10 research outputs found
Resource Allocation in Relay-based Satellite and Wireless Communication Networks
A two-level bandwidth allocation scheme is proposed for a slotted Time-Division Multiple Access high data rate relay satellite communication link to provide efficient and fair channel utilization. The long-term allocation is implemented to provide per-flow/per-user Quality-of-Service guarantees and shape the average behavior. The time-varying short-term allocation is determined by solving an optimal timeslot scheduling problem based on the requests and other parameters. Through extensive simulations, the performance of a suitable MAC protocol with two-level bandwidth allocation is analyzed and compared with that of the existing static fixed-assignment scheme in terms of end-to-end delay and successful throughput. It is also shown that pseudo-proportional fairness is achieved for our hybrid protocol.
We study rate control systems with heterogeneous time-varying propagation delays, based on analytic fluid flow models composed of first-order delay-differential equations. Both single-flow and multi-flow system models are analyzed, with special attention paid to the Mitra-Seery algorithm. The stationary solutions are investigated. For the fluctuating solutions, their dynamic behavior is analyzed in detail, analytically and numerically, in terms of amplitude, transient behavior, fairness and adaptability, etc.. Especially the effects of heterogeneous time-varying delays are investigated. It is shown that with proper parameter design the system can achieve stable behavior with close to pointwise proportional fairness among flows.
Finally we investigate the resource allocation in 802.16j multi-hop relay systems with rate fairness constraints for two mutually exclusive options: transparent and non-transparent relay systems (T-RS and NT-RS). Single-Input Single-Output and Multi-Input Multi-Output antenna systems are considered in the links between the Base Station (BS) and Relay Stations (RS). 1 and 3 RSs per sector are considered. The Mobile Station (MS) association rule, which determines the access station (BS or RS) for each MS, is also studied. Two rules: Highest MCS scheme with the highest modulation and coding rate, and Highest (Mod) ESE scheme with the highest (modified) effective spectrum efficiency, are studied along with the optimal rule that maximizes system capacity with rate fairness constraints. Our simulation results show that the highest capacity is always achieved by NT-RS with 3 RSs per sector in distributed scheduling mode, and that the Highest (Mod) ESE scheme performs closely to the optimal rule in terms of system capacity
Support infrastructures for multimedia services with guaranteed continuity and QoS
Advances in wireless networking and content delivery systems are enabling new challenging provisioning scenarios where a growing number of users access multimedia services, e.g., audio/video streaming, while moving among different points of attachment to the Internet, possibly with different connectivity technologies, e.g., Wi-Fi, Bluetooth, and cellular 3G. That calls for novel middlewares capable of dynamically personalizing service provisioning to the characteristics of client environments, in particular to
discontinuities in wireless resource availability due to handoffs. This dissertation proposes a novel middleware solution, called MUM, that performs effective and context-aware handoff management to transparently avoid service interruptions during both horizontal and vertical handoffs. To achieve the goal, MUM exploits the full visibility of wireless connections available in client localities and their handoff implementations (handoff awareness), of service quality requirements and handoff-related quality degradations (QoS awareness), and of network topology and resources available in current/future localities (location awareness). The design and implementation of the all main MUM components along with extensive on the field trials of the realized middleware architecture confirmed the validity of the proposed full
context-aware handoff management approach. In particular, the reported experimental results demonstrate that MUM can effectively maintain service continuity for a wide range of different multimedia services by exploiting handoff prediction mechanisms, adaptive buffering and pre-fetching techniques, and proactive re-addressing/re-binding
Cross-layer Optimization for Video Delivery over Wireless Networks
As video streaming is becoming the most popular application of Internet mo-
bile, the design and the optimization of video communications over wireless
networks is attracting increasingly attention from both academia and indus-
try. The main challenges are to enhance the quality of service support, and to
dynamically adapt the transmitted video streams to the network condition.
