted incoming frames during the waiting time. The OLT arbitrates the bandwidth assignment based on the queue status report from an GNU, the traffic prediction, and the agreed service contract. With respect to the performance evaluation, theoretical analysis on the frame loss, the frame delay, and the queue length has been conducted. The quantitative results demonstrate that 1) the innovative LSTP mechanism dynamically allocates the upstream bandwidth among multiple ONUs; 2) the traffic predictor at the OLT delivers satisfactory prediction for the bursty self-similar traffic, and thereby, contributing to the reduction of frame loss, frame delay, and queue length; and 3) the bandwidth arbitration at the OLT effectively restricts the aggressive bandwidth competition among ONUs by adopting the service level agreement (SLA) parameter as the upper bound. Aside from analysis, the LSTP mechanism has been substantiated by experimental simulations. In order to differentiate the service provisioning among diverse users, LSTP is further enhanced with the support of dynamic bandwidth negotiation based on multiple queues. The incoming traffics are first classified into three classes, and then enqueued into the corresponding queues. A traffic predictor is dedicated to one class of traffic from an GNU. Service differentiation among classes are provided by the combination of queuing and scheduling at the GNU side. At the OLT side, the bandwidth allocation for each class of traffic is based on the reported queue status and the traffic prediction, and is upper-bounded by the SLA parameter. Experimental simulations have justified the feasibility of providing service differentiation over the broadband EPONs

Next Generation Optical Access Networks: from TDM to WDM

Postprint (author’s final draft