The cross-layer methods, i.e., the exchange of information among different
layers of the system, is one of the key concepts to be exploited to achieve this
goals. In this thesis we propose novel cross-layer optimization frameworks
for scalable video coding (SVC) delivery and for HTTP adaptive streaming
(HAS) application over the downlink and the uplink of Long Term Evolution
(LTE) wireless networks. They jointly address optimized content-aware rate
adaptation and radio resource allocation (RRA) with the aim of maximiz-
ing the sum of the achievable rates while minimizing the quality difference
among multiple videos. For multi-user SVC delivery over downlink wireless
systems, where IP/TV is the most representative application, we decompose
the optimization problem and we propose the novel iterative local approxi-
mation algorithm to derive the optimal solution, by also presenting optimal
algorithms to solve the resulting two sub-problems. For multiple SVC de-
livery over uplink wireless systems, where healt-care services are the most
attractive and challenging application, we propose joint video adaptation
and aggregation directly performed at the application layer of the transmit-
ting equipment, which exploits the guaranteed bit-rate (GBR) provided by
the low-complexity sub-optimal RRA solutions proposed. Finally, we pro-
pose a quality-fair adaptive streaming solution to deliver fair video quality
to HAS clients in a LTE cell by adaptively selecting the prescribed (GBR)
of each user according to the video content in addition to the channel condi-
tion. Extensive numerical evaluations show the significant enhancements of
the proposed strategies with respect to other state-of-the-art frameworks
Cost based optimization for strategic mobile radio access network planning using metaheuristics
La evoluci贸n experimentada por las comunicaciones m贸viles a lo largo de las 煤ltimas
d茅cadas ha sido motivada por dos factores principales: el surgimiento de nuevas aplicaciones
y necesidades por parte del usuario, as铆 como los avances tecnol贸gicos. Los
servicios ofrecidos para t茅rminales m贸viles han evolucionado desde el cl谩sico servicio
de voz y mensajes cortos (SMS), a servicios m谩s atractivos y por lo tanto con una
r谩pida aceptaci贸n por parte de usuario final como, video telephony, video streaming,
online gaming, and the internet broadband access (MBAS). Todos estos nuevos servicios
se han convertido en una realidad gracias a los avances t茅cnologicos, avances
tales como nuevas t茅cnicas de acceso al medio compartido, nuevos esquemas de codificiaci贸n
y modulaci贸n de la informaci贸n intercambiada, sistemas de transmisi贸n y
recepci贸n basados en m煤ltiples antenas (MIMO), etc.
Un aspecto importante en esta evoluci贸n fue la liberaci贸n del sector a principios de
los a帽os 90, donde la funci贸n reguladora llevado a cabo por las autoridades regulatorias
nacionales (NRA) se ha antojado fundamental. Uno de los principales problemas
tratados por la NRA espc铆fica de cada naci贸n es la determinaci贸n de los costes por
servicios mayoristas, esto es los servicios entre operadores de servicios m贸villes, entre
los que cabe destacar el coste por terminaci贸n de llamada o de inteconexi贸n. El
servicio de interconexi贸n hace posible la comunicaci贸n de usuarios de diferente operadores,
as铆 como el acceso a la totalidad de servicios, incluso a aquellos no prestados
por un operador en concreto gracias al uso de una red perteneciente a otro operador,
por parte de todos los usuarios.
El objetivo principal de esta tesis es la minimizaci贸n de los costes de inversi贸n en
equipamiento de red, lo cual repercute en el establecimiento de las tarifas de interconexi贸n
como se ver谩 a lo largo de este trabajo. La consecuci贸n de dicho objetivo
se divide en dos partes: en primer lugar, el desarrollo de un conjunto de algoritmos
para el dimesionado 贸ptimo de una red de acceso radio (RAN) para un sistema de
comunicaciones m贸villes. En segundo lugar, el dise帽o y aplicaci贸n de algoritmos de
optimizaci贸n para la distribuci贸n 贸ptima de los servicios sobre el conjunto de tecnolog铆as
m贸viles existentes (OSDP).
El modulo de dise帽o de red proporciona cuatro algoritmos diferenciados encargados
del dimensionado y planificaci贸n de la red de acceso m贸vil. Estos algoritmos se aplican
en un entorno multi-tecnolog铆a, considerando sistemas de segunda (2G), tercera
(3G) y cuarta (4G) generaci贸n, multi-usuario, teniendo en cuenta diferentes perfiles
de usuarios con su respectiva carga de tr谩fico, y multo-servicio, incluyendo voz, servicios
de datos de baja velocidad (64-144 Kbps), y acceso a internet de banda ancha
m贸vil.
La segunda parte de la tesis se encarga de distribuir de una manera 贸ptima el conjunto
de servicios sobre las tecnolog铆as a desplegar. El objetivo de esta parte es
hacer un uso eficiente de las tecnolog铆as existentes reduciendo los costes de inversi贸n
en equipamiento de red. Esto es posible gracias a las diferencias tecnol贸gicas existente
entre los diferentes sistemas m贸viles, que hacen que los sistemas de segunda
generaci贸n sean adecuados para proporcionar el servicio de voz y mensajer铆a corta,
mientras que redes de tercera generaci贸n muestran un mejor rendimiento en la transmisi贸n
de servicios de datos. Por 煤ltimo, el servicio de banda ancha m贸vil es nativo
de redes de 煤ltima generad贸n, como High Speed Data Acces (HSPA) y 4G.
Ambos m贸dulos han sido aplicados a un extenso conjunto de experimentos para el
desarrollo de an谩lisis tecno-econ贸micos tales como el estudio del rendimiento de las
tecnolog铆as de HSPA y 4G para la prestaci贸n del servicio de banda ancha m贸vil, as铆
como el an谩lisis de escenarios reales de despliegue para redes 4G que tendr谩n lugar a
partir del pr贸ximo a帽o coinicidiendo con la licitaci贸n de las frecuencias en la banda
de 800 MHz. As铆 mismo, se ha llevado a cabo un estudio sobre el despliegue de redes
de 4G en las bandas de 800 MHz, 1800 MHz y 2600 MHz, comparando los costes
de inversi贸n obtenidos tras la optimizaci贸n. En todos los casos se ha demostrado
la mejora, en t茅rminos de costes de inversi贸n, obtenida tras la aplicaci贸n de ambos
m贸dulos, posibilitando una reducci贸n en la determinaci贸n de los costes de provisi贸n
de servicios.
Los estudios realizados en esta tesis se centran en la naci贸n de Espa帽a, sin embargo
todos los algoritmos implementados son aplicables a cualquier otro pa铆s europeo,
prueba de ello es que los algoritmos de dise帽o de red han sido utilizados en diversos
proyectos de regulaci贸n
Cost based optimization for strategic mobile radio access network planning using metaheuristics
La evoluci贸n experimentada por las comunicaciones m贸viles a lo largo de las 煤ltimas
d茅cadas ha sido motivada por dos factores principales: el surgimiento de nuevas aplicaciones
y necesidades por parte del usuario, as铆 como los avances tecnol贸gicos. Los
servicios ofrecidos para t茅rminales m贸viles han evolucionado desde el cl谩sico servicio
de voz y mensajes cortos (SMS), a servicios m谩s atractivos y por lo tanto con una
r谩pida aceptaci贸n por parte de usuario final como, video telephony, video streaming,
online gaming, and the internet broadband access (MBAS). Todos estos nuevos servicios
se han convertido en una realidad gracias a los avances t茅cnologicos, avances
tales como nuevas t茅cnicas de acceso al medio compartido, nuevos esquemas de codificiaci贸n
y modulaci贸n de la informaci贸n intercambiada, sistemas de transmisi贸n y
recepci贸n basados en m煤ltiples antenas (MIMO), etc.
Un aspecto importante en esta evoluci贸n fue la liberaci贸n del sector a principios de
los a帽os 90, donde la funci贸n reguladora llevado a cabo por las autoridades regulatorias
nacionales (NRA) se ha antojado fundamental. Uno de los principales problemas
tratados por la NRA espc铆fica de cada naci贸n es la determinaci贸n de los costes por
servicios mayoristas, esto es los servicios entre operadores de servicios m贸villes, entre
los que cabe destacar el coste por terminaci贸n de llamada o de inteconexi贸n. El
servicio de interconexi贸n hace posible la comunicaci贸n de usuarios de diferente operadores,
as铆 como el acceso a la totalidad de servicios, incluso a aquellos no prestados
por un operador en concreto gracias al uso de una red perteneciente a otro operador,
por parte de todos los usuarios.
El objetivo principal de esta tesis es la minimizaci贸n de los costes de inversi贸n en
equipamiento de red, lo cual repercute en el establecimiento de las tarifas de interconexi贸n
como se ver谩 a lo largo de este trabajo. La consecuci贸n de dicho objetivo
se divide en dos partes: en primer lugar, el desarrollo de un conjunto de algoritmos
para el dimesionado 贸ptimo de una red de acceso radio (RAN) para un sistema de
comunicaciones m贸villes. En segundo lugar, el dise帽o y aplicaci贸n de algoritmos de
optimizaci贸n para la distribuci贸n 贸ptima de los servicios sobre el conjunto de tecnolog铆as
m贸viles existentes (OSDP).
El modulo de dise帽o de red proporciona cuatro algoritmos diferenciados encargados
del dimensionado y planificaci贸n de la red de acceso m贸vil. Estos algoritmos se aplican
en un entorno multi-tecnolog铆a, considerando sistemas de segunda (2G), tercera
(3G) y cuarta (4G) generaci贸n, multi-usuario, teniendo en cuenta diferentes perfiles
de usuarios con su respectiva carga de tr谩fico, y multo-servicio, incluyendo voz, servicios
de datos de baja velocidad (64-144 Kbps), y acceso a internet de banda ancha
m贸vil.
La segunda parte de la tesis se encarga de distribuir de una manera 贸ptima el conjunto
de servicios sobre las tecnolog铆as a desplegar. El objetivo de esta parte es
hacer un uso eficiente de las tecnolog铆as existentes reduciendo los costes de inversi贸n
en equipamiento de red. Esto es posible gracias a las diferencias tecnol贸gicas existente
entre los diferentes sistemas m贸viles, que hacen que los sistemas de segunda
generaci贸n sean adecuados para proporcionar el servicio de voz y mensajer铆a corta,
mientras que redes de tercera generaci贸n muestran un mejor rendimiento en la transmisi贸n
de servicios de datos. Por 煤ltimo, el servicio de banda ancha m贸vil es nativo
de redes de 煤ltima generad贸n, como High Speed Data Acces (HSPA) y 4G.
Ambos m贸dulos han sido aplicados a un extenso conjunto de experimentos para el
desarrollo de an谩lisis tecno-econ贸micos tales como el estudio del rendimiento de las
tecnolog铆as de HSPA y 4G para la prestaci贸n del servicio de banda ancha m贸vil, as铆
como el an谩lisis de escenarios reales de despliegue para redes 4G que tendr谩n lugar a
partir del pr贸ximo a帽o coinicidiendo con la licitaci贸n de las frecuencias en la banda
de 800 MHz. As铆 mismo, se ha llevado a cabo un estudio sobre el despliegue de redes
de 4G en las bandas de 800 MHz, 1800 MHz y 2600 MHz, comparando los costes
de inversi贸n obtenidos tras la optimizaci贸n. En todos los casos se ha demostrado
la mejora, en t茅rminos de costes de inversi贸n, obtenida tras la aplicaci贸n de ambos
m贸dulos, posibilitando una reducci贸n en la determinaci贸n de los costes de provisi贸n
de servicios.
Los estudios realizados en esta tesis se centran en la naci贸n de Espa帽a, sin embargo
todos los algoritmos implementados son aplicables a cualquier otro pa铆s europeo,
prueba de ello es que los algoritmos de dise帽o de red han sido utilizados en diversos
proyectos de regulaci贸n
Real-time wireless networks for industrial control systems
The next generation of industrial systems (Industry 4.0) will dramatically transform manyproductive sectors, integrating emerging concepts such as Internet of Things, artificialintelligence, big data, cloud robotics and virtual reality, to name a few. Most of thesetechnologies heavily rely on the availability of communication networks able to offernearly鈥搃stantaneous, secure and reliable data transfer. In the industrial sector, these
tasks are nowadays mainly accomplished by wired networks, that combine the speed ofoptical fiber media with collision鈥揻ree switching technology.
However, driven by the pervasive deployment of mobile devices for personal com-munications in the last years, more and more industrial applications require wireless connectivity, which can bring enormous advantages in terms of cost reduction and flex-ibility. Designing timely, reliable and deterministic industrial wireless networks is a complicated task, due to the nature of the wireless channel, intrinsically error鈥損rone andshared among all the devices transmitting on the same frequency band.
In this thesis, several solutions to enhance the performance of wireless networks employed in industrial control applications are proposed. The presented approaches differ in terms of achieved performance and target applications, but they are all characterized by an improvement over existing industrial wireless solutions in terms of timeliness, reliability and determinism. When possible, an experimental validation of the designed
solutions is provided.
The obtained results prove that significant performance improvements are already possible, often using commercially available devices and preserving compliance to existing standards. Future research efforts, combined with the availability of new chipsets and
standards, could lead to a world where wireless links effectively replace most of the existing cables in industrial environments, as it is already the case in the consumer market
Mobile Ad-Hoc Networks
Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks
Recommended from our members
Measurement-Driven Algorithm and System Design for Wireless and Datacenter Networks
The growing number of mobile devices and data-intensive applications pose unique challenges for wireless access networks as well as datacenter networks that enable modern cloud-based services. With the enormous increase in volume and complexity of traffic from applications such as video streaming and cloud computing, the interconnection networks have become a major performance bottleneck. In this thesis, we study algorithms and architectures spanning several layers of the networking protocol stack that enable and accelerate novel applications and that are easily deployable and scalable. The design of these algorithms and architectures is motivated by measurements and observations in real world or experimental testbeds.
In the first part of this thesis, we address the challenge of wireless content delivery in crowded areas. We present the AMuSe system, whose objective is to enable scalable and adaptive WiFi multicast. AMuSe is based on accurate receiver feedback and incurs a small control overhead. This feedback information can be used by the multicast sender to optimize multicast service quality, e.g., by dynamically adjusting transmission bitrate. Specifically, we develop an algorithm for dynamic selection of a subset of the multicast receivers as feedback nodes which periodically send information about the channel quality to the multicast sender. Further, we describe the Multicast Dynamic Rate Adaptation (MuDRA) algorithm that utilizes AMuSe's feedback to optimally tune the physical layer multicast rate. MuDRA balances fast adaptation to channel conditions and stability, which is essential for multimedia applications.
We implemented the AMuSe system on the ORBIT testbed and evaluated its performance in large groups with approximately 200 WiFi nodes. Our extensive experiments demonstrate that AMuSe can provide accurate feedback in a dense multicast environment. It outperforms several alternatives even in the case of external interference and changing network conditions. Further, our experimental evaluation of MuDRA on the ORBIT testbed shows that MuDRA outperforms other schemes and supports high throughput multicast flows to hundreds of nodes while meeting quality requirements. As an example application, MuDRA can support multiple high quality video streams, where 90% of the nodes report excellent or very good video quality.
Next, we specifically focus on ensuring high Quality of Experience (QoE) for video streaming over WiFi multicast. We formulate the problem of joint adaptation of multicast transmission rate and video rate for ensuring high video QoE as a utility maximization problem and propose an online control algorithm called DYVR which is based on Lyapunov optimization techniques. We evaluated the performance of DYVR through analysis, simulations, and experiments using a testbed composed of Android devices and o the shelf APs. Our evaluation shows that DYVR can ensure high video rates while guaranteeing a low but acceptable number of segment losses, buffer underflows, and video rate switches.
We leverage the lessons learnt from AMuSe for WiFi to address the performance issues with LTE evolved Multimedia Broadcast/Multicast Service (eMBMS). We present the Dynamic Monitoring (DyMo) system which provides low-overhead and real-time feedback about eMBMS performance. DyMo employs eMBMS for broadcasting instructions which indicate the reporting rates as a function of the observed Quality of Service (QoS) for each UE. This simple feedback mechanism collects very limited QoS reports which can be used for network optimization. We evaluated the performance of DyMo analytically and via simulations. DyMo infers the optimal eMBMS settings with extremely low overhead, while meeting strict QoS requirements under different UE mobility patterns and presence of network component failures.
In the second part of the thesis, we study datacenter networks which are key enablers of the end-user applications such as video streaming and storage. Datacenter applications such as distributed file systems, one-to-many virtual machine migrations, and large-scale data processing involve bulk multicast flows. We propose a hardware and software system for enabling physical layer optical multicast in datacenter networks using passive optical splitters. We built a prototype and developed a simulation environment to evaluate the performance of the system for bulk multicasting. Our evaluation shows that the optical multicast architecture can achieve higher throughput and lower latency than IP multicast and peer-to-peer multicast schemes with lower switching energy consumption.
Finally, we study the problem of congestion control in datacenter networks. Quantized Congestion Control (QCN), a switch-supported standard, utilizes direct multi-bit feedback from the network for hardware rate limiting. Although QCN has been shown to be fast-reacting and effective, being a Layer-2 technology limits its adoption in IP-routed Layer 3 datacenters. We address several design challenges to overcome QCN feedback's Layer- 2 limitation and use it to design window-based congestion control (QCN-CC) and load balancing (QCN-LB) schemes. Our extensive simulations, based on real world workloads, demonstrate the advantages of explicit, multi-bit congestion feedback, especially in a typical environment where intra-datacenter traffic with short Round Trip Times (RTT: tens of s) run in conjunction with web-facing traffic with long RTTs (tens of milliseconds)
Radio and computing resource management in SDR clouds
The aim of this thesis is defining and developing the concept of an efficient management of radio and computing resources in an SDR cloud. The SDR cloud breaks with today's cellular architecture. A set of distributed antennas are connected by optical fibre to data processing centres. The radio and computing infrastructure can be shared between different operators (virtualization), reducing costs and risks, while increasing the capacity and creating new business models and opportunities.
The data centre centralizes the management of all system resources: antennas, spectrum, computing, routing, etc. Specially relevant is the computing resource management (CRM), whose objective is dynamically providing sufficient computing resources for a real-time execution of signal processing algorithms. Current CRM techniques are not designed for wireless applications. We demonstrate that this imposes a limit on the wireless traffic a CRM entity is capable to support. Based on this, a distributed management is proposed, where multiple CRM entities manage a cluster of processors, whose optimal size is derived from the traffic density.
Radio resource management techniques (RRM) also need to be adapted to the characteristics of the new SDR cloud architecture. We introduce a linear cost model to measure the cost associated to the infrastructure resources consumed according to the pay-per-use model. Based on this model, we formulate the efficiency maximization power allocation problem (EMPA). The operational costs per transmitted bit achieved by EMPA are 6 times lower than with traditional power allocation methods. Analytical solutions are obtained for the single channel case, with and without channel state information at the transmitter. It is shown that the optimal transmission rate is an increasing function of the product of the channel gain with the operational costs divided by the power costs.
The EMPA solution for multiple channels has the form of water-filling, present in many power allocation problems. In order to be able to obtain insights about how the optimal solution behaves as a function of the problem parameters, a novel technique based on ordered statistics has been developed. This technique allows solving general water-filling problems based on the channel statistics rather than their realization. This approach has allowed designing a low complexity EMPA algorithm (2 to 4 orders of magnitude faster than state-of-the-art algorithms).
Using the ordered statistics technique, we have shown that the optimal transmission rate behaviour with respect to the average channel gains and cost parameters is equivalent to the single channel case and that the efficiency increases with the number of available channels. The results can be applied to design more efficient SDR clouds. As an example, we have derived the optimal ratio of number of antennas per user that maximizes the efficiency. As new users enter and leave the network, this ratio should be kept constant, enabling and disabling antennas dynamically. This approach exploits the dynamism and elasticity provided by the SDR cloud.
In summary, this dissertation aims at influencing towards a change in the communications system management model (typically RRM), considering the introduction of the new infrastructure model (SDR cloud), new business models (based on Cloud Computing) and a more conciliatory view of an efficient resource management, not only focused on the optimization of the spectrum usage.El objetivo de esta tesis es de nir y desarrollar el concepto de gesti on e ciente de los recursos de radio y computaci on en un SDR cloud. El SDR cloud rompe con la estructura del sistema celular actual. Un conjunto de antenas distribuidas se conectan a centros de procesamiento mediante enlaces de comunicaci on de bra optica. La infraestructura de radio y procesamiento puede ser compartida entre distintos operadores (virtualizacion), disminuyendo costes y riesgos, aumentando la capacidad y abriendo nuevos modelos y oportunidades
de negocio.
La centralizaci on de la gesti on del sistema viene soportada por el centro de procesamiento, donde se realiza una gesti on de todos los recursos del sistema: antenas, espectro, computaci on, enrutado, etc. Resulta de especial relevancia la gesti on de los recursos de computaci on (CRM) cuyo objetivo es el de proveer, din amicamente, de su cientes recursos de computaci on para la ejecuci on en tiempo real de algoritmos de procesado del se帽al. Las t ecnicas actuales de CRM no han sido dise帽adas para aplicaciones de comunicaciones. Demostramos que esta caracter stica impone un l 铆mite en el tr 谩fi co que un gestor CRM puede soportar. En base a ello, proponemos una gesti on distribuida donde m ultiples entidades CRM gestionan grupos de procesadores, cuyo tama帽o optimo se deriva de la densidad de tr 谩fi co.
Las t ecnicas actuales de gesti on de recursos radio (RRM) tambi en deben ser adaptadas a las caracter sticas de la nueva arquitectura SDR cloud. Introducimos un modelo de coste lineal que caracteriza los costes asociados al consumo de recursos de la infraestructura seg un el modelo de pago-por-uso. A partir de este modelo, formulamos el problema de asignaci on de potencia de m axima e ciencia (EMPA). Mediante una asignaci on EMPA, los costes de operaci on por bit transmitido son del orden de 6 veces menores que con los m etodos tradicionales.
Se han obtenido soluciones anal ticas para el caso de un solo canal, con y sin informacion del canal disponible en el transmisor, y se ha demostrado que la velocidad optima de transmisi on es una funci on creciente del producto de la ganancia del canal por los costes operativos dividido entre los costes de potencia.
La soluci on EMPA para varios canales satisface el modelo "water- lling", presente en muchos tipos de optimizaci on de potencia. Con el objetivo de conocer c omo esta se comporta en funci on de los par ametros del sistema, se ha desarrollado una t ecnica nueva basada en estad铆 sticas ordenadas. Esta t ecnica permite solucionar el problema del water- lling bas andose en la estad铆 stica del canal en vez de en su realizaci on. Este planteamiento, despu es de profundos an alisis matem aticos, ha permitido desarrollar un algoritmo de asignaci on de potencia de baja complejidad (2 a 4 ordenes de magnitud m as r apido que el estado del arte).
Mediante esta t ecnica, se ha demostrado que la velocidad optima de transmisi on se comporta de forma equivalente al caso de un solo canal y que la e ciencia incrementa a medida que aumentan el numero de canales disponibles. Estos resultados pueden aplicarse a dise帽ar un SDR cloud de forma m as e ciente. A modo de ejemplo, hemos obtenido el ratio optimo de n umero de antenas por usuario que maximiza la e ciencia. A medida que los usuarios entran y salen de la red, este ratio debe mantenerse constante, a fin de mantener una efi ciencia lo m as alta posible, activando o desactivando antenas din amicamente. De esta forma se explota completamente el dinamismo ofrecido por una arquitectura el astica como el SDR cloud.
En de nitiva, este trabajo pretende incidir en un cambio del modelo de gesti on de un sistema de comunicaciones (t 铆picamente RRM) habida cuenta de la introducci on de una nueva infraestructura (SDR cloud), nuevos modelos de negocio (basados en Cloud Computing) y una visi on m as integradora de la gesti on e ciente de los recursos del sistema, no solo centrada en la optimizaci on del uso del espectro